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Understanding the foundations of the neurobiology of behavior and well-being can help us better achieve animal welfare. Behavior is the expression of several physiological, endocrine, motor and emotional responses that are coordinated by... more
Understanding the foundations of the neurobiology of behavior and well-being can help us better achieve animal welfare. Behavior is the expression of several physiological, endocrine, motor and emotional responses that are coordinated by the central nervous system from the processing of internal and external stimuli. In mammals, seven basic emotional systems have been described that when activated by the right stimuli evoke positive or negative innate responses that evolved to facilitate biological fitness. This review describes the process of how those neurobiological systems can directly influence animal welfare. We also describe examples of the interaction between primary (innate) and secondary (learned) processes that influence behavior.
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In all species, sexual behavior is directed by a complex interplay between steroid hormone actions in the brain that give rise to sexual arousability and experience with sexual reward that gives rise to expectations of competent sexual... more
In all species, sexual behavior is directed by a complex interplay between steroid hormone actions in the brain that give rise to sexual arousability and experience with sexual reward that gives rise to expectations of competent sexual activity, including sexual arousal, desire, and performance. Sexual experience allows animals to form instrumental and Pavlovian associations that predict sexual outcome and thereby directs the strength of sexual responding. Although the study of animal sexual behavior by neuroendocrinologists has traditionally been concerned with mechanisms of copulatory responding, more recent use of conditioning and preference paradigms, and a focus on environmental circumstances and experience, has revealed behaviors and processes that resemble human sexual responses. In this paper, we review behavioral paradigms used with rodents and other species that are analogous or homologous to human sexual arousal, desire, reward, and inhibition. The extent to which these b...
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The effects of stimulating environments on the neural plasticity of the adult brain have been well explored; however, how an enriched environment (EE) affects the mother-fetus interaction is poorly understood. We hypothesized that an... more
The effects of stimulating environments on the neural plasticity of the adult brain have been well explored; however, how an enriched environment (EE) affects the mother-fetus interaction is poorly understood. We hypothesized that an enriched environment restricted to pregnancy will succeed in accelerating the development of sensory and motor circuits in the offspring. Pregnant Wistar rats were maintained either under a standard condition - two animals per standard cage- or an enriched environment - eight subjects in larger cages with different physical configurations-. After birth, litters from both groups (n=16 per group) were cross-fostered with mothers that were simultaneously maintained under standard environment during pregnancy. Sensory and motor development were studied in the pups of both groups with a battery of reflex and physical tests. Auditory and gait reflexes appeared two days earlier in the offspring of EE rats as compared to control subjects (p<0.05). In addition, EE pups displayed a better performance in righting reflex, inclined board and geotaxis tests (p<0.05). Differences were found even three weeks after birth. We conclude that EE limited to the phase of pregnancy stimulates the development of pups inutero so that they are born with a higher grade of development.
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Conditioned same-sex partner preference can develop in male rats that undergo cohabitation under the effects of quinpirole (QNP, D2 agonist). Herein, we assessed the development of conditioned same-sex social/sexual preference in males... more
Conditioned same-sex partner preference can develop in male rats that undergo cohabitation under the effects of quinpirole (QNP, D2 agonist). Herein, we assessed the development of conditioned same-sex social/sexual preference in males that received either nothing, saline, QNP, oxytocin (OT), or QNP+OT during cohabitation with another male (+) or single-caged (-). This resulted in the following groups: (1) Intact-, (2) Saline+, (3) QNP-, (4) OT-, (5) QNP+, (6) OT+ and (7) QNP/OT+. Cohabitation occurred during 24h in a clean cage with a male partner that bore almond scent on the back as conditioned stimulus. This was repeated every 4 days for a total of three trials. Social and sexual preference were assessed four days after the last conditioning trial in a drug-free test in which experimental males chose between the scented familiar male and a novel sexually receptive female. Results showed that males from groups Intact-, Saline+, QNP- and OT- displayed a clear preference for the female (opposite-sex), whereas groups QNP+, OT+ and QNP/OT+ displayed socio/sexual preference for the male partner (same-sex). In Experiment 2, the brains were processed for Nissl dye and the area size of two sexually dimorphic nuclei (SDN-POA and SON) was compared between groups. Males from groups OT-, OT+ and QNP/OT+ expressed a smaller SDN-POA and groups QNP+ and QNP/OT+ expressed a larger SON. Accordingly, conditioned same-sex social/sexual partner preference can develop during cohabitation under enhanced D2 or OT activity but such preference does not depend on the area size of those sexually dimorphic nuclei.
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tested for sexual behavior every 4 days during 30-minute test sessions, for a total of five tests. On the day after the fifth sexual behavior test, capsules were removed and new capsules were implanted as described above and left in place... more
tested for sexual behavior every 4 days during 30-minute test sessions, for a total of five tests. On the day after the fifth sexual behavior test, capsules were removed and new capsules were implanted as described above and left in place for 20 days. Females were again tested every 4 days, for a total of five sexual behavior tests. During the second 20-day period, in addition to the testosterone capsule, each rat also received a subcutaneous injection of estradiol xylazine hydrochloride (4 mg/ml) mixed at a ratio of 4:3 and injected intraperitoneally in a volume of 1 ml per kg body weight. A small skin incision was made, the capsule was inserted subcutaneously on the back of the neck between the shoulder blades, and the incision was sutured shut. Postsurgical treatment consisted of local triple antibiotic ointment applied to the incision site.The capsules remained implanted for 20 days, during which time females were A group of 40 Wistar female rats was obtained from Charles River Canada (St-Constant, Quebec, Canada) and used to study the effects of hormone replacement on the sexual behavior of aged female rats. The animals were housed in pairs in plexiglas shoebox cages with beta chip as bedding, in a room maintained on a 12-h:12-h light:dark reverse light cycle (lights off at 8:00 AM), with water and commercial rat feed available
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Female sexual behavior is sensitive to stress and diseases. Some studies have shown that status epilepticus (SE) can affect sexual proceptivity and receptivity in female rats and also increases reject responses towards males. However,... more
Female sexual behavior is sensitive to stress and diseases. Some studies have shown that status epilepticus (SE) can affect sexual proceptivity and receptivity in female rats and also increases reject responses towards males. However, epidemiologic studies indicate that SE is more frequent in young individuals. Herein, we assessed the effects of SE in infant females on their sexual behavior during adulthood. Thirteen-day-old (P13) rat pups received intraperitoneal injections of lithium chloride (3 mEq/kg). Twenty hours later, at P14, SE was induced by subcutaneous injection of pilocarpine hydrochloride (100 mg/kg s.c.). Control animals were given an equal volume of saline subcutaneously. The animals were weaned at P21 and, later in adulthood, were ovariectomized and hormone-primed with estradiol+progesterone, and their sexual behavior assessed during 4 separate trials of 30 min each with a stud male. Our results indicate that proceptive behaviors (solicitations and hops and darts) were impaired during the first trial, but no alterations were observed for receptivity and attractivity. By trial 3, all SE females displayed normal proceptivity. These results indicate that SE in infancy readily affects proceptivity in a reversible manner. We discuss the role of sexual experience in recovery.
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Female rats display a conditioned partner preference for males that bear odors paired with different types of rewarding unconditioned stimuli (UCS). Here we examined whether tickling constitutes a rewarding UCS that supports the... more
Female rats display a conditioned partner preference for males that bear odors paired with different types of rewarding unconditioned stimuli (UCS). Here we examined whether tickling constitutes a rewarding UCS that supports the development of partner preferences. In Experiment 1, we tested the possibility that odors associated with a tickling UCS in prepubescent rats would induce a conditioned partner preference in adulthood. Two groups were formed with 31-day-old, single-housed females, tickled for 6 min daily for 10 days, by a hand that wore a scented glove (almond or lemon). At 47 days of age, females were ovariectomized (OVX), hormone-primed (EB+P), and tested for sexual partner preference with two scented stud males (one almond and one lemon). In each group, females displayed a sexual preference toward males bearing the odor paired with tickling, as observed with longer visits, more solicitations, hops & darts, and receiving more intromissions and ejaculations from the preferred male. In Experiment 2, we used 3-month old, OVX, hormone-primed rats conditioned every 4 days for 10 trials. In contrast to juvenile females, adult females failed to prefer males that bore the odor paired with tickling but instead preferred the novel male. These results suggest that tickling has opposite age-dependent effects in the conditioning of partner preference. Tickling in juvenile females appears to act as a rewarding UCS, whereas in adult females it may act as an aversive UCS. Further research is needed to understand brain mechanisms that might account for such differences.
Research Interests: Psychology, Aging, Medicine, Biological Sciences, Female, and 15 moreAnimals, Male, Reaction Time, Odors, Rats, Analysis of Variance, Conditioning, Operant Conditioning, Sexual Partners, Choice Behavior, Fluoroquinolones, Ovariectomy, Sex Characteristics, Psychology and Cognitive Sciences, and Medical and Health Sciences
Hypersexuality may be a symptom secondary to the treatment of Parkinson Disease (PD) and it is part of the disturbances of impulse control reported, ranging from 20-50% of the patients under PD treatment. Herein we review the... more
Hypersexuality may be a symptom secondary to the treatment of Parkinson Disease (PD) and it is part of the disturbances of impulse control reported, ranging from 20-50% of the patients under PD treatment. Herein we review the neurobiological evidence behind the hypersexuality observed during treatment with L-DOPA or dopaminergic agonists. A search was performed with the terms “Parkinson”, “Hypersexuality”, “Dopamine”, “Noradrenaline”, “L-DOPA”, “Brain”, “Impulse Control Disorders”, “Neurobiology”, in the scientific data bases PubMed, sciELO and Science Direct. PD is characterized by a progressive loss of dopaminergic neurons in the compact part of the substantia nigra projecting to the striatum, which disrupts the motor ability. Like 50 years ago the current treatment for PD includes the use of drugs that increase the availability of dopamine and other amines such as noradrenaline. Systemic treatment with L-DOPA or specific agonists increase the activity of these amines even in brai...
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AIM To analyse the biological and neural bases of partner preference formation in rodents as models to understand human pair bonding. DEVELOPMENT Rodents are social individuals, capable of forming short- or long-lasting partner... more
AIM To analyse the biological and neural bases of partner preference formation in rodents as models to understand human pair bonding. DEVELOPMENT Rodents are social individuals, capable of forming short- or long-lasting partner preferences that develop slowly by stimuli like cohabitation, or rapidly by stimuli like sex and stress. Dopamine, corticosteroids, oxytocin, vasopressin, and opioids form the neurochemical substrate for pair bonding in areas like the nucleus accumbens, the prefrontal cortex, the piriform cortex, the medial preoptic area, the ventral tegmental area and the medial amygdala, among others. Additional areas may participate depending on the nature of the conditioned stimuli by which and individual recognizes a preferred partner. CONCLUSIONS Animal models help us understand that the capacity of an individual to display long-lasting and selective preferences depends on neural bases, selected throughout evolution. The challenge in neuroscience is to use this knowledg...
Research Interests: Medicine, Rodentia, Brain, Female, Animals, and 4 moreMale, Behavioral Animal Models, Coitus, and Object Attachment
Animal welfare is commonly regarded as the physical and psychological well-being of animals, fulfilled if animals are free: 1) from hunger, thirst and malnutrition, 2) from discomfort, 3) from pain, 4) to express normal behavior, and 5)... more
Animal welfare is commonly regarded as the physical and psychological well-being of animals, fulfilled if animals are free: 1) from hunger, thirst and malnutrition, 2) from discomfort, 3) from pain, 4) to express normal behavior, and 5) from fear and distress. This paper is meant to provoke the reader to re-think the concept of welfare. Evidence indicates that animal welfare is not a constant state, but rather it must be fulfilled several times a day. A theory is proposed arguing that well-being occurs when the proportion of desiring and obtaining something occurs in a 80-20% proportion, respectively. The neurobiological bases of motivated behaviors are discussed to support a new view on animal welfare.
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Animal training is meant to teach specific behavioral responses to specific cues. Clicker training (CT) is a popular training method based on the use of a device that emits a sound of double-click to be associated as a first-order... more
Animal training is meant to teach specific behavioral responses to specific cues. Clicker training (CT) is a popular training method based on the use of a device that emits a sound of double-click to be associated as a first-order conditioned stimulus in contingency with positive reinforcements. After some repetitions, the clicker sound gains some incentive value and can be paired with the desired behavior. Animal trainers believed that CT can decrease training time compared to other types of training. Herein, we used two-month old miniature piglets to evaluate whether CT decreased the number of repetitions required to learn complex behaviors as compared with animals trained with voice instead of the clicker. In addition, we compared the number of correct choices of animals from both groups when exposed to object discriminative tests. Results indicated that CT decreased the number of repetitions required for pigs to learn to fetch an object but reduced the ability of animals to make...
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Dogs in shelters may be unattended at night. The purpose of this study is to describe the night-time behavior of dogs in a shelter and to determine if artificial light affected their sleeping patterns. Ten dogs were video-recorded under... more
Dogs in shelters may be unattended at night. The purpose of this study is to describe the night-time behavior of dogs in a shelter and to determine if artificial light affected their sleeping patterns. Ten dogs were video-recorded under both light and dark conditions and their behavior recorded using focal animal sampling. The dogs were lying down 649 ± 40 min (mean ± SD) in the light condition and 629 ± 58 min in the dark condition each night. They awoke, stood up, turned around and then lay down again every 48 to 50 min. There was no significant difference in time spent lying between the two conditions (p > 0.05). Light did not seem to affect their behavior. The conclusion is that dogs in shelters may sleep in the absence of people and that light does not disrupt their sleep patterns.
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Stress during puberty and obesity can represent conditions that facilitate the long-term development of diseases, especially for stress-related disorders that depend on neuroendocrine and immune responses. The prostate is prone to... more
Stress during puberty and obesity can represent conditions that facilitate the long-term development of diseases, especially for stress-related disorders that depend on neuroendocrine and immune responses. The prostate is prone to diseases that result from neuroendocrine or immune challenges, such as cancer. AIM In the present study, we assessed the long-term effects of an acute pubertal stressor (immune-challenge) or obesity on the development of precancerous lesions in rats. MATERIALS AND METHODS Pubertal male rats received a single injection of lipopolysaccharide (LPS) or saline during puberty (5 weeks of age). In adulthood (8 weeks old), subgroups of males were fed with hypercaloric liquid diet to induce obesity. This resulted in a total of six subgroups: (1) intact-non obese, (2) intact-obese, (3) saline-non obese, (4) saline-obese, (5) LPS-non obese, and (6) LPS-obese. At 16 weeks of age the rats were sacrified for prostate histology (hematoxylin and eosin stain) and hormone analysis (testosterone, corticosterone and prolactin). RESULTS As compared to intact-non obese rats, males treated with LPS and those with obesity expressed histological alterations in both the dorsolateral and ventral portions of the prostate. Only prolactin was altered in LPS-treated males, whereas corticosterone was altered in LPS-obese rats. CONCLUSIONS These results indicate that puberal exposure to an immune challenge or obesity facilitate the development of prostatic lesions in adult male rats. We discuss the role of hormones in the development of precancerous lesions.
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The neuropeptides oxytocin (OT) and vasopressin (AVP) are critical in the formation of pair bonding in the vole, and potentially in other species. The finding that normally promiscuous male rats display a conditioned ejaculatory... more
The neuropeptides oxytocin (OT) and vasopressin (AVP) are critical in the formation of pair bonding in the vole, and potentially in other species. The finding that normally promiscuous male rats display a conditioned ejaculatory preference (CEP) for females that bear an odor paired with the sexual reward state induced by ejaculation prompted us to examine whether similar mechanisms may mediate this rudiment of pair bonding. Sexually naïve Long-Evans male rats were given 9 multi-ejaculatory copulation trials at 4-day intervals with either almond-scented (paired) or unscented (unpaired) sexually receptive females. CEP was examined in an open field, in which each male had unrestricted access to two receptive females, one scented with almond and the other unscented. Males in both groups were given two reconditioning trials and presented with the almond odor on gauze for 1 h prior to sacrifice. Neuronal activation was assessed by immunohistochemical detection of Fos protein within OT or AVP neurons. Exposure to the odor induced significantly greater activation of OT neurons in parvocellular neurons of the paraventricular nucleus (PVN) and of AVP in magnocellular neurons of the supraoptic nucleus (SON) in the paired group compared to the unpaired group. The second experiment examined whether oxytocin or vasopressin could enhance the acquisition of a CEP. Sexually naïve male Long-Evans rats received a subcutaneous injection of OT, AVP, or the saline vehicle, prior to their first sexual experience with an almond-scented female. CEP was examined 4 days later in the open field. Males injected with OT, but not AVP or saline, displayed significant CEP. The selective activation of OT neurons by the conditioned odor in the paired group, and the ability of OT injections to enhance the association of the odor and sexual reward, indicates that enhanced OT transmission is critical in the formation of CEP in male rats.
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Purpose of ReviewThe aim of this review is to provide current evidence on the biological and psychological mechanisms that underlie sexual partner preferences (SPP) in humans and animals.Recent FindingsSPP depend mainly on prenatal... more
Purpose of ReviewThe aim of this review is to provide current evidence on the biological and psychological mechanisms that underlie sexual partner preferences (SPP) in humans and animals.Recent FindingsSPP depend mainly on prenatal (adaptive) organization of the brain, but can be drastically modified via learning under enhanced dopaminergic (DA) and oxytocinergic (OT) activity.SummarySPP can be categorized as in those directed towards partners who display indicators of biological fitness (IBF) or towards partners who do not show those indicators. The IBF function as unconditioned stimuli that presumably activate prenatally organized brain areas that mediate the salience of those stimuli. However, we discuss some evidence indicating that SPP not directed towards IBF (i.e., paraphilias) might be consequence of a learning process that occurs under enhanced DA or OT activity, resulting in new powerful learning with additional brain areas involved.
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The prostate is an exocrine reproductive gland that participates in ejaculation and it is prone to diseases, including cancer. Aim: In the present study, we assessed the longterm effects of copulation on the development of precancerous... more
The prostate is an exocrine reproductive gland that participates in ejaculation and it is prone to diseases, including cancer. Aim: In the present study, we assessed the longterm effects of copulation on the development of precancerous lesions in rats, and compared them with testosteroneinduced prostatic lesions. Materials and Methods: One group of Wistar males was given 10 copulatory sessions to one ejaculation with ovariectomized, hormoneprimed females. Sessions occurred twice per week for a total of ten trials. A second group was exposed to females during the same trials, but physical contact was prevented. In addition, each group received a subcutaneous implant in the back either filled with testosterone propionate (T, 100 mg/kg) or empty. This resulted in four subgroups: 1) Control + No sex, 2) Control + Sex, 3) T + No sex and 4) T + Sex. Two days after the 10th trial all the males were sacrificed for prostate histo logy (H&E) and hormone analysis (testosterone and prolactin...
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Puberty can be a critical period for the long-term development of diseases, especially for stress-related disorders that depend on neuroendocrine and immune responses. Some organs like the prostate are prone to diseases that result from... more
Puberty can be a critical period for the long-term development of diseases, especially for stress-related disorders that depend on neuroendocrine and immune responses. Some organs like the prostate are prone to diseases that result from neuroendocrine or immune challenges, such as cancer. Aim: In the present study, we assessed the long-term effects of an acute pubertal stressor (immune-challenge) on the development of precancerous lesions in adult rats, and compared them with testosterone-induced prostatic lesions. Materials and Methods: Pubertal male rats received a single injection of lipopolysaccharide (LPS) or saline during puberty (5 weeks old). At adulthood (8 weeks old) males were subcutaneously implanted with either an empty capsule or filled with testosterone propionate (100 mg/kg). This resulted in a total of five groups: 1) intact untreated, 2) saline-treated and implanted with a blank capsule, 3) saline-treated and implanted with a testosterone capsule, 4) LPS-treated an...
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The cerebellum is a structure of the central nervous system which has been previously studied with different techniques and animal models and even humans, so it is associated with multiple functions such as cognition, memory, emotional... more
The cerebellum is a structure of the central nervous system which has been previously studied with different techniques and animal models and even humans, so it is associated with multiple functions such as cognition, memory, emotional processing, balance, control of movement, among others. Its relationship with sensory systems has already been explored, however, the role it plays in olfactory processing in the cerebellum is unclear. Several hypotheses have been proposed from work done in humans and animal models with neuroimaging and immunohistochemical techniques. Everything seems to indicate that the cerebellar function is of vital importance for the olfactory perception, being able to be controlling not only the olfactory aspect, but also the olfactory processing. In this study we analyzed the multiunit activity in the granular layer of the cerebellar vermis during olfactory stimulation: a session being sexually naive and during four sessions of sexual behavior learning. The amp...
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Sexual preferences can be strongly modified by Pavlovian learning. For instance, olfactory conditioned same-sex partner preference can occur when a sexually naïve male cohabits with an scented male during repeated periods under the... more
Sexual preferences can be strongly modified by Pavlovian learning. For instance, olfactory conditioned same-sex partner preference can occur when a sexually naïve male cohabits with an scented male during repeated periods under the effects of enhanced D2-type activity. Preference is observed days later via social and sexual behaviors. Herein we explored brain activity related to learned same-sex preference (Fos-Immunoreactivity, IR) following exposure to a conditioned odor paired with same-sex preference. During conditioning trials males received either saline or the D2-type receptor agonist quinpirole (QNP) and cohabitated during 24 h with a stimulus male that bore almond scent on the back as conditioned stimulus. This was repeated every 4 days, for a total of three trials. In a drug-free final test we assessed socio/sexual partner preference between the scented male and a receptive female. The results indicated that QNP-conditioned males developed a same-sex preference observed vi...
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The cerebellum is a complex structure mainly recognized for its participation in motor activity and balance, and less understood for its role in olfactory processing. Herein, we assessed Fos immunoreactivity (Fos-IR) in the cerebellar... more
The cerebellum is a complex structure mainly recognized for its participation in motor activity and balance, and less understood for its role in olfactory processing. Herein, we assessed Fos immunoreactivity (Fos-IR) in the cerebellar vermis following exposure to different odors during sexual training in male rats. Males were allowed to copulate for either one, three or five sessions. One day after the corresponding session they were exposed during 60 min to woodshaving that was either: clean (Control), sprayed with almond scent (Alm) or from cages of sexually receptive females (RF). The vermis of the cerebellum was removed, cut in sagittal sections and analyzed for Fos-IR to infer activation. Our results showed that the cerebellum responded with more Fos-IR in the Alm and RF groups as compared to Control. More copulatory sessions resulted in more odor-induced Fos-IR, especially in the RF group. Accordingly, we discuss possible mechanisms on how the cerebellum mediates processing of...
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Cortical motor areas are influenced not only by peripheral sensory afferents and prefrontal association areas, but also by the basal ganglia, specifically the striatum. The dorsomedial striatum (DMS) and dorsolateral striatum are involved... more
Cortical motor areas are influenced not only by peripheral sensory afferents and prefrontal association areas, but also by the basal ganglia, specifically the striatum. The dorsomedial striatum (DMS) and dorsolateral striatum are involved in both spatial and stimulus-response learning; however, each of these areas may mediate different components of learning. The aim of the study is to determine the effect of electrolytic lesion to the DMS on the learning and performance of sexual behaviour and locomotor activity in male rats. Once the subjects had learned to perform motor tests of balance, maze navigation, ramp ascent, and sexual behaviour, they underwent electrolytic lesion to the DMS. Five days later, the tests were repeated on 2 occasions and researchers compared performance latencies for each test. Average latency values for performance on the maze and balance tests were higher after the lesion. However, the average values for the ramp test and for sexual behaviour did not differ between groups. Electrolytic lesion of the DMS modifies the performance of locomotor activity (maze test and balance), but not of sexual behaviour.
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Resumen Introducción: Existe evidencia para pensar que la presencia e interacción con perros produce efectos benéficos en la salud y bienestar de niños con trastorno espectro autista (TEA) y sus familias. Objetivo: Difundir y discutir el... more
Resumen Introducción: Existe evidencia para pensar que la presencia e interacción con perros produce efectos benéficos en la salud y bienestar de niños con trastorno espectro autista (TEA) y sus familias. Objetivo: Difundir y discutir el uso de los perros en el tratamiento del TEA, su efecto catalizador en las terapias, salud y vida de quien lo padece, y presentar algunas hipótesis que podrían explicar este fenómeno. Desarrollo: Las personas con TEA se caracterizan por una alteración en su capacidad comunicativa y social, así como por la presencia de conductas repetitivas y estereotipadas. Se ha visto que la incorporación de un perro en sus terapias incrementa la aparición de conductas sociales y potencializa los efectos de la misma. Así mismo, el uso de perros de servicio en las actividades diarias de niños con TEA parece mejorar la percepción de bienestar y seguridad de sus familias, y facilitar la realización de actividades en áreas públicas. Conclusiones: La evidencia y teorías ...
Evidence indicates that prolactin plays a crucial role in the normal function and development of the prostate, but abnormal high levels of the hormone are associated with hyperplasia and cancer of the gland. The present study was designed... more
Evidence indicates that prolactin plays a crucial role in the normal function and development of the prostate, but abnormal high levels of the hormone are associated with hyperplasia and cancer of the gland. The present study was designed to describe the progressive specific histological abnormalities in the prostate of rats with chronic hyperprolactinemia. Prolactin was administered during 4; 12 or 24 weeks, and the resulting prostatic alterations were compared with control rats, and also with those treated with testosterone, or the combination of prolactin + testosterone. Rats treated with prolactin, testosterone or prolactin + testosterone expressed precancerous histological abnormalities in the dorsolateral and ventral portions of the prostate as early as in 4 weeks of treatment, but in all cases the malignancy increased after 12 or 24 weeks of treatment. Our study confirms that chronic hyperprolactinemia is a cause of prostate precancerous pathologies.
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To compare the behavioral and neural bases of conditioned preferences induced by drugs and sex in animal models. Sex- and drug-induced preferences have certain commonalities. For example, sex and drug reward can induce the development of... more
To compare the behavioral and neural bases of conditioned preferences induced by drugs and sex in animal models. Sex- and drug-induced preferences have certain commonalities. For example, sex and drug reward can induce the development of new preferences, leading to the idea that the partner preferences that develop after sexual encounters and drug consumption are, in part, consequences of classical conditioning. Both phenomena depend on the activity of mesolimbic areas, and neurotransmitters such as dopamine, opioids and oxytocin. Agonists for these neurotransmitters facilitate conditioned preferences in the absence of sex and drug reward, whereas antagonists disrupt them even after sex or drug consumption. This review adds evidence to the idea that conditioned preferences induced by drugs use similar neural systems as those that evolved to sense and learn about natural rewards like sex.
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To analyse the biological and neural bases of partner preference formation in rodents as models to understand human pair bonding. Rodents are social individuals, capable of forming short- or long-lasting partner preferences that develop... more
To analyse the biological and neural bases of partner preference formation in rodents as models to understand human pair bonding. Rodents are social individuals, capable of forming short- or long-lasting partner preferences that develop slowly by stimuli like cohabitation, or rapidly by stimuli like sex and stress. Dopamine, corticosteroids, oxytocin, vasopressin, and opioids form the neurochemical substrate for pair bonding in areas like the nucleus accumbens, the prefrontal cortex, the piriform cortex, the medial preoptic area, the ventral tegmental area and the medial amygdala, among others. Additional areas may participate depending on the nature of the conditioned stimuli by which and individual recognizes a preferred partner. Animal models help us understand that the capacity of an individual to display long-lasting and selective preferences depends on neural bases, selected throughout evolution. The challenge in neuroscience is to use this knowledge to create new solutions for mental problems associated with the incapacity of an individual to display a social bond, keep one, or cope with the disruption of a consolidated one.
Research Interests: Medicine, Rodentia, Brain, Female, Animals, and 4 moreMale, Behavioral Animal Models, Coitus, and Object Attachment
The cerebellum has been linked to multiple functions, such as motor control, cognition, memory, and emotional processing. As for its involvement in the sensory systems, the role of the cerebellum in the sense of smell remains unclear. We... more
The cerebellum has been linked to multiple functions, such as motor control, cognition, memory, and emotional processing. As for its involvement in the sensory systems, the role of the cerebellum in the sense of smell remains unclear. We suggest that sexually naive male rats will present increased neuronal activity in the cerebellar vermis after being stimulated with almond odour or oestrous odour from receptive females. We compared activity in the cerebellar vermis using Fos immunoreactivity after olfactory stimulation. Stimulation took place during 60min in a cube-shaped acrylic chamber with a double bottom. Stimuli were clean woodchip bedding, bedding with almond extract, and bedding taken from a cage of receptive females. Male rats were subsequently anaesthetised with intraperitoneal sodium pentobarbital. Cerebellar tissue was fixed with paraformaldehyde for later immunohistochemical analysis. The number of Fos immunoreactive cells in all lobes of the cerebellar vermis was similar between groups stimulated with almond extract and with oestrous odour, and higher than in the clean woodchip group. Stimulation of the main olfactory system (almond) and the accessory system (oestrous odour) increases Fos protein production in the granular layer of the cortex of the cerebellar vermis in naive male rats.
Research Interests: Immunohistochemistry, Cerebellum, Female, Animals, Smell, and 6 moreMale, Neurons, Rats, Olfactory Bulb, Wistar Rats, and Neurología
We have previously shown that reward experienced during social play at juvenile age can be paired with artificial odors, and later in adulthood facilitate olfactory conditioned partner preferences (PP) in female rats. Herein, we examined... more
We have previously shown that reward experienced during social play at juvenile age can be paired with artificial odors, and later in adulthood facilitate olfactory conditioned partner preferences (PP) in female rats. Herein, we examined the expression of FOS immunoreactivity (FOS-IR) following exposure to the odor paired with juvenile play (CS+). Starting at day P31 females received daily 30-min periods of social play with lemon-scented (paired group) or unscented females (unpaired group). At day P42, they were tested for play-PP with two juvenile males, one bearing the CS+ (lemon) and one bearing a novel odor (almond). Females were ovariectomized, hormone-primed and at day P55 tested for sexual-PP between two adult stud males scented with lemon or almond. In both tests, females from the paired group displayed conditioned PP (play or sexual) toward males bearing the CS+. In the present experiments females were exposed at day P59 to the CS+ during 60 min and their brains processed for FOS-IR. One group of female rats (Play+Sex) underwent play-PP and sexual-PP, whereas a second group of females (Play-only) underwent exclusively play-PP but not sexual-PP. Results showed that in the Play-only experiment exposure to the CS+ induced more FOS-IR in the medial prefrontal cortex, orbitofrontal cortex, dorsal striatum, and ventral tegmental area as compared to females from the unpaired group. In the Play+Sex experiment, more FOS-IR was observed in the piriform cortex, dorsal striatum, lateral septum, nucleus accumbens shell, bed nucleus of the stria terminalis and medial amygdala as compared to females from the unpaired group. Taken together, these results indicate mesocorticolimbic brain areas direct the expectation and/or choice of conditioned partners in female rats. In addition, transferring the meaning of play to sex preference requires different brain areas.
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The suggestion of an anatomical and functional relationship between the basal ganglia and cerebellum is recent. Traditionally, these structures were considered as neuronal circuits working separately to organize and control goal-directed... more
The suggestion of an anatomical and functional relationship between the basal ganglia and cerebellum is recent. Traditionally, these structures were considered as neuronal circuits working separately to organize and control goal-directed movements and cognitive functions. However, several studies in rodents and primates have described an anatomical interaction between cortico-basal and cortico-cerebellar networks. Most importantly, functional changes have been observed in one of these circuits when altering the other one. In this context, we aimed to accomplish an extensive description of cerebellar activation patterns using cFOS expression (cFOS-IR) after acute and chronic manipulation of dopaminergic activity. In the acute study, substantia nigra pars compacta (SNc) activity was stimulated or suppressed by intra cerebral administration of picrotoxin or lidocaine, respectively. In addition, we analyzed cerebellar activity after the induction of a parkinsonism model, the tremulous jaw movements. In this model, tremulous jaw movements were induced in male rats by IP chronic administration of the dopamine antagonist haloperidol (1.5mg/kg). Acute stimulation of SNc by picrotoxin increased cFOS-IR in the vermis and cerebellar hemispheres. However, lidocaine did not produce an effect. After 14days of haloperidol treatment, the vermis and cerebellar hemispheres showed an opposite regulation of cFOS expression. Chronic dopaminergic antagonism lessened cFOS expression in the vermis but up-regulated such expression in the cerebellar hemisphere. Overall, the present data indicate a very close functional relationship between the basal ganglia and the cerebellum and they may allow a better understanding of disorders in which there are dopamine alterations.
Research Interests:
Research Interests:
Research Interests: Psychology, Cognitive Science, Medicine, Animals, Male, and 4 moreQuinpirole, Rats, Copulation, and Wistar Rats
The androgen receptor (AR) is a widely distributed molecule indicating the spread actions of its ligand steroid, and plays an important role underlying male sexual behavior. Nevertheless, the influence of steroid hormones and their... more
The androgen receptor (AR) is a widely distributed molecule indicating the spread actions of its ligand steroid, and plays an important role underlying male sexual behavior. Nevertheless, the influence of steroid hormones and their receptors on cerebellar neurons, as foundation of sexual behavior, is largely unknown. We sought to determine the influence of peripheral hormones on the AR expression in Purkinje neurons across cerebellar lobules in the vermis of male rats. First, we found a basal AR expression in Purkinje neurons that was higher in the superficial region than the deep region only in cerebellar lobules 2, 4, 5, 7, 8 and 9. Moreover, only the cerebellar lobule 10 showed a significant difference between the coordinates 0.1, 0.3 and 0.9. Second, males with four sessions of sexual training showed a decreased AR density in cerebellar lobules 7, 8, 9 and 10, but not in lobules 2, 4 or 5 when compared to males with one session of sexual training. However, sexual training did not affect AR expression in Purkinje neurons according to their location in any of the cerebellar lobules studied. Third, castration decreased the AR density in the cerebellar lobules 1, 2, 5 and 9 in the superficial region, while in the deep region all cerebellar lobules, except lobule 6, showed a lower AR density after castration. Finally, testosterone replacement restored AR density to control levels in all cerebellar lobules in the superficial region that were affected by castration. Contrary, in the deep region hormonal replacement failed to restore the AR density to control level in the majority of the cerebellar lobules that were affected by castration. Altogether, our findings indicate that Purkinje neurons in the vermis are influenced by systemic testosterone in a region-dependent manner highlighting a link between the cerebellum and gonads in the male rat. The AR function in Purkinje neurons may be related to cerebellar plasticity since both estrogen and progesterone receptors, members of the nuclear receptor family, regulate plasticity processes in Purkinje neurons. We concluded the cerebellum is an important component of the neural circuit for male sexual behavior.
Research Interests:
According to the World Health Organization, every year about 3.4 million adults die of consequences related to overweight or obesity. People with a Body Mass Index above 30 are more likely to express certain diseases, including some types... more
According to the World Health Organization, every year about 3.4 million adults die of consequences related to overweight or obesity. People with a Body Mass Index above 30 are more likely to express certain diseases, including some types of cancer. In this narrative review, we assess the role of adipose tissue as a modulator of the endocrine system and facilitator of chronic subclinical inflammation. We discuss how obesity can induce a suitable micro environment for the development of tumors, mainly by enhancing the levels of oxidative stress and the concentrations of hormones such as leptin, insulin and prolactin. We conclude that all together, these factors increase the probability of cancer development.
Addiction involves alterations in multiple brain regions that are associated with functions such as memory, motivation and executive control. Indeed, it is now well accepted that addictive drugs produce long-lasting molecular and... more
Addiction involves alterations in multiple brain regions that are associated with functions such as memory, motivation and executive control. Indeed, it is now well accepted that addictive drugs produce long-lasting molecular and structural plasticity changes in corticostriatal-limbic loops. However, there are brain regions that might be relevant to addiction other than the prefrontal cortex, amygdala, hippocampus and basal ganglia. In addition to these circuits, a growing amount of data suggests the involvement of the cerebellum in many of the brain functions affected in addicts, though this region has been overlooked, traditionally, in the addiction field. Therefore, in the present review we provide seven arguments as to why we should consider the cerebellum in drug addiction. We present and discuss compelling evidence about the effects of drugs of abuse on cerebellar plasticity, the involvement of the cerebellum in drug-induced cue-related memories, and several findings showing t...
In all species, sexual behavior is directed by a complex interplay between steroid hormone actions in the brain that give rise to sexual arousability and experience with sexual reward that gives rise to expectations of competent sexual... more
In all species, sexual behavior is directed by a complex interplay between steroid hormone actions in the brain that give rise to sexual arousability and experience with sexual reward that gives rise to expectations of competent sexual activity, including sexual arousal, desire, and performance. Sexual experience allows animals to form instrumental and Pavlovian associations that predict sexual outcome and thereby directs the strength of sexual responding. Although the study of animal sexual behavior by neuroendocrinologists has traditionally been concerned with mechanisms of copulatory responding, more recent use of conditioning and preference paradigms, and a focus on environmental circumstances and experience, has revealed behaviors and processes that resemble human sexual responses. In this paper, we review behavioral paradigms used with rodents and other species that are analogous or homologous to human sexual arousal, desire, reward, and inhibition. The extent to which these b...