The influence of leptin on orexin A and the interaction of leptin with ghrelin in regulating the ... more The influence of leptin on orexin A and the interaction of leptin with ghrelin in regulating the gonadotropic and somatotropic axes in seasonally polyestrous animals are not well understood. This study examined the effects of these factors as well as the mediating roles of specific ovine leptin antagonist (SOLA; mutant D23L/L39A/D40A/F41A) and photoperiod on luteinizing hormone (LH) and growth hormone (GH) secretion. Twenty-four ovariectomized, estradiol-implanted ewes were used in a replicated switchback design. The ewes were assigned randomly to 1 of 6 treatments (infused into the third ventricle 3 times at 0 (dusk), 1, and 2 h) as follows: control, Ringer-Locke buffer; leptin, 0.5 μg/kg b.w.; orexin A, 0.3 μg/kg b.w.; ghrelin, 2.5 μg/kg b.w.; SOLA, 50 μg/kg b.w. + orexin A, 0.3 μg/kg b.w.; and SOLA, 50 μg/kg b.w. + ghrelin, 2.5 μg/kg b.w. Blood samples (5 ml) were collected at 15-min intervals for 4 h. SOLA + orexin A resulted in an increase (P<0.01) in the LH plasma concentra...
In recent years obesity is treated as a civilization disorder. It is believed that it is the caus... more In recent years obesity is treated as a civilization disorder. It is believed that it is the cause of diseases of many system; moreover, moreover obesity can promote the development of many types of cancers and is a major health hazard for insulin resistance and type 2 diabetes. Currently, the mechanisms underlying the development of obesity are not completely known. Over many years of experiments different factors contributing to the formation of obesity have been recognized. The discovery of resistin as a protein linking obesity to type 2 diabetes marked the beginning of a period of intensive research on this molecule. However, until now its role in the body has been controversial. In rodent resistin is responsible for the development of insulin resistance, but in humans this effect is ambiguous. This protein has strong proinflammatory properties, which can be associated with the development of inflammatory diseases, including atherosclerosis. It is possible that resistin is invol...
This study aimed to expand the knowledge of the interactions between prolactin (PRL) and leptin i... more This study aimed to expand the knowledge of the interactions between prolactin (PRL) and leptin in the ovine mammary gland during pregnancy and lactation; we examined the mRNA expression of prolactin receptor (PRLR), the long form of the leptin receptor (LRb) and suppressor of cytokine signaling (SOCS)-3 in mammary gland biopsies collected on days 60, 90 and 120 of pregnancy and on days 30, 60 and 90 of lactation (n = 6 for each time point), along with the plasma PRL and leptin concentrations. The PRL concentrations were stable throughout pregnancy and increased during lactation. The plasma leptin concentrations were comparable among nonpregnant, early-pregnant, late-pregnant and lactating ewes, but this metric peaked during mid-pregnancy. Expression of PRLR and SOCS-3 in the mammary gland fluctuated during the transition from pregnancy to lactation, and differences in LRb expression occurred during the late stages of lactation. The LRb transcript abundance was approximately 31 time...
Bulletin of The Veterinary Institute in Pulawy, 2009
The aim of the present experiment was to determine the growth hormone (GH) and prolactin (PRL) se... more The aim of the present experiment was to determine the growth hormone (GH) and prolactin (PRL) secretions in relation to the milk yield of lambed sheep used for milk under different photoperiodic conditions. The study was carried out at the Experimental Station of the Department of Sheep and Goat Breeding of the Agricultural University in Krakow, using 60 Polish Long-wool sheep assigned to three groups. Sheep, which had lambed in January in group I (n=20) and in June in group II (n=20) were exposed to natural changes in the length of the photoperiod. In group III (n=20), sheep were lambed in June and kept under a long photoperiod (16L:8D) until the end of lactation. In the group I, the highest milk yield (0.43 ±0.08 l) was found in the first month of milking (May). Growth hormones and PRL concentrations in the blood were also the highest (5.49 ±4.2 and 312.6 ±24.3 ng/mL, respectively). In the group III, as in the group II, the milk yield consistently decreased from August to Novembe...
Simple Summary Research since the discovery of leptin has mainly focused on the long form of the ... more Simple Summary Research since the discovery of leptin has mainly focused on the long form of the leptin receptor. Currently, experiments on the short form of the leptin receptor have confirmed that not only is short form of leptin receptor present in the hypothalamus, but also expanded knowledge with information documenting the specific expression of that form of leptin receptor in selected areas of the hypothalamus and in the pituitary gland. In addition, we have shown that short form of leptin receptor expression levels are affected by day length, adiposity and resistin in sheep. Abstract The short form of the leptin receptor (LRa) plays a key role in the transport of leptin to the central nervous system (CNS). Here, the resistin (RSTN)-mediated expression of LRa in the preoptic area (POA), ventromedial and dorsomedial nuclei (VMH/DMH),arcuate nucleus (ARC) and the anterior pituitary gland (AP)was analyzed considering the photoperiodic (experiment 1) and nutritional status (experi...
Both long-term undernutrition and overnutrition disturb metabolic balance, which is mediated part... more Both long-term undernutrition and overnutrition disturb metabolic balance, which is mediated partially by the action of two adipokines, leptin and resistin (RSTN). In this study, we manipulated the diet of ewes to produce either a thin (lean) or fat (fat) body condition and investigated how RSTN affects endocrine and metabolic status under different leptin concentrations. Twenty ewes were distributed into four groups (n = 5): the lean and fat groups were administered with saline (Lean and Fat), while the Lean-R (Lean-Resistin treated) and Fat-R (Fat-Resistin treated) groups received recombinant bovine resistin. Plasma was assayed for LH, FSH, PRL, RSTN, leptin, GH, glucose, insulin, total cholesterol, nonesterified fatty acid (NEFA), high-density lipoprotein (HDL)-cholesterol, low-density lipoprotein (LDL)-cholesterol and triglycerides. Expression levels of a suppressor of cytokine signaling (SOCS-3) and the long form of the leptin receptor (LRb) were determined in selected brain re...
The effect of artificial conditions of a short daylight period (16 h darkness (D): 8 h light (L))... more The effect of artificial conditions of a short daylight period (16 h darkness (D): 8 h light (L)) and exogenous melatonin on milk yield parameters of sheep during spring and summer was examined to determine the impact of using sheep for milk on the secretion level of gonadotrophic hormones. The research was conducted on 60 sheep lambed in February. After raising the lambs, the sheep were divided into 3 groups and assigned for dairy use (May–September). The mothers in the control Group 1 (G1) were maintained under natural daylight conditions. The sheep in Group 2 (G2) were maintained under conditions of an artificial photoperiod (16 h D : 8 h L). Meanwhile, the mothers in Group 3 (G3) were given melatonin implants. A 6-hour collection of blood from 6 sheep of each group was performed every 4 weeks. The concentrations of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in plasma were measured using radioimmunoassay. The average LH concentration in G1 gradually increased...
The maintenance of energy homeostasis is achieved with ‘detectors’ that receive signals from the ... more The maintenance of energy homeostasis is achieved with ‘detectors’ that receive signals from the external and internal environment and with multidirectional ‘communication routes’ including neuronal networks and body fluids, such as blood and cerebrospinal fluid. Changes in the energy demands of organisms are caused by current physiological status and environmental conditions, including season and food availability. Little is known about the interactions between the metabolic indicators involved in the maintenance of energy homeostasis, e.g., leptin, orexins and ghrelin. Sheep and other seasonal animals are highly adaptable to their environments because of the plasticity of their neural and endocrine systems. Sheep exhibit leptin resistance and are thus an extremely interesting model for research on the relationship between hormonal indicators of energy metabolism. The paper is focused mainly on the anatomical and functional communication between leptin, ghrelin and orexins, which p...
Recent studies confirmed that pineal melatonin (MEL) secretion is regulated by ghrelin (GHRL) in ... more Recent studies confirmed that pineal melatonin (MEL) secretion is regulated by ghrelin (GHRL) in seasonally reproductive sheep. The first in vivo experiment investigated whether the effect of GHRL on nocturnal secretion of MEL in sheep is mediated by type 2 serotonin receptors. Sheep ( = 16) were intravenously injected with GHRL (2.5 μg/kg of BW) and meta-Chlorophenylpiperazine (mCPP; a mixed agonist of 5-HT2B/5-HT2C receptors; 1 mg/kg BW), either combined or individually, during the short-day (SDS) and long-day (LDS) seasons. Blood samples were collected at 15-min intervals for 4 h. The second in vitro experiment examined the effect of GHRL (10 ng/mL) on MEL secretion by pineal gland (PG) explants incubated for 5 h. The expression levels and/or concentrations of tryptophan 5-hydroxylase 1 (TPH1), aralkylamine N-acetyltransferase (AA-NAT), and the phosphorylated form of AA-NAT (p31T-AA-NAT) were determined at selected time points during the SDS and LDS seasons. The experiments demonstrated that GHRL reduced MEL secretion ( < 0.01) during the SDS season. Administration of mCPP or a combination of GHRL + mCPP stimulated MEL secretion ( < 0.01) regardless of the season. Furthermore, GHRL regulated nightly MEL secretion in a TPH1-independent manner. However, during the SDS season, GHRL reduced p31T-AA-NAT expression and the AA-NAT concentration ( < 0.01) and inhibited MEL secretion ( < 0.001), whereas during the LDS season, GHRL had no effect on MEL secretion or on the expression of the examined enzymes. These findings indicate that GHRL directly and indirectly affects PG activity in sheep and that the photoperiod modulates the effects of GHRL.
Ghrelin and leptin and their receptors GHSR and LEPR regulate food intake, the processes in adipo... more Ghrelin and leptin and their receptors GHSR and LEPR regulate food intake, the processes in adipose tissue, and the body’s energy homeostasis in mammals. The aim of the present study was to determine the effect of GHSR/Csp6I and LEPR/Bsh1236I polymorphisms on the meat production parameters of broiler chickens reared to 42 days of age. In 318 fast-growing Hubbard Flex and Ross 308 chickens, g.3051C > T substitution at the GHSR locus and a GGTCAA deletion at positions g.3407_3409del and g.3411_3413del were identified. The use of restriction enzyme Bsh1236I showed the presence of two transitions g.352C > T and g.427G > A in LEPR locus. The chickens were classified into four GHSR/Csp6I and into five LEPR/Bsh1236I diplotypes. GHSR and LEPR polymorphisms were found to influence final bodyweight, daily gain, dressing percentage without giblets, proportion of giblets and the quality characteristics of M. pectoralis superficialis. GHSR/Csp6I and LEPR/Bsh1236I had an effect on pH24 h...
the objective of this study was to determine the postnatal adaptation of 10 pairs of twin lambs a... more the objective of this study was to determine the postnatal adaptation of 10 pairs of twin lambs after treating their mothers (n = 5) with 25 mg of copper as cuso4∙ 5H2o per os (twins i and ii – experimental groups, each group n = 5) and 10 other ewes with saline (twins i and ii – control groups, n = 5). mothers were treated with copper daily for four weeks before conception, during pregnancy and for three weeks after parturition. blood samples were taken from each lamb at birth, at 6, 12, 24 hours of age, and at 3, 7 and 21 days of age. copper caused an increase (p<0.01) in actH concentrations after 24 hours of age in the group of experimental twins ii compared to the group of twins i. However, a higher concentration of cortisol in the experimental twins i compared to twins ii was noted. the total glucose concentration was lower in the group of experimental twins i compared to twins ii (p<0.05) and in both (p<0.01) control groups. the results showed that during the first da...
The influence of leptin on orexin A and the interaction of leptin with ghrelin in regulating the ... more The influence of leptin on orexin A and the interaction of leptin with ghrelin in regulating the gonadotropic and somatotropic axes in seasonally polyestrous animals are not well understood. This study examined the effects of these factors as well as the mediating roles of specific ovine leptin antagonist (SOLA; mutant D23L/L39A/D40A/F41A) and photoperiod on luteinizing hormone (LH) and growth hormone (GH) secretion. Twenty-four ovariectomized, estradiol-implanted ewes were used in a replicated switchback design. The ewes were assigned randomly to 1 of 6 treatments (infused into the third ventricle 3 times at 0 (dusk), 1, and 2 h) as follows: control, Ringer-Locke buffer; leptin, 0.5 μg/kg b.w.; orexin A, 0.3 μg/kg b.w.; ghrelin, 2.5 μg/kg b.w.; SOLA, 50 μg/kg b.w. + orexin A, 0.3 μg/kg b.w.; and SOLA, 50 μg/kg b.w. + ghrelin, 2.5 μg/kg b.w. Blood samples (5 ml) were collected at 15-min intervals for 4 h. SOLA + orexin A resulted in an increase (P<0.01) in the LH plasma concentra...
In recent years obesity is treated as a civilization disorder. It is believed that it is the caus... more In recent years obesity is treated as a civilization disorder. It is believed that it is the cause of diseases of many system; moreover, moreover obesity can promote the development of many types of cancers and is a major health hazard for insulin resistance and type 2 diabetes. Currently, the mechanisms underlying the development of obesity are not completely known. Over many years of experiments different factors contributing to the formation of obesity have been recognized. The discovery of resistin as a protein linking obesity to type 2 diabetes marked the beginning of a period of intensive research on this molecule. However, until now its role in the body has been controversial. In rodent resistin is responsible for the development of insulin resistance, but in humans this effect is ambiguous. This protein has strong proinflammatory properties, which can be associated with the development of inflammatory diseases, including atherosclerosis. It is possible that resistin is invol...
This study aimed to expand the knowledge of the interactions between prolactin (PRL) and leptin i... more This study aimed to expand the knowledge of the interactions between prolactin (PRL) and leptin in the ovine mammary gland during pregnancy and lactation; we examined the mRNA expression of prolactin receptor (PRLR), the long form of the leptin receptor (LRb) and suppressor of cytokine signaling (SOCS)-3 in mammary gland biopsies collected on days 60, 90 and 120 of pregnancy and on days 30, 60 and 90 of lactation (n = 6 for each time point), along with the plasma PRL and leptin concentrations. The PRL concentrations were stable throughout pregnancy and increased during lactation. The plasma leptin concentrations were comparable among nonpregnant, early-pregnant, late-pregnant and lactating ewes, but this metric peaked during mid-pregnancy. Expression of PRLR and SOCS-3 in the mammary gland fluctuated during the transition from pregnancy to lactation, and differences in LRb expression occurred during the late stages of lactation. The LRb transcript abundance was approximately 31 time...
Bulletin of The Veterinary Institute in Pulawy, 2009
The aim of the present experiment was to determine the growth hormone (GH) and prolactin (PRL) se... more The aim of the present experiment was to determine the growth hormone (GH) and prolactin (PRL) secretions in relation to the milk yield of lambed sheep used for milk under different photoperiodic conditions. The study was carried out at the Experimental Station of the Department of Sheep and Goat Breeding of the Agricultural University in Krakow, using 60 Polish Long-wool sheep assigned to three groups. Sheep, which had lambed in January in group I (n=20) and in June in group II (n=20) were exposed to natural changes in the length of the photoperiod. In group III (n=20), sheep were lambed in June and kept under a long photoperiod (16L:8D) until the end of lactation. In the group I, the highest milk yield (0.43 ±0.08 l) was found in the first month of milking (May). Growth hormones and PRL concentrations in the blood were also the highest (5.49 ±4.2 and 312.6 ±24.3 ng/mL, respectively). In the group III, as in the group II, the milk yield consistently decreased from August to Novembe...
Simple Summary Research since the discovery of leptin has mainly focused on the long form of the ... more Simple Summary Research since the discovery of leptin has mainly focused on the long form of the leptin receptor. Currently, experiments on the short form of the leptin receptor have confirmed that not only is short form of leptin receptor present in the hypothalamus, but also expanded knowledge with information documenting the specific expression of that form of leptin receptor in selected areas of the hypothalamus and in the pituitary gland. In addition, we have shown that short form of leptin receptor expression levels are affected by day length, adiposity and resistin in sheep. Abstract The short form of the leptin receptor (LRa) plays a key role in the transport of leptin to the central nervous system (CNS). Here, the resistin (RSTN)-mediated expression of LRa in the preoptic area (POA), ventromedial and dorsomedial nuclei (VMH/DMH),arcuate nucleus (ARC) and the anterior pituitary gland (AP)was analyzed considering the photoperiodic (experiment 1) and nutritional status (experi...
Both long-term undernutrition and overnutrition disturb metabolic balance, which is mediated part... more Both long-term undernutrition and overnutrition disturb metabolic balance, which is mediated partially by the action of two adipokines, leptin and resistin (RSTN). In this study, we manipulated the diet of ewes to produce either a thin (lean) or fat (fat) body condition and investigated how RSTN affects endocrine and metabolic status under different leptin concentrations. Twenty ewes were distributed into four groups (n = 5): the lean and fat groups were administered with saline (Lean and Fat), while the Lean-R (Lean-Resistin treated) and Fat-R (Fat-Resistin treated) groups received recombinant bovine resistin. Plasma was assayed for LH, FSH, PRL, RSTN, leptin, GH, glucose, insulin, total cholesterol, nonesterified fatty acid (NEFA), high-density lipoprotein (HDL)-cholesterol, low-density lipoprotein (LDL)-cholesterol and triglycerides. Expression levels of a suppressor of cytokine signaling (SOCS-3) and the long form of the leptin receptor (LRb) were determined in selected brain re...
The effect of artificial conditions of a short daylight period (16 h darkness (D): 8 h light (L))... more The effect of artificial conditions of a short daylight period (16 h darkness (D): 8 h light (L)) and exogenous melatonin on milk yield parameters of sheep during spring and summer was examined to determine the impact of using sheep for milk on the secretion level of gonadotrophic hormones. The research was conducted on 60 sheep lambed in February. After raising the lambs, the sheep were divided into 3 groups and assigned for dairy use (May–September). The mothers in the control Group 1 (G1) were maintained under natural daylight conditions. The sheep in Group 2 (G2) were maintained under conditions of an artificial photoperiod (16 h D : 8 h L). Meanwhile, the mothers in Group 3 (G3) were given melatonin implants. A 6-hour collection of blood from 6 sheep of each group was performed every 4 weeks. The concentrations of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in plasma were measured using radioimmunoassay. The average LH concentration in G1 gradually increased...
The maintenance of energy homeostasis is achieved with ‘detectors’ that receive signals from the ... more The maintenance of energy homeostasis is achieved with ‘detectors’ that receive signals from the external and internal environment and with multidirectional ‘communication routes’ including neuronal networks and body fluids, such as blood and cerebrospinal fluid. Changes in the energy demands of organisms are caused by current physiological status and environmental conditions, including season and food availability. Little is known about the interactions between the metabolic indicators involved in the maintenance of energy homeostasis, e.g., leptin, orexins and ghrelin. Sheep and other seasonal animals are highly adaptable to their environments because of the plasticity of their neural and endocrine systems. Sheep exhibit leptin resistance and are thus an extremely interesting model for research on the relationship between hormonal indicators of energy metabolism. The paper is focused mainly on the anatomical and functional communication between leptin, ghrelin and orexins, which p...
Recent studies confirmed that pineal melatonin (MEL) secretion is regulated by ghrelin (GHRL) in ... more Recent studies confirmed that pineal melatonin (MEL) secretion is regulated by ghrelin (GHRL) in seasonally reproductive sheep. The first in vivo experiment investigated whether the effect of GHRL on nocturnal secretion of MEL in sheep is mediated by type 2 serotonin receptors. Sheep ( = 16) were intravenously injected with GHRL (2.5 μg/kg of BW) and meta-Chlorophenylpiperazine (mCPP; a mixed agonist of 5-HT2B/5-HT2C receptors; 1 mg/kg BW), either combined or individually, during the short-day (SDS) and long-day (LDS) seasons. Blood samples were collected at 15-min intervals for 4 h. The second in vitro experiment examined the effect of GHRL (10 ng/mL) on MEL secretion by pineal gland (PG) explants incubated for 5 h. The expression levels and/or concentrations of tryptophan 5-hydroxylase 1 (TPH1), aralkylamine N-acetyltransferase (AA-NAT), and the phosphorylated form of AA-NAT (p31T-AA-NAT) were determined at selected time points during the SDS and LDS seasons. The experiments demonstrated that GHRL reduced MEL secretion ( < 0.01) during the SDS season. Administration of mCPP or a combination of GHRL + mCPP stimulated MEL secretion ( < 0.01) regardless of the season. Furthermore, GHRL regulated nightly MEL secretion in a TPH1-independent manner. However, during the SDS season, GHRL reduced p31T-AA-NAT expression and the AA-NAT concentration ( < 0.01) and inhibited MEL secretion ( < 0.001), whereas during the LDS season, GHRL had no effect on MEL secretion or on the expression of the examined enzymes. These findings indicate that GHRL directly and indirectly affects PG activity in sheep and that the photoperiod modulates the effects of GHRL.
Ghrelin and leptin and their receptors GHSR and LEPR regulate food intake, the processes in adipo... more Ghrelin and leptin and their receptors GHSR and LEPR regulate food intake, the processes in adipose tissue, and the body’s energy homeostasis in mammals. The aim of the present study was to determine the effect of GHSR/Csp6I and LEPR/Bsh1236I polymorphisms on the meat production parameters of broiler chickens reared to 42 days of age. In 318 fast-growing Hubbard Flex and Ross 308 chickens, g.3051C > T substitution at the GHSR locus and a GGTCAA deletion at positions g.3407_3409del and g.3411_3413del were identified. The use of restriction enzyme Bsh1236I showed the presence of two transitions g.352C > T and g.427G > A in LEPR locus. The chickens were classified into four GHSR/Csp6I and into five LEPR/Bsh1236I diplotypes. GHSR and LEPR polymorphisms were found to influence final bodyweight, daily gain, dressing percentage without giblets, proportion of giblets and the quality characteristics of M. pectoralis superficialis. GHSR/Csp6I and LEPR/Bsh1236I had an effect on pH24 h...
the objective of this study was to determine the postnatal adaptation of 10 pairs of twin lambs a... more the objective of this study was to determine the postnatal adaptation of 10 pairs of twin lambs after treating their mothers (n = 5) with 25 mg of copper as cuso4∙ 5H2o per os (twins i and ii – experimental groups, each group n = 5) and 10 other ewes with saline (twins i and ii – control groups, n = 5). mothers were treated with copper daily for four weeks before conception, during pregnancy and for three weeks after parturition. blood samples were taken from each lamb at birth, at 6, 12, 24 hours of age, and at 3, 7 and 21 days of age. copper caused an increase (p<0.01) in actH concentrations after 24 hours of age in the group of experimental twins ii compared to the group of twins i. However, a higher concentration of cortisol in the experimental twins i compared to twins ii was noted. the total glucose concentration was lower in the group of experimental twins i compared to twins ii (p<0.05) and in both (p<0.01) control groups. the results showed that during the first da...
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