Papers by patricia rosenfeld
Developmental Brain Research, Jul 1, 1988
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Physiology & Behavior, 1992
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Physiology & Behavior, 1991
In the following studies, we investigated the effects of 24-h maternal deprivation on the infant&... more In the following studies, we investigated the effects of 24-h maternal deprivation on the infant's hypothalamic-pituitary-adrenal system. Experiment 1 examined the effect of deprivation on the infant's corticosterone (CORT) response to adrenocorticotropin hormone (ACTH) injection. At all ages studied, deprivation resulted in a potentiation of the response. At some ages, deprived nontreated pups had higher CORT levels than nondeprived pups. Experiment 2 examined the ontogeny of the deprivation-induced stress response, and the capacity of the mother to inhibit it. From 8 days of age onwards, deprived animals showed a CORT response to saline injection that was either absent or far smaller in nondeprived pups. Saline-induced CORT secretion was diminished, or prevented, by returning the infant to its dam. Maternal reunion had no effect on ACTH-induced CORT elevations. Finally, Experiment 3 investigated the effects of deprivation over a more extended period of time. In maternally deprived pups, ACTH-induced CORT elevations persisted for at least 2 h following reunion, but by 6 h had returned to baseline. These data suggest that maternal factors are involved in the regulation of the responsiveness of the pup's hypothalamic-pituitary-adrenal system.
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Neuroendocrinology, 1993
Prolonged maternal deprivation during early ontogeny results in increased basal and stress-induce... more Prolonged maternal deprivation during early ontogeny results in increased basal and stress-induced corticosterone levels. In the following experiments we examined whether these increases were due, at least in part, to augmented ACTH secretion. Thus, ACTH levels were measured in 24-hour maternally deprived and nondeprived 6-, 9-, and 12-day-old pups exposed to a mild stressor (i.e. saline injection followed by placement in a novel environment at room temperature). The results showed: (1) nondeprived pups showed a small response to saline--the response of deprived pups, however, was greater than that of nondeprived pups; (2) the magnitude of the response increased with age; (3) ACTH levels remained elevated for at least 30 min. Subsequent experiments examined whether the continuous exposure to novelty and/or loss of body heat could explain the persistence of this response. Neither variable affected the ACTH response to saline. Our results indicate that factors of maternal origin are partly responsible for the regulation of the ACTH response to stress. Furthermore, the persistence of the response suggests that the negative feedback system in the infant is immature.
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Developmental Psychobiology, 1991
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Developmental Brain Research, 1996
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Developmental Brain Research, 1993
Twenty-four hours of maternal separation results in increased secretion of ACTH and corticosteron... more Twenty-four hours of maternal separation results in increased secretion of ACTH and corticosterone (CORT), suggesting the hypothalamic-pituitary-adrenal (HPA) axis is regulated by some aspect of maternal behavior. Previous results indicate that feeding plays a role in maintaining low levels of CORT in 12-day-old pups. In Experiment 1 basal and stress levels of CORT and ACTH were measured in maternally-deprived pups either provided or not with milk to determine whether: (1) feeding maintains ACTH secretion at low levels, and/or (2) feeding maintains the adrenal insensitive to ACTH. The results showed that, although ACTH levels were markedly low (compared to previous values reported by this laboratory) for both groups, only non-fed pups showed a robust increase in basal and stress CORT levels. During the deprivation period in Experiment 1, all pups were manually stroked to induce urination and defecation, suggesting an effect of stroking on ACTH secretion. Experiment 2 examined this hypothesis. Stroking suppressed stress-induced elevations of ACTH secretion due to maternal deprivation. CORT levels, however, were elevated in all deprived pups. The results indicate that maternal regulation of the infant's HPA axis occurs at multiple levels. Feeding appears to regulate adrenal sensitivity, whereas anogenital stroking inhibits the activation of centrally-controlled components of the axis.
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Cellular and Molecular Neurobiology, 1993
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Neuroscience & Biobehavioral Reviews, 1992
The hypothalamic-pituitary-adrenal system shows an overall diminished responsiveness throughout o... more The hypothalamic-pituitary-adrenal system shows an overall diminished responsiveness throughout ontogeny. Thus, during this period, the sensitivity of the adrenal gland to ACTH is markedly reduced. Furthermore, basal and stress-induced concentrations of corticosterone (CORT), ACTH and hypothalamic secretagogues remain at very low levels. Both structural immaturity and active inhibitory processes appear to underlie this overall hyporesponsiveness. The available data indicate that the characteristic developmental pattern of the HPA system results from multiple regulatory factors acting in conjunction at various levels of the axis. The primary rate-limiting steps, however, are probably at the brain and adrenal levels. The ultimate "goal" appears to be to keep CORT levels within the narrow range of concentrations required for normal development.
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Developmental Brain Research, 1990
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Progress in Brain Research, 1988
... This article is not included in your organization's subscription. However, you may be ab... more ... This article is not included in your organization's subscription. However, you may be able to access this article under your organization's agreement with Elsevier. E. Ronald De Kloet 1 , Patricia Rosenfeld 2 , J. Anke M. Van Eekelen 1 , Winardi Sutanto 1 and Seymour Levine 2. ...
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ABSTRACT
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Developmental …, 1993
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Papers by patricia rosenfeld