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Effects of early experience and dexamethasone on adrenocortical reactivity
Insights
Early life shock does not alter long-term adrenocortical reactivity via maternal or infant hormone changes. Blocking adrenocortical responses with dexamethasone in infant rats showed no mediation by circulating hormones.
Area of Science:
- Neuroendocrinology
- Developmental Psychology
- Behavioral Science
Background:
- Early life stress is known to have long-term effects on the neuroendocrine system.
- The role of adrenocortical hormones in mediating these effects is not fully understood.
Purpose of the Study:
- To test the hypothesis that changes in circulating adrenocortical hormones mediate the long-term effects of early life shock.
- To investigate the involvement of both maternal and infant adrenocortical responses.
Main Methods:
- Infant rats were exposed to peripheral shock stimulation.
- Dexamethasone was administered to mothers via drinking water to block adrenocortical responses in both mothers and pups.
- Control experiments confirmed dexamethasone presence in pups.
Main Results:
- Shock exposure reduced adrenocortical reactivity regardless of whether the mother, the young, or both could mount an adrenocortical response.
- Dexamethasone effectively blocked adrenocortical responses to shock stimulation.
Conclusions:
- The findings do not support the hypothesis that pituitary-adrenocortical responses in either the mother or the infant mediate the effects of early life stimulation on subsequent adrenocortical reactivity.
- Alternative mechanisms may underlie the long-term effects of early life stress on adrenocortical function.
Abstract:
This investigation tested the hypothesis that changes in circulating adrenocortical hormones mediate the long term effects of shocking infant rats. Dexamethasone administered through the mothers' milk was used to block adrenocortical responses to peripheral shock stimulation by the young. Control experiments indicated that the dexamethasone was present in the pups as early as 2 days after the mothers began drinking water containing dexamethasone. Shock reduced adrenocortical reactivity under conditions where the mother and the young were capable of an adrenocortical response to the shock, where either the mother or the young could have a response, and where neither the mother nor the young could have an adrenocortical response to this early stimulation. These data do not support the hypothesis that a pituitary-adrenocortical response of either the mother or the young mediates the effects of stimulation in infancy on subsequent adrenocortical reactivity.