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[Neuroendocrine changes associated with corticotropic axis activity during lactation in rats]
1Département de Psychiatrie, Université McGill, Centre de Recherche de l'Hôpital Douglas, Montréal, Canada.
Annales D'Endocrinologie
|January 1, 1995
Summary
Lactation in rats alters stress hormone responses and reproductive functions. Suckling influences the hypothalamic-pituitary-adrenal axis and gonadotropin-releasing hormone (GnRH) release, mediated by corticotropin-releasing factor (CRF).
Area of Science:
- Neuroendocrinology
- Reproductive Biology
- Stress Physiology
Background:
- Lactation induces significant neuroendocrine and behavioral adaptations in female rats to support offspring development.
- The suckling stimulus is known to impact both the maternal adrenocortical system and reproductive functions.
Purpose of the Study:
- To investigate how the suckling stimulus modifies the adrenocortical system (basal and stress-induced) and reproductive functions in lactating rats.
- To elucidate the mechanisms underlying altered adrenocorticotropic hormone (ACTH) secretion and its relationship with glucocorticoid feedback sensitivity.
- To explore the role of corticotropin-releasing factor (CRF) in mediating the inhibitory effects of suckling on reproductive hormone release.
Main Methods:
- Assessment of adrenocortical system activity under basal and stimulated conditions in lactating rats.
- Evaluation of stress-induced ACTH secretion and sensitivity to glucocorticoid negative feedback.
- Investigation of the involvement of CRF and vasopressin neurons in the hypothalamic paraventricular nucleus.
- Analysis of CRF's role in modulating luteinizing hormone (LH) and GnRH release.
Main Results:
- Lactating rats exhibit tonically elevated corticosterone levels but show decreased stress-induced ACTH secretion.
- This reduction in ACTH secretion is not due to increased sensitivity to glucocorticoid negative feedback.
- Central CRF release appears to partially mediate the inhibitory effects of suckling on LH and GnRH release.
- CRF may act in concert with other neurotransmitter systems and involve extra-paraventricular nucleus CRF populations.
Conclusions:
- Lactation-induced changes in the maternal neuroendocrine system involve modifications in stimulatory and inhibitory inputs to the hypothalamic paraventricular nucleus.
- Corticotropin-releasing factor plays a role in suppressing reproductive hormone release during lactation.
- These neuroendocrine adaptations are crucial for optimizing maternal care and offspring development.