Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.642154
Title: Central mechanisms of reduced neuroendocrine stress responses in pregnancy
Author: Brunton, P. J.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2002
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Abstract:
The hypothalamo-pituitary-adrenal (HPA) axis plays a vital role in restoring homeostasis following stress; responsiveness of the axis can change however. The adrenocorticotropic hormone (ACTH) and corticosterone secretory responses to emotional and physical stressors are reduced in late pregnancy. Here, experiments were designed to investigate changes in the brain mechanisms underlying these reduced responses, with particular focus on adaptations at the level of the hypothalamus. The responsiveness of the HPA axis to the emotional stressors, restraint and maternal aggression were markedly reduced in late pregnant (day 21) rats. This was at least partly a result of reduced activation of the parvocellular paraventricular nucleus (pPVN) corticotrophin-releasing hormone (CRH) and arginine vasopressin (AVP) neurones, as revealed by quantitative in situ hybridisation for CRH mRNA and AVP hnRNA expression. To seek changes in responses to immune challenge, lipopolysaccharide (LPS) and interleukin-lβ (IL-1β) were given acutely. Blood sampling from conscious rats revealed that the ACTH and corticosterone secretory responses to peripheral immune challenge are strongly attenuated in late pregnant rats. This was found to be a consequence of the CRH neurones being stimulated less by the stressor in pregnancy, resulting in reduced drive to the anterior pituitary by CRH. IL-1β has been shown to act via a brainstem pathway from the nucleus of the tractus solitarus (NTS) to the PVN. IL-1β was found to activate Fos expression in NTS neurones similarly in virgin and pregnant rats, indicating that signalling between the NTS and the PVN neurones is interrupted in pregnancy, resulting in reduced activation of the HPA axis.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.642154  DOI: Not available
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