Neuroscience 2004 Abstract
| Presentation Number: | 425.24 |
|---|---|
| Abstract Title: | Effects of posterior paraventricular thalamic nucleus lesions on acute and repeated restraint-induced HPA axis activation. |
| Authors: |
Gosselink, K. L.*1
; Sawchenko, P. E.1
1Lab Neuronal Structure & Function, Salk Inst, La Jolla, CA |
| Primary Theme and Topics |
Homeostatic and Neuroendocrine Systems - Stress and the Brain -- HPA axis |
| Secondary Theme and Topics | Homeostatic and Neuroendocrine Systems<br />- Neuroendocrine<br />-- Neuroendocrine regulation - other |
| Session: |
425. Anatomy Poster |
| Presentation Time: | Monday, October 25, 2004 11:00 AM-12:00 PM |
| Location: | San Diego Convention Center - Hall A-H, Board # DD17 |
| Keywords: | ACTH, CORTICOSTERONE, HABITUATION, IBOTENIC ACID |
Lesions of the posterior paraventricular thalamic nucleus (PVTp) have been reported to abolish the habituation of HPA secretory responses normally seen upon repeated exposure to an emotional stressor (restraint), without affecting acute stress responses (J. Neuroendocrinol. 14:403-10, 2002). In attempting to clarify the CNS underpinnings of this phenomenon, we made the ostensibly conflicting observation that PVTp lesions reduced activational responses, evidenced by decreased Fos induction, in paraventricular hypothalamic nucleus (PVH) neurons comprising the central limb of the HPA axis in acutely, but not repeatedly, restrained rats (SFN Program No. 506.19, 2003). We sought to reconcile these discrepant findings by evaluating hormonal and PVH activational profiles in a single experiment. Adult male rats, with and without lesions of the PVTp, were subjected to single (acute) or 14 consecutive daily (repeated) 30 min restraint sessions. Serial blood samples were drawn via indwelling jugular catheters, before and at regular intervals after their final or only restraint, for plasma adrenocorticotropin (ACTH) and corticosterone (Cort) determinations. Rats were perfused following the final blood sampling, and brain sections were stained for Fos-ir. Analysis of hormonal measures revealed a significant main effect of stress, but not lesion status. Acute restraint induced comparable ACTH and Cort responses in lesioned and control rats, and the release of both hormones was significantly reduced in response to repeated restraint in both groups. Fos induction in PVH was elevated following acute restraint in both lesioned and intact rats, and was similarly habituated following repeated stress exposure, independent of lesion status. These results fail to support a critical involvement of the PVTp in either the initiation of HPA responses to an acute emotional stressor or their adaptation to repeated stress exposure.
Supported by NS-21182, MH-66588
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2004 Neuroscience Meeting Planner. San Diego, CA: Society for Neuroscience, 2004. Online.
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