Bed Nucleus of the Stria Terminalis Subregions Differentially Regulate Hypothalmic-Pituitary-Adrenal Axis Activity: Implications for the Integration of Limbic Inputs Dennis C. Choi, Amy R. Furay, Nathan K. Evanson, Michelle M. Ostrander, Yvonne M. Ulrich-Lai, and James P. Herman

Introduction Amygdala, hippocampus, and medial prefrontal cortex influence HPA axis Limbic  BNST  PVN BNST subdivided

The Big Point Subregions of the BNST differentially regulate HPA axis responses to acute stress

Nijsen Paper: background information BNST is involved in autonomic and behavioral reactions BNST is a rostral forebrain structure Enclosed by lateral ventricle, lateral septum, fornix, nucleus accumbens, preoptic area, and hypothalamus Links amygdala and hippocampus with PVN and brain stem

Methods and Materials 36 male Sprague Dawley rats ( g) 3/cage Food/water ad libitum Temp and humidity controlled 12h light/dark (Lights on at 6am)

Methods and Materials Day 1: Surgery Days 2-8: Recovery Day 8: Restraint stress (9:30-10:30am) Day 9-15: Nonhandled recovery Day 16: 2 nd restraint stress and killed –Killed 30 min after restraint for peak of c-fos

Methods and Materials Lesions identified –Needle track –Loss of neurons –Gliosis (increase in size and number of astrocytes)

Animals included Bilateral damage included Partial unilateral lesions removed Missed lesions removed

Results Anterior BNST lesions damage fusiform and dorsomedial nuclei Posterior BNST lesions damage principle, interfascicular, and transverse nuclei

C-fos, CRH, GAD 65 mRNA expression in BNST C-fos decreased with anterior lesion CRF decreased with anterior lesion GAD 65 decreased with anterior lesion GAD 65 diminished with posterior lesion –  lesions were successful

Successful Lesions

C-Fos mRNA expression

Plasma ACTH Elevated at 30 and 60 min (all groups) Posterior lesion elevated Anterior lesion no effect Same at 0 or 120 min (all)

Plasma ACTH graph

Plasma Corticosterone Increased B to restraint Anterior lesion decreased B at 30 min Posterior lesion increased B at 60 min

Plasma Cort graph

Posterior BNST lesion and the HPA axis Increased secretion of ACTH and B Increased c-fos mRNA Increased CRH and AVP mRNA in PVN Inhibits HPA response to stress

Posterior BNST Restraint induced c-fos expression enhanced by lesion Principal nucleus inhibits the PVNmp Principal nucleus regulates HPA activity

Anterior BNST lesion and the HPA axis Decrease B and c-fos No alteration of CRH and AVP in PVN CRH and Glu activate HPA

Discussion Specific roles of BNST nuclei Anterior excites PVN, promotes B secretion Posterior inhibits PVN excitation, ACTH release, and B responses Posterior lesion enhances c-fos expression

McGill Paper Crh gene expressed in BNST Encodes CRH Increased anxiety and stress Overexpression  HPA dysfunction WT 308/Y

Nijsen Paper Restraint stress induces c-fos expression Stress activates the CRH system in BNST Not directly related to autonomic stress Site of CRH determines response CRH in medial BNST stress induced

Discussion BNST is a “clearing house” to regulate HPA Posterior BNST inhibits HPA activity to restraint Lesioning primary nuclei increased – ACTH and B –C-fos mRNA –CRH and AVP

The End