The hypothalamic paraventricular nucleus in two types of Wistar rats with different stress responses. II. Differential Fos-expression.
The present study investigates the role of corticotropin-releasing hormone (CRH) neurons in stress regulation by a comparison of stress induced Fos-immunoreactivity and CRH-immunoreactivity in the hypothalamic paraventricular nucleus (PVH) of APO-SUS (apomorphine-susceptible), APO-UNSUS (apomorphine-unsusceptible), normal Wistar and adrenalectomized Wistar (ADX) rats. The first two types represent a good model to study the role of the PVH in stress regulation, since they show different stress responses and a differential synaptic organization of the PVH. After placement on an open field for 15 min all rats showed an increase in the number of Fos-immunoreactive nuclei compared to control handling. Interestingly, open field stress, but not control handling, induces significantly fewer Fos-immunoreactive nuclei in the PVH of APO-SUS rats (1255 +/- 49) compared to APO-UNSUS rats (1832 +/- 201). Experiments with ADX rats revealed that 93% of the CRH-immunoreactive neurons contained a Fos-immunoreactive nucleus, which suggests that the differential Fos-expression in APO-SUS and APO-UNSUS rats represents a differential activation of the CRH neurons. This hypothesis is discussed in relation to reported differences in stress responses, stress-induced ACTH levels and synaptic organization of the PVH.
Mulders
W H
WH
Department of Psychoneuropharmacology, University of Nijmegen, The Netherlands.
Meek
J
J
Schmidt
E D
ED
Hafmans
T G
TG
Cools
A R
AR
D000311:Adrenal Glands / Q000502:physiology; D000818:Animals; D001058:Apomorphine / Q000494:pharmacology*; D003346:Corticotropin-Releasing Hormone / Q000032:analysis; D005106:Exploratory Behavior / Q000187:drug effects*; D007124:Immunoenzyme Techniques; D008297:Male; D010286:Paraventricular Hypothalamic Nucleus / Q000737:chemistry* / Q000187:drug effects; D016760:Proto-Oncogene Proteins c-fos / Q000032:analysis*; D051381:Rats; D017208:Rats, Wistar; D013045:Species Specificity; D013312:Stress, Physiological / Q000378:metabolism*
D016760:Proto-Oncogene Proteins c-fos; D003346:Corticotropin-Releasing Hormone; D001058:Apomorphine