The paraventricular nucleus (PVN) in the hypothalamus receives inputs from the hippocampus. The present study explored the influence of the hippocampus on genes mediating glucocorticoid feedback in the PVN. Accordingly
the expression of mRNAs for corticotrophin-releasing hormone (CRH)
the mineralocorticoid receptor (MR) and the glucocorticoid receptor (GR) in the PVN was examined by in situ hybridisation in rats subjected to transection of the fornix. Significant increases in CRH
MR and GR mRNAs were observed in the parvocellular PVN after fornix transection (FT). FT-animals subjected to adrenalectomy also showed an increase in the number of cells positive for CRH and GR mRNAs. CRH
MR and GR mRNA expression was also increased by bilateral adrenalectomy
and GR mRNA expression was further enhanced in the parvocellular PVN of the FT transected animals. However
no such changes were evident in the magnocellular PVN. These results suggest that the input from the hippocampus to the PVN
particularly to its parvocellular region
has distinct and differential inhibitory effects on the expression of MR
GR and CRH mRNAs that may operate independently from the feedback actions of corticosterone. c 2007 The Authors. Journal Compilation c 2007 Blackwell Publishing Ltd.
