Acute restraint stress increases 5-HT7 receptor mRNA expression in the rathippocampus

The brain serotonin (5-HT) system interacts closely with the hypothalamic-p ituitary-adrenal axis. We examined the effects of stress on hippocampal 5-H T7 receptor and corticosteroid receptor (mineralocorticoid receptor (MR) an d glucocorticoid receptor (GR)) mRNA expression measured by in situ hybridi sation histochemistry. Acute restraint stress increased 5-HT7 receptor mRNA in CA2 and CA3 hippocampal subregions (32% increase) and had a small effec t on GR but not MR mRNA (19% fall in GR in CA1). In contrast, chronic stres s (1 week of variable stressors) had little effect on hippocampal 5-HT7 rec eptor mRNA (9% rise in CA3) but decreased MR mRNA (e.g. 34% decrease in CA2 ) and GR mRNA expression selectively in the dentate gyrus (26% decrease). T he rise in 5-HT7 receptor mRNA expression following restraint stress parall els our previously reported increase in expression after inhibiting the syn thesis of adrenal steroids. These data suggest that acute but not chronic s tress regulates 5-HT7 receptor mRNA expression in a manner that is likely t o be independent of its glucocorticoid actions. (C) 2001 Elsevier Science I reland Ltd. All rights reserved.