5-HT1A RECEPTOR EXPRESSION IS MODULATED BY CORTICOSTEROID RECEPTOR AGONISTS IN PRIMARY RAT HIPPOCAMPAL CULTURE

The effects of corticosteroid receptor agonists on the expression of 5 -HT1A receptor mRNA were measured in rat hippocampal cultures using in situ hybridization histochemistry. In our normal culture system. grow n in serum and steroid-free media, moderate to heavy signal for 5-HT1A mRNA transcripts were detected in hippocampal neurons and glial cells . Aldosterone, a type I corticosteroid receptor agonist (10(-9) M), si gnificantly reduced the expression of 5-HT1A mRNA both in neurons and glial fibrillary acidic protein (GFAP)-immunoreactive (IR) cells. The type II corticosteroid receptor agonist, Ru28362 (10(-8) M), also sign ificantly decreased neuronal 5-HT1A mRNA expression. However, it was n ot as effective as aldosterone in reducing the label over GFAP-IR cell s. These data indicate that corticosteroids may directly regulate the expression of hippocampal 5-HT1A receptors at the mRNA level in cultur ed hippocampal cells.