Acute 17 beta-estradiol treatment down-regulates serotonin 5HT1A receptor mRNA expression in the limbic system of female rats.

In situ hybridization histochemistry was used to investigate acute estrogen effects on serotonin 5HT1A receptor mRNA levels in limbic-related brain areas in the female ovariectomized rat. Acute administration of 17 beta-estradiol (10 micrograms) decreased 5HT1A receptor mRNA expression levels within the medial amygdala (after 2 and 24 h), piriform cortex (after 2 and 24 h), and perirhinal cortex (after 24 h). No changes in 5HT1A mRNA levels were observed in hippocampus or retrosplenial cortex. The findings suggest specific regional effects of estrogen on 5HT functions mediated through regulation of the 5HT1A gene.