The effect of 5,7-dihydroxytryptamine on the serum corticosterone resistance to suppression by dexamethasone.

The effect of serotonin (5-HT) deficiency on hypothalamic-pituitary-adrenal (HPA) activity was investigated by using 5,7-dihydroxytryptamine (5,7-DHT) for the selective destruction of central 5-HT neurons, and corticosterone response to suppression by dexamethasone as the index of HPA activity. Dexamethasone was shown to significantly suppress serum corticosterone levels in sham-treated rats, but did not suppress corticosterone in the 5,7-DHT-lesioned animals. This finding supports the conclusion that 5-HT is involved in the negative feedback mechanism of HPA regulation.