NeuroendocrinologyRole of serotonin in the amygdala in hypothalamo-pituitaryadrenocortical responsesFeldman, Shaul1,2; Newman, Michael E1; Gur, Eitan1; Weidenfeld, Joseph1Author Information 1Departments of Neurology and Psychiatry, Hadassah University Hospital and Hebrew University, Hadassah Medical School, POB 12000, Jerusalem 91120, Israel. 2Corresponding Author: Shaul Feldman ACKNOWLEDGEMENTS: This research was supported by the Etty and Miguel Meilichson Neuroscience Research Fund and by the Lena P. Harvey Endowment Fund for Neurological Research. The technical assistance of Mrs A. Itzik is greatly appreciated. Website publication 10 June 1998 Received 6 March 1998; accepted 8 April 1998 NeuroReport: June 22nd, 1998 - Volume 9 - Issue 9 - p 2007-2009 Buy Abstract IN view of the fact that the amygdala (AMG) and hypothalamic serotonin (5-HT) have an excitatory effect on the hypothalamo-pituitary-adrenal (HPA) axis, we have investigated the role of 5-HT in the AMG on this response. In intact freely moving rats, a mildly stressing short photic stimulation caused depletion of median eminence CRH-41, due to its release into the portal circulation and a rise in serum ACTH and corticosterone levels. This effect was significantly inhibited in rats in which 5-HT was depleted in the AMG following local 5,7-dihydroxytryptamine administration, which did not affect hypothalamic 5-HT content. Also, local pretreatment with ketanserin (a 5-HT2 receptor antagonist) in the AMG had the same inhibitory effect on the HPA axis response. These results indicate that AMG 5-HT has an important role in the activation of the HPA axis following neural stimulation and that 5-HT2 receptors are involved. © Lippincott-Raven Publishers.