Effects of adrenergic and serotonergic agonists in the amygdala on the hypothalamo-pituitary-adrenocortical axis

• Published in: Brain research bulletin 2000-08, Vol.52 (6), p.531-536
• Main Authors: Feldman, Shaul, Newman, Michael E, Weidenfeld, Joseph
• Format: Article
• Language: English
• Subjects: ACTH; Adrenal Cortex - drug effects; Adrenal Cortex - metabolism; Adrenergic agonists; Adrenergic Agonists - pharmacology; Adrenocorticotropic Hormone - blood; Adrenocorticotropic Hormone - drug effects; Adrenocorticotropic Hormone - metabolism; Amygdala; Amygdala - cytology; Amygdala - drug effects; Amygdala - metabolism; Animals; Biological and medical sciences; Corticosterone; Cortisone - blood; Cortisone - metabolism; CRH-41; Fundamental and applied biological sciences. Psychology; General aspects. Hormone interactions. Hormone actions on several organ systems. Adaptive reactions; Hypothalamo-Hypophyseal System - drug effects; Hypothalamo-Hypophyseal System - metabolism; Hypothalamus; Male; Rats; Rats, Inbred Strains; Serotonergic agonists; Serotonin Receptor Agonists - pharmacology; Vertebrates: endocrinology
• ISSN: 0361-9230; 1873-2747
• DOI: 10.1016/S0361-9230(00)00292-6

The effect of direct administration of adrenergic and serotonergic (5-HT) agonists into the central nucleus of the amygdala (AMG) on the hypothalamo-pituitary-adrenal (HPA) axis have been studied in intact male rats and in animals with 6-hydroxydopamine (6-OHDA) or 5,7-dihydroxytryptamine (5,7-DHT) neurotoxic lesions in the paraventricular nucleus of the hypothalamus (PVN). In intact animals, the administration of phenylephrine, an α1 adrenergic agonist or 8-hydroxy-2-(di-n-propylamino)-tetralin (8-OH-DPAT) a 5-HT 1A agonist caused depletion of median eminence corticotropin releasing hormone and a rise in serum adrenocorticotrophic hormone (ACTH) and corticosterone (CS) levels. Isoproterenol a β agonist was more effective than phenylephrine and a 5-HT 1B agonist CP-93, 129 was less effective than 8-OH-DPAT on the adrenocortical activity. The 6-OHDA or 5,7-DHT hypothalamic lesions prevented the stimulatory effects of phenylephrine and 8-OH-DPAT, respectively, which where injected into the AMG, on serum ACTH and CS levels. In view of our previous studies on the effects of the adrenergic and 5-HT antagonists in the AMG and the present data, it is suggested that norepinephrine and 5-HT play an important role in the stimulatory effect of the AMG on the HPA axis. These effects depend on the presence of these excitatory neurotransmitters in the PVN.