RETURNYonago Acta medica 1991;34:227-236
Clonidine-Induced Secretion of Human Growth Hormone Is Correlated to Decrease of Cortisol
Akira Kishimoto, Junichi Nakamura, Hidebumi Hazama, Tatsuyoshi Tamura and Rokuro Mizukawa
Department of Neuro-Psychiatry, Faculty of Medicine, Tottori University, Yonago 683, Japan
The endocrinological response to oral administration of 2.5 µg/kg of clonidine was compared in a group of 44 depressed patients (42 with major depressive disorder and 2 with bipolar disorder, depressed) and a group of 22 normal controls. In the depressed patients, the rate and the amount of clonidine-induced decrease in plasma cortisol (COR) from the basal level were both significantly smaller (P < 0.01 and P < 0.05, respectively) than those in the control group. The secretory response of human growth hormone (HGH) in the depressed patient group was significantly diminished compared to that in the control group (P < 0.01). A significant positive correlation was found between the maximum HGH value after clonidine administration and the decrease of COR from the basal level (P < 0.01) in both control and depressed groups. In the patient group, there was a significant negative correlation between the minimum COR value after clonidine administration and the clonidine-induced decrease of COR (P < 0.01). These findings indicate that the hyposensitivity of postsynaptic alpha-2 receptors induces hyposecretion of HGH and constitutes one of the causes of the development of hypercortisolemia that is seen in depressed patients.
Key words: clonidine; cortisol; depression; growth hormone; postsynaptic alpha-2 receptor