Growth hormone responses to the alpha 2-adrenoceptor agonist guanfacine and to growth hormone releasing hormone in depressed patients and controls.
Growth hormone (GH) responses to the alpha 2-adrenoceptor agonist guanfacine and to GH releasing hormone (GHRH) were measured in 13 patients fulfilling Research Diagnostic Criteria and DSM-III criteria for major depressive disorder and in 13 controls matched for age and sex. Dexamethasone suppression tests were performed in all subjects. The peak GH response to guanfacine correlated to the peak GH response to GHRH both in depressed patients and in controls. Neither the response to guanfacine nor the response to GHRH was significantly lower in depressed patients than in controls. Dexamethasone suppression tests, which were performed about 3 days before the GH stimulation tests, were abnormal in 61% (8/13) of the depressed patients but in none of the controls. No difference between dexamethasone suppressors and nonsuppressors with respect to GH response to guanfacine or GHRH was observed. The data are discussed in relation to the blunted GH response to clonidine described in depression.