Growth Hormone and Prolactin in Unipolar and Bipolar Depressed Patients: Responses to Hypoglycemia and L-Dopa

In response to both insulin-induced hypoglycemia and the ingestion of 500 mg. of L-dopa, unipolar depressed patients (most of whom were postmenopausal women) secreted significantly less growth hormone (GH) than did normal subjects or bipolar depressed patients in the same age range (45 to 70 years). Prolactin responses to L-dopa were normal for nearly all subjects. Since it is believed that prolactin responses to L-dopa are mediated by brain dopamine and GH responses by brain norepinephrine, the data tend to support the hypothesis that there is a disturbance of brain norepinephrine metabolism in unipolar depressive illness. However, further study is needed to determine the effects of the menopause on GH secretion.