Chronic antidepressant drug treatment does not affect GH response to baclofen in depressed subjects

The growth hormone (GH) response to baclofen, a specific GABAB agonist, was tested in 8 male depressed patients before and after chronic treatment with amitriptyline (100 mg/day). No difference was seen in plasma GH response before and 28 days after amitriptyline treatment, suggesting that chronic antidepressant drug treatment does not increase hypothalamic GABAB receptor sites in humans. These data suggest that further studies need to support the hypothesis of a GABA involvement in the mechanism of action of antidepressant drugs.