5-HT(1A) RECEPTOR SENSITIVITY IN MAJOR DEPRESSION - A NEUROENDOCRINE STUDY WITH BUSPIRONE

The hypothermic, growth hormone and corticotrophin (ACTH) responses to the 5-HT1A receptor agonist buspirone (30 mg orally) were measured in 20 unmedicated patients with major depression and 20 healthy controls . Compared with the controls, the hypothermic responses of the depress ed patients to buspirone were significantly attenuated, particularly i n patients with melancholic depression. In contrast, the responses of growth hormone and ACTH to buspirone were unchanged. The data suggest that major depression may be associated with impaired sensitivity of 5 -HT1A autoreceptors but that the function of the post-synaptic 5-HT1A receptors that mediate growth hormone and ACTH release is unaltered. W ithin the limitations that attend the use of buspirone as a 5-HT1A pro be, our data suggest that the decrement in serotonin neurotransmission at post-synaptic 5-HT1A receptors in depression is due to decreased s erotonin release rather than impaired responsivity of post-synaptic 5- HT1A receptors.