INFLUENCE OF AGE ON THE GH RESPONSE TO SUMATRIPTAN ADMINISTRATION IN MAN

The present study was undertaken in order to assess the influence of a ging on the serotonergic control of GH secretion in humans. For this p urpose, 6 mg 5-HT1D-serotonergic receptor agonist sumatriptan (or plac ebo during control tests) was injected subcutaneously in a group of 9 young (26-40 yr old) and a group of 9 elderly male subjects (64-80 yr old). Sumatriptan-induced plasma GH rise was recorded during the next 2 hours. Plasma ACTH levels were also measured. The administration of the placebo was without effects in all subjects. Sumatriptan induced a striking increase in plasma GH levels in the younger group, whereas i t slightly increased GH secretion in the older group (f = 9.59, p < 0. 02). Plasma ACTH levels showed a similar physiological decline in all subjects during tests, regardless of sumatriptan treatment. These data show impaired serotonergic stimulatory regulation of GH secretion in elderly subjects.