Summary
Glucagon-induced growth hormone (GH) secretion was studied in healthy subjects under
basal conditions (n = 18), and when treated with TRH (n = 10), cyproheptadine (n =
8) and pimozide (n = 6). With glucagon alone, the mean serum GH level significantly
increased at 150 minutes and at 180 minutes. TRH administered as a bolus injection
completely suppressed the GH response to glucagon. Cyproheptadine pretreatment resulted
in a substantial suppression of the GH response to glucagon. A significant difference
between basal and post-cyproheptadine GH levels was observed at 150 minutes after
glucagon. Pimozide pretreatment was followed by a reduction of GH response to glucagon,
but the difference between control and pimozide-treated groups was not significant.
In conclusion, it is proposed that glucagon-induced GH secretion is at least partly
mediated via serotoninergic mechanisms while significant dopaminergic involvement
does not seem probable. It is further suggested that TRH plays a substantial inhibitory
role in glucagon-stimulated GH secretion.
Key-Words:
Glucagon
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Growth Hormone
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TRH
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Cyproheptadine
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Pimozide
