The effect of monoamine precursors on the release of growth hormone in the Rhesus monkey.
Jacoby-JH; Greenstein-M; Sassin-JF; Weitzman-ED
Neuroendocrinology 1974 Jan; 14(2):95-102
The short term effects were studied of several monoaminergic precursors which were administered to rhesus-monkeys because of their ready passage through the blood/brain barrier and, hence, because of their ability to activate monoamine neurons, as well as apomorphine in the release of growth hormone and sleep. An acute elevation in plasma growth hormone (GH) concentration was caused by intravenous injections of L-dihydroxyphenylalanine (L-dopa) at 15 to 200mg/kg and 5-HTP-monohydrate (5-HTP) at 20 to 60mg/kg. Behavioral and electroencephalographic (EEG) slow wave sleep were induced by 5- HTP. A delayed and smaller elevation was induced by L-tryptophan injected at 50 to 100mg/kg doses. No induced GH release, behavioral sleep or change in the EEG activity followed dosing with apomorphine at 50 to 75 micrograms. Both L-dopa and 5-HTP were potent stimuli for the rapid release of GH in the rhesus-monkey. GH release after L-dopa infusion ranged from 14 to 39 nanograms per milliliter (ng/ml) and after 5-HTP infusion ranged from 11 to 35ng/ml, however, these elevations were not dose related. No evidence was found that hypoglycemia was the stimulus for the GH release. The delayed peaks of GH that followed L-tryptophan infusion may have been due to a release of insulin which then lowered blood sugar. However, it is more likely that these secretory episodes occurred independent of blood glucose changes, reflecting a normally occurring spontaneous release of GH unrelated to L-tryptophan administration. While the mechanism by which these compounds may exert such an effect is not known, both catecholaminergic and serotoninergic pathways were implicated.
NIOSH-Publication; NIOSH-Grant; Grants-other; Laboratory-animals; Hormone-activity; Anterior-pituitary-hormones; Short-term-exposure;
Author Keywords: Monoamine precursors; Growth hormone; EEG
Division of Neurology Montefiore Hosp and Med Center Division of Neurology Bronx, N Y 10467
Other Occupational Concerns; Grants-other
Montefiore Hospital and Medical Center, New York, New York