Comparison of the effect of apomorphine and L-DOPA on serum growth hormone levels in normal men.
Apomorphine hydrochloride (0.75 mg s.c.) has been compared with L-dopa (500 mg p.o.) in their effects on growth hormone secretion in a double blind cross-over study involving nine healthy men. Apomorphine increased serum GH levels above 10 ng/ml in all nine subjects 30-60 min after injection. In contrast, only six of these subjects showed a similar elevation with L-DOPA and in only three had the level increased above 6 ng/ml by 60 min. One subject failed to respond to L-dopa and in two others the peak was less than 6 ng/ml. GH levels were significantly higher at 30, 45 and 60 min following apomorphine than following L-dopa. Apomorphine-induced GH release was not related to changes in serum cortisol or blood sugar. Benztropine mesylate (1 mg i.m.) had no effect on apomorphine-induced GH release. These results suggest: (a) apomorphine may have advantages over L-dopa as a provocative agent to assess GH secretory capacity; (b) a dopaminergic mechanism subserves GH secretion; (c) cholinergic mechanisms do not antagonize dopaminergic-related GH release.
D000328:Adult; D001058:Apomorphine / Q000494:pharmacology*; D001590:Benztropine / Q000494:pharmacology; D001786:Blood Glucose / Q000032:analysis; D013006:Growth Hormone / Q000097:blood*; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D007980:Levodopa / Q000494:pharmacology*; D008297:Male; D009325:Nausea / Q000139:chemically induced; D010919:Placebos; D011863:Radioimmunoassay
D001786:Blood Glucose; D010919:Placebos; D001590:Benztropine; D007980:Levodopa; D013006:Growth Hormone; D001058:Apomorphine; D006854:Hydrocortisone