Apomorphine-stimulated growth hormone release

Abstract

Apomorphine, a dopaminergic receptor stimulant, was tested and compared in subemetic doses (0.76 mg subcutaneously) to levodopa (500 mg orally) as a stimulant of growth hormone release in 10 normal volunteer subjects (five male, five female). The administration of levodopa failed to cause a normal increment in serum growth hormone levels (greater than 5 ng/ml from base line) in four patients, produced a borderline normal response in two patients with a normal response in four patients. Apomorphine stimulation produced a borderline normal response in one patient and a normal response in the remaining nine patients. The peak response to apomorphine administration was 26.94 +/- 6.60 ng/ml and to levodopa 9.76 +/- 2.67 ng/ml (p less than 0.025). There was no statistical difference between men and women in whom apomorphine testing was utilized. Side effects (nausea, vomiting) were seen in three patients tested with levodopa and in four patients tested with apomorphine. Such symptoms began within 20 minutes of apomorphine administration, persisted from 30 to 40 minutes and disappeared abruptly. All patients treated with apomorphine noted transient drowsiness.