[Attempt at potentiation of the action of L-dopa on the secretion of growth hormone by benserazide, disulfiram and propranolol].

Two tests of stimulation of growth hormone secretion were performed in 3 groups of normal children. In the first test L-Dopa was used on its own; in the second, L-Dopa was combined with Benserazide (group A), with Disulfirame (group B), or with Propranolol (group C). In group A the mean peak value after L-Dopa was 9.1 +/- 1.6 ng/ml; with the combination of L-Dopa and Benserazide it was 12.4 +/- 2.4 ng/ml. The difference between the means is not significant. In group B the mean peak value after L-Dopa was 8.9 +/- 3.6 ng/ml; with the combination of L-Dopa and Disulfirame it was 14.5 +/- 4.4 ng/ml. The difference is not significant. In group C the mean peak value after L-Dopa was 9.8 +/- 2.6 ng/ml; with the combination of L-Dopa and Propranolol, it was 10.1 +/- 1.9 ng/ml. Again the difference is not significant. These findings do not provide evidence in favour of the effect of L-Dopa on the secretion of growth hormone being facilitated by an inhibitor of L-Dopa decarboxylase (Benserazide) or of Dopamine beta hydroxylase (Disulfirame), or by a beta blocking agent (Propranolol). The mechanisms of action of L-Dopa and of the various combinations studied are discussed.