Altered growth hormone and prolactin responses to dopaminergic stimulation in Huntington's chorea

Seven patients affected by Huntington's chorea were given an acute administration of 2-Br-alpha-ergocryptine (CB 154, Sandoz), a direct agonist at dopamine receptor sites. Seven nonobese hospitalized patients were used as controls. Oral administration of CB 154 (2.5 mg) induced a more prompt and consistent rise in plasma growth hormone (GH) levels in patients than in controls. GH levels rose from baseline values of 0.3+/-0.1 ng/ml to mean peak values of 20.4+/-5.1 ng/ml (120-270 min) in choreic subjects and from baseline values of 1.0+/-0.4 ng/ml to mean peak values of 5.7+/-1.6 ng/ml (180-300 min) in control subjects (P less than 0.02). Baseline plasma prolactin (PRL) values were significantly higher in choreic than in control subjects (22.1+/-6.6 ng/ml vs. 8.1+/-1.4 ng/ml, respectively, P less than 0.02); administration of CB 154 induced a more consistent PRL decrease in control than in choreic subjects. Collectively, these results suggest the existence of an abnormal regulation of GH and PRL secretion in Huntington's chorea, probably due to alterations in central dopaminergic neurotransmission.