Impaired metoclopramide-induced pituitary prolactin release in men with human immunodeficiency virus infection

To investigate whether metoclopramide-induced prolactin release is impaired in HIV-infected men, we studied 10 clinically healthy HIV-negative adult m en (group 1) and 10 consecutive HIV-positive adult men (group 2) with anti- HIV antibodies confirmed by Western blot analysis and a CD4 cell count from 13 to 570 x 10(6)/L. After a 10- to 12-hour overnight fast, three basal bl ood samples were obtained at 15-minute intervals (-30, -15, and 0 minutes) and thereafter at 15, 30, 60, 90, 120, 180, and 240 minutes after a 10-mg i ntravenous bolus of metoclopramide. Duplicate serum prolactin concentration s were measured in each sample with commercially available radioimmunoassay kits. No significant differences between groups were observed in basal pro lactin levels. Group 2 had lower serum prolactin concentrations than group 1 throughout the test (P less than or equal to .002), The area under the pr olactin curve (mean +/- SD) was also lower in group 2 than in group 1 (7156 +/- 1433 ng/mL/240 min vs 12430 +/- 2454 ng/mL/240 min, P < .0001), and th e area under the prolactin curve had a significant correlation with the CD4 cell counts (r = 0.7912, P < .001), These findings suggest that the hypoth alamic dopaminergic tone, although present, was clearly diminished in these HIV-positive men regardless of their clinical stage.