Suppression of prolactin and growth hormone responses to 2-deoxy-D-glucose-induced glucoprivation by mazindol in humans

Abstract

Glucoprivation induced by 2-deoxy-D-glucose (2DG) 20 min infusions (50 mg/kg) increases growth hormone (GH) and prolactin (PRL) levels in humans. To determine if mazindol, a potent dopamine (DA) and norepinephrine (NE) reuptake blocking agent, might affect basal and stimulated GH and PRL levels in healthy male and female volunteers, mazindol (1 mg,TID,po) or placebo were administered for one week before 2DG infusions. Plasma samples for glucose, epinephrine (E), NE, PRL, and GH were collected before and after 2DG infusions. During placebo and mazindol therapy, basal values (ng/ml) did not differ for either PRL (8.8 ± 1.6 versus 8.9 ± 1.5 in females and 8.3 ± 0.9 versus 7.7 ± 0.6 in males) or GH (1.6 versus 1.7 ± 0.1 in males and 6.6 ± 3.3 versus 7.0 ± 2.6 in females). Peak stimulated PRL levels were greater in females than in males (97.1 ± 26.2 versus 21.4 ± 5.3 ng/ml, p < 0.05) while peak stimulated GH levels were greater in males than in females (28.2 ± 1.7 versus 7.0 ± 2.0 ng/ml, p < 0.05). Mazindol therapy reduced 2DG-stimulated PRL responses (ng/ml) from 97.1 ± 26.2 to 44.4 ± 25.3 (p < 0.0125) and from 21.4 ± 5.3 to 13.6 ± 3.4 (p < 0.025) in females and males respectively, and GH responses (ng/ml) from 28.2 ± 1.7 to 13.1 ± 3.8 (p < 0.05) and from 10.2 ± 2.0 to 3.4 ± 0.1 (p < 0.05) in males and females respectively, but baseline PRL and GH levels were unaffected. A 50%–60% overall suppression of stimulated GH and PRL levels by mazindol was not significantly different between sexes and not consistently related to elevations in plasma glucose or E although stimulated plasma NE levels were higher during mazindol therapy.