Dopaminergic inhibition of pulsatile luteinizing hormone secretion is abnormal in regularly menstruating women with insulin-dependent diabetes mellitus

Abstract

To examine the influence of low doses of dopamine (DA) (0.4 micrograms/kg per minute), on the secretion pattern of LH. Prospective randomized, single blind, placebo-controlled crossover study with infusion of DA or placebo in the follicular phase in regularly menstruating women with insulin-dependent diabetic mellitus (IDDM) and controls during 9.5 hours. Department of Endocrinology, Odense University Hospital, Odense, Denmark. Eight regularly menstruating IDDM women and eight controls. Mean LH, LH pulse amplitude, and LH pulse frequency. During placebo infusion no significant differences in basal LH values, pulse amplitude, and pulse frequency were seen between IDDM women and controls. In diabetics, basal LH levels and pulse amplitude decreased significantly during DA infusion (3.1 +/- 1.2 mIU/mL (conversion factor to SI unit, 1.00; mean +/- SD) and 0.9 +/- 0.3 mIU/mL, respectively) compared with placebo (4.5 +/- 1.1 and 1.2 +/- 0.4 mIU/mL, respectively). In normal women no significant changes were observed (basal LH 3.0 +/- 1.8 versus 3.2 +/- 1.6 mIU/mL and pulse amplitude 1.6 +/- 0.6 versus 1.5 +/- 0.9 mIU/mL). The LH pulse frequency during DA infusion was not different from placebo in either normal (9.0 +/- 2.7 versus 10.3 +/- 4.0) or diabetic women (11.8 +/- 2.1 versus 10.9 +/- 1.8). These results suggest that diabetic women are more sensitive to a small increase in peripheral DA concentration. An abnormal permeability of the blood-brain barrier in IDDM patients could explain a greater exposure of the hypothalamic structures, regulating the pituitary gonadotropin hormone secretion.