DOPAMINERGIC INHIBITION OF PULSATILE LUTEINIZING-HORMONE SECRETION ISABNORMAL IN REGULARLY MENSTRUATING WOMEN WITH INSULIN-DEPENDENT DIABETES-MELLITUS

Objective: To examine the influence of low doses of dopamine (DA) (0.4 mu g/kg per minute), on the secretion pattern of LH. Design: Prospect ive randomized, single blind, placebo-controlled crossover study with infusion of DA or placebo in the follicular phase in regularly menstru ating women with insulin-dependent diabetic mellitus (IDDM) and contro ls during 9.5 hours. Setting: Department of Endocrinology, Odense Univ ersity Hospital, Odense, Denmark. Patients: Eight regularly menstruati ng IDDM women and eight controls. Main Outcome Measures: Mean LH, LH p ulse amplitude, and LH pulse frequency. Results: During placebo infusi on no significant differences in basal LH values, pulse amplitude, and pulse frequency were seen between IDDM women and controls. In diabeti cs, 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 place bo (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 diabeti c women (11.8 +/- 2.1 versus Conclusion: These results suggest that di abetic women are more sensitive to a small increase in peripheral DA c oncentration. An abnormal permeability of the blood-brain barrier in I DDM patients could explain a greater exposure of the hypothalamic stru ctures, regulating the pituitary gonadotropin hormone secretion.