The effect of naloxone and metoclopramide on the hypothalamic pituitary axis in oligomenorrheic and eumenorrheic swimmers.

Eight highly competitive swimmers were followed over a 9-month period during a vigorous training schedule. When compared, four oligomenorrheic (group I, greater than 60 days without menses) and four eumenorrheic (group II) swimmers were not significantly different for age, years of training, body fat, intensity of training, and baseline estradiol (E2) levels. Both groups were challenged during the peak of their training schedule with 10 mg of naloxone and 10 mg of metoclopramide. The naloxone infusion revealed a significant increase in baseline luteinizing hormone (LH) levels in the oligomenorrheic swimmers when compared with the eumenorrheic swimmers. During the metoclopramide infusion prolactin (PRL) increased in all subjects, with a slightly higher increase in PRL in the eumenorrheic swimmers. The study suggests the menstrual dysfunction observed in these strenuously training swimmers to be related to the abnormalities of endorphin physiology as revealed by the elevation in LH after a naloxone infusion.