Effects of follicular-phase cocaine administration on menstrual and ovarian cyclicity in rhesus monkeys.

OBJECTIVE

The purpose of this study was to evaluate the effects of daily follicular-phase cocaine administration on menstrual cyclicity, gonadotropin and ovarian steroid levels, ovulation rates, and corpus luteum function in cycling rhesus monkeys.

STUDY DESIGN

Thirteen normally cycling, drug-naive adult rhesus monkeys were randomized to receive daily intravenous injections of either 4 mg/kg cocaine or an equal volume of saline solution. Treated animals were yoked to pair-fed controls to minimize differences in caloric intake. Daily blood samples were obtained through indwelling catheters for measurement of serum gonadotropin and ovarian steroid levels. Daily vaginal swabs were obtained to determine the onset of menses. Laparoscopy was performed 2 days after the midcycle estrogen peak to check for ovulation. Daily caloric intakes and pretreatment and posttreatment weights were recorded.

RESULTS

All six of the control monkeys had laparoscopically confirmed ovulation compared with one of seven in the cocaine-treated group (p < 0.004). Cycle length was normal in five of six controls versus one of seven cocaine-treated monkeys. Estradiol levels were significantly higher in the controls versus the cocaine-treated monkeys (p = 0.01) during the first 14 days of the treatment cycle. There were no differences in basal plasma gonadotropin levels between groups. Luteal-phase lengths and luteal-phase plasma progesterone levels were similar in the controls and the single ovulatory cocaine-treated monkey. There were no significant differences in weight change or caloric intake between the two groups.

CONCLUSIONS

Daily follicular-phase cocaine administration disrupts menstrual cyclicity and folliculogenesis independent of weight loss, caloric intake, and basal gonadotropin levels.