Amplification of LH response to LHRH by dopamine infusion in eugonadal women

Although the role of biogenic amines in the regulation of gonadotropin release has been studied extensively, the precise role of dopamine (DA) in stimulating LHRH and/or LH release is still controversial. In the present study 6 eugonadal women, aged 20–30, were given an LHRH infusion on day 6 of the menstrual cycle and the pattern and magnitude of LH and FSH responses were estimated. On day 6 of the next cycle, the experiment was repeated and DA was also infused beginning 60 min after the start of the LHRH infusion. Following LHRH infusion plasma LH showed a marked and significant rise with a mean peak increment at 4 h, and with a cumulative response (CR) of 9136 ± 955 mlU/ml/6h. The pattern of FSH response tended to parallel that of LH; however, mean peak increment at 4 h and a CR of 2640±169 mlU/ml/6h were markedly lower. Plasma prolactin levels remained unchanged. Addition of DA to LHRH at 60 min evoked a significantly greater mean peakLH increment at 4 h and a CR of 15514±1836 mlU/ml/6h (p < 0.001). There were no significant changes in either mean FSH peak at 4h or in the CR (3257 ± 309 mlU/ml/6h). As expected, a highly significant (p < 0.001) decrease in circulating PRL from 12.1 ± 3.1 to 3.0 ± 1.5 ng/ml was seen during DA infusion. In conclusion, DA given by iv infusion enhances LH response to LHRH in eugonadal women under the conditions of the present investigation, supporting a role for a dopaminergic component in the control of LH release in women.