Effect of alpha-MSH on plasma levels of LH, FSH, progesterone and cortisol during the corpus luteum phase of the menstrual cycle.

In healthy women (21-28 years) the influence of synthetic alpha-MSH upon the peripheral plasms levels of LH, FSH, progesterone and cortisol was determined during the corpus luteum phase of the menstrual cycle. As controls 3 women were given 6 intravenous infusions of 250 ml NaCl; 4 women received a total of 18 intravenous infusions of 5-20 mg alpha-MSH from 9.00 to 11.00 a.m. on the 5th and 7th hyperthermic day of the menstrual cycle. The blood levels of the hormones were usually followed for 24 h, and in two cases for 48 h. During and after the control as well as the experimental infusions with 5-20 mg alpha-MSH, no significant changes in the plasma concentrations of LH, FSH and progesterone were found. The cortisol concentrations, however, showed on the average a 2-fold increase over the initial values during the infusion of 5 mg and 10 mg alpha-MSH. During the control infusions they were not enhanced. One experiment was conducted with 20 mg alpha-MSH. The increase in the plasma cortisol levels following alpha-MSH administration generally seemed to be dose dependent, but statistically no significant differences regarding the increase in cortisol level could be detected between the 5 mg and 10 mg doses.