Antigonadotropic activity of two fractions of melatonin-free pineal extract separated by ultrafiltration

Using the mouse uterus weight test and the rat ventral prostate weight test in basal conditions and under exogenous stimulation, the activity of 2 fractions of molecular weight above and under 10,000 daltons obtained by ultrafiltration of a melatonin-free pineal extract was tested against a total pineal extract and the same extract subjected to dialysis. The results showed that the larger fraction is predominantly anti-LH whereas the smaller fraction is anti-FSH. The antigonadotropic activity of the total and partially purified pineal extract against the effects of pineal melatonin and arginine-vasotocin is discussed.