[Study on human pituitary gonadotropin synthesis and release during gestation by two steps LH-RF stimulation...

The pituitary gonadotropin response of synthesis and release to two step-stimulation at 60 minutes interval by 100 micrograms of luteinizing hormone-releasing factor was studied by radioimmunoassay of hLH-beta, hLH and hFSH in pregnant women. The immunological affinity of hLH-beta antiserum was 7.9% with hCG-beta, 3.4% with hLH-alpha and 0.41% with LER 907 as compared to 100% with hLH-beta. Serum mean levels of hLH in non pregnant women were 248.5 ng/ml serum before the first injection of LH-RF. The first injection caused an increase in the serum hLH level to 2185.0 ng/ml serum. After the second injection of the hormone, serum hLH levels increased further than the first peak, indicating the "self-stimulating" or "priming" effect of the first LH-RF on the second peak. Serum mean values of hLH-beta in normal menstrual women were 2.60 ng/ml before the first injection. The hLH-beta response to the second injection was significantly greater than to the first. The first peak of hLH-beta was 4.30 ng/ml serum and the second peak was 5.07 ng/ml serum. The FSH response to the second injection of LH-RF was not significantly peaked from that after the first injection. The value of the serum mean levels of hLH-beta during pregnancy were between 0.57 and 0.81 ng/ml and showed no significant increase through two LH-RF stimulations, suggesting that pituitary gonadotropins synthesis and release were depressed during gestation. Thus LH-RF two step stimulation was useful to clarify anterior pituitary function in both synthesis and release of gonadotropin.