[Effects of a new analogue of LH-RH, D-Ser(TBU)6- EA10-LH-RH, on gonadotropin liberation in males (author's transl)].

Effects on the secretion of gonadotropins by D-Ser (TBU)6-EA10-LH-RH were investigated in 7 male volunteers without known endocrine disturbances. One week after subcutaneous injection of 100 mug of LH-RH the probands were given 5 mug of the LH-RH analogue subcutaneously into the abdominal wall. LH, FSH and testosterone concentrations were estimated in the serum and compared with each other at varying intervals after each injection. LH-RH caused a marked increase of the LH content in serum after 20 minutes with a maximum after 40 minutes. The effect of the analogue occurred with a delay. After 40 minutes an LH level was reached which still persisted 6 hours later. Contrary to LH there were considerable individual differences in serum FSH levels. In the initial phase after injection of LH-RH and LH-RH analogue that increase of the FSH level in serum was almost parallel. However, the analogue showed a marked depot effect. Serum concentrations of testosterone showed no significant changes after administration of the releasing hormones. D-Ser(TBU)6-EA10-LH-RH is approximately 20 times effective as LH-RH. A dose of 5 mug is effective for 6-8 hours.