Effects of two kinds of chicken luteinizing hormone-releasing hormone (LH-RH), mammalian LH-RH and its analogs on the release of LH and FSH in Japanese quail and chicken.

A newly isolated and characterized chicken luteinizing hormone-releasing hormone-II (chicken LH-RH-II, Miyamoto et al., 1984) had luteinizing hormone (LH) and follicle-stimulating hormone (FSH) releasing activity in vitro and in vivo in Japanese quail: the activity was almost equal to chicken LH-RH-I and mammalian LH-RH. These three LH-RHs induced the release of LH several times higher than that of FSH in vitro and also in vivo. No significant difference between chicken LH-RH-I and LH-RH-II was observed in LH releasing activity in vitro using chicken pituitary gland in the same incubating condition as in quail. Another experiment indicated that no synergism existed between chicken LH-RH-I and -II and that there was neither LH nor FSH releasing activity in [D-Phe2, Pro3, D-Phe6]-LH-RH or in mesotocin. However, the same potency as in the chicken LH-RH-II was observed in [D-Ala6, des-Gly10]-LH-RH ethylamide, a superactive analog in mammals. The results indicate that an avian adenohypophysis differs from a mammalian adenohypophysis in its responsiveness to LH-RH suggesting that an avian LH-RH receptor may have a lower specificity in "recognition" of LH-RH molecules than a mammalian LH-RH receptor has.