Effects of steroid hormones on spermatogenesis and GnRH release in male Leopard frogs, Rana pipiens

摘要: Several lines of evidence suggest reproduction in the ranid frogs is potently regulated by gonadal steroids, particular 5α-dihydrotestosterone (DHT) and 17β-estradiol (E2), a non-gonadal steroid, stress hormone corticosterone (Cort). Little known about how these steroid hormones act upon GnRH system to regulate downstream reproductive events. We address gaps our knowledge investigating effects Cort, E2, DHT administration on vitro release spermatogenesis adult male leopard frog, Rana pipiens. R. pipiens were implanted for 20 days with silastic capsules containing cholesterol (Ch; control), or DHT. Upon sacrifice, acute hypothalamic explants cultured measured release, testes processed histological analysis. Although only E2 implant significantly reduced gonadosomatic index, all three altered spermatogenesis. Cort modestly but presence spermatids. The both stimulatory inhibitory, depending stage None baseline release. Interestingly, stimulated veratridine-induced suggesting treatment increased releasable pool and/or enhance excitability neurons. In sum, this first study report direct measurement secretion poikilothermic tetrapod. Our results revealed potent sometimes paradoxical hormones, especially regulation