Sex steroid hormone secretion in the wall lizard Podarcis sicula testis: The involvement of VIP

Vasoactive intestinal peptide (VIP) is a pleiotropic neuropeptide involved in different functions, including testosterone synthesis. Recently, we reported the presence of VIP in the testis of Podarcis sicula, throughout the reproductive cycle. Now, we investigated the effects of the VIP on steroidogenesis in significant periods of the Podarcis reproductive cycle: winter stasis, reproductive period, and summer stasis. Using VIP treatments in testis culture in absence or presence of receptors antagonists, we demonstrated for the first time that in P. sicula, VIP is involved not only in testosterone synthesis, as in mammals, but in 17β-estradiol synthesis too