Identification of a cDNA encoding for Ghrelin in the testis of the frog Pelophylax esculentus and its involvement in spermatogenesis.

GHRELIN (GHRL) is an acylated peptide that contains 28-amino acids prevalently expressed in the stomach of several species. Specifically, it contributes to energy balance, but some new evidence highlights its role in the regulation of reproductive functions. In fact, this protein has been detected at testicular level in the tubular and interstitial compartments of several vertebrate species, and previous research has demonstrated that GHRL affects various aspects of spermatogenesis and steroidogenesis. GHRL clearly plays an inhibitory role in mammalian reproduction, in contrast GHRL stimulates reproductive functions in non mammalian vertebrate. We have focused our attention on the comparative aspect of GHRL, thus studying its expression in an amphibian seasonal breeder, Pelophylax esculentus, to verify the presence and localization, of Ghrl transcript variations during the frog reproductive cycle, in order to demonstrate that Pelophylax esculentus may represent a useful animal model to assess the role of GHRL in male fertility.