First evidence of a cDNA encoding for a melatonin receptor (mel 1b) in brain, retina, and testis of Pelophylax esculentus.

Melatonin, nocturnally secreted by the pineal gland, regulates a variety of physiological functions, including reproduction. Here, we investigated the evidence of melatonin binding sites in frog tissue (brain, retina, and testis) through saturation and competition binding experiments. In the frog, Pelophylax esculentus, our results confirm the presence of a single class of melatonin-specific binding sites in the brain and retina, but not in the testis.

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.

Expression of prothymosin alpha in meiotic and post-meiotic germ cells during the first wave of rat spermatogenesis.

Prothymosin alpha (PTMA) is a highly acidic small polypeptide, that is, widely distributed and conserved among mammals. Its possible involvement in male gametogenesis has been mentioned but not clarified yet; in particular, it has been suggested that, in non-mammalian vertebrates, it could play a role during GC meiosis and differentiation. In the present work we investigated the possible association between PTMA and meiotic and post-meiotic phases of mammalian spermatogenesis.

Expression of melatonin (MT1, MT2) and melatonin-related receptors in the adult rat testes and during development.

It is well known that melatonin provokes reproductive alterations in response to changes in hours of daylight in seasonally breeding mammals, exerting a regulatory role at different levels of the hypothalamic-pituitary-gonadal axis. Although it has also been demonstrated that melatonin may affect testicular activity in vertebrates, until now, very few data support the hypothesis of a local action of melatonin in the male gonads. The aim of this study was to investigate whether MT1, MT2 melatonin receptors and the H9 melatonin-related receptor, are expressed in the adult rat testes and during development.

Evidence for the involvement of prothymosin alpha in the spermatogenesis of the frog Rana esculenta.

Prothymosin alpha (PTMA) is a small acidic protein abundantly and ubiquitously expressed in mammals and involved in different biological activities. Until now, its specific function in spermatogenesis has never been properly investigated. Recently, the isolation of a cDNA encoding for PTMA from the testis of the frog Rana esculenta has been reported: ptma transcript is highly expressed throughout the frog reproductive cycle, peaking in September/October, in concomitance with the germ cell maturation; it is specifically localized in the cytoplasm of primary and secondary spermatocytes and, at a lower level, in the interstitial compartment, in Leydig cells.

Effects of melatonin treatment on Leydig cell activity in the testis of the frog Rana esculenta.

This study was conducted to verify the effect(s) of melatonin treatment on frog Leydig cells. Morphological observation after melatonin treatment indicates that many frog Leydig cells show degenerative changes (i.e.

Inhibition of the increased 17beta-estradiol-induced mast cell number by melatonin in the testis of the frog Rana esculenta, in vivo and in vitro.

In the present study, we have utilized 17beta-estradiol to induce the increase of mast cell number in order to verify the melatonin effect on mast cell accumulation in the frog testicular interstitium. Data obtained from in vivo experiments confirm that 17beta-estradiol increases the mast cell number and indicate a melatonin-inhibitory role in their accumulation in the frog testis. In addition, melatonin interferes with the effects of estradiol on the increase of mast cell number in short-term cultured testes, and this result has also been obtained in a dose-response experiment at physiological concentration.

Ethane 1,2-dimethane sulphonate is a useful tool for studying cell-to-cell interactions in the testis of the frog, Rana esculenta.

Ethane 1,2-dimethane sulphonate (EDS), a toxin which specifically destroys Leydig cells (LC), has been used to study cellular interactions in the testis of the frog Rana esculenta. Animals received three consecutive EDS injections and were sacrificed on day 4, 8, and 28 from the first injection. No significant morphological differences were observed between present observation and that obtained, in a previous experiment, after four consecutive EDS injections.