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Over the last few decades, due to its relevant function in male reproduction assessment, important molecular achievements have been made in the molecular characterization of estrogen receptor genes in various species. Our work focuses on a male seasonal breeder, the bioindicator Podarcis sicula, because of its peculiar gonadal anatomy, similar to that of humans. Based on the cloned lizard’s gene sequence fragment of estrogen receptor beta, esr2 (GenBank JN705543.1), we found DNA binding domain identity of 99% as well as a homologous sequence with humans. Furthermore, in order to better illustrate how this gene is regulated in the lizard’s reproductive system organs, we investigated the transcriptional activity of esr2 in brain and testis tissues during mating and winter stasis phases of the reproductive cycle. Quantitative real time-polymerase chain reaction (qRT-PCR) analyses performed on male gonadal tissues demonstrate a significant increase in esr2 expression during mating compared to the winter stasis period, while in the brain, esr2 shows the opposite trend. Next, we provide morphological evidence of the detrimental effect on spermatogenesis of a pure anti-estrogen treatment (ICI 182,780) and the corresponding effect on esr2 expression in lizard specimens during the mating period which, upon treatment, was found to be no different from the expression levels in winter stasis both in the brain and in the testis. In this study, we explore the potential use of Podarcis sicula as a model for human testis development and maturation, as well as esr2 expression for toxicological screening in one-testis gonadectomy.

Alburnus albidus is an endangered and little known cyprinid fish species endemic in southern Italy. Histological characteristics of testes of A. albidus from River Alento, Campania Region, were analysed every month between January‐July 1996. Depending on the relative abundance of spermatogonia, spermatocytes, sper‐matides and spermatozoa in the testes, we devided the gonadal cycle into four stages: 1. quiescence, when mainly spermatogonia were present (January‐February); 2. recrudescence, when spermatocytes were abundant, although spermatids were also detectable (March‐April); 3. spawning, when cysts contained all stages of germ cells (May‐June); 4. Postspawning, when testes contained spermatogonia only (July). The concentration of sex steroids (an‐drogens, 17 α‐hydroxyprogesterone and 17 β‐estradiol) fluctuated throughout the year. Androgen levels were high during the quiescence and the spawning periods. 17 α‐hydroxyprogesterone concentration showed a sharp increase just before the spawning peri...

The evolution of sex steroids in the plasma and gonads of the lizard Podarcis s. sicula during the postreproductive period shows that these hormones could be involved in determining refractoriness. In the male, during this phase, the oestradiol could lower the hypothala‐mo‐hypophyseal system through a negative feed‐back. In the female a similar role could be assigned to progesterone.

Adult males of the lizard, Podarcis s. sicula Raf., were treated with arginine-vasotocin (AVT) during the reproductive period to investigate its effects on the spermatogenic and endocrine activities of the testis. Results showed that AVT can affect gonadal activity by blocking spermiohistogenesis and inhibiting interstitial tissue.