The Italian Wall Lizard Podarcis siculus as a Biological Model for Research in Male Reproductive Toxicology

Abstract

Spermatogenesis is a genetically driven differentiation process that occurs in the testis and leads to the formation of spermatozoa. This process is extensively studied in several experimental models, particularly in vertebrates that share the morphological structure and functionality of the mammalian testis. Although reptiles are not generally considered biological models, the lizard Podarcis siculus has represented a suitable organism for the study of spermatogenesis over the years. In this lizard, the process of spermatogenesis is regulated by the interaction between systemic factors such as gonadotropins and local factors, i.e., molecules produced by the somatic and germinal cells of the testis. Many exogenous substances are able to alter the production of these regulative factors, thus altering the course of spermatogenesis, and P. siculus has proven to be an excellent model for studying the effects of various endogenous or exogenous substances on mechanisms underlying spermatogenesis. This review summarizes the available data on the effects of different substances on the control of spermatogenesis, highlighting the induced morphological and molecular alterations. Overall, the data show that sex hormone levels as well as the final stages of spermatogenesis are most affected by an imbalance of endogenous compounds or contamination by environmental pollutants. This is helpful for the male individual, since the damage, not affecting the spermatogonial stem cells, can be considered transient and not irreversible.

Glyphosate Interference in Follicular Organization in the Wall Lizard Podarcis siculus

“…The most evident damage in Podarcis ovaries is observed in the theca, the collagen-rich compartment, enveloping the follicles, which become very thick and compact. Collagen accumulation has already been reported in the liver [ 24 , 34 ] and in the testis in Podarcis lizards [ 25 , 35 , 36 ] and rats [ 37 ]. Therefore, thecal cells are markedly compressed among fibers and apparently reduced in number.…”

Could Exposure to Glyphosate Pose a Risk to the Survival of Wild Animals? A Case Study on the Field Lizard Podarcis siculus

“…Thus, reptiles, not generally considered for toxicological studies, are becoming good unconventional animal models. Many current studies are investigating the consequences of pesticides and herbicides on terrestrial vertebrates using reptiles as model organisms [ 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 ]. The use of reptiles in toxicological studies, on the one hand, avoids experimentation on mammals, reducing ethical issues; on the other hand, it allows us to evaluate the effective risk that environmental contamination poses to these animals, opening up the possibility of drawing up specific protection plans for reptiles.…”

“…The use of reptiles in toxicological studies, on the one hand, avoids experimentation on mammals, reducing ethical issues; on the other hand, it allows us to evaluate the effective risk that environmental contamination poses to these animals, opening up the possibility of drawing up specific protection plans for reptiles. The first data were collected on turtles and crocodiles [ 34 , 35 ], while studies carried out on squamates, such as snakes and lizards, are becoming more common [ 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 36 ]. The latter are abundantly widespread in agricultural areas, and their diet is essentially based on insects [ 37 ]; consequently, they can be exposed to contaminants by ingestion and inhalation.…”

Molecular Research on Reproductive Toxicity

“…Finally, two articles published in this IJMS Special Issue [ 9 , 10 ] have an unconventional animal model as their subject, but which can be easily exposed in nature to environmental contamination, i.e., the field lizard Podarcis siculus . The first illustrates the adverse effects of glyphosate (Gly) on lizard testis.…”

“…The last article [ 10 ] is a review summarizing the available data on the effects of different environmental pollutants on the control of spermatogenesis in the lizard P. siculus . Data show that any exogenous substance capable of dysregulating the production of factors controlling spermatogenesis leads to the structural and functional alterations of the testis: changes in the levels of sex hormones, pituitary gonadotropins and androgen and estrogen receptors; the inhibition of aromatase enzyme; the thinning of seminiferous tubules epithelium; and the loss of connections between germ cells and Sertoli cells.…”