Cryoprotective effects of low-density lipoproteins, trehalose and soybean lecithin on murine spermatogonial stem cells

Heat stress disrupts spermatogenesis via modulation of sperm-specific calcium channels in rats

Heat is a detrimental environmental stressor that disrupts spermatogenesis and results in male infertility. Previous investigations have shown that heat stress reduces the motility, number, and fertilization ability of living spermatozoa. Sperm hyperactivation, capacitation, acrosomal reaction, and chemotaxis towards the ova are regulated by the cation channel of sperm (CatSper). This sperm-specific ion channel triggers the influx of calcium ions into sperm cells. The aim of this study in rats was to investigate whether heat treatment affected the expression levels of CatSper-1 and -2, together with the sperm parameters, testicular histology and weight. The rats were exposed to heat stress for 6 days and the cauda epididymis and testis were collected 1, 14, and 35 days after heat treatment to measure sperm parameters, gene and protein expression, testicular weight, and histology. Interestingly, we found that heat treatment caused a notable downregulation of CatSper-1 and -2 expression at all three time points. In addition, there were significant reductions in sperm motility and number and an increase in the percentage of abnormal sperm at 1 and 14 days, with cessation of sperm production at 35 days. Furthermore, expression of the steroidogenesis regulator, 3 beta-hydroxysteroid dehydrogenase (3β-HSD) was upregulated in the 1-, 14- and 35-day samples. Heat treatment also upregulated the expression of the apoptosis regulator, BCL2-associated X protein (BAX), decreased testicular weight, and altered testicular histology. Therefore, our data showed for the first time that heat stress downregulated CatSper-1 and -2 in the rat testis, and that this may be a mechanism involved in heat stress-induced impairment of spermatogenesis.

Exertional heat stroke on fertility, erectile function, and testicular morphology in male rats

The association of exertional heat stroke (EHS) and testicular morphological changes affecting sperm quality, as well as the association of EHS and hypothalamic changes affecting sexual behavior, has yet to be elucidated. This study aimed to elucidate the effects of EHS on fertility, erectile function, and testicular morphology in male rats. Animals were exercised at higher room temperature (36 ℃ relative humidity 50%) to induce EHS, characterized by excessive hyperthermia, neurobehavioral deficits, hypothalamic cell damage, systemic inflammation, coagulopathy, and multiple organ injury. In particular, EHS animals had erectile dysfunction (as determined by measuring the changes of intracavernosal pressure and mean arterial pressure in response to electrical stimulation of cavernous nerves). Rats also displayed testicular temperature disruption, poorly differentiated seminiferous tubules, impaired sperm quality, and atrophy of interstitial Leydig cells, Sertoli cells, and peri-tubular cells in the testicular tissues accompanied by no spermatozoa and broken cells with pyknosis in their seminal vesicle and prostatitis. These EHS effects were still observed after 3 days following EHS onset, at least. Our findings provide a greater understanding of the effect of experimentally induced EHS on masculine sexual behavior, fertility, stress hormones, and morphology of both testis and prostate.

Comparative proteomic analysis of heat stress proteins associated with rat sperm maturation

Heat stress is demonstrated to have an effect on the function of the male testis, however, limited information has been reported on its effects on sperm maturation. In the present study, a comparative proteomic analysis was performed on the rat caput epididymal fluids responsible for sperm maturation, to identify key heat‑stress‑associated sperm maturation proteins. The results demonstrated 21 proteins corresponding to 29 differential protein spots, including 10 downregulated and 11 upregulated proteins in the heat treatment group. Functional analysis demonstrated that these proteins were primarily involved in enriched reproduction and antioxidant activity. Analysis of western blot and immunohistochemical analysis demonstrated that the expression of antioxidant proteins peroxiredoxin 6 and clusterin were downregulated, and the expression of superoxide dismutase upregulated, in the heat treatment group. Morphological and TUNEL experiments demonstrated that altered nucleus activity occurred in the caput epididymis. The study provided, to the best of our knowledge, novel information for studies on the biological functions of the epididymis and sperm maturation.