Effects of long-term heat stress and dietary restriction on the expression of genes of steroidogenic pathway and small heat-shock proteins in rat testicular tissue.

The aim was to investigate the effects of long-term heat stress and dietary restriction on the expression of certain genes involving in steroidogenic pathway and small heat-shock proteins (sHSPs) in rat testis. Sprague Dawley rats (n = 24) were equally divided into four groups. Group I and II were kept at an ambient temperature of 22°C, while Groups III and IV were reared at 38°C for 9 weeks. Feed was freely available for Group I and Group III, while Group II and Group IV were fed 60% of the diet consumed by their ad libitum counterparts. At the end of 9 weeks, testicles were collected under euthanasia. Total RNA was isolated from testis tissue samples. Expression profiles of the genes encoding androgen-binding protein, follicle-stimulating hormone receptor, androgen receptor, luteinising hormone receptor, steroidogenic acute regulatory protein (StAR), cyclooxygenase-2 and sHSP genes were assessed at mRNA levels using qPCR. Long-term heat stress decreased the expression of StAR and HspB10 genes while dietary restriction upregulated StAR gene expression. The results suggested that long-term heat stress negatively affected the expression of StAR and HspB10 genes and the dietary restriction was able to reverse negative effect of heat stress on the expression of StAR gene in rat testis.