Effect of heat stress on Leptin hormone level and their relationship with sexual puberty in male rats

Abstract

This study aimed to show the effect of induced acute and chronic heat stress on leptin level and their relationship to puberty in male rats. Forty five (45) pups male rats divided randomly at weaning to 3 groups (15 males in each group). G1 (non-treated-control group), G2 (exposed to chronic heat stress) (38C°for 1 hour) daily from weaning to puberty, and G3 (exposed to acute heat stress (38C° for 4 hours at 35 day age for 5 successive days). Each of these groups are subdivided to 3 stages (pre, at , post puberty) (5 males for each stage). Serum samples from each stage of puberty were used for detection leptin and heat shock protein 70 by sandwich ELISA. The results showed significant increase of liptin in G2 and 3 in comparison with G1 (in pre and pubertal stages), while in the post pubertal stage this hormone decreased in G2 in comparison with G3. No significant differences between the 3 groups in pre and pubertal stages, while there is significant decrease in HSP70 occur in G2 in comparison with G1 and 2. First sperm occur in G3 at day 50 of age then G1 at 51 days, but the appearance of sperm delayed till 65 day age in G2. Thus the heat effect was positive in G3 and cause increasing HSP70 then leptin which lead to occurrence of puberty in this group firstly, while the puberty delayed in G2 as a result of negative effect of continuous exposure to heat in male rats.