REPRODUCTIVE FUNCTIONS IN HEAT ADAPTED FEMALE WISTAR RATS

Heat adaptation is the physiologic adaptation that occur in response to recurrent elevations in core and skin temperatures from high ambient temperatures over the course of 7-14 days or more, prompting the negative responses of heat stress. Heat adaptation plays a large role in the physical response and overall ability of the body to cope with heat exposure. The current climate change with attendant heat waves served as the basis to study the adaptive mechanism to the increase in environmental temperature. This study was therefore aimed at investigating the effect of heat-adaptation on the reproductive functions of female rats. A total of 48 (36 adult and 12 immature) virgin female Wistar rats and 6 male Wistar rats were used for this study. Experiment was carried out in different phases, with all phases having 6 animals each in control and heat adapted groups. The rats in heat adapted groups were housed in a special heated chamber 5 hours per day, maintaining a constant ambient temperature of 34-39°C for the different study phases, the control group animals were kept in an ambient temperature of 25-30°C. Baseline parameters and samples collected were used for estrous cycle classification, uterine contractility, hormonal, histological and gene expression assays. Statistical analysis was done using the GraphPad Prism version 8.1. It was observed in this study that heat adaptation had no significant effect on estrus cyclicity, uterine and ovarian weight, uterine and ovarian morphology, female reproductive hormonal levels, and contractility of both pregnant and non-pregnant isolated uterus as well as litter size and weight. There was a significant increase in both surface and core body temperature of the heat adapted group compared to the control group. Heat shock protein-70 (HSP-70) was significantly (P<0.05) upregulated in the heat adapted group. In conclusion relatively stable reproductive indices are associated with heat adapted female rats while significantly up-regulated Heat shock protein-70 (HSP-70) gene could be the regulatory adaptive mechanism to prevent any negative consequences.