Episodes of hyperthermia occur frequently from exposure to infections or adverse
climatic changes. Such hyperthermia has been linked to various detrimental health
effects. This study aimed to investigate the pathophysiological responses to acute
versus subacute whole-body hyperthermia (WBH) in rats, particularly on the brain,
with special reference to their medicolegal importance. Rats were randomly assigned to
three equal groups. The normothermic group was kept at room temperature, the acute
whole-body hyperthermic (AWBH) group was subjected to long-period WBH as a single
bout of 4 hours at 43 °C, and the subacute whole-body hyperthermic (SWBH) group was
subjected to repeated short-period WBH;2 hours daily for 7 successive days at 43°C. A
significant increase in body temperature and a significant decrease in body weight were
recorded in both the acute and subacute hyperthermic groups. However, significant
elevations in the serum glucose and cortisol levels and in the brain malondialdehyde
and 8-hydroxy-2'-desoxyguanosinelevels, with a significant reduction in brain total
antioxidant capacity, were observed only in the AWBH group. Moreover, exposure to
WBH induced various degrees of pathological changes, along with positive immune
reactivity for heat shock protein 70 and glial fibrillary acidic protein in the cerebrum
and cerebellum of rats in both hyperthermic groups. Overall, WBH induced various
adverse health effects, mediated by the induction of oxidative damage, particularly
following acute exposure. Hence, these findings provide evidence that acute exposure to
long-term WBH may markedly exacerbate brain injury more than repeated short-term
exposure, reflecting the role of the adaptive mechanisms to repeated heat exposure.
Interestingly, the obtained findings may be valuable in the forensic antemortem and
postmortem diagnosis of WBH and heat-related deaths.