Abstract
The organism's normal physiological function is greatly impacted in a febrile environment, leading to the manifestation of pathological conditions including elevated body temperature, dehydration, gastric bleeding, and spermatogenic dysfunction. Numerous lines of evidence indicate that heat stress significantly impacts the brain's structure and function. Previous studies have demonstrated that both animals and humans experience cognitive impairment as a result of exposure to high temperatures. However, there is a lack of research on the effects of prolonged exposure to high-temperature environments on learning and memory function, as well as the underlying molecular regulatory mechanisms. In this study, we examined the impact of long-term heat stress exposure on spatial memory function in rats and conducted transcriptome sequencing analysis of rat hippocampal tissues to identify the crucial molecular targets affected by prolonged heat stress exposure. It was found that the long-term heat stress impaired rats' spatial memory function due to the pathological damages and apoptosis of hippocampal neurons at the CA3 region, which is accompanied with the decrease of growth hormone level in peripheral blood. RNA sequencing analysis revealed the signaling pathways related to positive regulation of external stimulation response and innate immune response were dramatically affected by heat stress. Among the verified differentially expressed genes, the knockdown of Arhgap36 in neuronal cell line HT22 significantly enhances the cell apoptosis, suggesting the impaired spatial memory induced by long-term heat stress may at least partially be mediated by the dysregulation of Arhgap36 in hippocampal neurons. The uncovered relationship between molecular changes in the hippocampus and behavioral alterations induced by long-term heat stress may offer valuable insights for the development of therapeutic targets and protective drugs to enhance memory function in heat-exposed individuals.