Hyperthermia alters neurobehavior by affecting cell proliferation and neuronal survival in young male rats

Abstract

Maintenance of body temperature within physiological range is critical for the fetal and neonatal development. Hyperthermia is one of the most frequently encountered pediatric complaints and may cause neurological disorders due to neuronal injury. In this study, we aimed to investigate the effects of hyperthermia on behavioral alterations, neuronal survival, apoptosis, and cell proliferation in young male Sprague–Dawley rats. Twenty‐one 13‐day‐old rats were randomly divided into three groups (n = 7 per group). Body temperature was increased to 39°C and 41°C in a hyperthermia induction chamber for 30 min, whereas the animals in control group were maintained at 36°C. Twenty‐four hours after hyperthermia, animals were subjected to the open field test, elevated‐O‐maze test, and grip strength test to assess the locomotor activity, anxiety, and motor function. Neuronal survival, apoptosis, and cell proliferation were investigated in cortex, hippocampal dentate gyrus (DG) and CA1 regions, and corpus callosum (CC). Decreased locomotor activity and motor function and increased anxiety were observed in the hyperthermia groups, and these were more pronounced in the 41°C group. Neuronal survival was significantly decreased in DG, CA1, and CC in the hyperthermia groups (**p < 0.01). Apoptosis was significantly induced in cortex, DG, and CC of the animals exposed to heat (*p < 0.05). In addition, cell proliferation positivity decreased significantly only in DG and CC of the animals exposed to heat (*p < 0.05). Our results suggest that neurobehavioral deficits caused by hyperthermia may be due to the increased apoptosis and neuronal cell death and decreased cell proliferation in the brain of postnatal developing rats.

Postweaning Social Isolation Alters Puberty Onset by Suppressing Electrical Activity of Arcuate Kisspeptin Neurons

“…The stress response may be either through the sympathetic-adrenal-medullary axis in which the “flight or fight” is triggered by norepinephrine or epinephrin release [ 3 ], resulting in change in the heart rate, blood pressure, and breathing rate [ 4 ]. It may also be through the hypothalamic-pituitary-adrenal (HPA) axis which is responsible for the neuroendocrine adaptation of the physical or psychological stress by combining the central nervous system and the endocrine system [ 5 , 6 ]. Stress response by the HPA axis is characterized by hypothalamic release of corticotrophin-releasing hormone (CRH) and hence release of adrenocorticotropic hormone from the anterior pituitary causing secretion of glucocorticoids (GC) from the adrenal cortex [ 7 , 8 ].…”