Proceedings of The Physiological Society

University of Oxford (2011) Proc Physiol Soc 23, PC290

Poster Communications

Effects of hyperthermia on neurogenesis and neurobehavior in the young male rat

F. Mete1,2, E. Kilic2, S. Eyuboglu2, A. Vitrinel3, U. Kilic4, B. Yilmaz2

1. Pediatrics, Vakif Gureba Education and Research Hospital, Istanbul, Turkey. 2. Physiology, Yeditepe University, Medical School, Istanbul, Turkey. 3. Pediatrics, Yeditepe University, Medical School, Istanbul, Turkey. 4. Department of Medical Biology, Bezmi Alem University, Medical School, Istanbul, Turkey.

Hyperthermia may cause pathological changes in the brain including, neuronal cell death. In this study, we investigated effects of exogenously induced hyperthermia on neuronal survival, neurogenesis and sensorymotor behavior in young male Sprague-Dawley rats. Three groups of 13-day old rats were used. Body temperature was increased to 39°C (Group I) and 41°C (Group II) in a hyperthermia induction chamber for 30 min. An additional group of animals were used as sham control (Group III; 36 °C). Room temperature of the laboratory was 21°C. Core temperature of the animals was monitored by using a rectal probe throughout the experiments. All animals were decapitated 48 h after induction of hyperthermia (day 15). Brains were dissected out and frozen on dry ice. Coronal brain slices (18 µm) were prepared and processed for immunohistochemistry and Cresyl violet staining. To assess the activity, anxiety, and forepaw grip strength of the animals, the open field test, elevated-o-maze, and grip strength test, respectively, were used in all groups 24h before (day 12) and after (day 14) hyperthermia induction. 24 hours before completing the experiments, 100mg/kg (i.p.) BrdU was injected for the evaluation of neuronal proliferation. Experiments were approved by the local ethics committee. Results were statistically analyzed by using One-Way Analysis of Variance followed by LSD test. One day after induction of hyperthermia, animal activity was significantly reduced in both hyperthermia induced groups (p<0.01). Anxiety and grip strength deficits were observed in both test groups; however, it was significant in the 41°C hyperthermia group as compared with control animals (p<0.05). For the evaluation of neuronal survival and neurogenesis, Cresyl violet positive surviving neurons, doublecortin positive neuronal progenitor cells and BrdU positive proliferating cells were evaluated in the cerebral cortex, caudate putamen and hippocampal brain regions. In conclusion, heat stress induced hyperthermia appears to cause neurobehavioral deficits in post-natal developing male rats. Correlation of these neurological changes with cell proliferation and neuronal cell death in the cortex, caudate putamen and hippocampus with respect to the degree of hyperthermia will be elucidated and reported.

Where applicable, experiments conform with Society ethical requirements