I.G. Vlasova, V.I.Torshin, N. Mansur

Impulse activity of neurons in survival slices of rats and mice cerebellum at hypothermia (decrease of perfusate temperature from 34 to 20°C) and daily and seasonal fluctuations of nervous cells resistance to low temperature was investigated. In experiments in vitro, i.e. using survival slices of rats and mice cerebellum, the dynamics of im-pulse activity (IA) neurons changes at hypothermia (decrease of perfusate temperature from 34 to 20°C) was investigated. Phase changes of neurons IA, expressed by alternation of IA initial inhibition at temperature of 33-29°C, then IA activation phase at temperature 28-27°C, 50% inhibi-tion of activity at 26-24°C, and at last complete inability to generate spikes at 22-20°C. Observed phase fluctuations in neurons IA at hypothermia are likely to be due to phase metabolic changes in nervous cell and its enzymes systems, responsible for spikes generation, which are active at certain optimal temperature. Comparative analysis of fluctuations in daily and seasonal resistance of cerebellum neurons to hypothermia showed cerebellum neurons to be more resistant to hypothermia in cold period (winter, autumn), which is due to attuning of nervous cells metabolic processes, and body as a whole, to certain low temperature of the environment. At the same time in warm seasons (summer, spring) nervous cells turned out to be less resistant to hypothermia due to lack of adaptive mechanisms to low temperatures at warm period. Experiments, performed on neuronal model - cerebellum slices, ? allow to suppose, that nervous cell had developed metabolic mechanisms of resistance to low temperature, which realized first of all at cellular-tissue levels and revealed themselves in vitro. Set of biorhythmical experiments revealed oscillatory characteristics of nervous cells and showed role of biorhythms in development of adaptive reactions to extreme factors - hypothermia.