Thermal and motor behavior in experimental autoimmune encephalitis in Lewis rats

Abstract

Thermoregulation in patients, who suffer from multiple sclerosis (MS) is impaired and may result in either increases or decreases in body temperature. Disturbances in body temperature correlate with acute relapses, and for this reason, it is an important issue in everyday life of those who suffer from MS. Although rat experimental autoimmune encephalitis (EAE) appeared useful for the examination of current therapies against MS, it has not been thoroughly investigated in terms of body temperature. The purpose of this study was to examine the effect of EAE induction on thermal and motor behavior in the rats. Subcutaneous injection of encephalitogenic emulsion into both pads of hind feet of the Lewis rats provoked symptoms of EAE. Body temperature (Tb) and motor activity of rats were measured using biotelemetry system. We report a significant increase in body temperature within 24 h prior to the EAE manifestation (12 h average of Tb for EAE induced animals was higher by 1.07 ± 0.06 °C during day-time and by 0.5 ± 0.05 °C during night time in comparison to the control rats). On the other hand, the onset of EAE symptoms was associated with gradual decrease of body temperature, and during the first night-time Tb was lower by 1.03 ± 0.08 °C in comparison to the control rats. The inhibition of the motor activity started from the night time, 2 days before EAE onset. On the basis of our data, we concluded that the pattern of body temperature changes after EAE induction may be considered as useful symptom (prodrom) to predict precisely the time of EAE onset. Furthermore, we suggest that EAE in rats may be a suitable model to study mechanism of body temperature alternations observed in MS patients.