Accelerated senescence and adaptation to cold exposure

Abstract

A reduced ability to thermoregulate and to adapt to low temperatures is a prominent feature in aged animals. We investigated whether the ability to adapt to cold exposure was different between an accelerated senescence prone strain of mice, SAMP1, and an accelerated senescence resistant strain of mice, SAMR1, at a young age. Using a telemetry system, we recorded the core temperature of mice in a cold environment (5±1 °C) and under conventional conditions (23±2 °C). No significant differences were observed between these two strains for core temperature during both daytime and night at room temperature, and for the lowest core temperature during cold exposure. The SAMR1 mice took a significantly shorter time to reach their lowest core temperature than the SAMP1 mice. The SAMP1 mice showed a significant positive correlation between spontaneous motor activity (SMA) counts at room temperature and those under cold exposure. The norepinephrine levels of the SAMP1 mice were significantly higher than the SAMR1 mice at room temperature, but decreased to the same level as the SAMR1 mice after cold exposure for 3 h. These results suggest that the adaptation mechanism to low temperature of SAMP1 mice may be different from that of SAMR1 mice, even at a young age.