Daily rhythms of nonshivering thermogenesis in common spiny mice Acomys cahirinus under short and long photoperiods

摘要

Daily rhythms of nonshivering thermogenesis NST were studied in common spiny mice Acomvs cahirinus, acclimated to different photoperiod regimes (16L:8D and 81:I6D) at a constant ambient temperature of 26 deg C. Noradrenaline NA (1.5 mg/kg subcutaneous) was injected at: 06:00, 12:00, 18:00 and 24:00 h (+ - (15 min). NST was measured as the ratio between the maximal oxygen consumption (VO_2) as response to NA -- VO_2NA and VO_2 measured at 26 deg C -- VO_(2 min). Rectal temperatures T_(bNA) and T_(b min) respectively were recorded at the end of VO, measurements. Significant variations in T_(b min), T_(bNA), and NST were revealed, under the two different photo period regimes. Significant differences in CO_(2 min), NST, T_(b min) and T_(bNA) were also recorded within each photoperiod acclimation group. These results suggest that daily and photoperiod depended variations in the brown adipose tissue activity, presumably emerge from amount of unoccupied receptors or changes in the receptors affinity to NA.