| The present study was aimed at further exploring the process and mechanisms underlining the nutrients metabolism in animals. The correlations between rate of energy metabolism and the production of free radicals, as a by-product of metabolism and the damage to organs or tissues, as well as the physiological mechanisms underpinning the correlations were examined. In this paper, gross energy intake(GEI), digestive energy intake(DEI), digestibility, basal metabolic rate(BMR), oxidative stress makers and antioxidant enzymes were measured in striped hamsters, an experimental animal model. The main results and conclusions are follows:The striped hamsters were acclimated to moderate cold(15℃),room(23℃) and warm temperature(30℃) for 6 weeks. The results showed that energy intake, the rate of metabolism and nonshivering thermogenesis were significantly increased at 15°C, but decreased at 30°C. Effects of temperature on the markers of both oxidative stress and antioxidant activities were rarely significant. However, levels of H2O2 and lipid peroxide(LPO) and activities of superoxide dismutase(SOD) and catalase(CAT), total antioxidant capacity(T-AOC) and the capacity of inhibition of hydroxyl free radical(CIH) were significantly different among the tissues. The percentages of positive correlation between the 11 tissues(brain, BAT, liver, heart, lung, kidneys, stomach, small and large intestine, caecum and skeletal muscle) were 14.5%(8/55) for CAT, 7.3%(4/55) for CIH, 5.5%(3/55) for SOD, 1.8%(1/55) for T-AOC, 4.3%(2/46) for H2O2 and 11.1%(4/36) for LPO.The striped hamsters were exposed to 5℃ for 2, 7, 21 and 42 days, and were also exposed to decreased ambient temperatures of 21, 15, 8, 0 and-8℃. The results showed that cold exposure increased the rate of energy metabolism, but had no effect on body mass. MDA levels in heart and muscle were significantly increased in hamsters exposed to cold for 42 days relative to those in their counterparts maintained at room temperature. The decreases in ambient temperature significantly decreased H2O2 levels of brain and kidney, whereas increased MDA levels of brain, liver, lung and kidney. The SOD activity in skeletal muscle was significantly increased, but in heart was significantly decreased; The decreases in ambient temperature significantly increased SOD activity in brain and small intestine, but the SOD activity of liver and skeletal muscle were decreased. The coefficient differences in antioxidant and super-oxidative radicals were observed between different organs and tissues. The correlations between antioxidant and super-oxidative radicals within the same organs were 100% in kidney, 66.7% in liver and 50.0% in muscle.These finding suggest that 1) the variations of super-oxidative radical production are associated with the duration and gradient of the cold exposure; 2) the differences in super-oxidative radical production are dependent on the different organs and tissues; 3) there are strong correlations between antioxidant and super-oxidative radicals in some organs and tissues, which may be the important defensive system against the oxidative damages. |
