| Co-Investigator(Kenkyū-buntansha) |
OKANO Akira Sinshu University School of Medicine, Lipid Biochemistry, Assistant, 医学部・脂質生化学, 助手 (30020803)
YONEMURA Isamu Tokyo Ika Shika University School of Medicin, Legal Medicine, Lecturer, 医学部・法医学, 講師 (30020762)
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| Research Abstract |
Physiological characteristics, especially metabolic differences, were compared among five strains of mice, (l)the short-lived SAMP2, (2)long-lived SAMR1, (3)F1 hybrid generation from the mating of SAMP2 male and SAMR1 female, (4)F2 generation, (5)Back cross generation from the mating of SAMP2 male and SAMR1 female. The SAMP2 shows higher values than the SAMRl, F1, F2 and Back cross groups in food and water intake, oxygen consumption(V0_2)and thermal conductance, but in growth rate SAMRl shows higher values. The metabolic characteristics in Fl are very similar to SAMRl ones.
The value of metabolic rate in Back cross group is middle between SAMP2 and SAMRl. The life span in F1 and SAMR1 are the same in this study for both sex. These results suggest that the physiological characteristics and longevity of SAMR1 are dominant to those of the SAMP2. The values in metabolic rate, however, was based on resting metabolic rate(RMR) measured from 1PM to 5PM without exercising and eating. Thus we continuously measured VO_2 and revolutions in a running spontaneous wheel(RSW), since the metabolic rate of animals in every-day life contains activity during dark periods. We compared their rhythm change hourly in SAMP2 and SAMR1. During light periods of the SAMP2 RSW, VO_2 and food and water intake were significantly higher than those in SAMR1, whereas, during the dark periods the values of the two groups were not different. The finding suggest that resting metabolic rate in SAMP2 is higher than in SAMR1. The avenge age of death in SAMR1 obtained from our data was approximately 1.4 times longer than in SAMP2. Cold acclimation(10C) shortened the life span in both SAMR1 and SAMP2.
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