Serum lipid concentrations and mean life span are modulated by dietary polyunsaturated fatty acids in the senescence-accelerated mouse

The senescence-accelerated mouse (SAMP8) is an animal model used in studies of aging. This study was undertaken to investigate the effects of dietary PUFA on longevity (Experiment 1) and serum lipid concentrations (Experiment 2) in SAMP8 mice. Male mice were fed either an (n-3) PUFA-rich (9 g/100 g perilla oil) or an (n-6) PUFA-rich (9 g/100 g safflower oil) diet beginning at 6 wk of age. Experiment 1: The groups did not differ in body weight gain, but those fed perilla oil had significantly lower scores of senescence relative to those fed safflower oil (P < 0.05). The mean life span of mice fed perilla oil was 357 ± 21d and of those fed safflower oil, 426 ± 24 d (P < 0.05). Pathological studies revealed that the incidence of tumors was significantly lower in the perilla oil group than in the safflower oil group (P < 0.05). Approximately half the mice fed perilla oil had died after 10 mo, and the direct causes closely connected with death could not be specified. Experiment 2: The serum total cholesterol, HDL cholesterol, triglyceride and phospholipid concentrations were significantly lower in the perilla oil group than in the safflower oil group (P < 0.01). A marked decrease of serum HDL cholesterol and apolipoprotein A-II (ApoAII)concentrations in advanced age were observed in the mice fed perilla oil (P < 0.01). Ten-month-old mice fed perilla oil had a significantly greater ratio of apolipoprotein A-I (ApoA-I) to ApoA-II than those fed safflower oil. Separation of HDL subfractions revealed that the smaller HDL species were much more abundant than the larger HDL species in both dietary oil groups. These findings suggest that dietary (n-3) and (n-6) PUFA differ in their effects on serum lipid metabolism which may modulate the mean life span of SAMP8 mice fed each dietary oil.