OBJECTIVETo study the effect of exogenous nucleic acid on physical functions, morphology of hepatic cells and brain neurons in aged rats.

METHODSThirty two aged Wistar rats (20 month-old) were divided randomly into four groups (one aged control group and three aged experimental groups) and eight young rats (3 month-old) was set as young control group. Control groups were fed on standard chow and experimental groups were fed on standard chow supplemented with 93.75 mg/kg (high-dosage group), 46.88 mg/kg (middle-dosage group) and 9.38 mg/kg (low-dosage group) of yeast RNA respectively. SOD, MDA, HDL, sex hormone and growth hormone were determined at the end of a 4-week observation. The microcosmic images of the hepatic cells and brain neurons using the image-pro plus (V.4.0) were also observed.

RESULTSSOD, serum HDL and growth hormone levels in the high dosage group were significantly higher (P < 0.05) than that in the aged control group, and the levels were not different from that in the young control group. MDA level of all yeast RNA supplemented groups was significantly lower than that of aged control group (P < 0.05) and that was not different from the young control group. Serum testosterone of the high and middle dosage groups reached the level of young control group, and that was much higher than the aged control and low dosage group (P < 0.05). Estradiol levels among the aged rats were not different, and those were much lower than the young control group (P < 0.05). Much more number of brain neurons were observed in the high-dose group than other aged rats (P < 0.05). Brain neurons, hepatic cells and karyons in the high-dose group were bigger than that in other aged rats (P < 0.05).

CONCLUSIONExogenous yeast RNA might play an important role in physical functions, the morphology of brain neurons and hepatic cells in natural aged rats. There might have a dose-effect relationship in the process.