The possible role of lipoperoxide in aging.

According to the free radical theory by Harman, free radicals formed under various conditiors can cause the changes in DNA, which may result in chromosomal aberrations, and can initiate lipid peroxidation in subcellular and cellular membrane systems. The accumulation cf lipofuscin with age .also supports the significance of lipid peroxidation on aging. In this paper·;two lines of research were carried out. In experiment 1, peroxidized methyl linoleate was administered to the rats with or without supplementation of antioxi.dant (a-tocopherol felurate) in order to observe the toxic effects and the possibility of absorption from gastrointestinal tract. The changes of total nitrogen, total lipid, phospholipid, and total tocopherol and TBA reactive substances, which were estimated by two different ways, were observed in the livers of rats. The changes in appearance and the decrease of body weight were recognized in peroxidized oil administered groups. Total lipid and total tocopherol decreased in the liver of peroxidized oil administered groups, whereas ther e was no significant difference in the rat'.o of total tocopherol per total lipid. TBA reactive substances by non-shaking method increased in peroxidized oil administered groups. Considering the above findings, serious toxic effects due to the oral administration of peroxidized methyl linoleate could not be protected by supplementation of antioxidant, and the peroxidized methyl linoleate or the destroyed products of it might be absorbed directly from the gastrointestinal tract. In experiment II, age trends of the same substances as estimated in experiment I and of water soluble antioxidants by DPPH method were investigated in the liver of rats and human subjects. In both, content of water-soluble antioxidants decreased significantly with age and in contrast, total tocopherol increased in mature adult and mature old. In the rat liver the increase of TBA reactive substances was associated with age. In the human liver TBA reactive substances by shaking method increased from the young to the mature adult and decreased again in the old senescense. Assuming from the results of TBA reactive substances, the capacity of lipoperoxide formation reaches to maximum in mature adult and the amount of lipoperoxide formation may increase with age.