Mitochondrial electron transport chain complexes in aging rat brain and lymphocytes

Several lines of evidence suggest that mitochondria not only plays a key role in the causation of aging, but it is also the most adversely affected organelle during aging. The aim of the present study was to examine the role of mitochondria in the aging process by determining whether the activities of various 'electron transport chain' (ETC) complexes are deleteriously affected during aging in the rat brain and lymphocytes. The enzyme activity of ETC complexes I-V, and citrate synthase (CS) were assayed from discrete brain areas viz., cerebral hemisphere (CH), cerebellum (CB), brain stem (BS) and diencephalon (DC), along with the lymphocytes from four different age groups of rats, namely, 1-month-old rats, 3-4-month-old adults, 12-month-old adults and 24-month-old aged rats. Significant decline was observed in all the enzyme activities in 12 and 24-month-old rats as compared to 3-4-month-old adult rats. Moreover, one-month-old rats showed lower levels of ETC complexes as compared to three to four-month-old rats. Lymphocytes and discrete brain areas showed a parallel pattern of age-related alterations in the mitochondrial ETC complexes and CS. The analysis of such alterations is important in determining the ultimate basis of neuronal dysfunction associated with aging, and defining the nature of these changes may also help to develop therapeutic means to cure not only the elderly but also individuals suffering from certain organic or psychiatric disorders.