COENZYME-Q CONTENT IN SYNAPTIC AND NONSYNAPTIC MITOCHONDRIA FROM DIFFERENT BRAIN-REGIONS IN THE AGING RAT

We investigated the Coenzyme Q (CoQ) content of different mitochondrial fractions [free mitochondria (FM), synaptic heavy (HM) and light mitochondria (LM)I from three brain areas (cortex, striatum, hippocampus) of rats at different ages. In rats from 2 to 26 months of age, we observed only small differences in total CoQ content (CoQ(9) + CoQ(10)). In FM and LM fractions, values are very similar and appear to be much higher than in HM fractions. The CoQ(10)/CoQ(9) ratios are much higher in brain mitochondria than in other organs, suggesting possible modifications of CoQ biosynthetic pathways in brain; nevertheless they appear to remain constant during ageing. CoQ(9) and CoQ(10) contents slowly decrease reaching their minimum in rats of 18 months of age, then increase in the older ages. Considering ageing as partially driven by a summation of free radical-mediated processes, we can hypothesize that damage occurring to biological structures in the first half of life might be followed by induction phenomena tending to re-establish the primitive levels of antioxidant molecules.