Structural damage induced by peroxidation may account for functional impairment of heavy synaptic mitochondria.

Coenzyme Q distribution, as well as respiratory chain features, in rat brain mitochondria depend on mitochondrial subpopulation, brain region and age. Heavy mitochondria (HM) usually display the lowest content of respiratory components and the lowest enzymatic activities and it has been suggested that they represent the oldest mitochondrial population. In this study, we confirmed that HM are considerably compromised in their structure. In fact, HM showed to have the highest hydroperoxide content and the most consistent modifications in their fatty acid pattern with wide loss of fatty acids (or part of them) in the phospholipid moiety. Such situation could explain the typical impairment of HM and could support the hypothesis that they represent an old mitochondrial population.