Mitochondria in the Nuclei of Rat Myocardial Cells.

Electron microscopic study of cardiomyocytes taken from healthy Wistar and OXYS rats and naked mole rats (Heterocephalus glaber) revealed mitochondria in nuclei that lacked part of the nuclear envelope. The direct interaction of mitochondria with nucleoplasm is shown. The statistical analysis of the occurrence of mitochondria in cardiomyocyte nuclei showed that the percentage of nuclei with mitochondria was roughly around 1%, and did not show age and species dependency. Confocal microscopy of normal rat cardiac myocytes revealed a branched mitochondrial network in the vicinity of nuclei with an organization different than that of interfibrillar mitochondria. This mitochondrial network was energetically functional because it carried the membrane potential that responded by oscillatory mode after photodynamic challenge. We suggest that the presence of functional mitochondria in the nucleus is not only a consequence of certain pathologies but rather represents a normal biological phenomenon involved in mitochondrial/nuclear interactions.

Mitochondria-targeted antioxidant SkQ1 reduces age-related alterations in the ultrastructure of the lacrimal gland.

Dry eye syndrome is an eye disorder affecting many people at an old age. Because dry eye syndrome is accelerated by aging, a useful approach to the prevention of this syndrome may be an intervention into the aging process. Previously, we showed that the mitochondria-targeted antioxidant SkQ1 delays manifestations of aging and inhibits the development of age-related diseases including dry eye syndrome. Nevertheless, the link between SkQ1's effects and its suppression of age-related changes in the lacrimal gland remains unclear. Here we demonstrated that dietary supplementation with SkQ1 (250 nmol/[kg body weight] daily) starting at age 1.5 months significantly alleviated the pathological changes in lacrimal glands of Wistar rats by age 24 months. By this age, lacrimal glands underwent dramatic deterioration of the ultrastructure that was indicative of irreversible disturbances in these glands' functioning. In contrast, in SkQ1-treated rats, the ultrastructure of the lacrimal gland was similar to that in much younger rats. Morphometric analysis of electron-microscopic specimens of lacrimal glands revealed the presence of numerous secretory granules in acinar cells and a significant increase in the number of operating intercalary ducts. Our results confirm that dietary supplementation with SkQ1 is a promising approach to healthy ageing and to prevention of aberrations in the lacrimal gland that underlie dry eye syndrome.

Antioxidant SkQ1 delays sarcopenia-associated damage of mitochondrial ultrastructure.

A comparative electron-microscopic study of ultrastructure of mitochondria in skeletal muscles of the 3- and 24-month-old Wistar and OXYS rats revealed age-dependent changes in both general organization of the mitochondrial reticulum and ultrastructure of mitochondria. The most pronounced ultrastructure changes were detected in the OXYS rats suffering from permanent oxidative stress. In the OXYS rats, significant changes in mitochondrial ultrastructure were detected already at the age of 3 months. Among them, there were the appearance of megamitochondria and reduction of cristae resulting in formation of cristae-free regions inside mitochondria. In the 24-month-old OXYS rats, mitochondrial reticulum was completely destroyed. In the isotropic region of muscle fiber, only small solitary mitochondria were present. There appeared regions of lysed myofibrils as well as vast regions filled with autophagosomes. A mitochondrial antioxidant SkQ1 (given to rats with food daily in the dose of 250 nmol/kg of body weight for 5 months beginning from the age of 19 months) prevented development of age-dependent destructive changes in both the Wistar and OXYS rats.