Heart and liver connexin expression related to the first stage of aging: A study on naturally aged animals

[Display omitted] •Cx43 and Cx26 proteins are reduced during aging in cardiomyocytes of adult rat.•Cx26 and Cx32 proteins are reduced during aging in hepatocytes of adult rat.•Cx43/Cx26/Cx32 decrease with aging on the cardiomyocytes and hepatocytes membrane.•mRNA of Cx43/Cx26/Cx32 does not change during early aging in heart and liver. Connexins are membrane-spanning proteins that form membrane channels and hemichannels. They are involved in the cellular communication and in the maintenance of tissue homeostasis. Recent studies in humans and animals have demonstrated that the expression and distribution of Cx43, the most studied connexin, can change during aging. However, the research on the involvement of the other connexins in cardiac and hepatic aging is, at present, still very poor. Hence, the aim of this study is to evaluate the expression of Cx43 and Cx26 in the heart as well as Cx26 and Cx32 in the liver of a rat model that aged naturally, rather than prematurely because of genetic mutations or age-related diseases. The results obtained in the present study have demonstrated that these connexins decrease in rat cardiomyocytes and in rat hepatocytes as they age. This change was revealed only at protein level, as connexin-mRNAs remained unchanged during aging. Moreover, the aged rats showed an increase in body fat, whose subcutaneous layer tended to be higher. Finally, how these changes could represent signs of physiological adaptation in successful aging was discussed.