Histological and morphological studies of cardiac cells in response to aerobic exercise and rosemary extract in rat model of aging

Abstract

Objective The average age of the world population is growing increasingly. Since aging is the biggest risk factor for cardiac diseases, the incidence of these types of disease will increase significantly in the near future. However, their occurrence may be prevented by some factors, such as the practice of aerobic exercise and the use of herbal medicine. Materials and methods Thirty male Wistar rats, at 18 months old each, were divided into 5 groups (n = 6): control (NO), gavage (GO), exercised (EO), extract-fed (EXO), and exercised and extract-fed (EEO). The animals of the GO group received distilled water and were put on a silent electric running machine. The animals of the EO and EEO groups were assigned to a treadmill training protocol at low and moderate intensities for 1 hour/day, 5 days/week for 12 weeks. The animals of the EXO and EEO groups were treated with rosemary (Rosmarinus officinalis) extract for 12 weeks. At the end of the experiment, the hearts of the rats were collected and submitted to hematoxylin and eosin and Mallory trichrome staining. Images of these stained samples were captured, and a morphometric analysis of the cardiac tissue was performed. Results The rats in the EO, EXO and EEO groups showed a reduction in the intercellular space when compared with those of the NO and GO groups. The rats in the EO and EEO groups showed an increase in the clarification of the intercalated discs and in the width of the cardiomyocytes, when compared with those in the other groups. The nuclei of the heart cells of the animals in the EXO group were seen as more euchromatic than others. Conclusion Aerobic exercise causes changes in the cardiac muscles of rats and confirms the capacity of the fibers to adapt to the requirements of the proposed aerobic exercise. The antioxidants found in rosemary extract improve cell activity to achieve a better performance. However, applying these two factors simultaneously indicates the reduction of their positive influences.