Effects of resistance exercise on ascendent aorta on ovariectomized elderly rats

Studies have shown a strong relationship between menopause, diet, physical inactivity and presence of risk factors causing endothelial and tissue damages, leading to increased risk of developing cardiovascular disease. The aim of this study was to investigate the influence of resistance training on the effects of estrogen deprivation in aortic collagen and elastic tissue in aging. Fifteen Wistar female rats, 4 months-old, average weight 240 g were studied. All animals were ovariectomized at 6 months of age, after divided into 3 groups (n = 5): Sedentary adult (13 months), Sedentary old and Trained old (both with 17 months). All animals were ovariectomized at 6 months of age. The animals were observed for 8 months after its ovariectomy and then submitted to resistance training protocol during 12 weeks. At the end of the experiment the animals were euthanized. Samples of the ascending aorta were sectioned, fixed, processed and stained for examination by light microscopy. Photomicrographs were used for stereological study and analyzed the following parameters: body weight, volume density of collagen fibers and elastic lamellae. No significant difference was found between the initial and final weights in the studied groups. Resistance training attenuates the increase in volume density of elastic lamellae (21%) and collagen fibers (16%), when compared with the sedentary older group.

Structure of the aortic wall in the guinea pig and rat

The segmental microscopic architecture of the aortic wall of guinea pigs and albino rats was studied at the thoracicascending (T2-3), thoracic descending (T6-7) and abdominal infrarenal (L5-6) levels. Variables such as layer thickness,the number of elastic lamellae in the medial layer, and the diameter of the aortic segments were analyzedhistomorphometrically. The aortic wall of both species showed the usual elastic pattern, although variable amounts ofelastic lamellae, collagen fibers and smooth muscle cells were observed in the segmental analyses. A marked reductionin the number of elastic lamellae in the medial layer and in vascular diameter was observed in the abdominal aorticsegment of both species. Intimal folds, a gradual decrease in elastic lamellae from the ascending to the aorta abdominalaorta and a meshwork of adventitial collagen fibers and elastic lamellae were observed. These data indicate that thereare small but significant segmental variations in the aortic wall of these two species.