Vitamin A supplementation for different periods alters rat vascular redox parameters.

Vitamin A plays physiological and antioxidants properties and is associated with protective effects on arterial level. However, deleterious effects have been reported, including those observed by our group, which has demonstrated pro-oxidant properties in other systems. Therefore, it is needed to better understand the redox effects of retinoids on arterial system. Thus, our aim was to compare vascular redox parameters among animals supplemented or not with vitamin A. Eighty-five adult male rats were treated with different retinyl palmitate doses (1,000-9,000 IU kg(-1) day(-1)) or saline for 3 (25 rats, n=5 for each group), 7 (25 rats, n=5 for each group), and 28 (35 rats, n=7 for each group) days periods. Aorta artery was surgically removed, cleaned to remove the blood, and homogenized. It was evaluated thiobarbituric reactive species (TBARS), total reduced sulfhydryl (SH), and activities of superoxide dismutase (SOD) and catalase (CAT). Statistics were conducted by one-way ANOVA with Dunnet's post hoc and significance value of p≤0.05. About TBARS, we observed no modifications after 3 days, but a decrease after 7 days in all doses and after 28 days in three higher doses. The two higher doses yielded an increase on SH only after 3 days. SOD activity decreased in three higher doses after 3 days and in all doses after 28 days, but no modifications after 7 days, while CAT activity increased in all doses after 3 days, decreased in all doses after 7 days, and did not change after 28 days. In conclusion, vitamin A induces antioxidant status on vascular level.