Vitamin A Oral Supplementation Induces Oxidative Stress and Suppresses IL-10 and HSP70 in Skeletal Muscle of Trained Rats

Abstract

Exercise training intensity is the major variant that influences the relationship between exercise, redox balance, and immune response. Supplement intake is a common practice for oxidative stress prevention; the effects of vitamin A (VA) on exercise training are not yet described, even though this molecule exhibits antioxidant properties. We investigated the role of VA supplementation on redox and immune responses of adult Wistar rats subjected to swimming training. Animals were divided into four groups: sedentary, sedentary + VA, exercise training, and exercise training + VA. Over eight weeks, animals were submitted to intense swimming 5 times/week and a VA daily intake of 450 retinol equivalents/day. VA impaired the total serum antioxidant capacity acquired by exercise, with no change in interleukin-1β and tumor necrosis factor-α levels. In skeletal muscle, VA caused lipid peroxidation and protein damage without differences in antioxidant enzyme activities; however, Western blot analysis showed that expression of superoxide dismutase-1 was downregulated, and upregulation of superoxide dismutase-2 induced by exercise was blunted by VA. Furthermore, VA supplementation decreased anti-inflammatory interleukin-10 and heat shock protein 70 expression, important factors for positive exercise adaptations and tissue damage prevention. Our data showed that VA supplementation did not confer any antioxidative and/or protective effects, attenuating exercise-acquired benefits in the skeletal muscle.

Impact of Supplementary Amino Acids, Micronutrients, and Overall Diet on Glutathione Homeostasis

“…Fat-soluble vitamins (A, D, E, and K) have been evaluated for their potential effects on GSH homeostasis. These vitamins exhibit antioxidant properties, and there is evidence that status of vitamin A [116,117], vitamin D [118,119,120], and vitamin K [121] may affect GSH levels; supplementation has also been associated with adverse effects [117]. Given the nature of this review, we will focus on the fat-soluble vitamin that directly affects GSH concentrations through its antioxidant capabilities: vitamin E.…”

Lipoic Acid and Progesterone Alone or in Combination Ameliorate Retinal Degeneration in an Experimental Model of Hereditary Retinal Degeneration

“…Many other substances such as resveratrol, melatonin, vitamin A, lutein, zeaxanthin, etc. ( Kubota et al, 2009 ; Bian et al, 2012 ; Tian et al, 2013 ; Petiz et al, 2017 ; Tuzcu et al, 2017 ) have shown antioxidant and anti-inflammatory properties in the retina and in other tissues. However, the relation between antioxidant therapy and inflammatory diseases needs more study.…”

The Authors Reply

“…Yew et al made a comprehensive summary of the potential mechanisms by which vitamin A could play a role in TB reactivation and also mentioned controversies in the literature on the pro-or antioxidative effects of vitamin A (2). In the studies that they referenced, the antioxidative effect of vitamin A has been demonstrated in humans and mice (6, 7), whereas studies conducted using rat models showed that vitamin A supplementation enhanced oxidative stress (8,9). Whether the differential effect in the pro-or antioxidative properties of vitamin A lies in the different metabolic pathways in different organisms, the different dose administered in various studies, or the different tissues examined (e.g., serum, organ, skeletal muscle) remains to be elucidated.…”