The cytoprotective role of taurine in exercise-induced muscle injury

Abstract

Intense exercise is thought to increase oxidative stress and damage muscle tissue. Taurine is present in high concentration in skeletal muscle and may play a role in cellular defenses against free radical-mediated damage. The aim of this study was to determine if manipulating muscle levels of taurine would alter markers of free radical damage after exercise-induced injury. Adult male Sprague-Dawley rats were supplemented via the drinking water with either 3% (w/v) taurine (n = 10) or the competitive taurine transport inhibitor, beta-alanine (n = 10), for one month. Controls (n = 20) drank tap water containing 0.02% taurine and all rats were placed on a taurine free diet. All the rats except one group of sedentary controls (n = 10) were subjected to 90 minutes of downhill treadmill running. Markers of cellular injury and free radical damage were determined along with tissue amino acid content. The 3% taurine treatment raised plasma levels about 2-fold and 3% beta-alanine reduced plasma taurine levels about 50%. Taurine supplementation (TS) significantly increased plasma glutamate levels in exercised rats. Exercise reduced plasma methionine levels and taurine prevented its decline. Taurine supplementation increased muscle taurine content significantly in all muscles except the soleus. beta-alanine decreased muscle taurine content about 50% in all the muscles examined. Lipid peroxidation (TBARS) was significantly increased by exercise in the extensor digitorium longus (EDL) and gastrocnemius (GAST) muscles. Both taurine and beta-alanine completely blocked the increase in TBARs in the EDL, but had no effect in the GAST. Muscle content of the cytosolic enzyme, lactate dehydrogenase (LDH) was significantly decreased by exercise in the GAST muscle and this effect was attenuated by both taurine and beta-alanine. Muscle myeloperoxidase (MPO) activity was significantly elevated in the gastrocnemius muscle, but diet had no effect. MPO activity was significantly increased by exercise in the liver and both taurine and beta-alanine blocked this effect. There was no effect of either exercise or the diets on MPO activity in the lung or spleen. Running performance as assessed by a subjective rating scale was improved by taurine supplementation and there was a significant loss in body weight in the beta-alanine-treated rats 24 hours after exercise. In summary, taurine supplementation or taurine depletion had measurable cytoprotective actions to attenuate exercise-induced injury.

Exercise-induced changes in amino acid levels in skeletal muscle and plasma

“…On the other hand, we did not find changes in taurine levels in the plantaris or gastrocnemius muscle in rats that had exercised to exhaustion 34) . Dawson et al 35) similarly confirmed a lack of exercise-induced increases in muscle taurine levels. Differences in fasting times, rat species, and intensity of exercise are likely to account for the above differences; but the significance of the exercise-associated kinetics of muscle taurine remains unknown.…”

Lipid Peroxidation Potential and Antioxidants in the Heart Tissue of .BETA.-Alanine- or Taurine-Treated Old Rats

“…␤-Alanine is a well known antagonist of taurine transport which produces depletion of tissue taurine levels, since both amino acids share a common transport system, selective for ␤-amino acids (36,37). Although some investigators have reported that taurine-deficient diets did not cause further decreases in taurine levels in tissues of old rats due to adaptive reactions (15,16), there is not sufficient knowledge in the literature about the effect of ␤-alanine treatment on taurine levels in tissues of old rats.…”

Η Επίδραση Της Έκκεντρης Προπόνησης Σε Δείκτες Μυϊκής Βλάβης Και Οξειδωτικού Στρες

“…Οι θειόλες δεν φαίνεται να επηρεάζονται από την έκκεντρη άσκηση όπως έχει αναφερθεί σε σχετικές έρευνες τόσο σε ανθρώπους όσο και σε επίμυες (Child, et al, 1999;Dawson, Biasetti, Messina, & Dominy, 2002;You, et al, 2005). Παρόμοια, καμία αλλαγή δεν παρατηρήθηκε στην δραστικότητα των ενζύμων της υπεροξειδικής δισμουτάσης, της περοξειδάσης, της γλουταθειόνης και της καταλάσης (Molnar, et al, 2006).…”

“…Περιοριστικό σημείο αυτής της εργασίας είναι το γεγονός ότι οι μετρήσεις έγιναν μόνο αμέσως μετά το τέλος της έκκεντρης άσκησης και όχι για ένα σημαντικό χρονικό διάστημα μετά. Επίσης, η έκκεντρη άσκηση δεν φαίνεται να επηρεάζει τη συγκέντρωση των βιταμινών C και Ε στο μυ σε ανθρώπους και επίμυες (Dawson, et al, 2002;Meydani, et al, 1993;Umegaki, et al, 2000).…”

“…Αντίθετα, ο μυϊκή βλάβη, αύξησε την TAC στους ανθρώπους (Child, et al, 1999) και το ουρικό οξύ στον υποκνημίδιο μυ σε επίμυες (Dawson, et al, 2002).…”