Increased xanthine oxidase-related ROS production and TRPV1 synthesis preceding DOMS post-eccentric exercise in rats.

ABSTRACT

AIMS: It is well-known that unaccustomed exercise, especially eccentric exercise, is associated to delayed onset muscle soreness (DOMS). Whether DOMS is associated with reactive oxygen species (ROS) and the transient receptor potential vanilloid 1 (TRPV1) is still an open question. Thus, the aim of this study was to investigate the association between TRPV1 and xanthine oxidase-related ROS production in muscle and DOMS after a bout of eccentric exercise. MAIN METHODS: Male Wistar rats performed a downhill running exercise on a treadmill at a -16° tilt and a constant speed for 90min (5min/bout separated by 2min of rest). Mechanical allodynia and grip force tests were performed before and 1, 3, 6, 9, 12, 24, 48 and 72h after the downhill running. Biochemical assays probing oxidative stress, purine degradation, xanthine oxidase activity, Ca(2+) ATPase activity and TRPV1 protein content were performed in gastrocnemius muscle at 12, 24, and 48h after the downhill running. KEY FINDINGS: Our statistical analysis showed an increase in mechanical allodynia and a loss of strength after the downhill running. Similarly, an increase in carbonyl, xanthine oxidase activity, uric acid levels and TRPV1 immunoreactivity were found 12h post-exercise. On the other hand, Ca(2+) ATPase activity decreased in all analyzed times. SIGNIFICANCE: Our results suggest that a possible relationship between xanthine oxidase-related ROS and TRPV1 may exist during the events preceding eccentric exercise-related DOMS.