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

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 degrees tilt and a constant speed for 90 min (5 min/bout separated by 2 min of rest). Mechanical allodynia and grip force tests were performed before and 1, 3, 6, 9, 12, 24, 48 and 72 h after the downhill running. Biochemical assays probing oxidative stress, purine degradation, xanthine oxidase activity, Ca2+ ATPase activity and TRPV1 protein content were performed in gastrocnemius muscle at 12, 24, and 48 h 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 12 h post-exercise. On the other hand, Ca2+ 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. (c) 2016 Elsevier Inc. All rights reserved.