Single session, high-intensity aerobic exercise fails to affect plasticity-related protein expression in the rat...

Typical responses in muscle following acute aerobic exercise have been well documented, but the responses in brain have remained relatively unexplored. Recent reports suggest that a single bout of aerobic exercise can prime motor regions of the human brain to experience use-dependent plasticity, however, the mechanisms underlying this priming phenomenon are unclear. As a result, we asked whether a graded test to exhaustion (GXT), the most widely employed test to examine relationships between exercise and integrated responses within the musculoskeletal, cardiopulmonary, and neuropsychological systems, would be able to upregulate the expression of plasticity-related proteins in sensorimotor cortex in rats. We examined immediate responses in animals following either a GXT, or two resting conditions: non-exercising treadmill controls (TC), and acclimatization controls (AC). Young, male Sprague-Dawley rats (n = 20) on a reverse light cycle (12 h/12 h) were exposed to a treadmill acclimatization procedure consisting of 8 days of increasing exercise intensity (10 m/min up to 25 m/min) for 10 min at the same time each day. The acclimatization was followed by 2 days of rest to reduce any carryover effects. On testing day, rats performed either a GXT, or rested (TC and AC), were then sacrificed and sensorimotor cortex dissected. Homogenates were probed for a physiological marker of stress (HSP 70), and plasticity-related proteins (CaMKII, GluN2A, GluN1, GluA1, GluA2) by Western blotting analysis. Both our acclimatization protocol and single event GXT yielded no observable differences in protein expression, suggesting that single session exercise does not prime brain via altered plasticity-related protein expression.