Forced-exercise attenuates experimental autoimmune neuritis

Physical inactivity in combination with a sedentary lifestyle is strongly associated with an increased risk of development of inflammatory-mediated diseases, including autoimmune disorders. Recent studies suggest that anti-inflammatory effects of physical exercise may be of therapeutic value in some affected individuals. In this study, we determined the effects of forced-exercise (treadmill running) on the development and progression of experimental autoimmune neuritis (EAN), an established animal model of Guillain-Barre syndrome. Adult male Lewis rats were subjected to sedentary (control) or forced-exercise (1.2 km per day, 5 days a week) for three weeks prior to induction of EAN. P2 (53-78)-immunized sedentary control rats developed a monophasic course of EAN beginning on post-injection day 12.33 +/- 0.59 (n = 18) and reaching peak severity on day 15.83 +/- 0.35 (n = 18). At near peak of disease, ankle- and sciatic notch-evoked compound muscle action potential (CMAP) amplitudes in sedentary control rats were reduced (similar to 50%) while motor nerve conduction velocity (MNCV) was slowed (similar to 30%) compared with pre-induction evoked responses. In marked contrast, rats undergoing forced-exercise exhibited a significantly less severe clinical course of EAN beginning on post-injection day 12.63 +/- 0.53 (n = 16) and reaching peaking severity on day 14.69 +/- 0.73 (n = 16). At near peak of disease, ankle- and sciatic-notch-evoked CMAP amplitudes in forced-exercised rats were preserved while EAN-associated slowing of MNCV was modestly attenuated by exercise. Three weeks of forced-exercise reduced by 46% total plasma corticosterone content while elevating the levels of corticosteroid binding globulin. We conclude from this study that forced-exercise administered prior to and during development of EAN affords a novel measure of protection against autoimmune-associated deficits in peripheral nerve evoked responses independent of steroid-induced immune suppression. Published by Elsevier Ltd.