Autonomic dysfunction in experimental autoimmune neuritis: heart rate

Autonomic nervous system (ANS) dysfunction occurs in more than half of Guillain--Barré syndrome (GBS) patients and is an important cause of death in the disease. In this study we examined heart rate (HR) changes in an animal model of GBS, experimental autoimmune neuritis (EAN), induced by immunization with myelin extracted from bovine spinal roots. The animals developed progressive motor weakness accompanied by significant weight loss and hypothermia. HR was measured in 33 EAN rats at rest (rHR) and followings stressful stimulation (sHR). Average pre-immunization rHR was 341+/-28 beats per minute (b.p.m.) and sHR was 486+/-21 bpm. Although the mean rHR in rats with EAN was not significantly different compared to that at baseline, there was a significant increase of variation of rHR with six rats demonstrating bradycardia (<280 b.p.m.) and 10 tachycardia (>400 b.p.m.) (P<0.01, F-test). sHR in EAN rats was significantly lower (P<0.01), suggesting sympathetic system impairment. These findings may serve as a basis for testing treatments of ANS dysfunction in EAN.