Exercise tests and BBB method for evaluation of motor disorders in rats after contusion spinal injury

Contusion spinal injury of different severity was induced by the weight drop method in male rats by dropping standard weight from the heights of 6.5, 12.5, 25, and 50 mm on the spine after laminectomy at the Th9 level. The dynamics of recovery of voluntary movements was evaluated over 8 weeks after the operation by comparing the traditional semiquantitative BBB score with objective parameters of exercise tests. Exercise tests detected cessation of spontaneous recovery of impaired functions 1-2 weeks earlier than the BBB method. The maximum performance according to the rotarod and narrowing track tests was 20-40% lower than the level of voluntary movement recovery evaluated by the BBB score. No appreciable differences between the levels of maximum recovery of voluntary movements (BBB score) and swimming velocity were detected. According to morphometric analysis of the volumes of pathological cavities and intact white matter in the focus of injury, exercise tests adequately reflected the severity of spinal contusion in rats. Exercise tests used in the study are recommended for objective preclinical evaluation of the efficiency of new means for the treatment of spinal injuries.