TEMPORAL RELATIONSHIP BETWEEN THE RECOVERY OF LONGITUDINAL REFLEX SYSTEMS AND MOTOR RECOVERY IN CHRONIC SPINALLY-LESIONED RATS

This study was performed to determine whether a correlation exists in thr functional recovery of the longitudinal reflex systems and recover y of quadrupedal locomotion in chronic spinally-lesioned rats. Partial spinal lesions sparing only the right ventral quadrant (VQ) or dorsal quadrant (DQ) of the spinal cord al the lower thoracic (T9-10) levels were performed aseptically under Nembutal anesthesia. Quadrupedal loc omotion reappeared within 2-3 weeks after the initial operations in VQ rats. However, no recovery of hindlimb movement was observed in DQ ra ts. In terminal experiments with VQ and DQ rats? the right brachial pl exus (C6-T1) was dissected and mounted on a bipolar stimulating electr ode. Spino-bulbo-spinal and interlimb reflex potentials were recorded from bilateral hindlimb muscles under urethane-chloralose anesthesia a nd Nembutal anesthesia, respectively. In VQ rats, these longitudinal r eflex potentials could not be evoked for several days post-operatively . However, the early threshold elevation for evoking the reflex potent ials returned gradually to the normal range in accordance with locomot or recovery. In DQ rats, on the other hand, disappearance of the refle x potentials persisted over 1 month observation period. These results suggest that the functional recovery of these longitudinal reflex syst ems in the ventral quadrant parallels the quadrupedal locomotor recove ry after partial spinal cord lesions in rats.