A Method of Assessment of the Motor Function of Hind Limbs by Swim Test in Spinal Cord Injury Models

In most studies, various load tests are used to assess the recovery of functions after spinal cord injury in animals. However, the existing methods of assessing the movement in animals are not sufficiently accurate and objective. We developed a new method for assessing motor activity of laboratory animals that allows objective and highly accurate evaluation of movements in animals with serious neurological disorders caused by spinal cord injury. The swimming test was used as the main load test. Motor activity of swimming animals was assessed by measuring angles relative to the axis of motion, and the degree of angle spread for each joint and limb was estimated using the dispersion parameters depending on the values of the angles of the joints and the dispersion depending on the amplitudes of the angles. In Sprague-Dawley rats, contusion of the spinal cord at the Th9 level was modeled. In the swimming test, healthy control animals showed stability of both variance indicators over 6 weeks. In rats with spinal cord injury, motor activity of the hind limbs tended to increase from the first to the third weeks and remained at this level from the third to sixth weeks. The results suggest that the proposed method can become a good analogue of modern methods for assessing motor activity.