Changes in pubococcygeus muscle tension in the pelvic floor of rats after spinal cord injury

Abstract

The purpose of this study was to explore the changes in pelvic floor muscle tension at different times after suprasacral spinal cord injury (SS) and sacral cord injury (SC), and learn more about pelvic floor dysfunction (PFD) after spinal cord injury (SCI). A total of 70 healthy female Sprague-Dawley (SD) rats, weighing between 250 and 280 g, were randomly divided into seven groups with 10 rats in each group, which included five SS groups (3 days and 2, 4, 8 and 12 weeks after injury), one SC group (4 weeks after injury) and one normal group. Muscle tension, including muscle compliance, and contraction activity elicited using electrostimulation under two initial lengths were measured at different time points. (1) Muscle compliance decreased within 4 weeks in the SS group (P>0.05), began to increase at 8 weeks (P<0.05) and reached the peak at 12 weeks, which were all lower than the normal level; (2) contraction activity under both initial lengths tended to decrease within 4 weeks, peak at 8 weeks (P<0.05) and decline again at 12 weeks , which were all lower than that of the normal group as well; and (3) the SC group showed similar compliance with the normal group (P>0.05) and less contraction activity when compared with other SS groups (P<0.05). Measurement for the compliance and contraction activity of pubococcygeus indicates the changes from decreasing to increasing after suprasacral cord injury, and similar compliance combined with rather low contraction activity compared with the normal group after sacral cord injury, both of which are in accordance with PFD after spinal cord injury.