| Rats serve as one of the leading biomedical and behavioral animal models in research, especially
in the field of spinal cord injury, but very few studies have examined the role their tail plays in
movement. In vitro experiments have shown that the sacral spinal cord contains the neural
circuitry to produce tail movement, but there is limited in vivo research examining the motor
output of the sacral cord. Given the limited understanding of the tail and its contribution to
movement, and the associated sacral circuitry, the goal of the present study was to characterize
tail movement in both spinal and intact adult rats following an early neonatal spinal cord
transection. Additionally, hindlimb movement immediately preceded by tail movement was
analyzed to determine if movement of the tail might serve as a stimulus to induce movement of
the hindlimbs. On postnatal day 1 (P1), male and female rat pups underwent a complete, low-
thoracic spinal cord transection or sham surgery. On P50, rats were placed in an open-field
apparatus, and spontaneous locomotion was recorded for 20-min. The duration of tail movement,
type of tail movement (lateral, vertical, and mixed), and frequency of tail-induced hindlimb
movement was scored. There was no significant difference in total tail movement duration across
surgery condition and sex. However, there were significant differences in the type of tail
movement: spinal, female rats showed significantly more lateral tail movement (surgery x sex
interaction), sham rats and female rats showed significantly more vertical tail movement (main
effect of surgery and sex), and male rats showed significantly more mixed tail movement (main
effect of sex). For tail-induced hindlimb movement, there was no significant difference across
surgery condition and sex. We found significant differences in the type of tail movement that
precedes hindlimb movement: spinal rats showed more lateral tail-induced hindlimb movement
while sham rats showed more vertical tail-induced hindlimb movement. There was no difference
in mixed tail-induced hindlimb movement. Overall, our results provide insight into how the tail
moves in rats, as well as suggests a potential role for the tail and the sacrocaudal spinal cord in
influencing hindlimb movements.
Keywords: rat, tail, locomotion, spinal cord |