A Comparative Study on Spontaneous Homecage Behaviors of Spinal Cord Injury Mice

Abstract

ObjectiveTo investigate the dysfunction of spontaneous homecage behaviors in mice with spinal cord injury, including exploratory behaviors, voluntary movements, and self-care behaviors.MethodsEight-week female C57BL/6 mice (n = 10) were established into thoracic 10 contusion spinal cord injury models. Other mice (n = 11) were included in the sham group. From the first week to the fifth week after surgery, the mice were observed in homecages at 9 a.m. for 2 hours once a week. The HomeCageScan software was used to analyze the time percentages of 32 daily behaviors.ResultsCompared with the sham group, the spinal cord injury mice showed significant abnormalities in most aspects of daily behaviors, such as exploratory behaviors, voluntary movements, and self-care behaviors (P < 0.01). Some of these behaviors recovered over time after surgery. At 1⁃5 weeks after surgery, the spinal cord injury mice exhibited less exploratory behaviors than the sham mice, represented by rearing up and sniffing (P < 0.01), and showed recovery in the 4th week and the 3rd week (P < 0.05). The spinal cord injury mice also exhibited less voluntary movements (P < 0.05), represented by walking slowly and jumping, and showed recovery from the 2nd week and the 5th week, respectively (P < 0.05). The spinal cord injury mice exhibited more self-care behaviors than the sham mice (P < 0.01), represented by twitching and grooming, and showed no significant recovery over time.ConclusionBesides lower limb movement dysfunction, the spinal cord injury mice showed abnormalities in exploratory behaviors, voluntary movements, and self-care behaviors. From 1-5 weeks after injury, the exploratory behaviors and voluntary movements could show different degrees of recovery, while the self-care behaviors showed continuous abnormalities. The automated high-throughput behavior detection system accurately classified and comprehensively recognized dozens of behaviors, which could be used as a more comprehensive and sensitive evaluation index of spinal cord injury disorder.

Keywords

• spinal cord injury
• ethology
• homecage behaviors
• mice