Correlation between motor behavior and age-related intervertebral disc degeneration in cynomolgus monkeys

The motor behavior in patients with lumbar intervertebral disc degeneration (IDD) and animal models should be changed due to pain. However, there does not seem to be a strong correlation between IDD and motor behavior. Therefore, it is necessary to understand the correlation between motor behavior and age-related IDD.

Twenty-one healthy male cynomolgus monkeys (Macaca fascicularis) distributed across the age range were included in this study. The experimental animals were divided into two groups: caged group (n = 14) and free-range group (n = 7). The data of IDD and motor behavior were obtained through magnetic resonance imaging (MRI) and PrimateScan Automatic Behavior Analysis System. More than 20 basic motor behaviors could be recorded and quantified, and then reclassified into 9 combined categories. We defined the sum of the duration of activity-related combined categories as the total duration of activity in 3 hours. The activity zone of the cynomolgus monkeys in the cage could be divided into top and bottom zones. Analyze the correlation between motor behavior and IDD.

Age was correlated with both Pfirrmann grades (r = .700; P < .001) and T2 values (r = -.369; P < .001). The T2 value in the caged group was 45.97 ± 8.35 ms, which was significantly lower than the 55.90 ± 8.73 ms in the free-range group (P < .001). The mean T2 values were positively correlated with hanging duration (r = .548, P < .05), the total duration of activity (r = .496, P < .05), and top zone duration (r = .541, P < .05).

There is an interactional relationship between IDD and motor behavior. Motor behavior could be used as one of the diagnostic indicators of IDD. It could also be used to infer the presence or extent of IDD in animal models. Avoiding a sedentary lifestyle and engaging in exercise in daily life could alleviate IDD.