Motor training reduces psychomotor retardation via gliogenesis in rats with depression-like behaviour

Abstract

Adult-born oligodendrocytes are found to be continuously produced in rodent’s brain. The functional role of these cells has been highly correlated to motor-related activities of the healthy animals, such as in learning a new motor skill. In correlating these cells with the control of motor-related activities, it has not been investigated under a pathological condition. Psychomotor retardation (PMR) is one of the key symptoms found in depression. Consistent with the impairments shown in rodent’s motor performance, the proliferation and the survival of adult-born oligodendrocytes are altered under corticosterone-induced stress paradigm. Futhermore, we have found that these proliferating cells could possibly be involved in the neural circuitry of motor activity as these cells were activated (co-expressed with an immedaite-early gene marker, egr-1) upon motor stimulation. However, the activation level was found to be lowered under stress. Therapeutic rotarod training can reverse the above altered components. Surprisingly, the above changes were shown to be obvious in layer I of the motor cortex. Therefore, the current study has provided evidence on the functional involvement of adult-born oligodendrocytes in contributing to the motor impairments found in depressed animals. Also, layer I may possibly be a novel site of investigation in relation with the PMR symptom.