Differential expression of synaptophysin and its functional implication under conditions of both contused and transected spinal cord injury

Abstract

ObjectiveThis study was designed to investigate the effect of changes of synaptophysin in the spinal cord contusion (SCC) model and spinal cord transection (SCT) model, and collect more evidence about the role of synaptophysin for the treatment of spinal cord injury (SCI).MethodsHealthy Sprague‐Dawley rats were randomly divided into sham, SCC, and SCT groups. SCT model was induced at T10 cord transection, while SCC model was established through Allen's method. Motor function of hind limbs was evaluated with Basso, Beattie and Bresnahan (BBB) locomotor scale. Sensory function was indicated by the mechanical nociceptive withdrawal responses using paw withdrawal test and thermal hyperalgesia with tail‐flick latency. A quantitative real‐time polymerase chain reaction was used to detect the expression of synaptophysin on the level of mRNA. The location of synaptophysin in the spinal cord was detected with immunofluorescence.ResultsThe BBB score and expression level of mRNA coding synaptophysin in the SCT and SCC groups were both lower than those in the sham group; while the tail‐flick latency and threshold force were the highest in the SCT group, and the mRNA level of synaptophysin is the lowest, also. Synaptophysin immunostaining showed that it is mainly expressed in the spinal cord matter, scattered in the dorsal horn and anterior horn.ConclusionDifferential expression of synaptophysin in SCC and SCI models cause different dysfunction in behavior, especially in sensory function, suggesting that synaptophysin may be directly and differently related to sensory function remodeling in different SCI conditions.