Cellular expression profile of RhoA in rats with spinal cord injury.

RhoA, a small GTPase, is involved in a wide array of cellular functions in the central nervous system, such as cell motility, cytoskeleton rearrangement, transcriptional regulation, phagocytosis and cell growth. It is not known how spinal cord injury (SCI) affects the expression of RhoA in different nerve cells. In the present study, we investigated the changes of RhoA expression in remote areas of the injury at the 3rd, 7th and 30th day after SCI, which was established by T10 contusion method. Moreover, we examine its expression profile in neurons, astrocytes and microglia. RhoA was found to be weakly expressed in these nerve cells in normal spinal cord. Western blotting showed that, after SCI, the total RhoA expression was up-regulated, and the RhoA expression was increased and peaked at the 7th day. Double immunostaining revealed specific and temporal expression patterns of RhoA in different nerve cells. The expression of RhoA in neurons started to increase at day 3, peaked at day 7 and then decreased slightly at day 30. Expression of RhoA in astrocytes increased moderately after SCI and peaked at day 7. There was no obvious change in RhoA expression in microglia after SCI in remote areas. This study demonstrated that, after SCI, RhoA expression exhibited different patterns with different nerve cells of spinal cord. RhoA expression patterns also changed with time after SCI, and among different nerve cells in the injured spinal cord. These findings can help us better understand the roles of RhoA in SCI.