The spinal cord is well known to undergo inflammatory reactions in response to traumatic injury. Activation and proliferation of microglial cells, with associated proinflammatory
cytokines expression, plays an important role in the secondary damage following
spinal cord injury. It is likely that microglial cells are at the center of injury cascade and are targets for treatments of CNS traumatic diseases. Recently, we have demonstrated that the cell cycle inhibitor
olomoucine attenuates astroglial proliferation and
glial scar formation, decreases lesion cavity and mitigates functional deficits after
spinal cord injury (SCI) in rats [Tian, D.S., Yu, Z.Y., Xie, M.J., Bu, B.T., Witte, O.W., Wang, W., 2006. Suppression of astroglial
scar formation and enhanced axonal regeneration associated with functional recovery in a
spinal cord injury rat model by the cell cycle inhibitor
olomoucine. J. Neurosci. Res. 84, 1053-1063]. Whether
neuroprotective effects of cell cycle inhibition are involved in attenuation of microglial induced
inflammation awaits to be elucidated. In the present study, we sought to determine the influence of
olomoucine on microglial proliferation with associated inflammatory response after
spinal cord injury. Tissue
edema formation, microglial response and neuronal cell death were quantified in rats subjected to spinal cord hemisection. Microglial proliferation and neuronal apoptosis were observed by immunofluorescence. Level of the proinflammatory
cytokine interleukin-1beta (IL-1beta) expression in the injured cord was determined by Western blot analysis. Our results showed that the cell cycle inhibitor
olomoucine, administered at 1 h post injury, significantly suppressed microglial proliferation and produced a remarkable reduction of tissue
edema formation. In the
olomoucine-treated group, a significant reduction of activated and/or proliferated microglial induced IL-1beta expression was observed 24 h after SCI. Moreover,
olomoucine evidently attenuated the number of apoptotic neurons after SCI. Our findings suggest that modulation of microglial proliferation with associated proinflammatory
cytokine expression may be a mechanism of cell cycle inhibition-mediated neuroprotections in the CNS
trauma.