RÉSUMÉ
Objective To investigate the pattern and the role of cytoskeletal genes expression during nerve regeneration. Methods We examined the changes of expression of ? tubulin(? Tub)and three neurofilament(NF)subunits mRNA in rat corticospinal neurons of sensorimotor cortex on the 1st,3rd,5th,7th,10th,14th,21st,28th and 56th days after spinal cord semitransection injury by using in situ hybridization. Results Levels of ? Tub,NF L,NF M and NF H mRNA were dramatically downregulated within large sized pyramidal neurons in layer V of the sensorimotor cortex of side lateral after spinal cord injury.The level of ? Tub mRNA was decreased as early as 1 day postinjury,whereas the levels of NF subunits mRNA were not decreased until later time(on the 3rd days postinjury),and both of them did not return to control levels on the 56th days following the lesion. Conclusion ? Tub gene expression if inhibited in CNS neurons postinjury. The axotomy signeal and the continuance downregulation of NF mRNA expressioon following spinal cord injury may contribute to the ineffective regeneration response of CNS neurons.