Effects of acute and chronic administration of MK-801 on c-Fos protein expression in mice brain regions implicated in schizophrenia and antagonistic action of clozapine

Objective To investigate the effects of acute and chronic administration of the non-competitive NMDA receptor antagonists MK-801 on c-Fos protein expression in different brain regions of mice and an-tagonistic action of clozapine.Methods Immunohistochemistry was used to detect the expression of c-Fos protein.Results MK-801(0.6 mg·kg-1)acute administration produced a significant increase in the expression of c-Fos protein in the layers Ⅲ-Ⅳ of posterior cingulate and retrosplenial(PC/RS)cortex,which was consistent with the previous reports.Moreover,we presented a new finding that MK-801(0.6 mg·kg-1)chronic administration for 8 days produced a significant increase of c-Fos protein expression in the PC/RS cortex,prefrontal cortex(PFC)and hypothalamus of mice.Among that,c-Fos protein expression in the PC/RS cortex of mice was most significant.Compared acute administration with chronic administration,we found that MK-801 chronic administration significantly increased the expression of c-Fos protein in the PC/RS cortex,PFC and hypothalamus.Furthermore,pretreatment of mice with clozapine significantly decreased the expression of c-Fos protein induced by MK-801 acute and chronic administration.Conclusions Marked expression of c-Fos protein induced by MK-801 is associated with neurotransmitters' change noted in our previous studies,and c-Fos protein,the marker of neuronal activation,might play an important role in the chronic pathophysiological process of schizophrenic model induced by NMDA receptor antagonist.