EXPRESSION OF C-FOS, JUNB, C-JUN, MKP-1 AND HSP72 FOLLOWING TRAUMATICNEOCORTICAL LESIONS IN RATS - RELATION TO SPREADING DEPRESSION

The effects of a traumatic neocortical lesion on c-fos, junB, c-jun, M KP-1 and hsp72 expression were examined by in situ hybridization and i mmunocytochemistry 1-6 h following transcranial cold injury. The direc t current potential was recorded in the injury-remote cortex to evalua te the role of transient direct current shifts, i.e. spreading depress ions, in gene expression. In 14 out of 21 injured rats, spreading depr ession-like depolarizations of the direct current potential were notic ed, which were accompanied by a transient decrease in electroencephalo graphic activity and increase in laser Doppler flow. In seven injured animals, no spontaneous spreading depressions were seen. In animals wi thout spreading depressions, only a short-lasting response of c-fos, j unB, c-jun and MKP-1 messenger RNAs as well as c-Fos protein was bilat erally found in the piriform cortex, and-with ipsilateral dominance-th e dentate gyrus and hippocampal CA3/4 fields at Ih after lesioning. In injured animals with spreading depressions however, a strong elevatio n was seen in layers II-TV and VI of the injury-remote ipsilateral cer ebral cortex, which persisted over as long as 6 h. Messenger RNA level s for c-Sos, junB and MKP-1 were closely related to the time interval between the last depolarization and the end of experiment. Levels were highest shortly after transient direct current shifts, and decreased thereafter mono-exponentially with half-lives of 48, 75 and 58 min for c-Sos, junB and MKP-1 messenger RNAs, respectively. In 6 h animals wi th spreading depressions, hsp72 messenger RNA was slightly elevated in layer II of the injury-remote cortex, but heat shock protein 72 was n ot increased. The present results demonstrate that spreading depressio n is the most prominent factor influencing the trauma-related gene res ponse in the lesion-remote cortical tissue. (C) 1998 IBRO. Published b y Elsevier Science Ltd.