EFFECTS OF SINGLE CYCLOSPORINE-A PRETREATMENT ON PENTYLENETETRAZOL-INDUCED CONVULSION AND ON TRE-BINDING ACTIVITY IN THE RAT-BRAIN

Using electrophoretic mobility-shift assay (EMSA), we examined changes in DNA-binding activities of transcriptional factor-activated protein -1 (AP-1), which is a Fos-Jun protein complex, onto its responsive ele ment TRE in the hippocampus and amygdaloid nucleus of rats stimulated with pentylenetetrazol (PTZ) injection, and also investigated the effe cts of a single administration of the immunosuppressant cyclosporin A (CsA). In EMSA with nuclear extracts from the rat brain, the TRE-bindi ng activity of AP-1 in the hippocampus and amygdaloid nucleus markedly increased 2 h after the PTZ injection (75 mg/kg, i.p.). These PTZ-ind uced increases of the TRE-binding protein in these regions were comple tely suppressed by pretreatment with CsA (5 mg/kg, s.c.) 1 h before th e PTZ injection. In addition, the administration of CsA significantly ameliorated PTZ-induced convulsion. This therapeutic effect of single CsA pretreatment may be based, in part, on the effects on the TRE-bind ing activity of AP-1 ih the brain. Since single pretreatment of CsA in the present study had no effect on the PTZ-induced induction of c-fos mRNA, c-jun mRNA, Fos protein nor Jun protein, the inhibitory effects of single CsA administration an PTZ-induced TRE-binding activity in t he brain may be related to the effects of CsA on AP-1 itself. These re sults suggest that an immune response via activation of transcriptiona l factor in the brain tissue is involved in the convulsion.