Temporal change of hippocampal enkephalin and dynorphin mRNA following trimethyltin intoxication in rats: effect of anticonvulsant

Trimethyltin (TMT), an organic metal, has been known to induce behavioral a bnormalities including seizures and aggression. We administered TMT to rats , then, behavioral changes as well as the changes of dynorphin and Metenkep halin mRNA were observed with or without phenobarbital treatment in order t o reveal the role of neuropeptides in seizure-generating mechanisms. Met-en kephalin mRNA was significantly increased at the 2nd to 6th day after TMT a dministration when seizure was frequently observed. Meanwhile, dynorphin mR NA was decreased significantly from the 2nd day to 16th day du ring aggress ion score remained high. Phenobarbital abolished not only seizures and aggr ession, but also the changes of neuropeptide expressions. These results sug gest that the changes of dynorphin mRNA are more strongly associated with a ggression than seizures, while Met-enkephalin changes correlate more with s eizures. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.