PUTRESCINE has been suggested to have an inhibitory effect on the excitability of the central nervous system. In the present study we found that 2 and 3 weeks after status epilepticus induced by kainic acid, rats had increased concentrations of putrescine (3- and 1.7-fold, respectively) and spermidine (1.6- and 1.4-fold, respectively) in the hippocampus. These animals exhibited a higher susceptibility to pentylentetrazol than the saline group. In addition, several hours after the pentylentetrazol injection, the concentration of putrescine and spermidine increased again in the brain and also in the plasma. In conclusion, increased hippocampal putrescine and spermidine concentrations seem to be linked with a lower threshold of excitability.