In the present study, the P 2 X 7 receptor expression in the gerbil hippocampus and GABA-mediated responses of its expression was investigated in order to identify the roles of the P 2 X 7 receptor on seizure activity and recovery mechanisms. P 2 X 7 receptor immunoreactivity in seizure-resistant (SR) gerbils was similar to that in pre-seizure group of seizure-sensitive (SS) gerbils. The administration of baclofen, a GABA B receptor agonist, P 2 X 7 receptor immunoreactivity was decreased in the mossy fiber, compared with that of non-treated gerbils, whereas treatment with phaclofen, a GABA B receptor antagonist, elevated P 2 X 7 receptor expression. Neither the treatments with GABA A receptor agonist nor antagonist affected P 2 X 7 receptor expression in the hippocampus. These findings suggest that altered P 2 X 7 receptor expression may not be involved in the epileptogenesis or seizure activity in gerbils, and presynaptic GABA B receptor-mediated actions may be closely related with the regulation of P 2 X 7 receptor expression in the gerbil hippocampus.