The effect of P2X receptor activity on GABAA receptor-mediated inhibition in the gerbil hippocampus

In the present study, to elucidate the effect of altered P2X receptor transmission on GABA(A) receptor expression and its transmission, we studied the morphological and electrophysiological responses of GABA(A) receptor in the gerbil hippocampus following P2X receptor antagonist/agonist treatment. Suramin or pyridoxal phosphate-6-azophenyl-2,4-disulfonic acid (PPADS) treatment did not affect GABA(A) receptor immunoreactivities and paired-pulse responses in the gerbil hippocampus. In addition, ATP treatment did not significantly affect population spike amplitude ratios and EPSP slope ratios in the gerbil dentate gyrus. Co-application. but not pretreatment, of PPADS or suramin enhanced the effect of muscimol on paired-pulse inhibition in the dentate gyrus. In contrast, co-application of ATP reduced the effect of muscimol in the dentate gyrus. These findings indicate that the blockade of P2X receptor did not affect GABA(A) receptor immunoreactivities, and P2X receptor may modulate GABA(A) receptor-mediated inhibition when in co-activation with GABA(A) receptor. Therefore, our findings suggest that the relationship between GABA(A) receptor and P,X receptor may not be reciprocal, although GABA(A) receptor activity affects P2X receptor functionality and its expression. (C) 2005 Elsevier B.V. All rights reserved.