Changes in hippocampal and cortical B-1 bradykinin receptor biological activity in two experimental models of epilepsy

An increased response to the activation of receptors mediating excitatory e ffects may be involved in some forms of epilepsy. In this study, it has bee n tested whether B-1 bradykinin receptors (which mediate excitatory effects in the peripheral nervous system and have little constitutional expression in the central nervous system) may be proposed in this role. Two experimen tal models of epilepsy (kindling and kainate) have been employed, and gluta mate outflow experiments have been performed in hippocampal and cortical sl ices taken from control, kindled and kainate-treated rats. The endogenous B -1 receptor agonist Lys-des-Arg(9)-bradykinin (10(-7) M) did not affect ele ctrically-evoked glutamate overflow in control animals, but concentration-d ependently increased it in kindled rats (maximal effect +40 to +50%) and, t o a lesser extent ( + 20%), in kainate-treated rats. These effects were ful ly prevented by the selective B-1 receptor antagonist R-715 (10(-6) M), but not by the selective B-2 receptor antagonist Hoe 140 (10(-6) M). The observed changes in B-1 bradykinin receptor biological activity may pla y a role in epileptic hyperexcitability. (C) 1999 IBRO. Published by Elsevi er Science Ltd.