Autonomic neuroscience : basic & clinical
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The antihypertensive drugs moxonidine and clonidine are α2-adrenoceptor and imidazoline (I1) agonists. Previous results from our laboratory have shown that moxonidine can act in the commissural nucleus of the solitary tract (commNTS). In addition, some studies have shown that GABA or glutamate receptor blockade in the RVLM blunted the hypotension produced by these antihypertensive agents in spontaneously hypertensive rats. ⋯ Injection of the GABAA antagonist bicuculline (25 pmol/50 nL) into the commNTS reduced the hypotension as well as the sympathoinhibition elicited by moxonidine. Prior injection of the glutamate receptor antagonist kynurenic acid (2.5 nmol/50 nL) into the commNTS was not effective in reducing the hypotension and sympathoinhibition elicited by moxonidine. Therefore, we conclude that the hypotensive and sympathoinhibitory effects elicited by microinjection of moxonidine into the commNTS are dependent on GABA receptors, but not ionotropic glutamate receptors.