NON-NMDA GLUTAMATERGIC EXCITATORY TRANSMISSION IN THE DESCENDING-LIMBOF THE SPINOBULBOSPINAL MICTURITION REFLEX PATHWAY OF THE RAT

I.v. administration of GYKI-52466, a non-competitive AMPA/kainate glut amatergic receptor antagonist, inhibited bladder contractions elicited by electrical stimulation in the pontine micturition center (PMC) in urethane-anesthetized rats. The mean threshold dose of GYKI-52466 was 2 mg/kg i.v. (range = 1-4 mg/kg). Maximum inhibition (mean = 57.7 +/- 8.2%, range = 24-83.3% of control) occurred at a dose of 8 mg/kg. CNQX , a competitive AMPA/kainate glutamatergic receptor antagonist, did no t significantly alter the evoked contractions. These results indicate that AMPA/kainate receptors are involved in bulbospinal excitatory pat hway from the PMC to the parasympathetic nucleus in the lumbosacral sp inal cord in the rat.