The effects of MK-801, an NMDA receptor antagonist, on the micturition reflex in the rat

The effects of MK-801 (Dizocilpine) on the micturition reflex were studied in rats anesthetized with urethane (1.2 g/kg, s.c.). MK-801, a non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist (1-1000 micrograms/kg, i.v.) reduced, in a dose-dependent fashion the amplitude of rhythmic bladder contractions recorded isovolumetrically via a transurethral catheter. The largest doses (300-1000 micrograms/kg) completely abolished bladder activity. Bilateral section of the hypogastric nerves had no effect on MK-801 induced inhibition. MK-801 did not inhibit the bladder contractions induced by electrical stimulation of the pelvic nerve. These data suggest that MK-801 acts in the central nervous system to block glutaminergic excitatory transmission in the central micturition reflex pathway.