[The effect of N-methyl-D,L-aspartic acid on the nociceptive reaction of mice].

Intraperitoneal NMDLA was pharmacologically studied in mice for effects by using the hot-plate test. The agent given in a subconvulsive dose of 50 mg/kg showed a biphasic action: 5 minutes after administration there was hyperalgesia (Phase I) followed by hypoalgesia (Phase II) 15 minutes later. The effects of phencyclidine, ketamine, morphine, naloxone, bromocriptine and isradipine on NMDLA's analgetic action were also examined. Bearing in mind the fact that the action of NMDLA is decreased by isradipine in Phase I and by receptor-acting agents in Phase II it is suggested that there is a great difference in the patterns of the two phases of the analgetic action of NMDLA systemically used.