INVOLVEMENT OF PERIPHERAL NMDA RECEPTORS IN PERSISTENT NOCICEPTION INDUCED BY SUBCUTANEOUS BEE VENOM INJECTION: A BEHAVIORAL STUDY / 神经解剖学杂志

ABSTRACT

The present study was to investigate whether peripheral NMDA receptors were involved in the persistent nociceptioninduced by subcutaneous (s. C. ) bee venom injection in the conscious rat by using quatitative pain scoring methods, a.c. Bee venom injection into one hindpaw resulted in a persistent, monophasic nociceptive response characterized by continuously flinching.lifting and licking the injected paw for more than I h. The non-competitive. NMDA receptor channel blockers, ketamine and ME-801, were administered s.c. 5 or 20 min after bee venom. Local ketamine injection produced a suppression of flinching reflex by 20. 90±2.88% and 45.76±13.9%, while that of lifting/bcking time by 39. 53±10. 05% and 59.94±5.53%, at doses of 25mmol/L and 50 mmol/L respectively without any motor disturbance, Local MK-801 resulted in an inhibition of flinching reflexby 22.84±3.12% and 49.53±5.35%. While that of lifting/licking time by 17. 49±5.67%and 53.49±3. 87%. At doses of 10μmol/L and 100 ,μmol/L respectively also with no motor disturbance. However, s. C. Administration of ketamine and MK-801 inior region symmetrical to the bee venom injection site on the contralateral hindpaw produced no change in the nociceptive behaviors, suggesting that the analgesic actions of keramme and MK-8Ol were not the result of systemic effects. The present resultsuggests that peripheral NMDA receptors are involved in the production of persistent pain.