Send to

Choose Destination
Eur J Pharmacol. 1992 Oct 20;221(2-3):399-400.

NG-nitro-L-arginine prevents morphine tolerance.

Author information

Cotzias Laboratory of Neuro-Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY 10021.


NMDA receptor antagonists, such as MK-801, prevent the development of tolerance to morphine. Since many NMDA actions involve the production of nitric oxide, we examined the effects of a nitric oxide synthase inhibitor on morphine tolerance. The analgesic response to morphine (5 mg/kg s.c.) given daily diminishes from 60% in naive animals to 0% within 5 days. Coadministration of NG-nitro-L-arginine (8 mg/kg per day) along with morphine prevents the demonstration of appreciable tolerance for at least 11 days. These results suggest that morphine tolerance involves the activation of NMDA receptors followed by the subsequent release of nitric oxide.

[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Elsevier Science
Loading ...
Support Center