beta-funaltrexamine and kyotorphin

The antinociceptive effect of L-arginine in streptozotocin-induced diabetic mice was examined. Although s.c. administration of L-arginine produced a dose-dependent inhibition of the tail-flick response in both non-diabetic and diabetic mice, the antinociceptive response was greater in diabetic mice than in non-diabetic mice. The antinociceptive effects of L-arginine in both diabetic and non-diabetic mice were significantly antagonized by s.c. administration of naltrindole, a selective delta-opioid receptor antagonist. However, neither beta-funaltrexamine, a selective mu-opioid receptor antagonist, nor nor-binaltorphimin ++, a selective kappa-opioid receptor antagonist, significantly affected the antinociceptive effect of L-arginine in diabetic and non-diabetic mice. These results suggest that L-arginine produces a marked antinociceptive effect in diabetic mice through the activation of delta-opioid receptors.

Topics: Analgesics; Animals; Arginine; Diabetes Mellitus, Experimental; Dose-Response Relationship, Drug; Endorphins; Injections, Intraventricular; Injections, Subcutaneous; Male; Mice; Mice, Inbred ICR; Naltrexone; Narcotic Antagonists; Nitroarginine; Pain Measurement; Reaction Time