A novel analgesic toxin (hannalgesin) from the venom of king cobra ( Ophiophagus hannah)

• Published in: Toxicon (Oxford) Vol. 33; no. 11; pp. 1425 - 1431
• Main Authors: Pu, X.C., Wong, P.T.H., Gopalakrishnakone, P.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.11.1995; Elsevier Science
• Subjects: Analgesics; Analgesics - toxicity; Animals; Arginine - analogs & derivatives; Arginine - pharmacology; Biological and medical sciences; Cobra Neurotoxin Proteins - antagonists & inhibitors; Cobra Neurotoxin Proteins - toxicity; Female; Medical sciences; Mice; Naloxone - pharmacology; Narcotic Antagonists - pharmacology; Neuropharmacology; NG-Nitroarginine Methyl Ester; Nitric Oxide - antagonists & inhibitors; Ophiophagus hannah; Pain Measurement - drug effects; Pharmacology. Drug treatments; Rodentia; Animal origin; Biological activity; Ophidia; Toxin; Vertebrata; Mammalia; Analgesic; Mouse; Animal; Venom; Neurotoxin; Reptilia
• ISSN: 0041-0101; 1879-3150
• DOI: 10.1016/0041-0101(95)00096-5

The pharmacological effects of a purified neurotoxin from king cobra ( Ophiophagus hannah) venom were studied. Using the hot-plate test, it is shown that this neurotoxin increased latency time dose-dependently when administered i.p. Similar analgesic action was observed when it was administered p.o. or i.c.v. The rota-rod performance, which is a good index for neurological deficits including sedation, muscle relaxant and impairment of motor activity and coordination, was not significantly affected in the dose range of 16–32 ng/g that caused analgesia. The toxin did not increase the convulsion threshold in the dose range of 8–64 ng/g in the maximal electroshock seizure tests. These results demonstrated that this neurotoxin produced analgesia in the dose range of 16–32 ng/g (i.p.) without causing any neurological or muscular deficits. It is further shown that such analgesic action was blocked by naloxone and l-N G- nitro-arginine methyl ester, suggesting the possible involvement of the opioid and nitric oxide systems, respectively. In view of the source of this neurotoxin ( O. hannah) and its potent analgesic action, it is proposed that this toxin be named hannalgesin.