title: S-adenosyl methionine (SAM) attenuates the development of tolerance to analgesic activity of morphine in rats.
abstract: Development of tolerance to analgesic effect, on chronic administration of morphine, limits its clinical usefulness in pain management. S-adenosyl methionine (SAM) used for arthritis and approved as a supplement in many countries including United States was evaluated for reducing morphine tolerance.
  
  
  
  Male 'Wistar' rats were used. The analgesic activity was determined using tail flick analgesiometer (Columbus Instruments, USA). Rats given morphine (7mg/kg), intraperitoneally (i.p.), once daily for 5days developed tolerance to analgesic effect. To evaluate the effect of SAM on morphine tolerance, SAM 800mg/kg was administered orally (p.o.), 45min prior to each dose of morphine. The analgesic activity of SAM and opioidergic component in its activity was also evaluated.
  
  
  
  Co-administration of morphine and SAM reversed morphine tolerance. SAM exhibited analgesic effect after repeated administration which was reversed by naloxone administration.
  
  
  
  Since safety of SAM on chronic use is documented it can be a good option in morphine tolerance. Role in drug addiction and withdrawal should also be evaluated.
authors.affiliation: Department of Pharmacology, AIIMS, New Delhi 110029, India.
authors.forename: Jatinder
authors.initials: J
authors.lastname: Katyal
authors.affiliation: Department of Pharmacology, AIIMS, New Delhi 110029, India.
authors.forename: Hemant
authors.initials: H
authors.lastname: Kumar
authors.affiliation: Department of Pharmacology, AIIMS, New Delhi 110029, India.
authors.forename: Dinesh
authors.initials: D
authors.lastname: Joshi
authors.affiliation: Department of Pharmacology, AIIMS, New Delhi 110029, India. Electronic address: yk.ykgupta@gmail.com.
authors.forename: Yogendra Kumar
authors.initials: YK
authors.lastname: Gupta
mesh_terms: D000818:Animals; D004361:Drug Tolerance; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D009270:Naloxone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D009294:Narcotics / Q000494:pharmacology*; D017208:Rats, Wistar; D011930:Reaction Time; D012436:S-Adenosylmethionine / Q000494:pharmacology*; D013623:Tail
chemical_list: D009292:Narcotic Antagonists; D009294:Narcotics; D009270:Naloxone; D009020:Morphine; D012436:S-Adenosylmethionine
keywords: Morphine; Pain; S-adenosylmethionine (SAM); Tail flick latency; Tolerance