title: YFa and analogs: investigation of opioid receptors in smooth muscle contraction.
abstract: OBJECTIVE
  To study the pharmacological profile and inhibition of smooth muscle contraction by YFa and its analogs in conjunction with their receptor selectivity.
  
  
  METHODS
  The effects of YFa and its analogs (D-Ala2) YFa, Y (D-Ala2) GFMKKKFMRF amide and Des-Phe-YGGFMKKKFMR amide in guinea pig ileum (GPI) and mouse vas deferens (MVD) motility were studied using an isolated tissue organ bath system, and morphine and DynA (1-13) served as controls. Acetylcholine was used for muscle stimulation. The observations were validated by specific antagonist pretreatment experiments using naloxonazine, naltrindole and norbinaltorphimine norBNI.
  
  
  RESULTS
  YFa did not demonstrate significant inhibition of GPI muscle contraction as compared with morphine (15% vs 62%, P = 0.0002), but moderate inhibition of MVD muscle contraction, indicating the role of κ opioid receptors in the contraction. A moderate inhibition of GPI muscles by (Des-Phe) YFa revealed the role of anti-opiate receptors in the smooth muscle contraction. (D-Ala-2) YFa showed significant inhibition of smooth muscle contraction, indicating the involvement of mainly δ receptors in MVD contraction. These results were supported by specific antagonist pretreatment assays.
  
  
  CONCLUSIONS
  YFa revealed its side-effect-free analgesic properties with regard to arrest of gastrointestinal transit. The study provides evidences for the involvement of κ and anti-opioid receptors in smooth muscle contraction.
authors: Peptide Synthesis Laboratory, Institute of Genomics and Integrative Biology, Delhi 110007, India.
authors: Krishan
authors: K
authors: Kumar
authors: Ritika
authors: R
authors: Goyal
authors: Annu
authors: A
authors: Mudgal
authors: Anita
authors: A
authors: Mohan
authors: Santosh
authors: S
authors: Pasha
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000701:Analgesics, Opioid / Q000494:pharmacology; D000818:Animals; D018679:Cholinergic Agonists / Q000494:pharmacology; D004399:Dynorphins / Q000494:pharmacology; D004744:Enkephalin, Methionine / Q000494:pharmacology; D006168:Guinea Pigs; D007082:Ileum / Q000033:anatomy & histology; D008297:Male; D051379:Mice; D009020:Morphine / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects* / Q000502:physiology*; D009130:Muscle, Smooth / Q000187:drug effects* / Q000502:physiology*; D009270:Naloxone / Q000031:analogs & derivatives / Q000494:pharmacology; D009271:Naltrexone / Q000031:analogs & derivatives / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D018377:Neurotransmitter Agents / Q000494:pharmacology; D009842:Oligopeptides / Q000494:pharmacology*; D011957:Receptors, Opioid / Q000378:metabolism*; D014649:Vas Deferens / Q000033:anatomy & histology
chemical_list: D000701:Analgesics, Opioid; D018679:Cholinergic Agonists; D009292:Narcotic Antagonists; D018377:Neurotransmitter Agents; D009842:Oligopeptides; D011957:Receptors, Opioid; D009270:Naloxone; C051844:norbinaltorphimine; D004744:Enkephalin, Methionine; D009271:Naltrexone; D004399:Dynorphins; D009020:Morphine; C034643:naloxonazine; C055382:naltrindole; D000109:Acetylcholine