Relationship Between Inhibitory Effect of Endogenous Opioid via Mu-Receptors and Muscarinic Autoinhibition in Acetylcholine Release From Myenteric Plexus of Guinea Pig Ileum
| Autor: | Hideyuki Nishiwaki, Fumiaki Hata, Noriko Saitoh, Tadayoshi Takeuchi, Hideaki Nishio |
|---|---|
| Rok vydání: | 1998 |
| Předmět: |
Atropine
Male Enkephalin Narcotic Antagonists Guinea Pigs Receptors Opioid mu Myenteric Plexus Muscarinic Antagonists In Vitro Techniques Muscarinic Agonists Pharmacology chemistry.chemical_compound Ileum Muscarine Receptors Opioid delta Muscarinic acetylcholine receptor Animals Endogenous opioid Cyprodime Receptors Opioid kappa 3 4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide (trans)-Isomer Muscarinic acetylcholine receptor M3 Muscle Smooth Enkephalins Muscarinic acetylcholine receptor M1 Analgesics Non-Narcotic Enkephalin Ala(2)-MePhe(4)-Gly(5) Receptors Muscarinic Acetylcholine Electric Stimulation Naltrexone Analgesics Opioid DAMGO Morphinans Opioid Peptides chemistry |
| Zdroj: | Japanese Journal of Pharmacology. 77:279-286 |
| ISSN: | 0021-5198 |
| DOI: | 10.1254/jjp.77.279 |
| Popis: | Relationship between activation of opioid receptors and muscarinic autoinhibition in acetylcholine (ACh) release from the myenteric plexus was studied in longitudinal muscle myenteric plexus (LMMP) preparations of guinea pig ileum. A mu-receptor agonist, [D-Ala2, N-Me-Phe4, Gly5-ol] enkephalin (DAMGO), at a concentration of 1 microM inhibited the ACh release evoked by electrical field stimulation (EFS) at 1 Hz but not at 10 Hz. After the muscarinic autoreceptors were blocked with atropine (1 microM), DAMGO inhibited EFS-evoked ACh release also at 10 Hz. After the autoreceptors were potently activated with muscarine (200 microM), the inhibitory effect of DAMGO at 1 Hz was abolished. A kappa-receptor agonist, U-50,488, at 1 microM inhibited the EFS-evoked ACh release both at 1 and 10 Hz. U-50,488 inhibited ACh release regardless of the presence of atropine or muscarine. A delta-agonist, enkephalin [D-PEN2.5] (PDPDE), did not show any significant effect. On the other hand, a selective mu-receptor antagonist, cyprodime, increased ACh release evoked by EFS at 1 Hz, but not at 10 Hz. After the autoreceptors were blocked, cyprodime increased EFS-evoked ACh release also at 10 Hz. The selective kappa-receptor antagonist, nor-binaltorphimine, did not affect ACh release in the absence or presence of atropine. The results suggest that endogenous opioid(s) inhibits ACh release by activating mu-, but not kappa- and delta-receptors in the LMMP of guinea pig ileum and that the inhibitory effect of endogenous opioid(s) in the ACh release is important when muscarinic autoinhibition mechanism does not fully work. |
| Databáze: | OpenAIRE |
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