Regulation of contractile activity by magnolol in the rat isolated gastrointestinal tracts.
This study examined the pharmacological property of magnolol, a phenolic compound purified from Magnolia officinalis, on the GI motility using the rat isolated gastrointestinal (GI) strips. Magnolol (0.3-30 microM) dose-dependently stimulated the tone and amplitude of spontaneous contractions in ileum longitudinal muscles. Magnolol at 3 microM significantly increased the contractions of jejunum longitudinal and colon circular muscles, but not the longitudinal muscle contractions in fundus, antrum and colon. Pretreatment of ileum strips with either atropine (0.5 microM) or 4-diphenyllacetoxy-N(2-chloriethyl)-piperidine (4-DAMP, 0.5 microM) dramatically inhibited the acetylcholine (ACh, 0.1 microM)- and magnolol (3 microM)-induced longitudinal muscle contractions, but they were not affected by methoctramine (0.5 microM) and hexamethonium (0.5 microM). Ondansetron (0.1 microM) and GR113808 (2 microM) significantly reduced the tone of ileum longitudinal muscle contractions stimulated by 5-HT (10 microM), but not the amplitude. Magnolol (3 microM)-induced ileum longitudinal muscle contractions, both tone and amplitude, were significantly blocked by GR113808, but not by ondansetron. Taken together, magnolol differently regulates the spontaneous GI motility according to the region of GI tracts and orientation of smooth muscles, and magnolol-induced regulation of smooth muscle contractions in rat GI strips is likely to be mediated, at least in part, by activation of ACh and 5-HT receptors, possibly the M(3) and/or 5-HT(4) receptors.
Jeong
Seung Il
SI
Jeonju Biomaterials Institute, Jeonbuk 561-360, South Korea.
Kim
Young Sam
YS
Lee
Moon Young
MY
Kang
Jong Koo
JK
Lee
Seoul
S
Choi
Bong Kyu
BK
Jung
Kyu Yong
KY
D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001713:Biphenyl Compounds / Q000494:pharmacology*; D015220:Calcium Channels / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D005769:Gastrointestinal Motility / Q000187:drug effects; D041981:Gastrointestinal Tract / Q000187:drug effects* / Q000502:physiology; D007082:Ileum / Q000187:drug effects / Q000502:physiology; D066298:In Vitro Techniques; D017705:Lignans / Q000494:pharmacology*; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D043585:Receptor, Muscarinic M2 / Q000502:physiology; D044422:Receptors, Serotonin, 5-HT4 / Q000502:physiology
D001713:Biphenyl Compounds; D015220:Calcium Channels; D017705:Lignans; D043585:Receptor, Muscarinic M2; C005498:magnolol; D044422:Receptors, Serotonin, 5-HT4; D001285:Atropine