1993 Fiscal Year Final Research Report Summary
Modulation of peristalsis by neurotensin and evidence for mechanism of generation, in the intestine
| Project/Area Number |
03454107
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
基礎獣医学
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| Research Institution | Gifu University |
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Principal Investigator |
OHASHI Hidenori Gifu University, Faculty of Agriculture, Professor, 農学部, 教授 (40001531)
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| Co-Investigator(Kenkyū-buntansha) |
TAKEWAKI Tadashi Gifu University, The United Graduate School of Veterinary Sciences (Doctoral Cou, 大学院・連合獣医学研究科, 教授 (00021717)
KOMORI Seiichi Gifu University, Faculty of Agriculture, Associate Professor, 農学部, 助教授 (70195866)
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| Project Period (FY) |
1991 – 1993
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| Keywords | Neurotensin / Peptide / Smooth muscle / Voltage-dependent Calcium channel / GTP-protein / Signal transduction / Phospholipase C / Protein kinase C |
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| Research Abstract |
Our studies were designed to determine whether endogenous neurotensin (tridecapeptide) (NT) participates in the regulation of peristalsis of the intestine.
In the rectum of the fowl, all of the major characteristics of NT suggest a possible role for NT as a mediator in the excitatory non-adrenergic and non-cholinergic (NANC) transmission : NT is present in Remak ganglia and the rectum in which cell bodies and axon terminals of NANC neurones are located, respectively, NT causes the muscle membrane to depolarize, and NT has an ability to abolish the responses of the rectal muscle to stimulation of NANC neurones as well as the peptide itself.
In guinea-pig intestine, NT, whether acts directly or indirectly, may be involved in regulation of the peristalsis in the intestine. Its predominant effect is inhibitory in the upper region of the intestine in which discharge rate of peristaltic waves is higher, but excitatory in the lower region in which discharge rate of peristaltic waves is lower.
NT owes the greater part of the contractile effect to an indirect action brought about by releasing ACh from cholinergic nerves in the longitudinal muscle of the small intestine. The contractile effects of NT on the longitudinal muscle of the large intestine, taenia caecum and circular muscle are attributable to a direct action. The relaxant effects of NT are all attributable to a direct action and blocked by apamin. Patch-clamp studies showed that NT produces an increase in activation of voltage-gated calcium cannel through a G-protein.
In beta-escin-skinned smooth muscle, NT potentiates carbachol- and caffeine-induced tension developments brought about by release of Ca2+ stores. The potentiation may result from an increase in Ca2+ sensitivity of contractile elements, in which activation of phospholipase C through a pertussis toxin-sensitive G-protein and activation of PKC by diacylglycerol seem to be operated as a signal transduction system.
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