2005 Fiscal Year Final Research Report Summary
Improvement of intestinal drug absorption based on structural changes of tight junction and functional changes of P-glycoprotein
| Project/Area Number |
15590140
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Medical pharmacy
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| Research Institution | Tokyo University of Pharmacy and Life Sciences |
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Principal Investigator |
HAYASHI Masahiro Tokyo University of Pharmacy and Life Sciences, School of Pharmacy, Professor, 薬学部, 教授 (20012669)
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| Co-Investigator(Kenkyū-buntansha) |
TOMITA Makio Tokyo University of Pharmacy and Life Sciences, School of Pharmacy, Lecturer, 薬学部, 講師 (60207610)
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| Project Period (FY) |
2003 – 2005
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| Keywords | Tight Junction / P-glycoprotein / Absorption Enhancement / Peripheral Lymphocyte / Infective diseases / Ischemia / reperfusion / Inflammation Bowel Diseases / Gene Diagnosis |
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| Research Abstract |
We investigated the action mechanisms of absorption enhancers that improve paracellular and transcellular drug transport. Tartaric acid (TA) decreased the intracellular ATP level and the intracellular pH at the lower pH. From this results, it was considered that one of the action mechanism of TA is that the intracellular acidosis increases the calcium level through decrease in ATP levels, followed by opening the tight junction (TJ). TA and Pirotiodecan (PTD) also increased the transcellular transport based on the functional changes of P-glycoprotein (P-gp) in addition to TJ opening at the physiological pH. In particular, TA increased the absorption of rhodamine123 (Rho123) and daunorubicin in the ileum without TJ opening and change of expression level of P-gp. On the other hand, TA significantly inhibited the excretion of Rho123 from blood to lumen. These results suggest that TA increases the intestinal absorption of P-gp substrates, possibly by inhibiting the P-gp function without cha
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nge the expression level of P-gp in the rat intestine. PTD had enhancing effects on nasal and intestinal absorption of Rho123 based on functional changes of P-gp. Consequently, we showed the expansion of TJ and inhibition of P-gp increase intestinal absorption of hydrophilic compounds and P-gp substrates.
The multidrug resistance (mdr) gene codes for P-gp expressed on the surface of lymphocytes and intestinal epithelial cells. We measured peripheral lymphocyte (PBL) and mdr in infective diseases condition induced by lypopolysaccharide, ischemia/reperfusion (I/R), inflammation bowel diseases (IBD) and normal condition, to assess the relationship among PBL, mucosal intraepithelial lymphocyte (IEL) and mucosal epithelial cells (EC) mdr expression. Compared with controls, PBL mdr was significantly decreased in the diseases condition such as I/R and IBD. Both PBL and mucosal mdr expression appeared dependent of diseases activity, and there was a significant correlation both between PBL mdr expression and P-gp substrate absorption from intestine, and between IEL expression and EC expression. PBL and mucosal mdr expression may possibly play an important role in determination of the response of various diseases to P-gp substrate in the case such as glucocorticiod therapy. Less
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Research Products
(20 results)
