1996 Fiscal Year Final Research Report Summary
Low activity of dihydrofolate reductase induces poor bioavailability of folic acid in pigs
| Project/Area Number |
07660399
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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 |
Basic veterinary science/Basic zootechnical science
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| Research Institution | TOKYO UNIVERSITY OF AGRICULTURE AND TECHNOLOGY |
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Principal Investigator |
KOKUE Eiichi Tokyo University of Agriculture and Technology, Department of Veterinary Medicine, Professor, 農学部, 教授 (50014965)
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| Co-Investigator(Kenkyū-buntansha) |
SHIMODA Minoru Tokyo University of Agriculture and Technology, Department of Veterinary Medicin, 農学部, 助教授 (50154323)
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| Project Period (FY) |
1995 – 1996
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| Keywords | oxidized folate / reduced folate / dihydrofolate reductase / pigs / rats |
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| Research Abstract |
Plasma folate levels does not raise after oral synthetic or oxidized folate (FA) administration in pigs, however raise in rats. We have examined the causes of the different responses to oral FA in pigs and in rats.
1) in vivo experiment ; comparison of bile folate excretion The excretion rates of the reduced folate in bile were determined in pigs and rats to find the in vivo activity of dihydrofolate reductase. The preparations with bile cannula were constructed in anesthetized pigs and rats. The excretion rate of reduced folate from bile of pigs and rats were determined before and after FA administration. resulting in much less rate being observed in pigs compared with in rats.
2) in vitro experiment ; activity of dihydrofolate reductase
Dihydrofolate reductase enzymes were extracted from livers of pigs and rats, and determined the activity of FA transformation to tetrahydrofolic acid (THF) which is a reduced folate. The results of the determination showed the transform activity of FA to THF in pigs being 130 times less compared with in rats, although the Km values being not so different.
3) intestinal absorption of FA in pigs
FA was administered per os to pigs. The time course of plasma folate levels were determined. A relative large amount of FA was detected in pig plasma after FA administration. however the levels of the reduced folate levels does not change.
4) Conclusion
Pigs can absorb FA from intestine, however, the absorbed FA is not reduced in liver. The dihydrofolate reductase activity is quite low in pigs compared with in rats.
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