| Project/Area Number |
02404025
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
General pharmacology
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| Research Institution | Keio University |
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Principal Investigator |
KATO Ryuichi Keio Univ., Sch. of Med. Prof., 医学部, 教授 (40112685)
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| Co-Investigator(Kenkyū-buntansha) |
MURAYAMA Norie Keio Univ., Sch. of Med. Assistant, 医学部, 助手 (90219949)
NAGATA Miki Keio Univ., Sch. of Med. Assistant, 医学部, 助手 (10196488)
NAGATA Kiyoshi Keio Univ., Sch. of Med. Assistant, 医学部, 助手 (80189133)
YAMAZOE Yasushi Keio Univ., Sch. of Med. Associate Prof., 医学部, 助教授 (00112699)
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| Project Period (FY) |
1990 – 1992
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| Project Status |
Completed (Fiscal Year 1992)
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| Budget Amount *help |
¥28,000,000 (Direct Cost: ¥28,000,000)
Fiscal Year 1992: ¥8,500,000 (Direct Cost: ¥8,500,000)
Fiscal Year 1991: ¥7,300,000 (Direct Cost: ¥7,300,000)
Fiscal Year 1990: ¥12,200,000 (Direct Cost: ¥12,200,000)
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| Keywords | Cytochrome P-450 / Phenobarbital / Hepatocyte / Thyroid hormone / Growth hormone / GRE / HNF-4 / Dexamethasone / フェノバルビタール誘導 / トリヨードチロニン / チトクロ-ムPー450 / 単離肝細胞 / 薬物代謝酵素 / 酵素誘導 / 初代培養肝細胞 |
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| Research Abstract |
Summary
We used primary culture of hepatocytes to investigate a direct effect of hormonal factors on the expression at the molecular level of rat hepatic cytochrome P-450. The levels of a variety of hepatic cytochrome P-450 are rapidly decreased during primary culture of hepatocytes. We used, therefore,matrigel to prevent the decrease of P-450s and we successed induction of P-450 2B1(CYP2B1)by phenobarbital(PB)in the hepatocytes. Thyroid hormone showed a marked inhibition of PB induction. In addition,growth hormone showed synergistic inhibition with thyroid hormone of PB induction. On the other hand,dehydroepiandrosterone antagonized the induction by growth hormone. By using derivatives of phenobarbital, we showed the structure specificity of barbiturates on the potency of induction of each cytochrome P-450,such as CYP2B1, CYP2B2 and CYP3A. We succeeded in an effective transfection of P-450 gene by Ca^<++>-coprecipition method. We used chloramphenicol-acetyltransferase gene as a receptor gene and the mechanism of induction with phenobarbital was investigated. We revealed one position,which is related with PB induction and locates near TATA box of CYP2B1 gene. Moreover,we observed five sequences of glucocorticoid responsive element(GRE)in CYP3A2 gene 6betaA and two sequences related with hepatic nuclear factor 4(HNF-4). The mechanism of expression of by dexamethasone is now under investigation by using a variety of lengthes of CYP3A2(6betaA)-CAT fusion gene.
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