Peri- and postnatal changes in reduced nicotinamide adenine dinucleotide phosphate-cytochrome P-450 reductase content in hepatocytes of rats |
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Authors: | Jun Watanabe Youko Asaka and Shinsuke Kanamura |
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Institution: | (1) Department of Anatomy, Kansal Medical University, Moriguchi, 570 Osaka, Japan |
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Abstract: | Summary To study the process of the expression of reduced nicotinamide adenine dinucleotide phosphate-cytochrome P-450 reductase (EC
1.6.2.4) in the liver during development, the amount of enzyme in the cytoplasm of periportal and perivenular hepatocytes
in sections cut from livers of male rats was measured during peri- and postnatal growth by quantitative immunohistochemistry
with a video image processor. In livers of 19-day-old foetuses, the reductase content in the cytoplasm of periportal and perivenular
hepatocytes was 0.16 μM and 0.20 μM, respectively. From the 19th day of gestation to 5 days after birth, the enzyme content
increased markedly in the cytoplasm of periportal (288%) and perivenular hepatocytes (301%). Subsequently, the content in
the cytoplasm of periportal hepatocytes increased slightly (46%) from 5 to 20 days of age, remained unchanged from 20 to 45
days of age, and increased slightly (15%) from 45 to 90 days of age. However, the content in the cytoplasm of perivenular
hepatocytes increased progressively (125%) between 5 and 90 days of age. Thus, the amount of cytochrome P-450 reductase increases
markedly in periportal and perivenular hepatocytes during the perinatal period, and subsequently the enzyme content increases
gradually in periportal hepatocytes and progressively in perivenular hepatocytes. The present results also suggest that the
divergence between cytochrome P-450 expression and the cytochrome P-450-dependent drug metabolic activity in hepatocytes during
the perinatal period, found in previous studies, can be attributed to a low cytochrome P-450 reductase density in the membrane
of endoplasmic reticulum of periportal and perivenular hepatocytes. |
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