title: Quantitative analysis of endoplasmic reticulum and cytochrome P-450 in hepatocytes from rats injected with methylcholanthrene.
abstract: To examine whether the smooth endoplasmic reticulum (SER) proliferates in hepatocytes from animals treated with methylcholanthrene (MC) frequently used as an inducer for the enzymes of the microsomal mono-oxygenase system, we estimated the area of (smooth and rough) ER per unit cytoplasmic volume by morphometry in periportal, midzonal and perivenular hepatocytes from rats injected with 25 mg/kg MC once a day for 3 days. In addition, immunostaining intensity of major MC-inducible cytochrome P-450 (P-450) forms (1A1/1A2) and total P-450 content in the cytoplasm of hepatocytes in the three zones were measured by microphotometry to ascertain whether P-450 is sufficiently induced in each sublobular zone by the administration. In spite of significant increase in the staining intensity of P-450 1A1/1A2 and amount of total P-450, the proliferation of SER (and RER) did not occur in the three-zone hepatocytes from rats injected with MC. In perivenular hepatocytes, constitutive forms of P-450 other than 1A1/1A2 decreased (to 10%) instead of marked increase in P-450 1A1/1A2 (about 20 times), while the constitutive forms decreased to 50% in midzonal hepatocytes and remained unchanged in periportal hepatocytes after MC administration. In addition, the present results show divergence between biochemical and immumohistochemical results previously reported on MC-inducible P-450 after MC administration to be due primarily to a curvilinear relationship between content and intensity.
authors.affiliation: Department of Anatomy, Kansai Medical University, Osaka, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Tanaka
authors.forename: J
authors.initials: J
authors.lastname: Watanabe
authors.forename: Y
authors.initials: Y
authors.lastname: Asaka
authors.forename: R
authors.initials: R
authors.lastname: Ogawa
authors.forename: S
authors.initials: S
authors.lastname: Kanamura
mesh_terms: D000818:Animals; D019363:Cytochrome P-450 CYP1A1 / Q000032:analysis; D019388:Cytochrome P-450 CYP1A2 / Q000032:analysis; D003577:Cytochrome P-450 Enzyme System / Q000032:analysis*; D018870:Endoplasmic Reticulum, Rough / Q000187:drug effects*; D018871:Endoplasmic Reticulum, Smooth / Q000187:drug effects*; D007091:Image Processing, Computer-Assisted; D007124:Immunoenzyme Techniques; D008099:Liver / Q000166:cytology* / Q000201:enzymology; D008297:Male; D008748:Methylcholanthrene / Q000494:pharmacology*; D008862:Microsomes, Liver / Q000737:chemistry; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D008748:Methylcholanthrene; D003577:Cytochrome P-450 Enzyme System; D019363:Cytochrome P-450 CYP1A1; D019388:Cytochrome P-450 CYP1A2