Fasting for less than 24 h induces cytochrome P450 2E1 and 2B1/2 activities in rats.
Cytochrome P450 (CYP) 2E1 activity is induced after 24 h of fasting but no information is available for shorter fasting periods. We investigate the induction of CYP 2E1, 2B1/2 and 1A1 in young adult male F344 rats after 8, 16 and 24 h of fasting compared to control. Liver microsomes were analyzed for the following enzyme activities: p-nitrophenol hydroxylase (PNP) for CYP 2E1, pentoxyresorufin-O-dealkylase (PROD) for CYP 2B1/2 and ethoxyresorufin-O-deethylase (EROD) for CYP 1A1. After each fasting interval, the activities per mg microsomal protein for PNP and PROD increased but the activity of EROD remained unchanged. Western blots for CYP 2E1 and CYP 2B1 showed increases comparable to the PNP and PROD activities, respectively. On a whole organ basis, increases were found for PNP and PROD activities, while decreases were found for EROD activity and total microsomal protein. The results are consistent with an induction of CYP 2E1 and CYP 2B1/2 activities after as little as 8 h of fasting.
Health Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, USA.
B L
BL
Brown
J W
JW
Allis
J E
JE
Simmons
D E
DE
House
D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases; D015153:Blotting, Western; D019363:Cytochrome P-450 CYP1A1; D019362:Cytochrome P-450 CYP2B1; D019392:Cytochrome P-450 CYP2E1; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis*; D004790:Enzyme Induction; D005215:Fasting / Q000009:adverse effects*; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology*; D006899:Mixed Function Oxygenases / Q000096:biosynthesis; D010088:Oxidoreductases / Q000096:biosynthesis; D010089:Oxidoreductases, N-Demethylating / Q000096:biosynthesis*; D051381:Rats; D011916:Rats, Inbred F344; D013250:Steroid Hydroxylases / Q000096:biosynthesis*; D013997:Time Factors
D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; D010088:Oxidoreductases; D013250:Steroid Hydroxylases; D019392:Cytochrome P-450 CYP2E1; D001189:Aryl Hydrocarbon Hydroxylases; D019363:Cytochrome P-450 CYP1A1; D019362:Cytochrome P-450 CYP2B1; C025619:steroid 16-beta-hydroxylase; D010089:Oxidoreductases, N-Demethylating