TY - JOUR
T1 - Biochemical and immunochemical evidence for the induction of an ethanol-inducible cytochrome p-450 isozyme in male syrian golden hamsters
AU - McCoy, G. David
AU - Koop, Dennis R.
N1 - Funding Information:
Ac/cnowledgemenrs-Thisin vestigationw as supportedb y PHS Grant CA 32126a wardedb y the National Cancer Institute to G.D.M. and by Grant AA 07219f rom the National Institute on Alcohol Abuse and Alcoholism to D.R.K. We would like to thank Maria Birkel for prep-arationo f the manuscript.
PY - 1988/4/15
Y1 - 1988/4/15
N2 - The effects of ethanol and of phenobarbital pretreatment on hamster microsomal metabolism of aniline and p-nitrophenol have been investigated. Hydroxylation of both compounds was increased over 2-fold by ethanol pretreatment, whereas phenobarbital pretreatment had little effect on either activity. Ethanol pretreatment had no effect on the specific content of total cytochrome P-450, while phenobarbital pretreatment increased the specific content 1.6-fold. Comparison of the specific activities for aniline hydroxylation and p-nitrophenol hydroxylation of individual microsomal samples from control, ethanol-pretreated and phenobarbital-pretreated animals showed a high degree of correlation r2 = 0.98) consistent with the involvement of the same site for catalysis of these two compounds. Antibody to rabbit ethanol-inducible cytochrome P-450 (isozyme 3a) inhibited over 80% of the aniline (high affinity) and p-nitrophenol hydroxylase activities of microsomes from ethanol-treated hamsters. A comparison of the antibody-inhibitable rates for both hydroxylase activities with microsomes from untreated, ethanol- or phenobarbital-pretreated hamsters suggested that an isozyme homologous to rabbit isozyme 3a (hamster cytochrome P-450alc) was induced in hamsters about 3.5-fold by ethanol and was unaffected by phenobarbital. The induction of hamster cytochrome P-450alc was confirmed by immunoblot analysis of hamster microsomes. A single protein with a molecular weight of approximately 54,000 was recognized by antibody to the rabbit isozyme. Quantification of the immunoblots demonstrated that the hamster isozyme was increased about 3-fold, in good agreement with the induction determined by a comparison of the antibody-inhibitable rates. The results indicated that, although there was no change in the total spectrally observable cytochrome P-450, there was a marked change in the distribution of the isozymes of cytochrome P-450, with an increase in the alcohol-inducible form after 28-day ethanol consumption by chow-fed hamsters. This isozyme can be readily monitored by either high-affinity aniline or p-nitrophenol hydroxylation or by Western immunoblot analysis and appears to be the ethanol-inducible form of cytochrome P-450 in hamsters.
AB - The effects of ethanol and of phenobarbital pretreatment on hamster microsomal metabolism of aniline and p-nitrophenol have been investigated. Hydroxylation of both compounds was increased over 2-fold by ethanol pretreatment, whereas phenobarbital pretreatment had little effect on either activity. Ethanol pretreatment had no effect on the specific content of total cytochrome P-450, while phenobarbital pretreatment increased the specific content 1.6-fold. Comparison of the specific activities for aniline hydroxylation and p-nitrophenol hydroxylation of individual microsomal samples from control, ethanol-pretreated and phenobarbital-pretreated animals showed a high degree of correlation r2 = 0.98) consistent with the involvement of the same site for catalysis of these two compounds. Antibody to rabbit ethanol-inducible cytochrome P-450 (isozyme 3a) inhibited over 80% of the aniline (high affinity) and p-nitrophenol hydroxylase activities of microsomes from ethanol-treated hamsters. A comparison of the antibody-inhibitable rates for both hydroxylase activities with microsomes from untreated, ethanol- or phenobarbital-pretreated hamsters suggested that an isozyme homologous to rabbit isozyme 3a (hamster cytochrome P-450alc) was induced in hamsters about 3.5-fold by ethanol and was unaffected by phenobarbital. The induction of hamster cytochrome P-450alc was confirmed by immunoblot analysis of hamster microsomes. A single protein with a molecular weight of approximately 54,000 was recognized by antibody to the rabbit isozyme. Quantification of the immunoblots demonstrated that the hamster isozyme was increased about 3-fold, in good agreement with the induction determined by a comparison of the antibody-inhibitable rates. The results indicated that, although there was no change in the total spectrally observable cytochrome P-450, there was a marked change in the distribution of the isozymes of cytochrome P-450, with an increase in the alcohol-inducible form after 28-day ethanol consumption by chow-fed hamsters. This isozyme can be readily monitored by either high-affinity aniline or p-nitrophenol hydroxylation or by Western immunoblot analysis and appears to be the ethanol-inducible form of cytochrome P-450 in hamsters.
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U2 - 10.1016/0006-2952(88)90019-6
DO - 10.1016/0006-2952(88)90019-6
M3 - Article
C2 - 3358786
AN - SCOPUS:0023881605
SN - 0006-2952
VL - 37
SP - 1563
EP - 1568
JO - Biochemical Pharmacology
JF - Biochemical Pharmacology
IS - 8
ER -