Cytochrome P4502A5 expression and inducibility by phenobarbital is modulated by cAMP in mouse primary hepatocytes

Biochem Biophys Res Commun. 1994 Nov 30;205(1):631-7. doi: 10.1006/bbrc.1994.2712.


Factors involved in CYP2A5 expression were studied in mouse liver primary hepatocytes in culture. CYP2A5-mediated coumarin 7-hydroxylase (COH) activity was retained in simple culture conditions for at least 96 hours and the activity was inducible up to 33-fold by phenobarbital (PB). The constitutive activity and inducibility of COH was totally blocked by treatment of hepatocytes with actinomycin D, and short initial treatment with cycloheximide caused superinducibility when co-administered with PB. Treatment of hepatocytes with inhibitors of protein kinase C, tyrosine kinases and a generator of nitric oxide did not affect COH basal activity or inducibility. Administration of dibutyryl cAMP, forskolin, and 3-isobutyl-1-methylxanthine (IBMX) enhanced both basal and PB-induced COH activities and CYP2A5 mRNA levels, indicating that cAMP plays a major role in CYP2A5 expression.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 1-Methyl-3-isobutylxanthine / pharmacology
  • Animals
  • Aryl Hydrocarbon Hydroxylases*
  • Bucladesine / pharmacology*
  • Cells, Cultured
  • Colforsin / pharmacology
  • Cycloheximide / pharmacology
  • Cytochrome P-450 CYP2A6
  • Cytochrome P-450 Enzyme Inhibitors
  • Cytochrome P-450 Enzyme System / biosynthesis*
  • Cytochrome P-450 Enzyme System / genetics
  • Cytochrome P-450 Enzyme System / metabolism*
  • Cytochrome P450 Family 2
  • Dactinomycin / pharmacology
  • Enzyme Induction / drug effects
  • Liver / cytology
  • Liver / drug effects*
  • Liver / enzymology
  • Male
  • Mice
  • Mice, Inbred DBA
  • Mixed Function Oxygenases / antagonists & inhibitors
  • Mixed Function Oxygenases / biosynthesis*
  • Mixed Function Oxygenases / genetics
  • Mixed Function Oxygenases / metabolism*
  • Phenobarbital / pharmacology*
  • RNA, Messenger / metabolism


  • Cytochrome P-450 Enzyme Inhibitors
  • RNA, Messenger
  • Dactinomycin
  • Colforsin
  • Bucladesine
  • Cytochrome P-450 Enzyme System
  • Cycloheximide
  • Mixed Function Oxygenases
  • Aryl Hydrocarbon Hydroxylases
  • Cyp2a5 protein, mouse
  • Cytochrome P-450 CYP2A6
  • Cytochrome P450 Family 2
  • 1-Methyl-3-isobutylxanthine
  • Phenobarbital