Differences in the expression and inducibility of cytochrome P450 2B isoenzymes in cultured rat brain neuronal and glial cells
Studies initiated to investigate the distribution of cytochrome P450 2B (CYP2B) isoenzymes in rat brain cells revealed significant activity of CYP2B-dependent 7-pentoxyresorufin-O-dealkylase (PROD) in microsomes prepared from both, cultured rat brain neuronal and glial cells. Neuronal cells exhibited 2-fold higher activity of PROD than the glial cells. RT-PCR and immunocytochemical studies demonstrated significant constitutive mRNA and protein expression of CYP2B in cultured neuronal and glial cells. Induction studies with phenobarbital (PB), a known CYP2B inducer, revealed significant concentration dependent increase in the activity of PROD in cultured brain cells with glial cells exhibiting greater magnitude of induction than the neuronal cells. This difference in the increase in enzyme activity was also observed with RT-PCR and immunocytochemical studies indicating differences in the induction of CYP2B1 and 2B2 mRNA as well as protein expression in the cultured brain cells. Furthermore, a greater magnitude of induction was observed in CYP2B2 than CYP2B1 in the brain cells. Our data indicating differences in the expression and sensitivity of the CYP2B isoenzymes in cultured rat brain cells will help in identifying and distinguishing xenobiotic metabolizing capability of these cells and understanding the vulnerability of the specific cell types toward neurotoxins.
KeywordsBrain cells Primary culture CYP2B Phenobarbital Immunocytochemistry RT-PCR Enzyme
Authors are grateful to Director, ITRC for his keen interest in the work. The financial assistance of Council of Science & Technology, U.P and CSIR (CMM-0018) for carrying out the above studies is gratefully acknowledged. The help of Dr. Pankaj Seth, National Brain Research Centre (NBRC), Manesar, Gurgaon, India, in the immunocytochemical analysis is also gratefully acknowledged. The technical assistance of Mr. B.S. Pandey and Mr. Rajesh Misra is gratefully acknowledged. ITRC Manuscript Communication Number: 2458.
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