title: Neonatal exposure to xenobiotics alters adult hepatic protein kinase C alpha levels and testosterone metabolism: differential effects by diethylstilbestrol and phenobarbital.
abstract: Hepatic enzymes that metabolize endogenous and xenobiotic compounds have been shown to be altered in adult rats that had been exposed to xenobiotics as neonates. Protein kinase C (PKC) is important in intracellular signaling and has been implicated in the regulation of hepatic monooxygenases. Therefore, we examined the effects of neonatal exposure to diethylstilbestrol (DES) and phenobarbital (PB) on hepatic microsomal testosterone metabolism and on the alpha form of protein kinase C (PKC alpha) in adult rats. In adult males, neonatal exposure to DES altered adult testosterone metabolism such that 7 alpha-hydroxylation was increased by 58% but 2 alpha-, 16 alpha-, and 6 beta-hydroxylations and conversion to androstenedione were decreased 31-44%. In contrast, adult males neonatally exposed to PB showed increased (20-27%) testosterone 2 alpha- and 16 alpha-hydroxylations and androstenedione formation, but no effect was observed in the rate of 6 beta- or 7 alpha-hydroxylations. Western blot analyses indicated that cytosolic PKC alpha levels in male rats neonatally exposed to PB were decreased by approximately 63% relative to the vehicle control group but were not significantly altered in the DES males. The PKC alpha levels generally correlated (r = -.75) with 16 alpha-hydroxytestosterone formation in all samples. These results show that neonatal treatment with DES or PB differentially alters hepatic monooxygenase enzyme activities and PKC alpha levels in adult rats.
authors.affiliation: Institute of Chemical Toxicology, Wayne State University, Detroit, Michigan, USA.
authors.forename: R C
authors.initials: RC
authors.lastname: Zangar
authors.forename: D R
authors.initials: DR
authors.lastname: Buhler
authors.forename: D L
authors.initials: DL
authors.lastname: Springer
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D015153:Blotting, Western; D002851:Chromatography, High Pressure Liquid; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D004054:Diethylstilbestrol / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006900:Hydroxylation; D007527:Isoenzymes / Q000378:metabolism*; D008099:Liver / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D010634:Phenobarbital / Q000633:toxicity*; D011493:Protein Kinase C / Q000378:metabolism*; D051571:Protein Kinase C-alpha; D051381:Rats; D017207:Rats, Sprague-Dawley; D013739:Testosterone / Q000097:blood / Q000378:metabolism*
chemical_list: D007527:Isoenzymes; D013739:Testosterone; D004054:Diethylstilbestrol; D003577:Cytochrome P-450 Enzyme System; D011493:Protein Kinase C; D051571:Protein Kinase C-alpha; D010634:Phenobarbital