Induction protocols for cytochromes P450IIIA in vivo and in primary cultures of animal and human hepatocytes.
Explore the source record for details and available documents.
Animals↗
Biomedical subjects
T Pineau
Publications and source records attributed to T Pineau.
Purification of a sheep liver cytochrome P-450 from the P450IIIA gene subfamily. Its contribution to the N-dealkylation of veterinary drugs.
Oral administration of troleandomycin at a dose of 100 mg/kg/day for 6 days to three adult male Lacaune sheep produced a 1.6-fold increase in specific content of liver microsomal cytochrome P-450. In sodium dodecyl sulfate-polyacrylamide gel electrophoresis, microsomal preparations from treated animals exhibited a strong band in the zone of electrophoretic mobility of cytochromes P-450. This band corresponded to a cytochrome P-450 which cross-reacted with rabbit P450IIIA6 antibodies, as demonstrated by immunoblotting. The ovine isozyme was purified to electrophoretic homogeneity by means of successive DEAE cellulose, CM cellulose and hydroxylapatite chromatographic separations. This hemoprotein had an apparent molecular weight of 52 kD as determined by calibrated sodium dodecyl sulfate-polyacrylamide gel electrophoresis and was characterized in terms of spectral data, NH2-terminal amino acid sequence, immunologic and catalytic properties. This study revealed some interspecies differences with the orthologous rabbit isozyme. The contribution of this form to the N-demethylation of erythromycin and of three veterinary drugs: chlorpromazine, chlorpheniramine and bromhexine was demonstrated from inhibition by TAO, from immunoinhibition studies, using polyclonal antibodies raised in rabbit and from the existence of significant correlations between its microsomal level and these N-demethylase activities. In contrast, the results suggest that ovine P450IIIA could not be predominantly involved in the N-dealkylation of benzphetamine, ephedrine, ivermectine or spiramycin.
Administration, Oral↗
Ontogenesis of rabbit liver cytochrome P450. Evidence for a cytochrome P450-IIE (3a)-related form prevailing during the post-natal period.
The liver hydroxylating system, mainly composed of cytochromes P450, is not highly active during foetal life. If develops after birth and reaches the adult level several weeks post-partum. We have studied the ontogenesis of rabbit cytochrome P450 during the post-natal period. Total P450 as well as isozymes 2, 3b, 3c, 4 and 6 were measured. The evolution of these proteins with ageing, together with qualitative modification of an electrophoretic profile, produced evidence of an early developing P450 prevailing from one week to three weeks after birth. We isolated and characterized a cytochrome, called P450 2y, from two-week liver microsomes. It is closely related to P450 3a, an adult form of rabbit P450 induced by ethanol. They have similar molecular masses, the same lambda max of CO-reduced spectrum and exhibit immunological cross-reactivity. However, we cannot conclude that the two proteins are identical from N-terminal amino acid analysis or the two-dimensional gel electrophoresis pattern. These results, as well as the recent evidence of two different genes coding for the P450 3a family, strengthen the idea that P450 2y and 3a are distinct proteins. P450 2y seems to be an early developing form abundant soon after birth, while P450 3a is a delayed form appearing like most P450 isozymes during the fourth post-natal week. Besides the quantitative development during perinatal life, there is an important qualitative modification of liver cytochrome P450 content.
Aging↗
Incidence of a subclinical fascioliasis on antipyrine clearance and metabolite excretion in sheep.
1. The pharmacokinetics of i.v. antipyrine (25 mg/kg) used as a model compound, were determined in young male sheep, before and each month after an oral infestation by 150 metacercariae of Fasciola hepatica, and 8 weeks following a flukicidal treatment. 2. The parasitic pathology was ascertained by the clinical observation of animals and the increase in plasma antibodies directed against liver flukes. 3. A significant decrease in the total plasma clearance of the drug occurred by week 4 to 16, and a 1.7 fold increase in mean residence time occurred by week 12 post-infection. 4. Urinary excretion of antipyrine metabolites was determined before and 8 weeks following the infestation. 4-Hydroxyantipyrine was the major urinary metabolite and its excretion was decreased by 30% in infected sheep, whereas there was no change in the excretion of norantipyrine, 3-hydroxymethylantipyrine or unmetabolized drug. 5. It is concluded that the impairment of antipyrine clearance in the course of fascioliasis could be related to the decrease in liver microsomal cytochrome P-450-dependent mono-oxygenases observed in sheep with a similar parasitic burden.
Animals↗