Cytochromes P450 of the liver are involved in maintenance of lipid homeostasis (cholesterol, vitamin D, oxysterol and bile acid metabolism) and in detoxification processes of endogenous compounds (i. ...e. bile acids) and xenochemicals (drugs). This review describes the roles of various CYPs in production of cholesterol related endogenous metabolites. These metabolites (oxysterols, bile acids, vitamin D3) act as activators of a battery of nuclear receptors, in particular liver X receptor (LXR), pregnane X receptor (PXR), constitutive androstane receptor (CAR), farnesoid X receptor (FXR) and vitamin D receptor (VDR). Nuclear receptors that are activated by cholesterol metabolites or by drugs (i. e. PXR or CAR) bind to promoter regions of responsive genes. The downstream genes include CYPs from cholesterol metabolism and/or from drug metabolism whose transcription is activated in a feedback manner. Cholesterol metabolites are thus major actors of the cross-talk that is mediated by nuclear receptors and activated CYPs. This results in a simultaneous regulation of genes from cholesterol metabolism, drug metabolism and also other pathways. The interplay between metabolism of endogenous and exogenous compounds is a frequent cause of drug failures that can now be explained at the molecular level.
Statins are well known lipid lowering agents that inhibit the enzyme 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase. They also activate drug metabolism but their exact receptor-mediated action ...has not been proven so far. We tested whether atorvastatin and rosuvastatin are direct ligands of human constitutive androstane receptor (CAR). We measured binding activities of atorvastatin and rosuvastatin to the human constitutive androstane receptor/retinoid X receptor
ligand-binding domain (CAR/RXR
-LBD) heterodimer with surface plasmon resonance (SPR). Additionally, three-dimensional models of CAR/RXR
-LBD were constructed by ligand-based and structure-based in silico modeling. Experiments and computational modeling show that atorvastatin and rosuvastatin bind to the human CAR/RXR
-LBD heterodimer, suggesting both can modulate the activity of CAR through direct interaction with the LBD of this receptor. We confirm that atorvastatin and rosuvastatin are direct ligands of CAR. The clinical consequences of CAR activation by statins are in their potential drug-drug interactions, and changes in glucose and energy metabolism.
With particular emphasis on interactions between cholesterol homeostasis and drug metabolism we investigate the transcriptome of human primary hepatocytes treated by two commonly prescribed ...cholesterol lowering drugs atorvastatin and rosuvastatin and by rifampicin that serves as an outgroup as well as a model substance for induction of nuclear pregnane X receptor.
Hepatocytes from human donors have been treated with rosuvastatin, atorvastatin, and rifampicin for 12, 24, and 48 h. Expression profiling with cholesterol and drug metabolism enriched low density Steroltalk cDNA and whole genome Affymetrix HG-U133 Plus 2.0 arrays has been applied. Differential expression (DE) of genes and gene set enrichment analysis of KEGG pathways were performed. Lists of differentially expressed genes and gene sets were cross-compared. Selected genes were confirmed by quantitative real-time PCR.
Statins lead to: (a) upregulation of cholesterol-related genes indicating an increased LDL uptake and storage of esterified cholesterol, elevated bile acid/drug export and lower capacity to form HDL; (b) perturbation of genes in glucose and fatty acid homeostasis, influencing acetyl-CoA pools, promoting gluconeogenesis and glucose export; (c) elevated expression of ADIPOR2 suggesting increased sensitivity to adiponectin; (d) perturbations in genes of lipoprotein particle formation, differently for each statin; (e) perturbed expression of many metabolic genes that are directly controlled by nuclear receptors constitutive androstan and/or pregnane X.
These data provide a novel global insight into hepatic effects of statins, offering biochemical explanations for higher blood glucose in statin-treated patients, and for drug-induced secondary fatty liver disease.
We described the use of a food supplementation with D-phenylalanine, L-glutamine and L-5-hydroxytriptophan in the alleviation of alcohol withdrawal symptoms in patients starting a detoxification ...therapy. Since abstinence from ethanol causes a hypodopaminergic and a hypoopioidergic environment in the reword system circuits, manifesting with withdrawal symptoms, food supplements that contains D-phenylalanine a peptidase inhibitor (of opioide inactivation) and L-amino-acids (for dopamine synthesis) were used to replenish a lack in neurotransmitters and alleviate the symptoms of alcohol withdrawal. 20 patients suffering from alcohol addictions starting a detoxification therapy have been included in a prospective, randomized, double blind study. The patients have been randomly devided in two groups. One group recieved for a period of 40 days a food supplement containing D-phenylalanine, L-glutamine and L-5-hydroxytriptophan (investigation group), and the control (placebo) group. On the first day of hospitalization the patients performed a SCL-90-R test, and blood samples were taken for measuring liver enzymes, total bilirubin, unbound cortisol and lymphocyte populations. The same was done on the 40th day of hospitalization. During the therapy a significant decrease in SCL-90-R psychiatric symptoms scores and a significant increase in CD4 lymphocyte count was observed in the investigation group. The cortisol values were significantly, but equally decreased in both groups, the same was with the liver enzymes and the total bilirubin values. We conclude that abstinence causes a major stress for the patients. The use of food supplement containing D-phenylalanine, L-glutamine and L-5-hydroxytriptophan alleviates the withdrawal symptoms and causes a rise in CD4 lymphocyte population, but it dose not affect the serum cortisol levels, which are probably more affected by liver inflammation and the liver restitution.
We described the use of a food supplementation with D-phenylalanine, L-glutamine and L-5-hydroxytriptophan in
the alleviation of alcohol withdrawal symptoms in pateints starting a detoxification ...terapy. Since abstinence from ethanol
causes a hypodopaminergic and a hypoopioidergic environment in the reword system circuits, manifesting with
withdrawal symptoms, food supplements that contains D-phenylalanine a peptidase inhibitor (of opioide inactivation)
and L-amino-acids (for dopamine synthesis) were used to replenish a lack in neurotransmitters and alleviate the symptoms
of alcohol withdrawal. 20 patienets suffering from alcohol addictions starting a detoxification therapy have been
included in a prospective, randomized, double blind study. The patients have been randomly devided in two groups. One
group recieved for a period of 40 days a food supplement containing D-phenylalanine, L-glutamine and L-5-hydroxytriptophan
(investigation group), and the control (placebo) group. On the first day of hospitalization the patients performed
a SCL-90-R test, and blood samples were taken for measuring liver enzymes, total bilirubin, unbound cortisol
and lymphocyte populations. The same was done on the 40th day of hospitalization. During the therapy a significant decrease
in SCL-90-R psychiatric symptoms scores and a significant increase in CD4 lymphocyte count was observed in the
investigation group. The cortisol values were significantly, but equally decreased in both groups, the same was with the
liver enzymes and the total bilirubin values.We conclude that abstinence causes a major stress for the patients. The use of
food supplement containing D-phenylalanine, L-glutamine and L-5-hydroxytriptophan alleviates the withdrawal symptoms
and causes a rise in CD4 lymphocyte population, but it dose not affect the serum cortisol levels, which are probably
more affected by liver inflammation and the liver restitution.
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