Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0030567 (Parkinson's disease)
 63,064 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Because drug transporters such as P-glycoprotein, the product of the multidrug resistance (MDR1 ) gene, contribute to the function of the blood-brain barrier, we hypothesized that differences in their expression could affect the uptake of neurotoxic xenobiotics, thereby modulating interindividual susceptibility for neurological disorders such as Parkinson's disease. In a pilot case-control study comprising 95 Parkinson's disease patients (25 early-onset patients with onset age < or = 45 years) and 106 controls we analysed the three common polymorphisms, 3435C >T in exon 26, 2677G > T,A in exon 21, and -129T > C in exon 1b. There were no statistically significant associations between any of these polymorphisms and Parkinson's disease. However, a distribution pattern consistent with our hypothesis was observed in that the frequency of the 3435T/T genotype, which had previously been associated with decreased P-glycoprotein expression and function, was highest in the early-onset Parkinson's disease group (36.0%), second-highest in the late-onset Parkinson's disease group (22.9%), and lowest in the control group (18.9%). Furthermore, we confirmed that the MDR1 exon 21 and exon 26 polymorphisms are in significant linkage disequilibrium since the [2677G, 3435C] and [2677T, 3435T] haplotypes were far more frequently observed than expected. In conclusion, MDR1 and other drug transporters represent plausible candidates as Parkinson's disease risk genes. Larger studies are required to confirm this role in the etiology of Parkinson's disease.
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PMID:Expression polymorphism of the blood-brain barrier component P-glycoprotein (MDR1) in relation to Parkinson's disease. 1236 Jan 3

P-glycoprotein is a membrane protein encoded by the MDR1 gene, which demonstrates functional polymorphism. It is present in endothelial cells of the blood-brain barrier, thus limiting accumulation of its substrates in the central nervous system. Many epidemiological studies suggest an association between pesticides, which are substrates for P-glycoprotein, and Parkinson's disease. It was hypothesized that polymorphism of the MDR1 gene could modulate interindividual susceptibility for the disease in subjects exposed to pesticides. In a pilot case-control study involving 107 Parkinson's disease patients (30 early onset and 77 late onset patients; 59 exposed to pesticides and 48 non-exposed) and 103 controls, C3435T polymorphism of the gene was analysed. No statistically significant correlation between MDR1 gene polymorphism and Parkinson's disease was found. The 3435TT genotype was noted more frequently, but not significantly, in patients with early onset compared to late onset disease (23.3% versus 10.4%, respectively). A significant association between patients with parkinsonism exposed to pesticides and C3435T polymorphism of the MDR1 gene was found. Comparing the exposed and non-exposed patients, a statistically higher frequency of heterozygous subjects was observed (72.9% versus 47.9%, respectively). This genotype was associated with a significant, almost three-fold increased risk of disease. Similarly, a higher frequency of 3435TT subjects was revealed in exposed subjects (15.5%) compared to non-exposed patients (12.5%). In exposed versus non-exposed subjects, patients carrying at least one 3435T allele (i.e. homozygous and heterozygous) had a significant, five-fold higher risk of Parkinson's disease. Thus, it appears that mutation of the MDR1 gene predisposes to damaging effects of pesticides, and possibly other toxic xenobiotics transported by P-glycoprotein, leading to Parkinson's disease.
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PMID:Polymorphism in the P-glycoprotein drug transporter MDR1 gene: a possible link between environmental and genetic factors in Parkinson's disease. 1272 17

The multi-drug resistant transporter MDR1/P-glycoprotein, the gene product of MDR1, is a glycosylated membrane protein of 170 kDa, belonging to the ATP-binding cassette (ABC) superfamily of membrane transporters. MDR1 was originally isolated from resistant tumor cells as part of the mechanism of multi-drug resistance, but over the last decade, it has been elucidated that human MDR1 is also expressed throughout the body to confer intrinsic resistance to the tissues by exporting unnecessary or toxic exogeneous substances or metabolites. A number of various types of structurally unrelated drugs are substrates for MDR1, and MDR1 and other transporters are recognized as an important class of proteins for regulating pharmacokinetics and pharmacodynamics. In 2000, Hoffmeyer et al. performed a systemic screening for MDR1 polymorphisms and indicated that a single nucleotide polymorphism (SNP), C3435T in exon 26, which caused no amino acid change, was associated with the duodenal expression of MDR1 and thereby the plasma concentrations of digoxin after oral administration. Interethnic differences in genotype frequencies of C3435T have been clarified, and, at present, a total of 28 SNPs have been found at 27 positions on the MDR1 gene. Clinical studies on the effects of C3435T on MDR1 expression and function in the tissues, and also on the pharmacokinetics and pharmacodynamics have been performed around the world; however, there are still discrepancies in the results, suggesting that the haplotype analysis of the gene should be included instead of SNP detection, and the design of clinical trials must be carefully planned to avoid misinterpretations. A polymorphism of C3435T is also reported to be a risk factor for a certain class of diseases such as the inflammatory bowel diseases, Parkinson's disease and renal epithelial tumor, and this might also be explained by the effects on MDR1 expression and function. In this review, the latest reports are summarized for the future individualization of pharmacotherapy based on MDR1 genotyping.
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PMID:Pharmacogenetics of MDR1 and its impact on the pharmacokinetics and pharmacodynamics of drugs. 1283 20

Drug transporters are increasingly recognized to be important to drug disposition and response. P-glycoprotein, the encoded product of the human MDR1 (ABCB1) gene, is of particular clinical relevance in that this transporter has broad substrate specificity, including a variety of structurally divergent drugs in clinical use today. Moreover, expression of this efflux transporter in certain tissue compartments such as the gastrointestinal tract and brain capillary endothelial cells limits oral absorption and central nervous system entry of many drugs. Recently, a number of single-nucleotide polymorphisms (SNPs) in MDR1 have been identified. An increasing number of studies have also implicated certain commonly occurring SNPs in MDR1 in problems including altered drug levels and host susceptibility to diseases such as Parkinson's disease, inflammatory bowel disease, refractory seizures, and CD4 cell recovery during human immunodeficiency virus therapy. However, in many such cases, the reported effects of MDR1 SNPs have been inconsistent and, in some cases, conflicting. In this review SNPs in MDR1 in relation to population frequencies, drug levels, and phenotypes are outlined. In addition, issues relating to MDR1 haplotypes, environmental factors, and study design, as potential confounding factors of the observed MDR1 polymorphism effect in vivo, are also discussed.
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PMID:Polymorphisms in human MDR1 (P-glycoprotein): recent advances and clinical relevance. 1474 89

Most drug responses are determined by the interplay of several gene products that influence pharmacokinetics and pharmacodynamics, i.e., drug metabolizing enzymes, drug transporters, and drug targets. With the sequencing of the human genome, it has been estimated that approximately 500-1200 genes code for drug transporters. Concerning the effects of genetic polymorphisms on pharmacotherapy, the best characterized drug transporter is the multidrug resistant transporter P-glycoprotein/MDR1, the gene product of MDR1. Little such information is available on other drug transporters. MDR1 is a glycosylated membrane protein of 170 kDa, belonging to the ATP-binding cassette superfamily, and is expressed mainly in intestines, liver, kidneys and brain. A number of various types of structurally unrelated drugs are substrates for MDR1, and their intestinal absorption, hepatobiliary secretion, renal secretion and brain transport are regulated by MDR1. The first investigation on the effects of MDR1 genotypes on pharmacotherapy was reported in 2000: a silent single nucleotide polymorphism (SNP), C3435T in exon 26, was found to be associated with the duodenal expression of MDR1, and thereby the plasma concentration of digoxin after oral administration. At present, a total of 28 SNPs have been found at 27 positions on the MDR1 gene. Clinical investigations on the association of MDR1 genotypes with the expression and function of MDR1 in tissues, and with pharmacokinetics and pharmacodynamics have mainly focused on C3435T; however, there are still discrepancies in the results, suggesting that the haplotype of the gene should be analyzed instead of a SNP. C3435T is also reported to be a risk factor for a certain class of diseases including the inflammatory bowel diseases, Parkinson's disease and renal epithelial tumor, and this also might be explained by the effects on MDR1 expression and function. In this review, the latest reports on the effects of genetic polymorphisms of MDR1 on pharmacotherapy are summarized, and the pharmacogenetics of other transporters is briefly introduced.
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PMID:Pharmacogenetics of drug transporters and its impact on the pharmacotherapy. 1537 52

Drug transporters significantly influence drug pharmacokinetics and pharmacodynamics. P-glycoprotein (P-gp), the product of the MDR1 (ABCB1) gene, is among the most well-characterized drug transporters, particularly in veterinary medicine. A number of clinically relevant, structurally and functionally unrelated drugs are substrates for P-gp. P-gp is expressed by a variety of normal tissues including the intestines, renal tubular cells, brain capillary endothelial cells, biliary canalicular cells, and others, where it functions to actively extrude substrate drugs. In this capacity, P-gp limits oral absorption and central nervous system entry of many substrate drugs. A number of MDR1 polymorphisms have been described in human patients, some of which result in altered drug pharmacokinetics and susceptibility to diseases such as Parkinson's disease, inflammatory bowel disease, refractory seizures, and others. An MDR1 polymorphism in herding breed dogs, including collies and Australian shepherds, has been demonstrated to be the cause of ivermectin sensitivity in these breeds. Recent evidence suggests that this polymorphism, a 4-bp deletion mutation, results in increased susceptibility to the toxicity of several drugs in addition to ivermectin. Furthermore, data in rodent models suggest that P-gp may play an important role in regulating the hypothalamic-pituitary-adrenal axis.
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PMID:Therapeutic implications of the MDR-1 gene. 1550 May 62

Parkinson's disease (PD) is associated with a loss of neurons from the midbrain. The cause of PD is unknown, but it is established that certain neurotoxins can cause similar syndromes. The brain is normally protected from these noxious blood-borne chemicals by the blood-brain barrier which includes specialized proteins on the inside of blood vessels in the brain. These act as molecular efflux pumps and P-glycoprotein (P-gp) is an abundant representative. Vulnerability to PD appears codetermined by the genotype for the P-gp gene. We hypothesized that PD patients have reduced P-gp function in the blood-brain barrier. We used positron emission tomography to measure brain uptake of [(11)C]-verapamil, which is normally extruded from the brain by P-gp. Here, we show significantly elevated uptake of [(11)C]-verapamil (18%) in the midbrain of PD patients relative to controls. This is the first evidence supporting a dysfunctional blood-brain barrier as a causative mechanism in PD.
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PMID:Blood-brain barrier dysfunction in parkinsonian midbrain in vivo. 1566 74

Cabergoline is used in the treatment of Parkinson's disease (PD). Clarithromycin is a potent inhibitor of CYP3A4 and P-glycoprotein and is often co-administered with cabergoline in usual clinical practice. We studied the effect of clarithromycin co-administration on the blood concentration of cabergoline in healthy male volunteers and in PD patients. Study 1: Ten healthy male volunteers were enrolled and were randomized to take a single oral dose of cabergoline (1 mg/day) for 6 days or a single oral dose of cabergoline plus clarithromycin (400 mg/day) for 6 days. Study 2: Seven PD patients receiving stable cabergoline doses were enrolled. They were evaluated for the plasma cabergoline concentration before and after the addition of clarithromycin 400 mg/day for 6 days, and again 1 month after discontinuation of clarithromycin. The dose and duration of clarithromycin were decided according to usual clinical practice. In healthy male volunteers, mean Cmax and AUC(0-10 h) of cabergoline increased to a similar degree during co-administration of clarithromycin. Mean plasma cabergoline concentration over 10 h post-dosing increased 2.6-fold with clarithromycin co-administration. In PD patients, plasma cabergoline concentration increased 1.7-fold during clarithromycin co-administration. Co-administration with clarithromycin may increase the blood concentration of cabergoline in healthy volunteers and in PD patients.
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PMID:Effect of clarithromycin on the pharmacokinetics of cabergoline in healthy controls and in patients with Parkinson's disease. 1641 Jun 77

In the treatment of Parkinson's disease, levodopa, DCI, MAO-B inhibitor, COMT inhibitors, dopamine receptor agonists, amantadine, anticholinergics have been applied and new drugs are being developed. Levodopa is still the golden standard in the treatment of Parkinson's disease. The study on levodopa bioavailability showed 3-4 times differences in individual patients. Drug-food interactions are prominent in levodopa. Low protein food increased levodopa bioavailability and improved no ON or delayed ON in the treatment of Parkinson's disease. Vitamine C or magnesium did not alter the bioavailability of levodopa. The bioavailability of levodopa between the levodopa/carbidioa (100/12.5) group and the levodopa/benserazide (100/25) group was studied in patients with Parkinson's disease by population PK study. C(max) of levodopa in levodeopa/benserazide group was twice as high as in levodopa/carbidopa group. Domperidone, a dopamine receptor antagonist applied as an antiemetic inceases vowel movement. The effect of domperidone on levodopa bioavailability was studied, and the combination of domperidone with levodopa increased AUC of levodopa. Clarythromycin or grape fruit juice inhibits both of CYP3A4 and P-glycoprotein which work on metabolism and absorption of drugs. Coadministration of clarythromycin with ergot alkaloids such as cabergoline or bromocriptine increased the AUC up to 2-3 times. Amantadine is excreted through kidney without being metabolized and renal function is the most important factor in the blood concentration of amantadine. In elder women with the body weight of 50 kg or less, creatinine clearance is less than 50 ml/min even though the serum creatinine is within the normal range. Selegiline is metabolized through CYP2D6 and 3A4. Coadministration of qunidine, cimetidine, maclorides, antifungals, grape fruit juice increase the bioavailability of selegiline and may augment the antiparkinsonian effect.
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PMID:[Inter- and intraindividual pharmacokinetic variations in the treatment of Parkinson's disease]. 1644 56

Decreased blood-brain barrier (BBB) efflux function of the P-glycoprotein (P-gp) transport system could facilitate the accumulation of toxic compounds in the brain, increasing the risk of neurodegenerative pathology such as Parkinson's disease (PD). This study investigated in vivo BBB P-gp function in patients with parkinsonian neurodegenerative syndromes, using [11C]-verapamil PET in PD, PSP and MSA patients. Regional differences in distribution volume were studied using SPM with higher uptake interpreted as reduced P-gp function. Advanced PD patients and PSP patients had increased [11C]-verapamil uptake in frontal white matter regions compared to controls; while de novo PD patients showed lower uptake in midbrain and frontal regions. PSP and MSA patients had increased uptake in the basal ganglia. Decreased BBB P-gp function seems a late event in neurodegenerative disorders, and could enhance continuous neurodegeneration. Lower [11C]-verapamil uptake in midbrain and frontal regions of de novo PD patients could indicate a regional up-regulation of P-gp function.
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PMID:Decreased blood-brain barrier P-glycoprotein function in the progression of Parkinson's disease, PSP and MSA. 1826 29


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