Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Reduction of the cerebral metabolic rate of glucose is one of the most predominant abnormalities generally found in the Alzheimer brain, whereas the cerebral metabolic rate of oxygen is only slightly diminished or not at all the beginning of this dementive disorder. This metabolic abnormality may induce severe functional disturbances, obviously preceding morphobiological changes. From the cerebral metabolic rates of oxidized glucose and oxygen, the cerebral ATP formation rate was calculated in incipient early-onset, incipient late-onset and stable advanced dementia of Alzheimer type. A reduction of ATP formation was found from at least 7% in incipient early-onset, to around 20% in incipient late-onset DAT, and from 35% to more than 50% in stable advanced dementia. This approximation was adjusted to findings demonstrating diminished activities of enzymes active in glucose metabolism and formation of oxidation equivalents for ATP production from substrates other than glucose. A reduction for energy formation to the same range was found, as was also recently reported, in vivo in Alzheimer patients. From this rather theoretical point of view, a permanent loss of energy by at least 7-20% in incipient and progressively advancing dementia of the Alzheimer type may be assumed, with an increasing tendency in stable advanced dementia to around 50% energy loss. This energy deficit may have drastic impacts on brain function.
Mol Chem Neuropathol 1992 Jun
PMID:Oxidative energy metabolism in Alzheimer brain. Studies in early-onset and late-onset cases. 141 18

2,4-Diaminotoluene (2,4-DAT), a high volume synthetic compound, is moderately carcinogenic to rodents. We report here that 2,4-DAT is a substrate for the peroxidase activity of prostaglandin H synthase (PHS). In contrast to many aromatic amines which are activated as mutagens by PHS, we find that 2,4-DAT is not mutagenic to six S. typhimurium strains with this activation system. The strains tested include YG1006, YG1024, and YG1029, which are far more sensitive to the mutagenicity of aromatic amines and nitroarenes than are the standard tester strains. Although not mutagenic itself, 2,4-DAT does enhance the mutagenicity of 2-aminofluorene (2-AF) in the PHS-catalyzed system in strains TA98, YG1006, and YG1024, with maximal enhancement of 140%, 1831%, and 1216%, respectively. Half-maximal enhancement of 2-AF mutagenicity is observed at 15-20 microM 2,4-DAT for strains YG1006 and YG1024, and about 80 microM for TA98. Studies with compounds structurally related to 2,4-DAT revealed enhancement of 2-AF mutagenicity with 2,5-DAT and o-phenylenediamine (o-PD) but not for other DAT isomers, toluidines, and phenylenediamines. Maximal enhancement of 2-AF mutagenicity observed in TA98 with PHS-catalyzed activation was 110% for o-PD and 60% for 2,5-DAT. This comutagenic effect of 2,4-DAT appears quite specific for 2-AF, as it fails to enhance either the PHS-dependent mutagenicity of the aromatic amines benzidine and 2-naphtylamine, or the direct mutagenicity of N-acetoxy-acetylaminofluorene,2-nitrofluorene,4- nitroquinoline-N-oxide and 1,1,1-trichloropropene-2,3-oxide. Enhancement of 2-AF mutagenicity by 2,4-DAT is also observed with cytochrome P-450-dependent activation, however the half-maximal 2,4-DAT concentration was 400 microM, and the maximal enhancement was only 50%. The ability of 2,4-DAT, under conditions where it is not itself mutagenic, to enhance the genotoxicity of the potent carcinogen 2-AF comprises an intriguing toxicological interaction, and underscores the inherent difficulties in assessing the genotoxic risks posed by mixtures of compounds.
Environ Mol Mutagen 1992
PMID:Prostaglandin H synthase-dependent genotoxicity of 2,4-diaminotoluene. 157 43

The effects of amphetamine and cocaine were studied in [3H]-dopamine-loaded and superfused COS-7 cells transfected with either the cDNA of the plasmalemmal dopamine transporter ("DAT cells") or the cDNA of the vesicular amine transporter ("VAT cells"), or with both transporters ("DAT/VAT cells"). Amphetamine (0.01-100 microM, added for 4 min of superfusion) led to a concentration-dependent increase in dopamine release in DAT cells, as well as in DAT/VAT cells. The EC50 of the effect of amphetamine on DAT cells was 1.1 +/- 0.6 microM; the effect on DAT/VAT cells did not reach a plateau in the concentration range tested. With longer exposure to amphetamine, dopamine efflux from DAT cells reached a peak and quickly returned to baseline, in spite of the continued presence of the drug, whereas in DAT/VAT cells and in VAT cells the effect was sustained. Cocaine (up to 100 microM) did not exert any effect of its own in DAT cells or VAT cells but inhibited the amphetamine-induced release of dopamine from DAT cells in a competitive manner. In DAT/VAT cells cocaine and its analogue (-)-2 beta-carbomethoxy-3 beta-(4-fluorophenyl)tropane caused an efflux of dopamine resembling that caused by amphetamine but quantitatively much smaller. The rank order of potency was the same as in uptake experiments [(-)-2 beta-carbomethoxy-3 beta-(4-fluorophenyl)tropane > cocaine]. The effect of cocaine was mimicked by the reduction of chloride. The results indicate that there is a plasmalemmal component and a vesicular component in the dopamine-releasing action of amphetamine. The releasing action of cocaine is dependent on the existence of a vesicular pool of the neurotransmitter and seems to be linked to inhibition of the plasmalemmal dopamine transporter.
Mol Pharmacol 1995 Feb
PMID:Mechanism of the dopamine-releasing actions of amphetamine and cocaine: plasmalemmal dopamine transporter versus vesicular monoamine transporter. 787 46

Three genotoxic mouse carcinogens, 4-chloro-o-phenylenediamine (4-C-o-PDA), 2-nitro-p-phenylenediamine (2-N-p-PDA), and 2,4-diaminotoluene (2,4-DAT), were tested in the Big Blue transgenic mouse mutation assay. Each experiment consisted of a vehicle control group with ten Big Blue C57BL/6 mice, five of either sex, and an equally sized group treated with a high dose of the test chemical. In addition, four animals were treated with the vehicle and six animals with the test compound for the measurement of bromodeoxyuridine (BrdU) incorporation to determine cellular proliferation. Prior to the mutagenicity experiments, the maximally tolerated dose of each compound was determined using nontransgenic C57BL/6 mice. Based on these results the doses used in the main study were 200 mg/kg/day for 4-C-o-PDA, 150 mg/kg/ day for 2-N-p-PDA, and 80 mg/kg/day for 2,4-DAT. Animals were treated for 10 days over a 2 week period and were killed 10 days after the ast treatment. In an additional experiment with 2,4-DAT, animals were killed 28 days after treatment. Since all three chemicals are liver carcinogens in the mouse, the DNA of the liver was analyzed using the standard procedures for the Big Blue assay. Hepatocyte proliferation was assessed by immunohistochemical detection of proliferating cell nuclear antigen (PCNA) and, in some studies, by measuring BrdU incorporation. 4-C-o-PDA and 2-N-p-PDA did not induce an increase in PCNA expression when measured 10 days after the last treatment. There was no increase in BrdU incorporation immediately after treatment with 4-C-o-PDA or with 2,4-DAT. However, 10 days after the last treatment with 2,4-DAT, a strong mitogenic effect was found with both techniques, i.e., in the PCNA and BrdU assays. 4-C-o-PDA, a liver carcinogen in both genders of mice, induced a small, statistically significant increase of the mutant frequencies in females. No increase was found in males. 2-N-p-PDA, which has been reported to induce liver tumors only in females, was found positive in males and was clearly negative in females. 2,4-DAT, a liver carcinogen in female mice, was positive in females and negative in males when the animals were killed 10 days after the last treatment. After an expression time of 28 days, 2,4-DAT induced a statistically significant increase in both sexes. The effect in females was marginally stronger than after 10 days' expression time and almost identical to the effect observed in males under these test conditions. In conclusion, the experiments showed that the Big Blue assay detects the genotoxicity of the three carcinogenic monocyclic aromatic amines tested. However, it seems that the sex specificity of the carcinogenic effects of these compounds is not reflected by the mutagenicity data in Big Blue mice.
Environ Mol Mutagen 1996
PMID:Evaluation of the in vivo genotoxic potential of three carcinogenic aromatic amines using the Big Blue transgenic mouse mutation assay. 899 Oct 64

The cellular expression of DAT mRNA and VMAT2 mRNA was investigated in sections of the human post-mortem substantia nigra in control and Parkinson's disease tissue using in situ hybridisation techniques. Short synthetic oligodeoxynucleotides were used to detect these gene transcripts at the cellular level. In the control human nigra, high levels of expression were seen in all sub-divisions of the substantia nigra, especially within medial regions. By contrast, the level of expression of both DAT mRNA and VMAT2 mRNA was markedly reduced in Parkinson's disease; these reductions in hybridisation signal were associated with (i) a marked loss of dopamine-containing cells in the substantia nigra, and (ii) a reduction in both DAT and VMAT2 signal per cell in the remaining pigmented neurones. These disease-related decreases in the cellular abundance of both DAT and VMAT2 gene transcripts in the surviving cells of the parkinsonian nigra may reflect compensatory changes in catecholamine signalling or may be a consequence of neuronal dysfunction.
Brain Res Mol Brain Res 1996 Feb
PMID:Dopamine transporter (Dat) and synaptic vesicle amine transporter (VMAT2) gene expression in the substantia nigra of control and Parkinson's disease. 901 52

Quantitative in situ hybridization was utilized to map the distribution and abundance of the serotonin, dopamine and norepinephrine transporter (SERT, DAT and NET, respectively) mRNAs. SERT mRNA was quantified within the dorsal raphe (DR) and the median raphe (MR), DAT mRNA within the ventral tegmental area -substantia nigra (VTA-SN) region and NET mRNA within the locus coeruleus (LC). SERT mRNA expression within the raphe complex was organized into distinct subregional domains with the rank order of mRNA abundance: ventromedial (vm) DR > dorsomedial (dm) DR > MR > dorsolateral (dl) DR. The relative abundance of DAT mRNA also varied across subregions: SN pars compacta > the parabrachial pigmentosis (PBP) > the intrafascicular (IF). The effects of a 'binge' paradigm of cocaine administration on SERT, DAT and NET mRNA abundance were compared in the brains of behaviorally sensitized rats. Cocaine significantly decreased the abundance of the SERT mRNA within the dlDR and DAT mRNA abundance within the SNc and the PBP, and increased the abundance of the NET mRNA within the LC. Finally, correlational analysis indicated that post-cocaine levels of DAT, SERT and NET mRNAs were not associated with cocaine-induced sensitization.
Brain Res Mol Brain Res 1997 Oct 03
PMID:Serotonin, dopamine and norepinephrine transporter mRNAs: heterogeneity of distribution and response to 'binge' cocaine administration. 938 68

Catecholaminergic neurotransmission is normally terminated by rapid re-uptake of the neurotransmitter by a high-affinity Na+/Cl--dependent plasma membrane transporter. Specific transporters have been cloned for both dopamine (DAT) and noradrenaline (NAT) in the rat. While DAT has been studied extensively, NAT expression has received less attention, particularly at the protein level. We used an antibody generated against a 49 residue segment of an extracellular loop region of NAT to study expression of the transporter protein throughout the rat pons and medulla oblongata. NAT was expressed in over 95% of noradrenergic neurones in the A1, A2/area postrema, A5, A6/locus subcoeruleus, and A7 noradrenergic groups. Approximately 10% of C1 adrenergic neurones located in the rostral ventrolateral medulla (RVL) also expressed NAT. Expression of NAT mRNA in bulbospinal C1 cells was confirmed using single-cell reverse transcription polymerase chain reaction (RT-PCR) of acutely isolated RVL neurones. Spinally projecting neurones were identified by retrograde labelling with rhodamine beads, and C1 neurones were identified by RT-PCR using primers specific for tyrosine hydroxylase (TH) or phenylethanolamine N-methyltransferase (PNMT) mRNAs. Thirteen percent of adrenergic bulbospinal neurones tested expressed NAT mRNA. C1 neurones are potentially important in cardiovascular control and blood pressure regulation, and the identification of NAT expression in a sub-population of these neurones provides further evidence for the heterogeneity of this neuronal population.
Brain Res Mol Brain Res 1998 Nov 12
PMID:Noradrenaline transporter expression in the pons and medulla oblongata of the rat: localisation to noradrenergic and some C1 adrenergic neurones. 979 40

We investigated the gene expression of three monoamine transporters (norepinephrine transporter, NET; serotonin transporter, SERT; and dopamine transporter, DAT) in the rat superior cervical ganglion (SCG). Most of principal ganglion neurons abundantly expressed NET mRNA. In addition, about 30% of principal ganglion neurons also expressed SERT mRNA. However, DAT mRNA expression was not observed there. These results suggest that serotonin as well as norepinephrine works as a neurotransmitter in a subset of principal ganglion neurons.
Brain Res Mol Brain Res 1999 Apr 06
PMID:Expression of norepinephrine and serotonin transporter mRNAs in the rat superior cervical ganglion. 1010 Dec 35

The mechanism of release mediated by the human dopamine and norepinephrine transporter (DAT and NET, respectively) was studied by a superfusion technique in human embryonic kidney 293 cells stably transfected with the respective transporter cDNA and loaded with the metabolically inert substrate [(3)H]1-methyl-4-phenylpyridinium. Release was induced by amphetamine, dopamine, and norepinephrine or by lowering the sodium or chloride concentration in the superfusion buffer (iso-osmotic replacement by lithium and isethionate, respectively). Efflux of [(3)H]1-methyl-4-phenylpyridinium was analyzed at 30-s time resolution. In both transporters, release induced by the substrates amphetamine, dopamine, and norepinephrine followed the same time course as release induced by the removal of chloride and was faster than that caused by the removal of sodium. In the presence of low sodium (DAT: 10 mM; NET: 5 mM) none of the substrates was able to induce release from either type of cell, but adding back sodium to control conditions promptly restored the releasing action. In the presence of low chloride (DAT: 3 mM; NET: 2 mM), however, amphetamine as well as the catecholamines stimulated release from both types of cell. In contrast with the ion dependence of release observed in superfusion experiments, uptake initial rates of substrates at concentrations used in release experiments were the same or even higher at low sodium than at low chloride. The results indicate a decisive role of extracellular sodium for carrier-mediated release unrelated to the sodium-dependent uptake of the releasing substrate, and suggest a release mechanism different from simple exchange diffusion considering only the amines as substrates.
Mol Pharmacol 1999 Nov
PMID:Ion dependence of carrier-mediated release in dopamine or norepinephrine transporter-transfected cells questions the hypothesis of facilitated exchange diffusion. 1053 12

Polygenic factors play important roles in animal models of substance abuse and susceptibility to dopaminergic neurodegeneration. Genetic factors are also likely to contribute to the etiology of human drug abuse disorders, and may alter human vulnerabilities to Parkinsonian neurodegeneration. The dopamine transporter (DAT; SLC6A3) is densely expressed by the dopaminergic midbrain neurons that play central roles in drug reward and is believed to be a primary site of action for cocaine reward. This transporter is necessary for the action of selective dopaminergic neurotoxins, and is uniquely expressed on neurons that are the primary targets of Parkinsonian neurodegeneration. To study possible influences of variant DAT expression on these processes, we have constructed transgenic mice (THDAT) in which tyrosine hydroxylase (TH) promoter sequences drive expression of a rat DAT cDNA variant, increase striatal DAT expression by 20-30%, and provide modest alterations in striatal levels of dopamine and its metabolites. THDAT mice habituate more rapidly to a novel environment than wildtype littermates. These animals display enhanced reward conferred by cocaine, as measured by conditioned place preference. However, locomotor responses to cocaine administration are similar to those of wildtype mice, except at high cocaine doses. THDAT mice display more than 50% greater losses of dopaminergic neurons following a course of MPTP treatment than do wildtype control mice. These results document a model for allelic variation at a gene locus that can exert significant effects in murine models of human substance abuse vulnerability and dopaminergic neurodegeneration.
Brain Res Mol Brain Res 1999 Nov 10
PMID:Cocaine reward and MPTP toxicity: alteration by regional variant dopamine transporter overexpression. 1058 96


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