Biomedical subjects

R A Harris

Publications and source records attributed to R A Harris.

At least 109 records · Page 6Linked to original sources

PubMed1999

In vitro expansion of T-cell-receptor Valpha2.3(+) CD4(+) T lymphocytes in HLA-DR17(3), DQ2(+) individuals upon stimulation with Mycobacterium tuberculosis.

The T-cell receptor (TCR) Valpha/beta gene product expression upon in vitro stimulation with mycobacteria was investigated to assess whether T-cell proliferation was associated with any specific TCR V gene usage. T-cell-enriched populations from peripheral blood of Mycobacterium bovis BCG-vaccinated healthy blood donors were stimulated in vitro with live or killed M. tuberculosis or with a soluble extract thereof. TCR Valpha/beta repertoire analysis of reactive CD4(+) and CD8(+) T cells revealed a selective HLA-DR17(3), DQ2-restricted expansion of Valpha2.3(+) CD4(+) T cells upon stimulation with live M. tuberculosis or its soluble extract. Third-complementarity-determining-region (CDR3) length analysis of the expanded Valpha2.3(+) T cells indicated an oligoclonal pattern with short CDR3 lengths in six of seven HLA-DR17(3), DQ2(+) individuals tested. In addition, Valpha/Vbeta repertoire analysis of T lymphocytes from a DR17(3), DQ2(+) donor before and after BCG vaccination revealed that positivity of skin test reactivity was associated with expansion of Valpha2.3(+) CD4(+) T lymphocytes with preferential use of a short CDR3 peak length after in vitro stimulation. Separation of M. tuberculosis soluble extract by fast protein liquid chromatography (FPLC) purification indicated that fractions corresponding to molecular masses of 60 to 70 and 15 to 25 kDa were particularly effective in eliciting Valpha2.3(+) CD4(+) T-cell expansion.

BCG Vaccine↗

PubMed1999

Mechanism responsible for inactivation of skeletal muscle pyruvate dehydrogenase complex in starvation and diabetes.

Regulation of the activity of the pyruvate dehydrogenase complex in skeletal muscle plays an important role in fuel selection and glucose homeostasis. Activation of the complex promotes disposal of glucose, whereas inactivation conserves substrates for hepatic glucose production. Starvation and diabetes induce a stable increase in pyruvate dehydrogenase kinase activity in skeletal muscle mitochondria that promotes phosphorylation and inactivation of the complex. The present study shows that these metabolic conditions induce a large increase in the expression of PDK4, one of four pyruvate dehydrogenase kinase isoenzymes expressed in mammalian tissues, in the mitochondria of gastrocnemius muscle. Refeeding starved rats and insulin treatment of diabetic rats decreased pyruvate dehydrogenase kinase activity and also reversed the increase in PDK4 protein in gastrocnemius muscle mitochondria. Starvation and diabetes also increased the abundance of PDK4 mRNA in gastrocnemius muscle, and refeeding and insulin treatment again reversed the effects of starvation and diabetes. These findings suggest that an increase in amount of this enzyme contributes to hyperphosphorylation and inactivation of the pyruvate dehydrogenase complex in these metabolic conditions. It was further found that feeding rats WY-14,643, a selective agonist for the peroxisome proliferator-activated receptor-alpha (PPAR-alpha), also induced large increases in pyruvate dehydrogenase kinase activity, PDK4 protein, and PDK4 mRNA in gastrocnemius muscle. Since long-chain fatty acids activate PPAR-alpha endogenously, increased levels of these compounds in starvation and diabetes may signal increased expression of PDK4 in skeletal muscle.

Animals↗

PubMed1999

Hepatic branched-chain alpha-keto acid dehydrogenase complex in female rats: activation by exercise and starvation.

The effects of acute exercise and starvation on hepatic branched-chain alpha-keto acid dehydrogenase (BCKDH) complex activity were examined in female rats fed high (30%)- or low (8%)-protein diets. The total activity of the complex was significantly higher in the high protein-fed rats than in the low protein-fed rats but was not affected by acute exercise and starvation in either diet group. The proportion of the active form of BCKDH complex was less than 10% in both diet groups. Acute exercise and starvation markedly increased the active form of the complex in both diet groups. The activity of BCKDH kinase, which is responsible for inactivation of the BCKDH complex by phosphorylation, tended to be decreased by acute exercise and starvation in both diet groups. These results suggest that the activity of the BCKDH kinase is an important factor determining the proportion of the active form of BCKDH complex in exercise and starvation, and that the female rat is a useful model for studying the regulation of hepatic BCKDH complex activity.

3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗

PubMed1999

Comparison of antiadhesive treatments using an objective rat model.

Intraperitoneal adhesions are a significant problem (increased morbidity, mortality, and cost) for patients undergoing abdominal procedures. Although a variety of approaches (e.g., fibrinolytic agents, anti-inflammatory drugs, or barrier/separation methods) have been used with some success in preventing adhesions, a comparison of these different modalities has yet to be performed in a model that objectively measures intraperitoneal adhesion formation. Our objectives were to establish an objective, reproducible model of intraperitoneal adhesion formation and to establish efficacy of different treatment modalities in decreasing the strength and extent of intraperitoneal adhesions. In this two-part study, a rat model establishing an objective measure of both the strength and extent of intraperitoneal adhesions was used to compare different treatment modalities. Fibrinolytic agents [recombinant tissue plasminogen activator (rtPA), streptokinase, and urokinase], anti-inflammatory drugs (dexamethasone and tolmetin sodium), and barrier methods [sodium carboxymethylcellulose (CMC), and sodium hyaluronate] and a control group were compared in the first phase. In the second phase, the two most successful agents (rtPA, CMC) were compared both alone and in combination against a commercially available barrier agent (Seprafilm) and a control group. In the first phase of the study, rtPA was the only agent that had a statistically significant effect in decreasing the strength of adhesions. CMC was the only agent that demonstrated a decrease in the extent of adhesions, and the difference tended toward significance. In the second phase, the combination of rtPA and CMC showed a significant decrease in both the strength and extent of adhesions when compared with those of the control group. This decrease was also observed in the group treated with Seprafilm, which showed no difference from the rtPA + CMC group. We conclude that, in this reproducible adhesion model, only the combination of rtPA + CMC and Seprafilm significantly reduced both the strength and the extent of intraperitoneal adhesions.

Animals↗

PubMed1999

Effects of ethanol on recombinant human neuronal nicotinic acetylcholine receptors expressed in Xenopus oocytes.

Alcohol and tobacco use is highly correlated in humans, and studies with animal models suggest an interaction of alcohol with neuronal nicotinic acetylcholine receptors (nAChRs). The aim of the present study was to characterize the effect of acute ethanol treatment on different combinations of human nAChR (hnAChR) subunits expressed in Xenopus oocytes. Ethanol (75 mM) potentiated ACh-induced currents in alpha2beta4, alpha4beta4, alpha2beta2, and alpha4beta2 receptors. This effect was due to an increase in Emax, without a change in the EC50 or Hill coefficient. hnAChR alpha2beta4 did not develop tolerance to repeated applications of ethanol or continuous exposure (10 min). The alpha3beta2 and alpha3beta4 combinations were insensitive to ethanol. Low concentrations of ethanol (25 and 50 mM) significantly inhibited homomeric alpha7 receptor function, but these receptors showed highly variable responses to ethanol. These results indicate that ethanol effects on hnAChRs depend on the receptor subunit composition. In light of recent evidence indicating that nAChRs mediate and modulate synaptic transmission in the central nervous system, we postulate that acute intoxication might involve ethanol-induced alterations in the function of these receptors.

Acetylcholine↗

PubMed1999

Ethanol actions on multiple ion channels: which are important?

BACKGROUND: This review is based on a plenary lecture presented at the 1999 meeting of the Research Society on Alcoholism. It provides an overview of the search for sites of action for ethanol in the brain. Initial studies were directed at interaction of ethanol with membrane lipids, but during the past decade, emphasis has been shifted to protein sites, particularly those on ion channels. Molecular biological techniques have provided the opportunity to study isolated channels in cellular expression systems and also provide the opportunity to manipulate these channels in mutant mice. CONCLUSIONS: There is now compelling evidence that multiple ion channels are affected by ethanol and growing support for the idea that ethanol interacts directly with specific sites on ion channels. The key, and unanswered, question is which of these channels are responsible for alcohol-induced behaviors such as intoxication, tolerance, dependence, or craving. Mutant mice will likely give (some) answers to these questions during the next decade.

Animals↗

PubMed1998

Isoenzymes of pyruvate dehydrogenase phosphatase. DNA-derived amino acid sequences, expression, and regulation.

Pyruvate dehydrogenase phosphatase (PDP) is one of the few mammalian phosphatases residing within the mitochondrial matrix space. It is responsible for dephosphorylation and reactivation of the pyruvate dehydrogenase complex (PDC) and, by this means, is intimately involved in the regulation of utilization of carbohydrate fuels in mammals. PDP is a dimeric enzyme consisting of catalytic and regulatory subunits. The catalytic subunit of PDP is a Mg2+-dependent enzyme homologous to the cytosolic phosphatases of the 2C family. In the present study, we isolated two cDNAs encoding for mitochondrial phosphatases. The first cDNA is highly homologous to the previously identified cDNA encoding for the catalytic subunit of PDP (PDP1). The second cDNA encodes a previously unknown catalytic subunit of PDP (PDP2). The new phosphatase, expressed as the recombinant protein in Escherichia coli, shows strict substrate specificity toward PDC and does not use phosphorylated branched chain alpha-ketoacid dehydrogenase as substrate. Like PDP1, PDP2 is a Mg2+-dependent enzyme, but its sensitivity to Mg2+ ions is almost 10-fold lower than that of PDP1. In contrast to PDP1, PDP2 is not regulated by Ca2+ ions. Instead, it is sensitive to the biological polyamine spermine, which, in turn, has no effect on the enzymatic activity of PDP1. Western blot analysis of PDP extracted from mitochondria isolated from liver and skeletal muscle revealed that PDP1 is predominantly expressed in mitochondria from skeletal muscle, whereas PDP2 is much more abundant in the liver rather than muscle mitochondria. Both isoenzymes are expressed in mitochondria from 3T3-L1 adipocytes, but the level of expression of PDP2 is considerably higher. These observations are consistent with previous findings on the enzymatic parameters of PDP in adipose tissue. Thus, our results provide the first evidence that there are at least two isoenzymes of PDP in mammals that are different with respect to tissue distribution and kinetic parameters and, therefore, are likely to be different functionally.

3T3 Cells↗

PubMed1998

Trypanosoma rangeli sialidase: kinetics of release and antigenic characterization.

The epimastigote stage of Trypanosoma rangeli release a sialidase with a high sialic acid hydrolysis capacity. We demonstrate that sialidase secretion is an active process that is reduced at low temperatures and in the presence of sodium azide. The enzyme is continuously released until certain maximally active concentrations are attained in the BHI culture medium when the parasite density reaches 2-3 x 10(6) cells. When introduced into culture medium already containing such enzyme levels, freshly harvested parasites do not secrete additional sialidase. These findings suggest a self-regulating mechanism and a biological role for the secreted T. rangeli sialidase. The secreted enzyme was purified to homogeneity by fractionation with ammonium sulphate and affinity chromatography. Antibodies raised against the purified molecule recognized antigens of similar molecular weights (73 kDa) in western immunoblotting analyses of T. rangeli and T. cruzi whole cell lysates. No antigenic recognition was recorded against T. cruzi active sialidase/trans-sialidase polypeptides or Clostridium perfringens and Vibrio cholerae commercial sialidases. These observations may indicate the expression of different antigenic domains in T. rangeli, T. cruzi and bacterial sialidases.

Animals↗

PubMed1998

Mutations of gamma-aminobutyric acid and glycine receptors change alcohol cutoff: evidence for an alcohol receptor?

Alcohols in the homologous series of n-alcohols increase in central nervous system depressant potency with increasing chain length until a "cutoff" is reached, after which further increases in molecular size no longer increase alcohol potency. A similar phenomenon has been observed in the regulation of ligand-gated ion channels by alcohols. Different ligand-gated ion channels exhibit radically different cutoff points, suggesting the existence of discrete alcohol binding pockets of variable size on these membrane proteins. The identification of amino acid residues that determine the alcohol cutoff may, therefore, provide information about the location of alcohol binding sites. Alcohol regulation of the glycine receptor is critically dependent on specific amino acid residues in transmembrane domains 2 and 3 of the alpha subunit. We now demonstrate that these residues in the glycine alpha1 and the gamma-aminobutyric acid rho1 receptors also control alcohol cutoff. By mutation of Ser-267 to Gln, it was possible to decrease the cutoff in the glycine alpha1 receptor, whereas mutation of Ile-307 and/or Trp-328 in the gamma-aminobutyric acid rho1 receptor to smaller residues increased the cutoff. These results support the existence of alcohol binding pockets in these membrane proteins and suggest that the amino acid residues present at these positions can control the size of the alcohol binding cavity.

Alcohols↗

PubMed1998

Sites of volatile anesthetic action on kainate (Glutamate receptor 6) receptors.

Molecular mechanisms of anesthetic action on neurotransmitter receptors are poorly understood. The major excitatory neurotransmitter in the central nervous system is glutamate, and recent studies found that volatile anesthetics inhibit the function of the alpha-amino-3-hydroxyisoxazolepropionic acid subtype of glutamate receptors (e.g. glutamate receptor 3 (GluR3)), but enhance kainate (GluR6) receptor function. We used this dissimilar pharmacology to identify sites of anesthetic action on the kainate GluR6 receptor by constructing chimeric GluR3/GluR6 receptors. Results with chimeric receptors implicated a transmembrane region (TM4) of GluR6 in the action of halothane. Site-directed mutagenesis subsequently showed that a specific amino acid, glycine 819 in TM4, is important for enhancement of receptor function by halothane (0. 2-2 mM). Mutations of Gly-819 also markedly decreased the response to isoflurane (0.2-2 mM), enflurane (0.2-2 mM), and 1-chloro-1,2, 2-trifluorocyclobutane (0.2-2 mM). The nonanesthetics 1, 2-dichlorohexafluorocyclobutane and 2,3-dichlorooctafluorobutane had no effect on the functions of either wild-type GluR6 or receptors mutated at Gly-819. Ethanol and pentobarbital inhibited the function of both wild-type and mutant receptors. These results suggest that a specific amino acid, Gly-819, is critical for the action of volatile anesthetics, but not of ethanol or pentobarbital, on the GluR6 receptor.

Amino Acid Sequence↗

PubMed1998

Enhancement of glycine receptor function by ethanol is inversely correlated with molecular volume at position alpha267.

Glycine and gamma-aminobutyric acid (GABA)A receptors are members of the "superfamily" of ion channels, and are sensitive to allosteric modulation by n-alcohols such as ethanol and butanol. We recently demonstrated that the mutation of Ser-267 to Ile in the alpha1 subunit abolished ethanol regulation of glycine receptors (Gly-R). In the present study, a pair of chimeric receptors was studied, in which a 45-amino acid domain comprising transmembrane domains 2 and 3 was exchanged between the Gly-Ralpha1 and gamma-aminobutyric acid rho1 subunits. Detailed pharmacologic analysis of these chimeras confirmed that this domain of the Gly-R confers enhancement of receptor function by ethanol and butanol. An extensive series of mutations at Ser-267 in the Gly-Ralpha1 subunit was also prepared, and the resulting homomeric receptors were expressed and tested for sensitivity to glycine, and allosteric modulation by alcohols. All of the mutant receptors expressed successfully in Xenopus oocytes. Mutation of Ser-267 to small amino acid residues such as Gly or Ala produced receptors in which glycine responses were potentiated by ethanol. As we have reported previously, the mutant Gly-Ralpha1 (Ser-267 --> Ile) was completely insensitive to ethanol; mutation of Ser-267 to Val had a similar effect. Mutation of Ser-267 to large residues such as His, Cys, or Tyr resulted in inhibition of Gly-R function by ethanol. These results demonstrate that the size of the amino acid residue at position alpha267 plays a crucial role in determining the functional consequences of allosteric modulation of the Gly-R by alcohols.

Animals↗

PubMed1998

Evidence for existence of tissue-specific regulation of the mammalian pyruvate dehydrogenase complex.

Tissue distribution and kinetic parameters for the four isoenzymes of pyruvate dehydrogenase kinase (PDK1, PDK2, PDK3 and PDK4) identified thus far in mammals were analysed. It appeared that expression of these isoenzymes occurs in a tissue-specific manner. The mRNA for isoenzyme PDK1 was found almost exclusively in rat heart. The mRNA for PDK3 was most abundantly expressed in rat testis. The message for PDK2 was present in all tissues tested but the level was low in spleen and lung. The mRNA for PDK4 was predominantly expressed in skeletal muscle and heart. The specific activities of the isoenzymes varied 25-fold, from 50nmol/min per mg for PDK2 to 1250nmol/min per mg for PDK3. Apparent Ki values of the isoenzymes for the synthetic analogue of pyruvate, dichloroacetate, varied 40-fold, from 0.2 mM for PDK2 to 8 mM for PDK3. The isoenzymes were also different with respect to their ability to respond to NADH and NADH plus acetyl-CoA. NADH alone stimulated the activities of PDK1 and PDK2 by 20 and 30% respectively. NADH plus acetyl-CoA activated these isoenzymes nearly 200 and 300%. Under comparable conditions, isoenzyme PDK3 was almost completely unresponsive to NADH, and NADH plus acetyl-CoA caused inhibition rather than activation. Isoenzyme PDK4 was activated almost 2-fold by NADH, but NADH plus acetyl-CoA did not activate above the level seen with NADH alone. These results provide the first evidence that the unique tissue distribution and kinetic characteristics of the isoenzymes of PDK are among the major factors responsible for tissue-specific regulation of the pyruvate dehydrogenase complex activity.

Acetyl Coenzyme A↗

PubMed1998

Starvation and diabetes increase the amount of pyruvate dehydrogenase kinase isoenzyme 4 in rat heart.

This study investigated whether conditions known to alter the activity and phosphorylation state of the pyruvate dehydrogenase complex have specific effects on the levels of isoenzymes of pyruvate dehydrogenase kinase (PDK) in rat heart. Immunoblot analysis revealed a remarkable increase in the amount of PDK4 in the hearts of rats that had been starved or rendered diabetic with streptozotocin. Re-feeding of starved rats and insulin treatment of diabetic rats very effectively reversed the increase in PDK4 protein and restored PDK enzyme activity to levels of chow-fed control rats. Starvation and diabetes also markedly increased the abundance of PDK4 mRNA, and re-feeding and insulin treatment reduced levels of the message to that of controls. In contrast with the findings for PDK4, little or no changes in the amounts of PDK1 and PDK2 protein and the abundance of their messages occurred in response to starvation and diabetes. The observed shift in the relative abundance of PDK isoenzymes probably explains previous studies of the effects of starvation and diabetes on heart PDK activity. The results indicate that control of the amount of PDK4 is important in long-term regulation of the activity of the pyruvate dehydrogenase complex in rat heart.

Animals↗

PubMed1998

The formation of small-pore gels by an electrically charged agarose derivative.

Previous studies have shown that, during the formation of an underivatized agarose gel, agarose molecules laterally aggregate to form thicker fibers called suprafibers; the suprafibers branch to form a gelled network. In the present study, electron microscopy of thin sections is used to investigate both the thickness and the spacing of the fibers of gels formed by agarose chemically derivatized with carboxymethyl (negatively charged) groups. For carboxymethyl agarose, electron microscopy reveals that gels cast in water consist of both fibers narrower and pores smaller than those observed for water-cast underivatized agarose gels at the same concentration. This result is confirmed by using the electrophoretic sieving of spheres to determine the radius (PE) of the effective pore of the gel. At a given concentration of gel less than 1%, the PE for a water-cast carboxymethyl agarose gel is 0.25-0.30x the PE for a water-cast underivatized agarose gel. The value of PE predicts the extent of the electrophoretic sieving that is observed when double-stranded DNA is subjected to electrophoresis through a water-cast carboxymethyl agarose gel; DNA bands formed in a water-cast carboxymethyl agarose gel are comparable in quality to DNA bands formed in a water-cast underivatized agarose gel of equal PE. The following observation supports the hypothesis that electrical charge-charge repulsion among carboxymethyl agarose molecules inhibits the formation of suprafibers in water-cast carboxymethyl agarose gels: Increased content of suprafibers in carboxymethyl agarose gels is observed when the ionic strength is raised by the presence of NaCl, MgCl2, or any of several buffers during gelation of carboxymethyl agarose.

DNA↗

PubMed1998

Methylmalonic semialdehyde dehydrogenase deficiency: psychomotor delay and methylmalonic aciduria without metabolic decompensation.

A patient presenting with developmental delay but no episodes of metabolic acidosis was found to excrete significant amounts of methylmalonate (MMA) without any associated increased excretion of malonate, ethylmalonate, 3-hydroxypropionate, or beta-alanine. In contrast to patients with methylmalonic aciduria due to deficient mutase or impaired cobalamin metabolism, there was no increase of propionylcarnitine in blood or urine. The activity of methylmalonyl-CoA mutase and the pathway for cobalamin metabolism were also intact. The quantitative levels of the various labeled enantiomers of 3-hydroxyisobutyric (3-HIBA), 3-aminoisobutyric (3-AIBA), MMA, and propionylcarnitine were compared following separate intravenous infusions of equimolar doses of [2H8]-valine or [2H4]thymine in this patient and another with methylmalonyl-CoA mutase deficiency. Levels of labeled S- and R-3-HIBA and S- and R-3-AIBA indicated an isolated defect in methylmalonic semialdehyde dehydrogenase in this patient. This condition can be recognized by plasma MMA levels of approximately 8.5 microM (cf. 400 microM in mutase deficiency), urine MMA of 20-55 micromol/kg/24 h (cf. 1150 micromol/kg/24 h), no increase in propionylcarnitine following an oral carnitine load, and increased excretion of S-3-AIBA-nearly 10 times that observed in mutase deficiency. The ratio of R-AIBA to S-AIBA of <1 also reflects this disorder.

Aldehyde Oxidoreductases↗

PubMed1998

Insulin downregulates pyruvate dehydrogenase kinase (PDK) mRNA: potential mechanism contributing to increased lipid oxidation in insulin-resistant subjects.

Oxidative metabolism of glucose is regulated by pyruvate dehydrogenase (PDH) that can be inhibited by isoforms of PDH kinase (PDK). Recently, increased PDK activity has been implicated in the pathogenesis of insulin resistance and non-insulin-dependent diabetes mellitus (NIDDM) in obese subjects. Using quantitative RT-PCR, we measured mRNA of PDK2 and PDK4 isoforms in skeletal muscle biopsies from nondiabetic Pima Indians, a population with a high prevalence of NIDDM associated with obesity. PDK2 and PDK4 mRNAs were positively correlated with fasting plasma insulin concentration, 2-h plasma insulin concentration in response to oral glucose, and percentage body fat, whereas both isoforms were negatively correlated with insulin-mediated glucose uptake rates. Measurements of PDK2 and PDK4 mRNA during the hyperinsulinemic-euglycemic clamp and of PDK2 in cell culture indicated that both transcripts decrease in response to insulin. Increased fatty acid (FA) oxidation has been traditionally viewed as the cause for increased PDK activity contributing to insulin resistance in obese subjects. In contrast, our data indicate that insufficient downregulation of PDK mRNA in insulin-resistant individuals could be a cause of increased PDK expression leading to impaired glucose oxidation followed by increased FA oxidation.

Adult↗

PubMed1998

Enhanced prevalence of T cells expressing TCRBV8S2 and TCRBV8S3 in hearts of chronically Trypanosoma cruzi-infected mice.

We have analysed the relative T cell receptor (TCR) BV gene usage in T cells from hearts and spleens of CBA/HJ mice chronically infected with the Tulahuén strain of Trypanosoma cruzi. During chronic infection, CBA/HJ mice recruit T cells at the major site of inflammation (i.e. the heart), with over-representation of certain TCRBV gene subfamilies (TCRBV8S2 and TCRBV8S3). In contrast, no signal or a very weak message from a limited number of T cells was recorded from one heart of the control group. No alteration of TCRBV distribution was recorded in spleens of chronically infected CBA/HJ. Our findings indicate that there is a preferential TCRBV gene usage in the T cell response in the hearts of chronically infected mice. Furthermore, the pattern of CDR3 lengths in inflammatory T cells was altered.

Animals↗

PubMed1998

Ethanol tolerance and synaptic plasticity.

Current concepts of the mechanisms underlying many of the pharmacological effects of ethanol on the CNS involve disruption of ion channel function via the interaction of ethanol with specific hydrophobic sites on channel subunit proteins. Of particular clinical importance is the development of tolerance and dependence to ethanol, and it is likely that adaptive changes in synaptic function in response to ethanol's actions on ion channels play a role in this process. In this article, Judson Chandler, Adron Harris and Fulton Crews discuss potential mechanisms of ethanol-induced changes in synaptic function that might provide a cellular basis for ethanol tolerance and dependence. It is proposed that multiple mechanisms are involved that include both transcriptional and post-translational modifications in NMDA and GABAA receptors.

Cytoskeletal Proteins↗