Buprenorphine modulates methamphetamine-induced dopamine dynamics in the rat caudate nucleus.

Methamphetamine (METH) abuse and addiction present a major problem in the United States and globally. Oxidative stress associated with exposure to METH mediates to the large extent METH-evoked neurotoxicity. While there are currently no medications approved for treating METH addiction, its pharmacology provides opportunities for potential pharmacotherapeutic adjuncts to behavioral therapy in the treatment of METH addiction.

Eps15 interacts with ubiquitinated Cx43 and mediates its internalization.

Gap junctions (GJ) are specialized cell-cell contacts that provide direct intercellular communication (IC) between eukaryotic cells. Regulation of GJIC by degradation of Cx43 has been a matter of debate over the last two decades and both the proteasome and the lysosome have been implicated. However, the underlying mechanism and molecular players involved remain elusive.

Myrip uses distinct domains in the cellular activation of myosin VA and myosin VIIA in melanosome transport.

Myrip is a Rab27a and MyosinVIIa (MyoVIIa) linking protein that may regulate melanosome transport in the retinal pigment epithelium (RPE). Myrip also binds MyosinVa (MyoVa) in vitro however it is unclear whether this interaction is of sufficient affinity to be physiologically relevant. Here, we addressed the questions of whether Myrip interacts with MyoVa in cells and the molecular basis of cellular activation of MyoVa and MyoVIIa by Myrip.

Methamphetamine changes NMDA and AMPA glutamate receptor subunit levels in the rat striatum and frontal cortex.

Methamphetamine (METH) is a powerful psychostimulant whose noxious effects depend largely on the pattern of abuse. METH-induced glutamate release may overactivate N-methyl-d-aspartate and alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptors (NMDAR and AMPAR, respectively) causing excitotoxicity. In the brain, these receptors are also known for their essential role in mediating memory consolidation.

Acute increase of the glutamate-glutamine cycling in discrete brain areas after administration of a single dose of amphetamine.

The glutamate-glutamine cycle between neurons and glia is tightly related to excitatory glutamatergic and inhibitory GABAergic regulation in brain. The role of this neuron-astrocyte cross-talk on the neurotoxicity induced by amphetamines is not understood. Also, the impact of neurotoxic doses of amphetamines on the balance between glutamatergic and GABAergic circuits is largely unknown.

Methamphetamine-induced early increase of IL-6 and TNF-alpha mRNA expression in the mouse brain.

The mechanisms by which methamphetamine (METH) causes neurotoxicity are not well understood. Recent studies have suggested that METH-induced neuropathology may result from a multicellular response in which glial cells play a prominent role, and so it is plausible to suggest that cytokines may participate in the toxic effects of METH. Therefore, in the present work we evaluated the effect of an acute administration of METH (30 mg/kg in a single intraperitoneal injection) on the interleukin (IL)-1beta, IL-6, and tumor necrosis factor (TNF)-alpha mRNA expression levels in the hippocampus, frontal cortex, and striatum of mice.

New approaches in drug delivery systems: application for diabetes treatment.

Advanced drug delivery systems present indubitable advantages for drug administration. During the past three decades, new approaches for the development of new carriers for this topic have been suggested. This led to explosion of publication activity in the area.

Methamphetamine induces alterations on hippocampal NMDA and AMPA receptor subunit levels and impairs spatial working memory.

Methamphetamine (METH) is a powerful psychostimulant that increases glutamate (Glu) levels in the mammalian brain and it is currently known that hippocampi are particularly susceptible to METH. Moreover, it is well established that the overactivation of N-methyl-d-aspartate (NMDA) and AMPA ionotropic Glu receptors causes excitotoxicity. In the present study, we investigated the effect of acute (30 mg/kg) versus escalating dose (ED) administration of METH on NMDA receptor 1, NMDA receptor 2 and glutamate receptor 2 (GluR2) subunit expression in the hippocampus and on memory.

The proteasome regulates the interaction between Cx43 and ZO-1.

Gap junction (GJ) intercellular communication (GJIC) is vital to ensure proper cell and tissue function. GJ are multimeric structures composed of proteins called connexins. Modifications on stability or subcellular distribution of connexins have a direct impact on the extent of GJIC.

Oxidative stress upregulates ubiquitin proteasome pathway in retinal endothelial cells.

Purpose: To establish whether oxidative stress in retinal endothelial cells upregulates the ubiquitin proteasome pathway (UPP) leading to increased protein degradation in diabetes.

Methods: Retinal endothelial cells were exposed to a continuous flux of hydrogen peroxide produced by glucose oxidase. Endogenous ubiquitin conjugates were detected by western blotting.

Subcellular redistribution of components of the ubiquitin-proteasome pathway during lens differentiation and maturation.

Purpose: To determine the subcellular distribution of components of the ubiquitin-proteasome pathway (UPP) in lens epithelium and differentiating fibers and to evaluate potential roles of the UPP in eliminating nuclei and other organelles during maturation of lens fibers.

Methods: Adult bovine lens cryosections were stained for immunofluorescence and analyzed by confocal microscopy. The specificities of the antibodies used in this study were determined by Western blot.

Downregulation of retinal GLUT1 in diabetes by ubiquitinylation.

Purpose: To investigate the effect of chronic hyperglycemia on the levels of the glucose transporter GLUT1 in retina and its ubiquitinylation.

Methods: Two diabetic animal models (Goto Kakizaki rats and alloxan-induced diabetic rabbits) and retinal endothelial cells in culture were used. GLUT1 content was determined by western blotting.

7-Ketocholesterol modulates intercellular communication through gap-junction in bovine lens epithelial cells.

BACKGROUND: Connexin43 (Cx43) is an integral membrane protein that forms intercellular channels called gap junctions. Intercellular communication in the eye lens relies on an extensive network of gap junctions essential for the maintenance of lens transparency. The association of Cx43 with cholesterol enriched lipid raft domains was recently demonstrated.

High glucose down-regulates intercellular communication in retinal endothelial cells by enhancing degradation of connexin 43 by a proteasome-dependent mechanism.

Intercellular communication through gap junctions (GJIC) is most likely relevant to maintaining the integrity of the blood-retinal barrier. In this study, we investigated the mechanism whereby high glucose enhances degradation of connexin 43 (Cx43), thus contributing to a decrease in GJIC. The levels of Cx43 in bovine retinal endothelial cells exposed to high glucose (25 mm) decreased about 50% as compared with controls (5.

Mouse genetic corneal disease resulting from transgenic insertional mutagenesis.

Background/aims: To report the generation of a new mouse model for a genetically determined corneal abnormality that occurred in transgenesis experiments.

Methods: Transgenic mice expressing mutant forms of Rab27a, a GTPase that has been implicated in the pathogenesis of choroideremia, were generated.

Results: Only one transgenic line (T27aT15) exhibited an unexpected eye phenotype.

Cholesterol oxides mediated changes in cytoskeletal organisation involves Rho GTPases.

The small GTPases Rho, Rac, and Cdc42 regulate the actin cytoskeleton in all eukaryotic cells. In this study we have evaluated the effect of cholesterol oxides (7-ketocholesterol and 25-hydroxycholesterol) on cell migration, cell adhesion, and cytoskeletal organisation of lens epithelial cells (LEC). Effects of cholesterol oxides on cytoskeleton were evaluated by immunofluorescence confocal microscopy.

7-ketocholesterol stimulates differentiation of lens epithelial cells.

Purpose: To establish if oxysterols stimulate differentiation of lens epithelial cells (LEC).

Methods: Primary cultures of lens epithelial cells were incubated with 7-ketocholesterol (7-keto), 25-hydroxycholesterol (25-OH) or cholesterol at 10 microg/ml for 10 days. Cells incubated with 100 ng/ml basic fibroblast growth factor (b-FGF) were used as positive controls for differentiation.

Phosphorylation of connexin 43 acts as a stimuli for proteasome-dependent degradation of the protein in lens epithelial cells.

Purpose: The lens is an avascular organ in which gap junctions provide a pathway for intercellular communication, which is vital to maintain lens transparency. Connexin43 (Cx43) is the main gap-junctional protein in lens epithelial cells. Phosphorylation of connexins is implicated in the regulation of intercellular communication.

Cholesterol may act as an antioxidant in lens membranes.

Purpose: Oxidative damage has been considered as a major factor involved in cataract formation. We have recently shown that cholesterol oxides accumulate in human cataractous lenses. The biological significance of accumulation of oxysterols in the lens is still poorly understood.

Evaluation of a non-invasive fluorescence technique as a marker for diabetic lenses in vivo.

Background: A fluorescence spectrometer has been constructed to study in vitro and in vivo fluorescence of human lenses. This instrument can measure fluorescence emission spectra, which can be useful in the characterisation of the lens endogenous fluorophores and evaluation of the feasibility of fluorescence measurement as a non-invasive marker for diabetes. The spectrometer allows determination of the optimum excitation and emission wavelengths, which can be used in simpler instrumentation for monitoring purposes.

Cholesterol oxides accumulate in human cataracts.

Human lens membranes contain the highest cholesterol content of any known biological membrane. Although cholesterol is prone to oxidation, the presence of its oxidation products in human cataract has not been shown before. This study was designed to investigate the presence of cholesterol oxides in human cataractous lenses.

Crystallin composition of human cataractous lens may be modulated by protein glycation.

Background: This study was designed to establish whether increased glycation of human crystallins could be related to an increased susceptibility to aggregation and insolubilization. The study was focused particularly on the glycation levels and composition of low-molecular-weight (LMW) peptides present in human cataractous lenses.

Methods: Lens crystallins from the water-soluble fraction were separated on a preparative scale by gel filtration.

Bendazac decreases in vitro glycation of human lens crystallins. Decrease of in vitro protein glycation by bendazac.

Bendazac has been used as an anti-cataractogenic drug. It has been reported that this acts by preventing protein denaturation. In this study the ability of bendazac to inhibit in vitro glycation of human lens crystallins was evaluated.

Ocular fluorometry: standardization and instrumentation development. A Concerted Action in the European Community (EUROEYE).

A Concerted Action on Ocular Fluorometry, stressing standardization and instrumentation development has been funded by the European Community. Agreement was reached on harmonization of protocols. The results obtained show that the protocols proposed for Clinical Ocular Fluorometry were generally appropriate and may be followed closely, with reproducible and meaningful results.