Although lisdexamfetamine is used as a recreational drug, little research exists regarding its potential for dependence or its precise mechanisms of action. This study aims to evaluate the psychoactivity and dependence profile of lisdexamfetamine using conditioned place preference and self-administration paradigms in rodents. Additionally, biochemical techniques are used to assess alterations in the dopamine levels in striatal synaptosomes following administration of lisdexamfetamine. Lisdexamfetamine increased both conditioned place preference and self-administration. Moreover, after administration of the lisdexamfetamine, dopamine levels in the striatal synaptosomes were significantly increased. Although some modifications should be made to the analytical methods, performing high performance liquid chromatography studies on synaptosomes can aid in predicting dependence liability when studying new psychoactive substances in the future. Collectively, lisdexamfetamine has potential for dependence possible via dopaminergic pathway.
Chromatography, Liquid ; Dopamine ; In Vitro Techniques* ; Lisdexamfetamine Dimesylate* ; Rodentia ; Synaptosomes

Although lisdexamfetamine is used as a recreational drug, little research exists regarding its potential for dependence or its precise mechanisms of action. This study aims to evaluate the psychoactivity and dependence profile of lisdexamfetamine using conditioned place preference and self-administration paradigms in rodents. Additionally, biochemical techniques are used to assess alterations in the dopamine levels in striatal synaptosomes following administration of lisdexamfetamine. Lisdexamfetamine increased both conditioned place preference and self-administration. Moreover, after administration of the lisdexamfetamine, dopamine levels in the striatal synaptosomes were significantly increased. Although some modifications should be made to the analytical methods, performing high performance liquid chromatography studies on synaptosomes can aid in predicting dependence liability when studying new psychoactive substances in the future. Collectively, lisdexamfetamine has potential for dependence possible via dopaminergic pathway.
Chromatography, Liquid ; Dopamine ; In Vitro Techniques* ; Lisdexamfetamine Dimesylate* ; Rodentia ; Synaptosomes

AIMTo study changes of function of transmitter glycine in nitrogen narcosis.

METHODSSynaptosomes of rat spinal cord were prepared. Glycine uptake of synaptosomes of rat spinal cord in 0.7 MPa (7ATA) hyperbaric air pressure was observed by the methods of isotope.

RESULTSGlycine uptake slowed down and took a longer period of time to reach saturation in 0.7 MPa (7ATA). The maximum glycine uptake was lessened. Vm was diminished, but Km was increased. Vm rose in 0.7 MPa (7ATA) when corticosterone was added.

CONCLUSIONWhen nitrogen narcosis arose in 0.7 MPa (7ATA), the function of transporters of glycine re-uptake was reduced, the affinity of glycine for transporters subsided. Corticosterone was conductive to the recovery of the function of glycine transporters of high affinity.

Air Pressure ; Animals ; Glycine ; metabolism ; Rats ; Rats, Sprague-Dawley ; Spinal Cord ; metabolism ; Synaptosomes ; metabolism

The aim of this study was to investigate the role of Ca2+-channel blockers in norepinephrine (NE) release from rat hippocampus. Slices and synaptosomes were incubated with [3H]-NE and the releases of the labelled products were evoked by 25 mM KCl stimulation. Nifedipine, diltiazem, nicardipine, flunarizine and pimozide did not affect the evoked and basal release of NE in the slice. But, diltiazem, nicardipine and flunarizine decreased the evoked NE release with a dose-related manner without any change of the basal release from synaptosomes. Also, a large dose of pimozide produced modest decrement of NE release. omega-conotoxin (CTx) GVIA decreased the evoked NE release in a dose-dependent manner without changing the basal release. And omega-CTxMVIIC decreased the evoked NE release in the synaoptosomes without any effect in the slice, but the effect of decrement was far less than that of omega-CTxGVIA. In interaction experiments with omega-CTxGVIA, omega-CTxMVIIC slightly potentiated the effect of omega-CTxGVIA on NE release in the slice and synaptosomal preparations. These results suggest that the NE release in the rat hippocampus is mediated mainly by N-type Ca2+-channels, and that other types such as L-, T- and/or P/Q-type Ca2+-channels could also be participate in this process.
Animals ; Diltiazem ; Flunarizine ; Hippocampus ; Nicardipine ; Nifedipine ; Norepinephrine* ; omega-Conotoxins ; Pimozide ; Rats* ; Synaptosomes*

The aim of this study was to investigate the role of the 5-HT receptors in acetylcholine (ACh) release from the striatum. Slices from the rat striatum and synaptosomes were incubated with [3H]-choline and the release of the labelled products was evoked by electrical (3 Hz, 2 ms, 5 V/cm, rectangular pulses, 2 min) and potassium-stimulation (25 mM), respectively, and the influence of various serotonergic drugs on the evoked tritium outflows was investigated. Serotonin decreased the electrically-evoked ACh release in striatum in a concentration-dependent manner without the change of basal release. In hippocampal and entorhinal cortical slices, serotonin did not affect the evoked and basal release of ACh, but, at large dose (30 microM) decreased the evoked ACh release in hippocampus. 2,5-Dimethoxy-4-iodoamphetamine (DOI), a specific 5-HT 2A/2C agonist, decreased evoked ACh release in the striatum. CGS-12066A (5-HT 1B agonist), m-chlorophenyl-biguanide (5-HT 3 agonist) and 5-[(dimethyl -amino)methyl]-3-(1-methyl-1H-indol-3-yl)-1,2,4-oxadiazole (5-HT 3 antagonist) did not affect the evoked and basal ACh release in all tissues. Ritanserin, a specific 5-HT 2A/2C antagonist, blocked the inhibitory effects of serotonin and DOI, whereas, ketanserin, an another type of specific 5-HT 2A/2C antagonist did not affect the inhibitory effects of serotonin and DOI. In striatal synaptosomal preparation, serotonin and DOI did not affect the K +-evoked ACh release. These findings suggest that ritanserin-sensitive 5-HT 2A/2C receptors located in the soma and/or axons of the striatal cholinergic neurons play a important role in ACh release.
Acetylcholine* ; Animals ; Axons ; Carisoprodol ; Cholinergic Neurons ; Hippocampus ; Ketanserin ; Rats* ; Receptors, Serotonin* ; Ritanserin ; Serotonin Agents ; Serotonin* ; Synaptosomes ; Tritium

OBJECTIVETo explore the inhibitory effects of highly toxic organophosphorus compound and its substitute (methamidophos and acephate) on acetylcholinesterase (AChE) and their toxic mechanisms.

METHODSEllman method was used to measure AChE activity in vitro and vivo.

RESULTSAcephate and methamidophos could directly inhibit AChE activities in human erythrocyte membrane and rat brain synatosomal membrane in dose- and time-dependent manners in vitro, and this effect was irreversible. The IC50 of acephate and methamidophos affecting human erythrocyte membrane and rat synatosomal membrane were approximately 10(-4) mol/L and 10(-5) mol/L respectively and the Ki were 10(2) mol.L-1.min-1 and 10(3) mol.L-1.min-1 respectively. In vivo, after rats being administered with them for 5 d, the inhibitory rate of AChE activities in blood were increased to 68.24% and 54.80% respectively. When rats being administrated with acephate, there was 31.68% of inhibition on the brain stem, but no significant inhibition in other brain region was noticed, while methamidophos had a strong inhibitory effect on the activity of AChE in all brain regions, especially the cerebellum and brain-stem(71.51% and 61.85% respectively).

CONCLUSIONAcephate and methamidophos could directly inhibit the AChE activities in vitro, but the inhibition degree was different. In vivo, both could also inhibit AChE activities in blood. The difference in inhibition on brain regions may be one of the reason of various toxic effect of them.

Animals ; Cholinesterase Inhibitors ; toxicity ; Erythrocyte Membrane ; enzymology ; Humans ; Insecticides ; toxicity ; Organothiophosphorus Compounds ; toxicity ; Phosphoramides ; Rats ; Synaptosomes ; enzymology

To investigate the effect of thiopental sodium on the release of glutamate and gamma-aminobutyric acid (GABA) from synaptosomes in the prefrontal cortex, synaptosomes were made, the spontaneous release and the evoked release by 30 mmol/L KCl or 20 micromol/L veratridine of glutamate and GABA were performed under various concentrations of thiopental sodium (10-300 micromol/L), glutamate and GABA concentrations were determined by reversed-phase high-performance liquid chromatography. Our results showed that spontaneous release and evoked release of glutamate were significantly inhibited by 30 micromol/L, 100 micromol/L and 300 micromol/L thiopental sodium, IC50 of thiopental sodium was 25.8 +/- 2.3 micromol/L for the spontaneous release, 23.4 +/- 2.4 micromol/L for KCl-evoked release, and 24.3 +/- 1.8 micromol/L for veratridine-evoked release. But GABA spontaneous release and evoked release were unaffected. The study showed that thiopental sodium with clinically related concentrations could inhibit the release of glutamate, but had no effect on the release of GABA from rats prefrontal cortical synaptosomes.
Glutamic Acid/*metabolism ; Hypnotics and Sedatives/pharmacology ; Prefrontal Cortex/*metabolism ; Rats, Sprague-Dawley ; Synaptosomes/*metabolism ; Thiopental/*pharmacology ; gamma-Aminobutyric Acid/*metabolism

Antioxidant effects of serotonin and L-DOPA on neuronal tissues were examined by studying the oxidative damages of brain synaptosomal components. The study further explored the mechanism by which they exert protective actions. Serotonin and L-DOPA (1 muM to 1 mM) significantly inhibited lipid peroxidation of brain tissues by either Fe2+ and ascorbate or t-butyl hydroperoxide in a dose dependent fashion. Protective effect of serotonin on the peroxidative actions of both systems was greater than that of L-DOPA. Protein oxidation of synaptosomes caused by Fe2+ and ascorbate was attenuated by serotonin and L-DOPA. Protein oxidation more sensitively responded to L-DOPA rather than serotonin. Serotonin and L-DOPA (100 muM) decreased effectively the oxidation of synaptosomal sulfhydryl groups caused by Fe2+ and ascorbate. The production of hydroxyl radical caused by either Fe3+, EDTA, H2O2 and ascorbate or xanthine and xanthine oxidase was significantly decreased by serotonin and L-DOPA (1 mM). Equal concentrations of serotonin and L-DOPA restored synaptosomal Ca2+ uptake decreased by Fe2+ and ascorbate, which is responsible for SOD and catalase. Protective effects of serotonin and L-DOPA on brain synaptosomes may be attributed to their removing action on reactive oxidants, hydroxyl radicals and probably iron-oxygen complex, without chelating action on iron.
Antioxidants* ; Brain* ; Catalase ; Edetic Acid ; Hydroxyl Radical ; Iron ; Levodopa* ; Lipid Peroxidation ; Neurons ; Oxidants ; Serotonin* ; Synaptosomes* ; tert-Butylhydroperoxide ; Xanthine ; Xanthine Oxidase

RalA GTPase, a member of Ras superfamily proteins, shows alternative forms between the active GTP-binding and the inactive GDP-binding states. Ral-specific guanine nucleotide exchange factor such as RalGDS interacts with activated Ras and cooperates with Ras indicating that Ral can be activated through Ras signaling pathway. Another activation path for Ral are through Ca2+-dependent but Ras-independent manner. In this study, studies were carried out to examine possible effects of Ca2+ and calmodulin, Ca2+-binding protein, directly on the GTP/GDP-binding state to recombinant unprenylated GST-RalA proteins. The results showed that Ca2+ stimulated the binding of GTP to RalA, whereas it reduced the binding of GDP to RalA. However, it does not involve a high affinity association of Ca2+ with RalA. Ca2+/calmodulin stimulated the GTPase activity of RalA. These results indicate that Ca2+ alone activates RalA by stimulating GTP-binding to RalA and Ca2+/calmodulin inactivates RalA by increasing the activity of RalGTPase.
Animal ; Brain/metabolism ; Calcium/*metabolism ; Calmodulin/*metabolism ; GTP Phosphohydrolases/*metabolism ; Guanosine Diphosphate/metabolism ; Guanosine Triphosphate/*metabolism ; Rats ; Support, Non-U.S. Gov't ; Synaptosomes/metabolism

PURPOSE: Excessive amounts of glutamate are released into the extracelluar space during hypoxia/ischemia and contribute to neuronal injury through overactivation of the NMDA receptors. It will be expected that the changes of the NMDA receptors to decrease the injury are developed as a kind of defense mechanism. The NMDA receptors are composed of NR1 and NR2, and there are four NR2 subunits; NR2A, NR2B, NR2C, and NR2D. The NR1 is essential for the function of the NMDA receptors and multiple NR2 subunits potentiate and differentiate the function of the NMDA receptors. The NR2 subunits alone show no ability to respond to several agonists, however when coexpressed with the NR1, the NR2 subunits markedly potentiated the NR1 activity and produced functional variability of the NMDA receptors. Compared with the NR2C and the NR2D, the NR2A and the NR2B show prominent expression in the hippocampus. In an in vitro model of rat hippocampal slices after hypoxia, we investigated the changes of the NR2A and the NR2B amounts through immunoblot with anti-NR2A and anti-NR2B antisera. METHODS: Hippocampi from adult rats(Sprague Dawley) were isolated and sliced into a 500 m section in a glucose containing artificial CSF medium on ice. In order to induce a hypoxia, sample slices were treated with 95% N2/5% CO2 for 10 min, 20 min, 30 min, and 60 min, respectively and control slices were treated with 95% O2/5% CO2 to supply sufficient oxygen as the same way. And then the control and the sample slices were homogenated and 40 g of each homogenates were electrophoresed in a 6% SDS-gel, transfered to nitrocellulose, and immunostained with anti-NR2A and anti-NR2B antisera. RESULTS: 1) Anti-NR2A antisera were produced by recombinant DNA technology. 2) The NR2A and the NR2B were enriched in the order of PSD, synaptosome and brain homogenate. 3) There was no difference of the NR2A and the NR2B expression in both control and experimental group. CONCLUSIONS: At least up to one hour after hypoxic damage, it is likely that there is no prominent changes of the NR2A and the NR2B amounts. Considering that the changes could occur locally or microscopically in this experimental protocol, the relative amounts of the NR2A and the NR2B in the hippocampal homogenates are too small to be detected by immunoblot analyses. And we can not exclude the possibility of no changes in one hour after hypoxia, if these changes evolve with a extremely slow progression.
Adult ; Animals ; Anoxia ; Brain ; Collodion ; DNA, Recombinant ; Glucose ; Glutamic Acid ; Hippocampus ; Humans ; Ice ; Immune Sera ; Infant, Newborn ; N-Methylaspartate* ; Neurons ; Oxygen ; Rats* ; Receptors, N-Methyl-D-Aspartate ; Synaptosomes