Neuroprotective and MAOB inhibitory effects of a series of caffeine-8-thioglycolic acid amides

The effects of new derivatives of caffeine-8-thioglycolic acid (100 µM) on isolated rat brain synaptosomes, human neuroblastoma cell line SH-SY5Y and human recombinant MAOB enzyme (hMAOB) (1 µM) were evaluated. Most of the compounds, administered alone, didn't show statistically significant neurotoxic effects on SH-SY5Y, when compared to the control (non-treated cells). Of all studied structures JTA-2Ox, JTA-11, JTA-12 and JTA-13 decreased cell viability. In combination with 6-hydroxydopamine (6-OHDA) (100 µM), only JTA-1 and JTA-2 revealed neuroprotective effects, stronger than those of caffeine. All compounds administered alone revealed, neurotoxic effects on synaptosomes, as compared to non-treated synaptosomes. JTA-1, JTA-2 and JTA-3 showed lowest neurotoxic effects and were investigated in a model of 6-OHDA-induced oxidative stress. In this model of neurotoxicity, only JTA-1 and JTA-2 showed statistically significant neuroprotective effect, by preserving the synaptosomal viability and the level of reduced glutathione. Inhibition of hMAOB, was revealed by JTA-1 and JTA-2. They inhibited the enzyme by 23% and 25% respectively, thus approaching the selegiline activity, which was 42%. The possible mechanisms of neuroprotection of JTA-1 and JTA-2 might be a result from the inhibition of hMAOB, which catalyze the production of neurotoxic p-quinone from 6-OHDA.

Preparation of Rat Spinal Synaptosome and Qualitative and Quantitative Test of Neurotransmitters / 中国康复理论与实践

Objective:To prepare rat spinal synaptosomes, and to conduct qualitative and quantitative analysis of various neurotransmitters in rat spinal synaptosomes to explore the physiological activities. Methods:Rat spinal synaptosomes were prepared by discontinuous Percoll density gradient centrifugation and their morphology and structure were observed under transmission electron microscopy. The properties and content of neurotransmitters in rat spinal synaptosomes were determined by ultra performance liquid chromatography-tandem mass spectrometry. Results:Under the experimental conditions, rat spinal synaptosomes were found to contain dopamine, norepinephrine, serotonin, homovanillic acid, 3,4-dihydroxybenzene, 5-hydroxyindoleacetic acid, methoxytyramine, tryptophan, γ-aminobutyric acid, kynurenine, 3-hydroxy kynurenine and 3-hydroxy-2-aminobenzoic acid, and so on. The corresponding neurotransmitter contents were detected, and the corresponding linear relationship and correlation coefficient were obtained. Conclusion:Discontinuous Percoll density gradient centrifugation could prepare rat spinal synaptosomes and detect neurotransmitters and their contents in rat spinal synaptosomes.

Analysis of Physiologically Active Substances in Rat Spinal Synaptosome / 中国康复理论与实践

@#Objective To analyze the physiologically active substances, named amino acid neurotransmitters, ATP and Ca2+ in rat spinal synaptosomes. Methods The spinal synaptosome was extracted by discontinuous Percoll density gradient centrifugation from a female Sprague-Dawley rat. The amino acid neurotransmitters were determined with high performance liquid chromatography, ATP content, Na+-K+-ATPase activity, Ca2+-Mg2+-ATPase activity and total ATPase activity with ultraviolet spectrophotometer, and Ca2+ concentration with fluorescence spectrophotometer. Results The amino acid neurotransmitters contained mainly aspartic acid, glycine, glutamic acid and r-aminobutyric acid. The concentration of ATP was about 414.7461 μmol/mg, total ATPase activity > Na+-K+-ATPase activity > Ca2+-Mg2+-ATPasese activity. The concentration of Ca2+ could be calculated from absorbancy directly. Conclusion The rat spinal synaptosome contains a variety of physiologically active substances, which can be accurately analyzed to explore their activities.

Striatal synaptosomal dopamine and serotonin cross-talk synthesis in aging rat.

Aims: The existence of a dopamine (DA)-serotonin (5-HT) interaction in the brain has been validated by numerous studies. Nevertheless, interaction between DA- 5-HT synthesis in aging brain has not been highly considered. The central aim of this study was to investigate the interaction between DA and 5-HT synthesis in rat brain striatal synaptosomes. Methodology: Male Wistar rats (3 and 30 months old) were killed by decapitation and the brain sriatal synaptosomes were prepared by discontinuous Ficoll/sucrose gradient technique. DA or 5-HT synthesized during an appropriate incubation period was measured by the synaptosomes in the presence of added substrates (tyrosine or tryptophan) and a monoamine oxidase inhibitor (pargiline). Results: Dopamine synthesis in the synaptosomes prepared from young animals was markedly inhibited (about 30%) by the addition of 5 μM 5-HT and increasing 5-HT up to 50 μM caused only a relatively small additional inhibition. However, different concentrations of 5-HT (0-50μM) had little effect on dopamine synthesis of the synaptosomes preparations from old animals. In case of 5-HT synthesis, exogenously added 5 μM DA inhibited 5-HT synthesis in the synaptosomes of both ages by about 40%, whereas with higher concentration of DA (10-50 μM) the rate of inhibition was highly pronounced in the old rats as compared to that of young animals. Conclusion: It is concluded that DA- 5-HT cross reaction might be considered, where long-term treatment with L-DOPA of patients suffering from Parkinson's disease renders patients experience variations in response and even psychiatric problems.

Ageing-induced changes of peripheral benzodiazepine receptors in rat spinal cord synaptosoms / 中华老年医学杂志

Objective To investigate the changes of peripheral benzodiazepine receptors (PBRs)in rat spinal cord synaptosomes during ageing and to explore the correlation between PBRs in spinal cord synaptosomes and PBRs on platelet membranes.Methods A total of 24 Sprague-Dawley rats were divided into 3-month group and 24-month group (n=6 males and 6 females for each).All animals were sacrificed by decapitation and the spinal cords were immediately removed.Synaptosomal fractions from spinal cords were isolated by gradient centrifugation.The platelet membranes were prepared from venous blood by the method of hypotonic haemolysis.The specific binding of the radioactive PBRs antagonist [3H]PK11195 to membranes was determined.Results No significant differences in [3H] PK11195 binding activity in spinal cords and platelet membranes were observed between male and female rats in the same group (all P＞0.05).[3H] PK11195 binding activity in spinal cords and platelet membranes were higher in 3-month group than in 24 month group [(213.94±10.65) fmol/mg pro.vs.(50.65± 2.74) fmol/mg pro.,(104.97± 2.24) fmol/mg pro.vs.(56.20±5.36) fmol/mg pro.,respectively,t=51.418,29.041,both P＜ 0.001].There was a positive correlation between [3H]PK11195 binding activity in platelet membranes and in spinal cord synaptosomes (r=0.985,P＜0.001).Conclusions The level of PBRs is gradually decreased in rat spinal cord synaptosomes with ageing.[3H] PK11195 binding activity of platelet membranes can reflect the changes of PBRs in spinal cords.

Proteomic analysis of cerebral synaptosomes isolated from rat model of Alzheimer’s disease.

Alzheimer’s disease (AD) is a common and devastating disease and there is no readily available biomarker to aid diagnosis or monitor progression of it. To further understand the pathogenic mechanism of AD, proteomic approach was used to study the cerebral synaptosomes proteins of rats injected with A1-40. Compared with the untreated samples, 14 proteins were found apparently altered through 2-dimensional gel electrophoresis. 12 of them were down-regulated and 2 were up-regulated. Three proteins including alpha-2-globin chain, peptidyl-prolycis-trans isomerase A (PPIaseA) and cofilin-1 protein were identified by matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS) and SWISS-PROT database query. Alpha-2-globin chain has not been shown to be associated with AD. PPIaseA and cofilin-1 protein are correlated with cell apoptosis and signaling. The altered proteins identified may help to understand the pathogenesis of AD.

Effects of isoflurane anesthesia on hippocampus synaptosomes proteome in aged rats / 中华麻醉学杂志

ObjectiveTo investigate the effects of isoflurane anesthesia on hippocampus synaptosomes proteome in aged rats.MethodsTwenty-seven 22- month-old SD rats weighing 480-550 g were randomly divided into 2 groups: control group (group C,n =6) and isoflurane group (group Ⅰ,n =21 ).In group C inhaled mixed gas containing 80％ oxygen for 2 h.In group Ⅰ the animals were endotracheal intubated after induction by 3％ isoflurane and inhaled 2％ isoflurane and 80％ oxygen for 2 h.Cognition function was evaluated by Y-maze at 24 h after anesthesia and the total training times were recorded.The total training times ＞ 75 was defined as cognitive dysfuction.In group Ⅰ the animals were divided into cognitive dysfuction group (group ⅠA) and non-cognitive dysfuction group (group IB) according to the results of Y-maze test.The animals were sacrificed and their hippocampi were removed and synaptosomes were extracted for two-dimensional gel electrophoresis.The different protein spots were analyzed by mass chromatographic analysis.ResultsSix rats had cognitive dysfuction (group IA) and another thirteen rats had no cognitive dysfuction (group IB).The total training times were significantly higher in group IA than in groups C and IB( P ＜ 0.05).There was no significant difference in the total training times between groups C and IB (P ＞ 0.05).There were 21 (11/10) different protein spots between groups IB and IA,and 19 (12/7) different protein spots between groups C and IA.Thirty-one protein spots were identified by means of MALDI-TOF-MS.ConclusionThe cognitive dysfuction after isoflurane anesthesia in aged rats may be related to the changes of energy metabolism protein,cytoskeletal structure and regulatory protein in synapse of hippocampus.

Role of P2X7 receptors in release of glutamate and γ-aminobutyric acid during oxygen-glucose deprivation in rat hippocampus and neuronal synaptosome / 中华麻醉学杂志

Objective To evaluate the role of P2X7 receptors in release of glutamate (Glu) and γ-aminobutyric acid (GABA) during oxygen-glucose deprivation (OGD) in rat hippocampus and neuronal synaptosome.Methods Healthy male SD rats weighing 150-200 g were decapitated. Their hippocampi were isolated and cut into slices 400 μm thick or made into neuronal synaptosomes. The hippocampal slices and neuronal synaptosomes were incubated in artificial cerebro-spinal fluid (aCSF) at 35℃ for 30 min and divided into 3 groups ( n = 32 or 24 each): control group (group C); group OGD and group OGD + BBG (brilliant blue G, a specific P2X7 receptor antagonist). OGD was induced by incubating the slices and synaptosomes in glucose-free aCSF aerated with 95% N2-5% CO2. In group OGD + BBG the slices and synaptosomes were incubated in O2-glucose deprived aCSF containing BBG 1 μmol/L 2 ml. Release of Glu and GABA from hippocampal slices and synaptosomes was determined by HPLC at 0, 20, 40, 60 min of OGD (T1-4). Hippocampal slices were examined with microscope.Results ( 1 ) The release of Glu and GABA from hippocampal slices and synaptosomes were significantly increased after OGD ( P ＜ 0.05). (2) Glu released from hippocampal slices was significantly decreased at T3-4 and Glu released from synaptosomes increased at T2-4 in group OGD + BBG as compared with group OGD ( P ＜ 0.05). (3)GABA released from hippocampal slices was significantly decreased at T4 in group OGD + BBG as compared with group OGD ( P ＜ 0.05). There was no significant difference in GABA released from synaptosomes between group OGD and OGD + BBG (P ＞ 0.05). (4) Microscopic examination showed that OGD induced significant histopathological damage to hippocampal slices which was attenuated by BBG treatment. Conclusion P2X7 receptors mediates the release of Glu and GABA during OGD in rat hippocampus and the P2X7 receptors in glial cells plays a leading role.

A New Rapid Method for Preparing Synaptosomes of Mouse / 中国康复理论与实践

@#ObjectiveTo establish a new method for preparing synaptosomes.MethodsDensity gradient centrifugation method was used to isolate synaptosomes of mouse, checking by transmission electron microscopy.ResultsSynaptosomes prepared by this method had intact morphological characteristics, surrounding with a continuous oval-shaped membrane structure, moreover, mitochondrion and lots of synaptic vesicle in them.ConclusionThis method is applicable to establish a rapid, convenient and useful method for preparing synaptosomes.

Inhibitory Effect of Tyrphostin AG126 on Brain Synaptosomal Dysfunction Induced by Cholesterol Oxidation Products

BACKGROUND: Formation of cholesterol oxidation products is a suggested mechanism of neurodegenerative disorders. Neuronal cell death is mediated by an increased release of excitotoxic glutamate from the presynaptic nerve endings. Tyrosine-specific protein kinases modulate neurotransmitter release at the nerve terminals. Tyrphostin AG126 has anti-inflammatory and cytoprotective effects. However, it remains uncertain whether tyrphostin AG126 has a preventive effect on the alteration of nerve terminal function induced by cholesterol oxidation products. METHODS: The present study was performed to assess the effect of cholesterol oxidation products against nerve terminal function using synaptosomes isolated from rat cerebrum. We determined the preventive effect of tyrphostin AG126 against oxysterol toxicity by measuring the effects on the glutamate release, depolarization of the membrane potential, changes in Ca2+ levels, and Na+/K+-ATPase activity. RESULTS: Synaptosomes treated with 7-ketocholesterol or 25-hydroxycholesterol exhibited a sustained release of glutamate, depolarization of membrane potential, early rapid increase in cellular Ca2+ levels and decrease in Na+/K+-ATPase activity. Those responses were concentration-dependent. Treatment of tyrphostin AG126 interfered with alteration of synaptosomal functions and decrease in Na+/K+-ATPase activity induced by 7-ketocholesterol or 25-hydroxycholesterol. CONCLUSIONS: The results show that 7-ketocholesterol and 25-hydroxycholesterol seem to cause the release of glutamate by inducing depolarization of the membrane potential and early rapid increase in cellular Ca2+ levels and by inactivating Na+/K+-ATPase in the cerebral synaptosomes. Treatment of tyrphostin AG126 may prevent the oxysterol-induced nerve terminal dysfunction.

The role of synaptic plasticity on rats with visceral hypersensitivity induced by transient intestinal infection / 中华消化杂志

Objective To investigate the role of synaptic plasticity on the formation of visceral hypersensitivity induced by transient intestinal infection in rats. Methods Thirty male Sprague-Dawley rats were divided into normal control, acute infection and chronic infection groups with 10 each. The area under curve (AUC) of electromyography (EMG) in 10 s was used to evaluate the visceral sensitivity induced by different eolorectal distention (20,40,60 and 80 mmHg). Histological change of the colon was evaluated by H-E staining. Synaptic uhrastrueture such as synaptic cleft and synaptic vesicles was observed using transmission electron mieroseope. The mRNA and protein expressions of synaptophysin and postsynaptic density protein-95 (PSD-95) were examined by RT-PCR and Western blot, respectively. significantly higher than those of normal controls(P=0. 012, 0. 005, respectively ). In contrast, AUC of acute infection were significantly lower than those of normal controls ( P = 0. 018,0. 012, respectively ). Under the distention of 20 and 80 mmHg, no significant difference was observed among three groups (P= rats compared to normal controls(23.45±4.10 vs. 9.10±2.42, P=0. 027),but there was no statistical difference between chronic infection rats and normal controls (13. 95±7.96 vs. 9.15±2.42, P=0.78). increased. In acute infection rats, mitochondria cristae disappeared, synaptic vesicles and the length of controls, mRNA and protein of synaptophysin in ileocecum, proximal colon and distal colon were significantly increased in chronic infection rats (P＜0. 05 ), but decreased in acute infection rats with no significant difference. Compared with controls, no significant downregulation was noted in the expression protein expressions of PSD-95 were both increased in chronic infection rats (P＜0.05), and decreased in acute infection rats (P＜0.05). Conclusion Synaptic plasticity plays an important role in the formation of visceral hypersensitivity induced by transient intestinal infection in rats.

The Changes of Peripheric Auditory Activity Induced the Expression of Synaptic NMDA Receptors in Auditory cortex in Vivo / 听力学及言语疾病杂志

Objective To study the changes of N-methyl-D-aspartate receptors(NMDARs) expression at local sy-(napses) in auditory cortices after ototoxic deafened and following electrical intracochear stimulation(EIS).Methods We prepared highly purified synaptosomes from primary auditory cortex by two discontinuous gradient centrifugations, and compared the differences of NMDA receptors expression in ototoxic deafened group control group, normal control group and different experimental groups (EIS from 0.5h to 2h ) by Western blotting.Results We found that EIS for as little as half and one hour the adult and developmental rats of auditory deprivation can induce a significant increase in NMDAR subunit2A (NR2A) protein. But the changes of NMDAR subunit1(NR1) and NMDAR subunit2B(NR2B) are not significant.Conclusion There is a rapid activity-dependent expression of synaptic NR2A receptors in primary auditory cortex in vivo.

Effect of thiopental sodium on the release of gluamate and ?-aminobutyric acid from rats prefrontal cortical synatosomes / 中国药理学通报

Aim To investigate the effect of thiopental sodium on the release of glutamate and GABA from synaptosomes of rats prefrontal cortex. Methods Synaptosomes were made from rats prefrontal cortex and incubated with artificial cerebral and spinal fluid (aCSF), then divided into five groups: group base release (Base), group thiopental sodium 10 ?mol?L -1 (THS 10), group thiopental sodium 30 ?mol?L -1 (THS 30), group thiopen tal sodium 100 ?mol?L -1 (THS 100) and group thiopental sodium 300 ?mol? L -1 (THS 300). Various concentrations of thiopental sodium were added to aC SF, the release of glutamate and GABA were performed under 37℃ and measured using reversed-phase high-performance liquid chromatography (RP-HPLC). When Ca 2+-independent release of glutamate and GABA were studied, Ca 2+ was omitted from aCSF.Results Compared with Base, thiopental sodium 30 , 100 and 300 ?mol?L -1 inhibited Ca 2+-dependent release of gluta mate evoked by KCl or veratridine significantly (P

The role of synaptic plasticity in a rat model of visceral hypersensitivity induced by acute restraint stress / 中华消化杂志

Objective To explore the role of synaptic plasticity on the formation of visceral hyper- sensitivity induced by acute restraint stress in rats.Methods Twenty male Sprague-Dawley rats were randomly divided into control group and acute restraint stress group(model group).Visceral hypersensi- tivity was made by acute restraint stress for 1 h.The colorectal distension(CRD) with different pressure were performed and the abdominal electromyography(EMG) was recorded.The visceral sensitivity was determined by the frequency of EMG.The ultrastrueture of synapse was observed with transmission electron microscope.The expression of synaptophysin was measured by RT-PCR and Western-blot. Results①The frequency of EMG was significantly correlated with CRD pressure(control group,r=0.992, P=0.008;model group,r=0.978,P=0.022).The frequencies of EMG in model group(at 40,60 and 80 mm Hg) were significantly more than that in control group(P value=0.043,0.024,0.038,respectively).②There were more synaptic vesicles accumulated in presynaptical terminal.The post synaptic density was increased in model group compared to control group.③In the proximal and distant colon,the expressions of rnRNA and protein of synaptophysin were higher in model group (P

Antioxidant effects of serotonin and L-DOPA on oxidative damages of brain synaptosomes

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.

Effects of tetrandrine and fructose-1,6-diphosphate on the elevated intrasynaptosomal [Ca~2+]_i induced by excitatory amino acids / 中国病理生理杂志

AIM: To study the effects of tetrandrine(Tet) and fructose-1,6-diphosphate(FDP) on the elevated intrasynaptosomal [Ca 2+ ] i induced by excitatory amino acids (EAA). METHODS: A rapid method for preparing synaptosomes was used, and intrasynaptosomal free calcium ([Ca 2+ ] i) was measured by using the fluorescent indicator quin-2. RESULTS: L-glutamate (Glu, 100 ?mol/L), aspartate (Asp, 100 ?mol?L -1 ), N-methy1-D-aspartate (100 ?mol/L) and Glu (50 ?mol/L) plus Asp (50 ?mol/L) all elevated intrasynaptosomal [Ca 2+ ] i in a dose-dependent manner. Pretreatment with Tet (10,30,60 ?mol/L) , FDP (15, 30, 75, 150 ?mol/L), MK-801 (10, 20 ?mol/L) and Tet (15, 30 ?mol/L) plus FDP(15, 30 ?mol/L) all attenuated the increase in intrasynaptosomal [Ca 2+ ] i induced by EAAs mentioned as above in a dose-dependent manner, and the effect of Tet plus FDP was most significant. CONCLUSION: Both Tet and FDP inhibited a rise in intrasynaptosomal [Ca 2+ ] i induced by EAAs, which may be one of mechanisms that Tet and FDP pretect cerebral tissues against ischemia injury.

Effect of t-butylhydroperoxide on Na+/-dependent glutamate uptake in rabbit brain synaptosome

The effect of an organic peroxide, t-butylhydroperoxide (t-BHP), on glutamate uptake was studied in synaptosomes prepared from cerebral cortex. t-BHP inhibited the Na+/-dependent glutamate uptake with no change in the Na+/-independent uptake. This effect of t-BHP was not altered by addition of Ca2+ channel blockers (verapamil, diltiazem and nifedipine) or PLA2 inhibitors (dibucaine, butacaine and quinacrine). However, the effect was prevented by iron chelators (deferoxamine and phenanthroline) and phenolic antioxidants (N,N'-diphenyl-phenylenediamine, butylated hydroxyanisole, and butylated hydroxytoluene). At low concentrations (< 1.0 mM), t-BHP inhibited glutamate uptake without altering lipid peroxidation. Moreover, a large increase in lipid peroxidation by ascorbate/Fe2+ was not accompanied by an inhibition of glutamate uptake. The impairment of glutamate uptake by t-BHP was not intimately related to the change in Na+/-K+/-ATPase activity. These results suggest that inhibition of glutamate uptake by t-BHP is not totally mediated by peroxidation of membrane lipid, but is associated with direct interactions of glutamate transport proteins with t-BHP metabolites. The Ca2+ influx through Ca2+ channel or PLA2 activation may not be involved in the t-BHP inhibition of glutamate transport.

Effect of etomidate on calcium dynamics in rat cerebrocortical synaptosomes / 中华麻醉学杂志

Objective To study the effect of etomidate on the changes in [Ca2+]i in rat cerebrocortical synaptosomes induced by KCI. Methods Freshly isolated SD rat cerebrocortical synaptosomes were prepared. KCI was used as chemical stimulant. Neurochemical method was employed (Fura-2 was used as calcium indicator) . Etomidate was added (the end concentration was 0.4, 4, 40 and 100 ?mol?L-1 respectively) before and after stimulation with KCI 50 mmol?L-1 to determine the peak and plateau [Ca2+]i in the cerebrocortical synaptomes. Results Before KCI stimulation etomidate inhibited KCl-evoked increase in intra-synaptosomal [Ca2+ ]i in a concentration-dependent manner. The inhibitory ratio of peak calcium concentration was 5%?3% , 11%?6% , 24%?10% and 33%?12% respectively as compared with control. Etomidate at concentration of 40 ?mol?L-1 and above had significant effect on [Ca2+]i. When added immediately after KCI stimulation, 4,40 ?mol?L-1 etomidate significantly increased plateau [Ca2+]i in synaptosomes.Conclusion Etomidate alters KC1-induced calcium dynamics in rat cerebrocortical synaptosomes. Presynaptic calcium channels and calcium removal mechanism are involved in its anesthetic action.

Effects of propofoi on Ca~(2+)-ATPase activity in rat cerebral synaptie membrane in vivo / 中华麻醉学杂志

Tn investigate the effects of propofol on Ca~(2+) ATPase activity in rat cerebral synaptic membrane. Method: Thirty SD rats were divided randomly into three groups. The aminals were administtered introperi toneally(ip) propofol 50mg?kg~(-1), 100mg?kg~(-1) or normal saline 10mg?kg~(-1)(control group), respectively. These rats were immediately decapitated after having disappeared righting reflex. In oredr to prepare synaptosomes, brain tissues were dissected on ice, then homogenized and centrifuged. Ca~(2+)-ATPase activity was assaed with spcetrophotometric analysis. Result: Propofol 100mg?kg~(-1) ip significantly inhibited Ca~(2+)-ATPase activity of cerebrocortical, brain stems and hippocampal synaptic membrane as compared with that of normal saline group(P

GABA_A receptor mediated inhibitory effect of thiopental sodium on glutamate release from prefrontal cortical synaptosomes in rats / 中华麻醉学杂志

Objective To investigate the effect of thiopental sodium (TPS) on spontaneous and KCl-evoked glutamate release from prefrontal cortical synaptosomes in rats and the effect of bicuculline on this effect ofTPS.Methods SD rats of both sexes (200-250 g) were decapitated and brains were removed. The prefrontalcortex was dissected and added to ice-cold sucrose solution and homogenized. The homogenate was centrifuged at1000 g at 0℃-4℃ for 5 min. The supernatant was again centrifuged at 12 000 g for 20 min. The sediment wascrude synaptosomes, which was added to artificial cerebro-spinal fluid (ACSF). The crude synaptosomes weredivided into 5 groups (n = 8): control group and 4 TPS groups. In control group no TPS was added while in TPSgroups different concentrations of TPS was added and the final concentration of TPS was 10, 30, 100, 300?mol?L~(-1) respectively. The synaptosomes were then placed with or without KCl in water bath at 37℃ for 15 min. Thespontaneous or KCl-evoked glutamate release was measured using high-performance liquid chromatograph (HPLC).In another set of experiment bicuculline 0. 1 mmol?L~(-1) was added to ACSF in each group before 15 min water bathto see if it could antogonize the effect of TPS on glutamate release. Results TPS 30, 100 and 300 ?mol?L~(-1)could significantly inhibit the spontaneous or KCl-evoked glutamate release compared with control group (P0.05). Bicuculline 0. 1 mmol?L~(-1) had no effect on the glutamate release in control group but could antagonize the inhibitory effect of TPS on glutamate release. Afteraddition of bicucculline the glutamate released in control group was not significantly different from that in the TPSgroups.Conclusion TPS sodium can inhibit the spontaneous or KCl-evoked glutamate release from prefrontalcortical synaptosomes in a concentration-dependent manner. The inhibitory effect is mediated by GABA_A receptors.