Zinc Hydroxystannate/Carbon Nanotube Hybrids as Flame Retardant and Smoke Suppressant for Epoxy Resins.

Novel hybrid flame retardants containing zinc hydroxystannate and carbon nanotubes (ZHS-CNTs) were synthesized using the coprecipitation method, and the structure and morphology of ZHS-CNTs were investigate using an X-ray powder diffractometer (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM) and thermogravimetric analyzer (TGA). Then, the ZHS, CNTs and ZHS-CNTs were incorporated into EP, respectively, and the flame-retardant and smoke inhibition performance of the composites were compared and studied. Among the three composites, the EP/ZHS-CNT composites have the highest improvements on the fire resistance and smoke inhibition properties. With only 2.0 wt.% ZHS-CNT hybrids, the pHRR of EP/ZHS-CNT composite materials is reduced by 34.2% compared with EP. Moreover, the release of toxic gases including CO, CO2 and SPR from the composites was also effectively inhibited. The mechanisms of flame retardant and smoke inhibition were investigated and the improved properties were generally ascribed to the synergistic flame-retardant effects between ZHS and CNTs, the catalyzing effect of ZHS and the stable network structure of CNTs.

Utilizing network pharmacology, molecular docking, and animal models to explore the therapeutic potential of the WenYang FuYuan recipe for cerebral ischemia-reperfusion injury through AGE-RAGE and NF-κB/p38MAPK signaling pathway modulation.

BACKGROUND: Stroke is a debilitating condition with high morbidity, disability, and mortality that significantly affects the quality of life of patients. In China, the WenYang FuYuan recipe is widely used to treat ischemic stroke. However, the underlying mechanism remains unknown, so exploring the potential mechanism of action of this formula is of great practical significance for stroke treatment. OBJECTIVE: This study employed network pharmacology, molecular docking, and in vivo experiments to clarify the active ingredients, potential targets, and molecular mechanisms of the WenYang FuYuan recipe in cerebral ischemia-reperfusion injury, with a view to providing a solid scientific foundation for the subsequent study of this recipe. MATERIALS AND METHODS: Active ingredients of the WenYang FuYuan recipe were screened using the traditional Chinese medicine systems pharmacology database and analysis platform. Network pharmacology approaches were used to explore the potential targets and mechanisms of action of the WenYang FuYuan recipe for the treatment of cerebral ischemia-reperfusion injury. The Middle Cerebral Artery Occlusion/Reperfusion 2 h Sprague Dawley rat model was prepared, and TTC staining and modified neurological severity score were applied to examine the neurological deficits in rats. HE staining and Nissl staining were applied to examine the pathological changes in rats. Immunofluorescence labeling and Elisa assay were applied to examine the expression levels of certain proteins and associated factors, while qRT-PCR and Western blotting were applied to examine the expression levels of linked proteins and mRNAs in disease-related signaling pathways. RESULTS: We identified 62 key active ingredients in the WenYang FuYuan recipe, with 222 highly significant I/R targets, forming 138 pairs of medication components and component-targets, with the top five being Quercetin, Kaempferol, Luteolin, ß-sitosterol, and Stigmasterol. The key targets included TP53, RELA, TNF, STAT1, and MAPK14 (p38MAPK). Targets related to cerebral ischemia-reperfusion injury were enriched in chemical responses, enzyme binding, endomembrane system, while enriched pathways included lipid and atherosclerosis, fluid shear stress and atherosclerosis, AGE-RAGE signaling in diabetic complications. In addition, the main five active ingredients and targets in the WenYang FuYuan recipe showed high binding affinity (e.g. Stigmasterol and MAPK14, total energy <-10.5 Kcal/mol). In animal experiments, the WenYang FuYuan recipe reduced brain tissue damage, increased the number of surviving neurons, and down-regulated S100ß and RAGE protein expression. Moreover, the relative expression levels of key targets such as TP53, RELA and p38MAPK mRNA were significantly down-regulated in the WenYang FuYuan recipe group, and serum IL-6 and TNF-a factor levels were reduced. After WenYang FuYuan recipe treatment, the AGE-RAGE signaling pathway and downstream NF-kB/p38MAPK signaling pathway-related proteins were significantly modulated. CONCLUSION: This study utilized network pharmacology, molecular docking, and animal experiments to identify the potential mechanism of the WenYang FuYuan recipe, which may be associated with the regulation of the AGE-RAGE signaling pathway and the inhibition of target proteins and mRNAs in the downstream NF-kB/p38MAPK pathway.

Dual char-forming strategy driven MXene-based fire-proofing epoxy resin coupled with good toughness.

It is challenging that the functionalized MXene-based nanofillers are designed to modify the inherent flammability and poor toughness of epoxy polymeric materials and further to facilitate the application of EP composites. Herein, silicon-reinforced Ti3C2Tx MXene-based nanoarchitectures (MXene@SiO2) are synthesized by simple self-growth method, and its enhancement effects on epoxy resin (EP) are investigated. The as-prepared nanoarchitectures realize homogeneous dispersion in EP matrix, indicating well performance-enhancing potential. The incorporation of MXene@SiO2 achieves improved thermal stability for EP composites with higher T-5% and lower Rmax values. Moreover, EP/2 wt% MXene@SiO2 composites obtain a 30.2% and 34.0% reduction in peak heat release rate (PHRR) and peak smoke production rate (PSPR) compared to those of pure EP, respectively, also achieving a 52.5% fall in smoke factor (SF) values and increased yield and stability of chars. The dual char-forming effects of MXene@SiO2 nanoarchitectures, including the catalytic charring of MXene and the migration of SiO2 to induce charring, are accounted for the results, as well as lamellar barrier effects. Additionally, EP/MXene@SiO2 composites achieve an enhanced storage modulus of 51.5%, along with improved tensile strength and elongation at break, compared to those of pure EP.

Construction of Ti3C2 MXene based fire resistance nanocoating on flexible polyurethane foam for highly efficient photothermal conversion and solar water desalination.

In this work, a bilayer nanocoating was constructed on the surface of flexible polyurethane (FPU) foam with Ti3C2 MXene and polyethyleneimine-modified silica nanoparticles (mSiO2-NP@PEI) through layer-by-layer self-assembly technology, successfully obtaining modified flexible polyurethane composites (MFPU) with excellent flame retardancy, photothermal conversion and solar water desalination properties. The structure and morphology of MFPU foams were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Transmission electron microscope (TEM) and Scanning electron microscope (SEM). The MFPU with three coating cycles (MFPU3) had the best flame retardancy and smoke suppression performances, mainly in terms of decreased peak heat release rate (pHRR), peak smoke production rate (pSPR) and total smoke production (TSP) by 71.3 %, 62.1 % and 74.5 %, respectively, compared to those of neat FPU. In addition, MFPU foams exhibited extraordinary light-to-heat conversion and solar water desalination capabilities. MFPU3 could reach 120 °C in 138 s and its steam conversion efficiency η was as high as 89.6 %, which was 116.0 % higher than that of unmodified foam and had a 262.8 % increase over pure water. The flame retardant MFPU foams with excellent photothermal conversion efficiency will exhibit great application potential in solar water desalination and power generation.

High doses of salicylate and aspirin are inhibitory on acid-sensing ion channels and protective against acidosis-induced neuronal injury in the rat cortical neuron.

Aspirin and its main metabolite salicylate are widely used to relieve pain, treat inflammatory diseases, and prevent ischemic stroke. Multiple pathways are responsible for the therapeutic actions exerted by these drugs. One of the pathways is targeting neuronal receptors/ion channels in the central nervous system. Correspondingly, increasing evidence has implicated acid-sensing ion channels (ASICs) in the processes of the diseases that are medicated by aspirin and salicylate. We therefore employed whole-cell patch-clamp recordings to examine the effects of salicylate as well as aspirin on ASICs in cultured cortical neurons of the rat. We recorded rapid and reversible inhibition of ASIC current by millimolar concentrations of aspirin and salicylate and found that salicylate reduced acidosis-induced membrane depolarization. These data suggest that ASICs in the cortex are molecular targets of high doses of aspirin and salicylate. In addition, the results from lactate dehydrogenase release measurement showed that high doses of aspirin and salicylate protected the cortical neuron from acidosis-induced neuronal injury. These findings may contribute to a better understanding of the therapeutic mechanisms of aspirin and salicylate actions in the brain and provide new evidence on aspirin and salicylate used as neuroprotective agents in the treatment of ischemic stroke.

Flame-retardant activity of ternary integrated modified boron nitride nanosheets to epoxy resin.

In order to improve the fire safety of epoxy resin, ZIF-8 nanoparticle in-situ decorated boron nitride nanosheet (BN-OH/ZIF-8) is fabricated via self-assembly method and then ternary integrated BN-OH/ZIF-8/PA hybrids are prepared through the chemical etching effect of phytic acid. FTIR, XRD, XPS, TEM and TGA measurements are used to characterize the structure and morphology of the nanohybrids. The researches show that BN-OH/ZIF-8/PA not only uniformly distributed in EP matrix, but also improve the thermal stability of EP. The peak heat release rate, peak smoke production rate, total smoke production values, the fire growth index and peak CO production rate obtained from cone test are significantly decreased, demonstrating the reduction of the fire hazards of EP composites containing BN-OH/ZIF-8/PA. The nano barrier effect and catalytic activity of BN-OH/ZIF-8/PA may be conducive to suppress the release of combustible volatile products and heat, facilitate the formation of graphitized carbon layer, and protect matrix from flame damage. The ternary integrated method developed in this study explores a new way to improve the flame retardant properties of EP, thereby promoting its application range.

Waste to resource: preparation of an efficient adsorbent and its sustainable utilization in flame retardant polyurethane composites.

In order to realize the comprehensive utilization of industrial solid waste and the treatment of water eutrophication, the flower-like magnesium hydroxide (MH) was synthesized from phosphorus tailings by sulfuric acid hydrolysis and a hydrothermal method and then was modified with a metal organic framework (MOF) to remove the phosphates enriched in water through adsorption. Both MH and MOF-modified MH (MH@MOF) presented good removal performance of phosphates. The phosphate-adsorbed composites (MH-P and MH@MOF-P) were sustainably used as effective flame retardants for thermoplastic polyurethane (TPU) at low loadings by a solution blending method. The cone calorimetry test results showed that MH@MOF-P can significantly reduce the heat release rate (HRR), smoke production rate (SPR), total smoke release (TSR), CO release rate and CO2 release rate of TPU composites, compared with those of neat TPU. The novel strategy proposed in this work is of great significance for resource recycling, environmental governance and improving fire safety of polymer materials.

Increased MANF Expression in the Inferior Temporal Gyrus in Patients With Alzheimer Disease.

Alzheimer disease (AD) is an aging-related disorder linked to endoplasmic reticulum (ER) stress. The main pathologic feature of AD is the presence of extracellular senile plaques and intraneuronal neurofibrillary tangles (NFTs) in the brain. In neurodegenerative diseases, the unfolded protein response (UPR) induced by ER stress ensures cell survival. Mesencephalic astrocyte-derived neurotrophic factor (MANF) protects against ER stress and has been implicated in the pathogenesis of AD. MANF is expressed in neurons of the brain and spinal cord. However, there have been no investigations on MANF expression in the brain of AD patients. This was addressed in the present study by immunohistochemistry, western blotting, and quantitative analyses of postmortem brain specimens. We examined the localization and expression levels of MANF in the inferior temporal gyrus of the cortex (ITGC) in AD patients (n = 5), preclinical (pre-)AD patients (n = 5), and age-matched non-dementia controls (n = 5) by double immunofluorescence labeling with antibodies against the neuron-specific nuclear protein neuronal nuclei (NeuN), ER chaperone protein 78-kDa glucose-regulated protein (GRP78), and MANF. The results showed that MANF was mainly expressed in neurons of the ITGC in all 3 groups; However, the number of MANF-positive neurons was significantly higher in pre-AD (Braak stage III/IV) and AD (Braak stage V/VI) patients than that in the control group. Thus, MANF is overexpressed in AD and pre-AD, suggesting that it can serve as a diagnostic marker for early stage disease.

The influence of cerium dioxide functionalized reduced graphene oxide on reducing fire hazards of thermoplastic polyurethane nanocomposites.

In this work, CeO2/rGO hybrids were successfully synthesized by a facile one-step hydrothermal method to reduce fire hazards of thermoplastic polyurethane. The structure, element components and morphology of the synthesized products were characterized by XRD, FTIR, Raman spectra and TEM. Then, 2.0 wt% CeO2/rGO hybrids were incorporated into thermoplastic polyurethane matrix (TPU) to improve thermal stability, flame retardancy and smoke toxicity suppression. The introduction of CeO2/rGO hybrids could remarkably suppress heat release and smoke release, indicated by the reduction of the peak heat release rate, smoke produce rate, as well as the release rate of CO and CO2. The significant improvement in thermal stability and smoke suppression properties was mainly due to the synergistic function between physical barrier effect of rGO and catalytic effect of CeO2. This work provided an effect way to enhance the thermal stability and fire safety of TPU.

A novel phosphorus-containing MoS2 hybrid: Towards improving the fire safety of epoxy resin.

Layered molybdenum disulfide (MoS2) has received significant attention due to various applications, such as catalysis, supercapacitors, batteries, and polymer nanocomposites. However, developing highly effective MoS2-based polymer nanocomposites with superior dispersion resulting in improved thermal and flame retardant properties still remains a huge challenge. Herein, a kind of MoS2 hybrid was synthesized by the reaction of exfoliated MoS2 nanosheets with (4-carboxybutyl) triphenylphosphoniumbromide (TPP) via a cost-effective method, where TPP serves as a synergistic agent to further improve the dispersion and flame retardant efficiency of MoS2. Then the TPP-MoS2 hybrid was added to epoxy resin (EP) matrix to improve its fire safety properties. The hybrid was characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). The TPP-MoS2 hybrid was uniformly dispersed in the matrix, leading to significant improvement of fire safety. After the addition of 2 wt% TPP-MoS2, the char residue of the EP nanocomposites was increased by 46% compared with that of pure EP, while the peak heat release rate (PHRR) and total smoke release (TSR) were reduced by 26% and 21%, respectively. The superior dispersion of the hybrid improved the physical barrier effect of MoS2 nanosheets thereby delaying the diffusion of volatile pyrolysis products and the transmission of heat and oxygen to underlying material.

Fluoxetine potentiates GABAergic IPSCs in rat hippocampal neurons.

The GABA system is highly involved in the pathophysiology of mood disorders such as depression. Altered GABAergic function is evident in depressed patients and animal models of depression. Currently, the most widely used antidepressants are selective 5-HT reuptake inhibitors, such as fluoxetine. However, the effects of fluoxetine on GABAergic synaptic neurotransmission remain poorly investigated. Whole-cell patch-clamp recordings from cultured rat hippocampal neurons were therefore conducted to investigate the effects of fluoxetine on GABAergic neurotransmission. The spontaneous inhibitory postsynaptic current (sIPSC) was completely blocked by 10 microM bicuculline and reversibly potentiated by 30 microM fluoxetine. The fluoxetine potentiation on either amplitude or frequency of sIPSCs was dose-dependent, with the EC(50) values of 10.96 and 14.26 microM, respectively. This potentiation was also TTX-insensitive, suggesting independence of presynaptic action potentials. The ritanserin (5 microM), a selective 5-HT(2) receptor antagonist, did not alter the fluoxetine potentiation on miniature inhibitory postsynaptic currents. Taken together, our data suggest that fluoxetine can potentiate GABAergic neurotransmission without depending on presynaptic firing of action potentials and its elevating of 5-HT receptor activities. This potentiation by fluoxetine may normalize the hippocampal GABA deficit during depression and in part exert its antidepressant activity.

Sodium salicylate suppresses serotonin-induced enhancement of GABAergic spontaneous inhibitory postsynaptic currents in rat inferior colliculus in vitro.

Available evidence suggests that sodium salicylate (SS) may produce tinnitus through altering the balance between inhibition and excitation in the central auditory system. Since serotonin (5-hydroxytryptamine, 5-HT) containing fibers preferentially innervate inhibitory GABA neurons, there exists a possibility that SS causes the imbalance between inhibition and excitation through influencing serotonergic modulation of the GABAergic synaptic transmission. In the present study, we examined the effects of SS on 5-HT-mediated GABAergic spontaneous inhibitory postsynaptic currents (sIPSCs) from neurons of the central nucleus of rat inferior colliculus with whole-cell patch-clamp technique and brain slice preparation. Perfusion of 40 microM 5-HT robustly enhanced both frequency and amplitude of GABAergic sIPSCs and this 5-HT-induced enhancement of GABAergic sIPSCs could be suppressed by 1.4mM SS. Tetrodotoxin at 0.5 microM produced a similar effect as SS did, suggesting that SS suppresses the 5-HT-induced enhancement of GABAergic sIPSCs through depressing spontaneous action potentials of GABA neurons. Our findings suggest that SS may preferentially target GABA neurons and consequently interrupt a normal level of GABAergic synaptic transmissions maintained by the serotonergic system in SS-induced tinnitus.

In situ growth of 0D silica nanospheres on 2D molybdenum disulfide nanosheets: Towards reducing fire hazards of epoxy resin.

This report described a facile process for the preparation of 2D/0D MoS2-SiO2 hybrids using a simple in situ growth method, with the purpose of promoting the dispersion of MoS2 in polymer matrices and improving the properties of polymer materials. FTIR, XPS, TGA and TEM measurements were performed to characterize the structure and morphology of the synthesized hybrids which were then introduced into epoxy to reduce flammability. The hybrids dispersed well in the epoxy matrix. No obvious agglomerations were observed. In comparison with those of neat epoxy, the incorporation of a low loading of MoS2-SiO2 hybrids resulted in significant decrements in heat release rate, total heat release and volume of toxic effluents released during combustion, which indicated that the fire hazards of epoxy composites were strongly reduced. The good dispersion, labyrinth barrier effect and the catalytic effect of MoS2-SiO2 hybrids on char formation may contribute to the observed decrease in the flammability of epoxy resin.

Construction of sandwich-structured CoAl-layered double hydroxide@zeolitic imidazolate framework-67 (CoAl-LDH@ZIF-67) hybrids: towards enhancing the fire safety of epoxy resins.

In this work, sandwich-like structured CoAl-LDH@ZIF-67 hybrids were constructed by in situ growth of nanosized ZIF-67 crystallites on CoAl-LDH nanoplates. The structure and morphology of CoAl-LDH@ZIF-67 hybrids were represented by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Transmission Electron Microscopy (TEM). Accordingly, the hybrids were introduced into epoxy resins to explore their effect on the thermal and fire safety properties of epoxy composites. With the introduction of 2% CoAl-LDH@ZIF-67 hybrids, the T 10%, T 50% and T max values were decreased to some extent and the char residue yield was higher than that of pristine epoxy. The peak heat release rate (PHRR) of epoxy composites declined by 26.4%, in comparison with those of pure epoxy. Moreover, the quantity of smoke produced, toxic CO released and CO2 produced were suppressed markedly and decreased by 16.7%, 59.8% and 32.2%, respectively. A possible mechanism for improving fire safety was put forward based on the analysis of the carbon residues.

The influence of a novel two dimensional graphene-like nanomaterial on thermal stability and flammability of polystyrene.

Significant improvements in thermal stability and fire resistance properties of polymer materials with nanofillers at low loadings hold tremendous promise for fire safety materials. In this study, a novel two dimensional (2D) graphene-like nanomaterial (VOP) was synthesized by a simple refluxing method and then modified with typical organic surfactants. Subsequently, the novel graphene-like nanomaterials were incorporated into polystyrene (PS) matrix for reducing fire hazards. The SEM and TEM images indicated that the VOP nanosheets were well dispersed throughout the matrix without obvious aggregates, leading to remarkable improvements of thermal stability and fire safety properties. With the loading of 1wt% modified VOP, the T5%, T10%, T50% and Tmax values were increased by 15, 22, 29 and 33°C, respectively. In addition, the presence of VOP nanosheets decreased the decomposition rate of PS and increased the amount of char residues. Furthermore, the peak heat release rate and total heat release of PS composites was decreased by 48.3% and 43.6%, respectively, compared to that of neat PS. The well dispersion, physical barrier effect and catalytic carbonization effect of VOP nanosheets were the main causations for the reduction of fire hazards.

Morphology, thermal and mechanical properties of poly (ε-caprolactone) biocomposites reinforced with nano-hydroxyapatite decorated graphene.

In this work, hydroxyapatite (HAP) nanorods decorated on graphene nanosheets (HAP-Gs) was synthesized by a hydrothermal method. The structure, elemental composition and morphology of the HAP-Gs hybrids were characterized by X-ray diffraction, Fourier transform infrared and Transmission electron microscopy. Subsequently, the hybrids were incorporated into poly (ε-caprolactone) (PCL) via a solution blending method. Optical images and scanning electron microscopy observation revealed not only a well dispersion of HAP-Gs hybrids but also a strong interfacial interaction between hybrids and PCL matrix. The influence of HAP-Gs hybrids on the crystallization behavior, crystal structure, thermal stability, mechanical properties and biocompatibility of the PCL nanocomposites was investigated in detail. The results showed that the crystallization temperature of PCL was enhanced obviously, but the crystal structure was not affected by the incorporation of HAP-Gs hybrids. The mechanical properties of PCL bionanocomposites were improved obviously.

Self-assembly of exfoliated molybdenum disulfide (MoS2) nanosheets and layered double hydroxide (LDH): Towards reducing fire hazards of epoxy.

In present study, LDH/MoS2 hybrids were facilely prepared by self-assembly of exfoliated MoS2 nanosheets and LDH via electrostatic force. The structure and morphology of the LDH/MoS2 hybrids were characterized and then introduced into epoxy for reducing its fire hazards. Compared with single MoS2, LDH/MoS2 hybrids showed a more homogeneous dispersion in the epoxy matrix and no obvious agglomerates were observed. Compared with MoS2, the addition of LDH/MoS2 hybrids endowed more excellent fire resistance to epoxy matrix, which was reflected by the significantly reduced peak heat release rate, total heat release and total smoke production. A rational flame retardant mode of action for LDH/MoS2 hybrids was proposed based on the analysis of pyrolysis fragments and char residues.

Facile synthesis and characterization of a novel silica-molybdenum disulfide hybrid material.

To improve the dispersion of MoS2 in polymer matrix, a facile synthesis approach was developed in this study through a synergetic effect between two kinds of nanofillers with different dimensionality. The nanohybrids based on two dimensional (2D) MoS2 and 0D silica nanospheres were fabricated by in situ growth method without any surfactants. Characterizations of the hybrid materials were done by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Solid-state 29Si nuclear magnetic resonance (NMR) spectra, transmission electron micrographs (TEM) and scanning electron microscopy (SEM). The TEM and SEM results demonstrated that the dispersibility of MoS2 was greatly improved and the agglomeration was suppressed, with the introduction of silica nanospheres.

Sodium salicylate reduces inhibitory postsynaptic currents in neurons of rat auditory cortex.

Sodium salicylate (SS) is a medicine for anti-inflammation and for chronic pain relief with a side effect of tinnitus. To understand the cellular mechanisms of tinnitus induced by SS in the central auditory system, we examined effects of SS on evoked and miniature inhibitory postsynaptic currents (eIPSCs and mIPSCs) recorded from layer II/III pyramidal neurons of rat auditory cortex in a brain slice preparation with whole-cell patch-clamp techniques. Both eIPSCs and mIPSCs recorded from the auditory cortex could be completely blocked by bicuculline, a selective GABA(A) receptor antagonist. SS did not change the input resistance of neurons but was found to reversibly depress eIPSCs in a concentration-dependent manner. SS reduced eIPSCs to 82.3% of the control level at 0.5 mM (n=7) and to 60.9% at 1.4 mM (n=12). In addition, SS at 1.4 mM significantly reduced the amplitude of mIPSCs from 24.12+/-1.44 pA to 19.92+/-1.31 pA and reduced the frequency of mIPSCs from 1.34+/-0.23 Hz to 0.89+/-0.13 Hz (n=6). Our results demonstrate that SS attenuates inhibitory postsynaptic currents in the auditory cortex, suggesting that the alteration of inhibitory neural circuits may be one of the cellular mechanisms for tinnitus induced by SS in the central auditory region.

Modulation of gamma-aminobutyric acid A receptor function by thiopental in the rat spinal dorsal horn neurons.

To assess the actions of thiopental at the spinal dorsal horn level, we examined the effects of thiopental using the whole cell patch-clamp technique on mechanically dissociated rat spinal dorsal horn neurons. Thiopental, at large concentrations, elicited a current (I(Thio)) through activation of chloride conductance, and its threshold concentration was approximately 50 microM. I(Thio) was sensitive to bicuculline, a gamma-aminobutyric acid (GABA)A receptor antagonist, but not to strychnine, a glycine receptor antagonist. At a clinically relevant concentration (30 muM), thiopental markedly enhanced the peak amplitude of a subsaturating GABA-induced current (I(GABA)) but not that of a saturating GABA-induced current. Furthermore, thiopental prolonged the time constants of both desensitization and deactivation of I(GABA). At a large concentration (300 muM), it inhibited the peak amplitude of I(GABA), which may be the result of open-channel blockade. In addition, at 30 microM, thiopental increased the duration and decreased the frequency of GABAergic miniature inhibitory postsynaptic currents. These results indicate that thiopental enhances GABAergic inhibitory transmission and suggest that GABA(A) receptors in the spinal cord are a potential target through which thiopental causes immobility and depresses the response to noxious stimuli.