AMPA Receptor and PET Tracer Limitation.The alpha-amino-3-hydroxy-5-methyl-4-isoxazolpropionic acid receptor(AMPAR)is a subtype of ionotropic glutamate receptor.It functions as a ligand-gated ion channel and is primar...AMPA Receptor and PET Tracer Limitation.The alpha-amino-3-hydroxy-5-methyl-4-isoxazolpropionic acid receptor(AMPAR)is a subtype of ionotropic glutamate receptor.It functions as a ligand-gated ion channel and is primarily responsible for rapidly transmitting the signal from glutamate in the central nervous system[1].This receptor plays a crucial role in various cognitive functions including learning,memory,cognition,synaptic plasticity,and neurodevelopment.AMPARs are typically composed of four subunits,namely GluA1,GluA2,GluA3,and GluA4,which can form homo-or hetero-tetramers.These subunits bind directly or indirectly to various scaffolding proteins such as transmembrane AMPA receptor regulatory proteins(TARPs).展开更多
Objective To explore the effects of exposure to aluminum （AI） on long-term potentiation （LTP） and AMPA receptor subunits in rats in vivo. Methods Different dosages of aluminum-maltolate complex [Al（mal）3] were g...Objective To explore the effects of exposure to aluminum （AI） on long-term potentiation （LTP） and AMPA receptor subunits in rats in vivo. Methods Different dosages of aluminum-maltolate complex [Al（mal）3] were given to rats via acute intracerebroventricular （i.c.v.） injection and subchronic intraperitoneal （i.p.） injection. Following AI exposure, the hippocampal LTP were recorded by field potentiation technique in vivo and the expression of AMPAR subunit proteins （GluR1 and GluR2） in both total and membrane-enriched extracts from the CA1 area of rat hippocampus were detected by Western blot assay. Results Acute AI treatment produced dose-dependent suppression of LTP in the rat hippocampus and dose-dependent decreases of GluRz and GluR2 in membrane extracts; however, no similar changes were found in the total cell extracts, which suggests decreased trafficking of AMPA receptor subunits from intracellular pools to synaptic sites in the hippocampus. The dose-dependent suppressive effects on LTP and the expression of AMPA receptor subunits both in the membrane and in total extracts were found after subchronic AI treatment, indicating a decrease in AMPA receptor subunit trafficking from intracellular pools to synaptic sites and an additional reduction in the expression of the subunits. Conclusion Al（mal）3 obviously and dose-dependently suppressed LTP in the rat hippocampal CA1 region in vivo, and this suppression may be related to both trafficking and decreases in the expression of AMPA receptor subunit proteins. However, the mechanisms underlying these observations need further investigation.展开更多
To study the effect of glutamate on the intracellular calcium signal of pure cultured rat astrocytes and the role of NMDA and AMPA receptors in the procedure, the change of calcium signal was investigated by monitorin...To study the effect of glutamate on the intracellular calcium signal of pure cultured rat astrocytes and the role of NMDA and AMPA receptors in the procedure, the change of calcium signal was investigated by monitoring the fluctuation of intracellular Ca 2+ concentration ([Ca 2+ ] i) on the basis of Fura-2 single cell fluorescent ratio (F345/F380). The changes in the effect of glutamate on the intracellular calcium signal were observed after blockage of NMDA and(or) AMPA receptors. It was found that L-glutamate could induce an increased [Ca 2+ ] i in most of the cells in concentration- and time-dependent manner. D-(-)-2-amino-5-phosphonopentanoic acid (D-AP-5, a selective antagonist of the NMDA receptor) and 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, a selective antagonist of the AMPA receptor) could abolish the effects of NMDA and AMPA respectively. The treatment of D-AP-5 and CNQX simultaneously or respectively could attenuate the effect of L-glutamate at varying degrees. All these indicated that glutamate could modulate intracellular Ca 2+ of pure cultured rat astrocytes through different pathways. The activation of NMDA and AMPA receptors took part in the complex mechanisms.展开更多
OBJECTIVE Respiratory depression hinders the use of anaesthetics and sedative hyp.notics.To explore the mechanism of LCX001 on protection against respiratory depression,a novel AMPA receptor modulator LCX001,synthesiz...OBJECTIVE Respiratory depression hinders the use of anaesthetics and sedative hyp.notics.To explore the mechanism of LCX001 on protection against respiratory depression,a novel AMPA receptor modulator LCX001,synthesized by our Institute of Medicinal Chemistry,is expected to relieve suppressed respiration.METHODS LCX001 was tested to alleviate respiratory depression triggered by opioid(fentanyl and TH-030418),propofol and pentobarbital in the plethysmography recording.The acetic acid writhing and hot-plate tests were conducted to evaluate analgesic effect of LCX001.Binding assay and whole-cell recording were used to analyze the property of LCX001 on positive modulation.The function of AMPA receptors were determined by location of receptors in the membrane and state of channel opening,and both processes were impressed by AMPA receptor regulatory proteins.Ac.cording to the theory,the effect of LCX001 on the expression of stargazin was measured firstly by west.ern blotting.The variation of receptor surface location was observed by live cell imaging.The regula.tion on neuronal Ca^(2+) and cell function was investigated intensively by Ca^(2+) imaging to clarify mecha.nism of LCX001.RESULTS LCX001 effectively rescued and prevented opioid(fentanyl and TH-030418),propofol,and pentobarbital-induced respiratory depression by strengthening respiratory fre.quency and minute ventilation in rats.The acetic acid writhing test and hot-plate test revealed potent anti-nociceptive efficacy of LCX001,in contrast to some ampakines that did not affect analgesia.Fur.thermore,LCX001 potentiated [3 H]AMPA and L-glutamate binding affinity to AMPA receptors,and facili.tated glutamate-evoked inward currents in HEK293 cells stably expressing GluA2(R).Importantly,appli.cation of LCX001 generated a significant increase in GluA2(R) surface expression in a mechanism of stargazin up-regulation,and restrained opioid-induced abnormal intracellular Ca^(2+) load,which might par.ticipate in breathing modulation.CONCLUSION The novel pharmacological effect and potential new mechanism of LCX001 might promote ampakines to be a therapeutic option for protection against respi.ratory depression.展开更多
OBJECTIVE Respiratory depression hinders the use of anaesthetics and sedative hypnotics.For emergency use,specific antagonists are currently administered to counteract respiratory depression.However,antagonists are of...OBJECTIVE Respiratory depression hinders the use of anaesthetics and sedative hypnotics.For emergency use,specific antagonists are currently administered to counteract respiratory depression.However,antagonists are often short-lasting and can have multiple unexpected side effects.A novel AMPA receptor modulator LCX001,synthesized by our Institute of Medicinal Chemistry,is expected to relieve suppressed respiration.To explore the mechanism and impact of LCX001 on protection against respiratory depression.METHODS LCX001 was tested to alleviate respiratory depression triggered by opioid,propofol and pentobarbital in the plethysmography recording.The acetic acid writhing and hot-plate tests were conducted to evaluate potential analgesic effect of LCX001.Binding assay and whole-cell recording were used to analyze the property of LCX001 on positive modulation.The function of AMPA receptors were determined by location of receptors inthe membrane and state of channel opening,and both processes were impressed by AMPA receptor regulatory proteins.According to the theory,the effect of LCX001 on the expression of stargazin was measured firstly by Western blotting.The variation of receptor surface location were observed by live cell imaging.The regulation on neuronal Ca2+and cell function was investigated intensively by Ca2+imaging to clarify mechanism of LCX001.RESULTS LCX001 effectively rescued and prevented opioid(fentanyl and TH-030418),propofol,and pentobarbitalinduced respiratory depression by strengthening respiratory frequency and minute ventilation by 30%-50% in rats.The acetic acid writhing test and hot-plate test revealed potent anti-nociceptive efficacy of LCX001 on increasing the inhibition rate and %MPE to 80% and 65% respectively,in contrast to some ampakines that did not affect analgesia.Furthermore,LCX001 potentiated[3 H]AMPA and L-glutamate binding affinity to AMPA receptors,and facilitated glutamateevoked inward currents in HEK293 cells stably expressing GluA2(R).At 10 mmol·L^(-1) glutamate evoked amplitudes,LCX001 at 100 μmol·L^(-1) increased the potency of glutamate induced currents by(1120 ± 60) pA,compared with that of(752 ± 35) pA in the control group.LCX001 also prominently promoted steady state/peak amplitude ratio.LCX001 significantly slowed down the desensitization rates of the AMPA ion channel,and inhibited current decay.Importantly,application of LCX001 generated a significant increase in GluA2(R) surface expression in a mechanism of stargazin up-regulation,and restrained opioidinduced abnormal intracel ular Ca2+load,which might participate in breathing modulation.CONCLUSION The typical positive modulatory impact and potential new mechanism of LCX001 might promote ampakines to be a therapeutic option for protection against respiratory depression.展开更多
基金supported by the National Natural Science Foundation of China(32371066)the Guangdong Basic and Applied Basic Research Foundation(2022A1515010134)+1 种基金the Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions(NYKFKT2019009)the Shenzhen Technological Research Center for Primate Translational Medicine(XMHT20220104005).
文摘AMPA Receptor and PET Tracer Limitation.The alpha-amino-3-hydroxy-5-methyl-4-isoxazolpropionic acid receptor(AMPAR)is a subtype of ionotropic glutamate receptor.It functions as a ligand-gated ion channel and is primarily responsible for rapidly transmitting the signal from glutamate in the central nervous system[1].This receptor plays a crucial role in various cognitive functions including learning,memory,cognition,synaptic plasticity,and neurodevelopment.AMPARs are typically composed of four subunits,namely GluA1,GluA2,GluA3,and GluA4,which can form homo-or hetero-tetramers.These subunits bind directly or indirectly to various scaffolding proteins such as transmembrane AMPA receptor regulatory proteins(TARPs).
基金supported by the Natural Science Foundation of China(NSFC,30972512 and 81202182)the Research Foundation for the Doctoral Program of Higher Education(20121417110002)
文摘Objective To explore the effects of exposure to aluminum （AI） on long-term potentiation （LTP） and AMPA receptor subunits in rats in vivo. Methods Different dosages of aluminum-maltolate complex [Al（mal）3] were given to rats via acute intracerebroventricular （i.c.v.） injection and subchronic intraperitoneal （i.p.） injection. Following AI exposure, the hippocampal LTP were recorded by field potentiation technique in vivo and the expression of AMPAR subunit proteins （GluR1 and GluR2） in both total and membrane-enriched extracts from the CA1 area of rat hippocampus were detected by Western blot assay. Results Acute AI treatment produced dose-dependent suppression of LTP in the rat hippocampus and dose-dependent decreases of GluRz and GluR2 in membrane extracts; however, no similar changes were found in the total cell extracts, which suggests decreased trafficking of AMPA receptor subunits from intracellular pools to synaptic sites in the hippocampus. The dose-dependent suppressive effects on LTP and the expression of AMPA receptor subunits both in the membrane and in total extracts were found after subchronic AI treatment, indicating a decrease in AMPA receptor subunit trafficking from intracellular pools to synaptic sites and an additional reduction in the expression of the subunits. Conclusion Al（mal）3 obviously and dose-dependently suppressed LTP in the rat hippocampal CA1 region in vivo, and this suppression may be related to both trafficking and decreases in the expression of AMPA receptor subunit proteins. However, the mechanisms underlying these observations need further investigation.
基金ThisprojectwassupportedbyagrantfromNationalNaturalSciencesFoundationofChina (No .30 0 4 0 0 37)
文摘To study the effect of glutamate on the intracellular calcium signal of pure cultured rat astrocytes and the role of NMDA and AMPA receptors in the procedure, the change of calcium signal was investigated by monitoring the fluctuation of intracellular Ca 2+ concentration ([Ca 2+ ] i) on the basis of Fura-2 single cell fluorescent ratio (F345/F380). The changes in the effect of glutamate on the intracellular calcium signal were observed after blockage of NMDA and(or) AMPA receptors. It was found that L-glutamate could induce an increased [Ca 2+ ] i in most of the cells in concentration- and time-dependent manner. D-(-)-2-amino-5-phosphonopentanoic acid (D-AP-5, a selective antagonist of the NMDA receptor) and 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, a selective antagonist of the AMPA receptor) could abolish the effects of NMDA and AMPA respectively. The treatment of D-AP-5 and CNQX simultaneously or respectively could attenuate the effect of L-glutamate at varying degrees. All these indicated that glutamate could modulate intracellular Ca 2+ of pure cultured rat astrocytes through different pathways. The activation of NMDA and AMPA receptors took part in the complex mechanisms.
基金supported by Major Science and Technology Project of China(2015ZX09501003)
文摘OBJECTIVE Respiratory depression hinders the use of anaesthetics and sedative hyp.notics.To explore the mechanism of LCX001 on protection against respiratory depression,a novel AMPA receptor modulator LCX001,synthesized by our Institute of Medicinal Chemistry,is expected to relieve suppressed respiration.METHODS LCX001 was tested to alleviate respiratory depression triggered by opioid(fentanyl and TH-030418),propofol and pentobarbital in the plethysmography recording.The acetic acid writhing and hot-plate tests were conducted to evaluate analgesic effect of LCX001.Binding assay and whole-cell recording were used to analyze the property of LCX001 on positive modulation.The function of AMPA receptors were determined by location of receptors in the membrane and state of channel opening,and both processes were impressed by AMPA receptor regulatory proteins.Ac.cording to the theory,the effect of LCX001 on the expression of stargazin was measured firstly by west.ern blotting.The variation of receptor surface location was observed by live cell imaging.The regula.tion on neuronal Ca^(2+) and cell function was investigated intensively by Ca^(2+) imaging to clarify mecha.nism of LCX001.RESULTS LCX001 effectively rescued and prevented opioid(fentanyl and TH-030418),propofol,and pentobarbital-induced respiratory depression by strengthening respiratory fre.quency and minute ventilation in rats.The acetic acid writhing test and hot-plate test revealed potent anti-nociceptive efficacy of LCX001,in contrast to some ampakines that did not affect analgesia.Fur.thermore,LCX001 potentiated [3 H]AMPA and L-glutamate binding affinity to AMPA receptors,and facili.tated glutamate-evoked inward currents in HEK293 cells stably expressing GluA2(R).Importantly,appli.cation of LCX001 generated a significant increase in GluA2(R) surface expression in a mechanism of stargazin up-regulation,and restrained opioid-induced abnormal intracellular Ca^(2+) load,which might par.ticipate in breathing modulation.CONCLUSION The novel pharmacological effect and potential new mechanism of LCX001 might promote ampakines to be a therapeutic option for protection against respi.ratory depression.
基金National Science and Technology Major Project of China (2015ZX09501003).
文摘OBJECTIVE Respiratory depression hinders the use of anaesthetics and sedative hypnotics.For emergency use,specific antagonists are currently administered to counteract respiratory depression.However,antagonists are often short-lasting and can have multiple unexpected side effects.A novel AMPA receptor modulator LCX001,synthesized by our Institute of Medicinal Chemistry,is expected to relieve suppressed respiration.To explore the mechanism and impact of LCX001 on protection against respiratory depression.METHODS LCX001 was tested to alleviate respiratory depression triggered by opioid,propofol and pentobarbital in the plethysmography recording.The acetic acid writhing and hot-plate tests were conducted to evaluate potential analgesic effect of LCX001.Binding assay and whole-cell recording were used to analyze the property of LCX001 on positive modulation.The function of AMPA receptors were determined by location of receptors inthe membrane and state of channel opening,and both processes were impressed by AMPA receptor regulatory proteins.According to the theory,the effect of LCX001 on the expression of stargazin was measured firstly by Western blotting.The variation of receptor surface location were observed by live cell imaging.The regulation on neuronal Ca2+and cell function was investigated intensively by Ca2+imaging to clarify mechanism of LCX001.RESULTS LCX001 effectively rescued and prevented opioid(fentanyl and TH-030418),propofol,and pentobarbitalinduced respiratory depression by strengthening respiratory frequency and minute ventilation by 30%-50% in rats.The acetic acid writhing test and hot-plate test revealed potent anti-nociceptive efficacy of LCX001 on increasing the inhibition rate and %MPE to 80% and 65% respectively,in contrast to some ampakines that did not affect analgesia.Furthermore,LCX001 potentiated[3 H]AMPA and L-glutamate binding affinity to AMPA receptors,and facilitated glutamateevoked inward currents in HEK293 cells stably expressing GluA2(R).At 10 mmol·L^(-1) glutamate evoked amplitudes,LCX001 at 100 μmol·L^(-1) increased the potency of glutamate induced currents by(1120 ± 60) pA,compared with that of(752 ± 35) pA in the control group.LCX001 also prominently promoted steady state/peak amplitude ratio.LCX001 significantly slowed down the desensitization rates of the AMPA ion channel,and inhibited current decay.Importantly,application of LCX001 generated a significant increase in GluA2(R) surface expression in a mechanism of stargazin up-regulation,and restrained opioidinduced abnormal intracel ular Ca2+load,which might participate in breathing modulation.CONCLUSION The typical positive modulatory impact and potential new mechanism of LCX001 might promote ampakines to be a therapeutic option for protection against respiratory depression.
