Triggering of Major Brain Disorders by Protons and ATP: The Role of ASICs and P2X Receptors / 神经科学通报·英文版

Adenosine triphosphate (ATP) is well-known as a universal source of energy in living cells. Less known is that this molecule has a variety of important signaling functions: it activates a variety of specific metabotropic (P2Y) and ionotropic (P2X) receptors in neuronal and non-neuronal cell membranes. So, a wide variety of signaling functions well fits the ubiquitous presence of ATP in the tissues. Even more ubiquitous are protons. Apart from the unspecific interaction of protons with any protein, many physiological processes are affected by protons acting on specific ionotropic receptors-acid-sensing ion channels (ASICs). Both protons (acidification) and ATP are locally elevated in various pathological states. Using these fundamentally important molecules as agonists, ASICs and P2X receptors signal a variety of major brain pathologies. Here we briefly outline the physiological roles of ASICs and P2X receptors, focusing on the brain pathologies involving these receptors.

Acid-sensing ion channels differentially affect ictal-like and non-ictal-like epileptic activities of mouse hippocampal pyramidal neurons in acidotic extracellular pH / 南方医科大学学报

OBJECTIVE@#To investigate the effects of acid-sensing ion channels (ASICs) on electrophysiological epileptic activities of mouse hippocampal pyramidal neurons in the extracellular acidotic condition.@*METHODS@#We investigated effects of extracellular acidosis on epileptic activities induced by elevated extracellular K concentration or the application of an antagonist of GABA receptors in perfusate of mouse hippocampal slices under field potential recordings. We also tested the effects of extracellular acidosis on neuronal excitability under field potential recording and evaluated the changes in epileptic activities of the neurons in response to pharmacological inhibition of ASICs using a specific inhibitor of ASICs.@*RESULTS@#Extracellular acidosis significantly suppressed epileptic activities of the hippocampal neurons by converting ictal-like epileptic activities to non-ictal-like epileptic activities in both high [K ]o and disinhibition models, and also suppressed the intrinsic excitability of the neurons. ASICs inhibitor did not antagonize the inhibitory effect of extracellular acidosis on ictal epileptic activities and intrinsic neuronal excitability, but exacerbated non-ictal epileptic activities of the neurons in extracellular acidotic condition in both high [K]o and disinhibition models.@*CONCLUSIONS@#ASICs can differentially modulate ictal-like and non-ictallike epileptic activities via its direct actions on excitatory neurons.

Identification and Function of Acid-sensing Ion Channels in RAW 264.7 Macrophage Cells / 华中科技大学学报（医学）（英德文版）

Activation of acid-sensing ion channels (ASICs) plays an important role in neuroinflammation.Macrophage recruitment to the sites of inflammation is an essential step in host defense.ASIC 1 and ASIC3 have been reported to mediate the endocytosis and maturation of bone marrow derived macrophages.However,the expression and inflammation-related functions of ASICs in RAW 264.7 cells,another common macrophage,are still elusive.In the present study,we first demonstrated the presence of ASIC 1,ASIC2a and ASIC3 in RAW 264.7 macrophage cell line by using reverse transcriptase polymerase chain reaction (RT-PCR),Western blotting and immunofluorescence experiments.The non-specific ASICs inhibitor amiloride and specific homomeric ASIC 1 a blocker PcTx 1 reduced the production of iNOS and COX-2 by LPS-induced activating RAW 264.7 cells.Furthermore,not only amiloride but also PcTx 1 inhibited the migration and LPS-induced apoptosis of RAW 264.7 cells.Taken together,our findings suggest that ASICs promote the inflammatory response and apoptosis of RAW 264.7 cells,and ASICs may serve as a potential novel target for immunological disease therapy.

Identification and Function of Acid-sensing Ion Channels in RAW 264.7 Macrophage Cells / 华中科技大学学报（医学）（英德文版）

Activation of acid-sensing ion channels (ASICs) plays an important role in neuroinflammation.Macrophage recruitment to the sites of inflammation is an essential step in host defense.ASIC 1 and ASIC3 have been reported to mediate the endocytosis and maturation of bone marrow derived macrophages.However,the expression and inflammation-related functions of ASICs in RAW 264.7 cells,another common macrophage,are still elusive.In the present study,we first demonstrated the presence of ASIC 1,ASIC2a and ASIC3 in RAW 264.7 macrophage cell line by using reverse transcriptase polymerase chain reaction (RT-PCR),Western blotting and immunofluorescence experiments.The non-specific ASICs inhibitor amiloride and specific homomeric ASIC 1 a blocker PcTx 1 reduced the production of iNOS and COX-2 by LPS-induced activating RAW 264.7 cells.Furthermore,not only amiloride but also PcTx 1 inhibited the migration and LPS-induced apoptosis of RAW 264.7 cells.Taken together,our findings suggest that ASICs promote the inflammatory response and apoptosis of RAW 264.7 cells,and ASICs may serve as a potential novel target for immunological disease therapy.

Effect of low pH on acid-sensing ion channel 1a expression in vascular endothelial cell induced by serum IgA 1 from Henoch-Sch?nlein purpura children and its mechanism / 基础医学与临床

Objective To investigate the effect of low pH on acid-sensing ion channel 1a( ASIC1a) expression in vascular endothelial cells induced by serum IgA 1 from Henoch-Sch?nlein purpura ( HSP ) children and regulatory role of ASIC1a in it.Methods Human dermal microvascular endothelial cells ( HDMECs) treated by serum IgA1 from children with HSP were incubated in different pH medium .ASIC1a, destrin and α-SM mRNA expressions in HDMECs were evaluated by real-time quantitative polymerase chain reaction (q-PCR).The level of inflammatory cytokines released by vascular endothelial cells was detected by ELISA .Moreover destrin and α-SM protein expres-sion in HDMECs was evaluated by Western blot .Results The results showed that in low pH condition , IgA1 from HSP children could induce the upregulation of ASIC 1a mRNA expression , stimulate IL-8, NO and TM release of vascular endothelial cells of HSP children .And blockers of ASICs could reduce acid-induced cytokine release of vascular endothelial cells .Moreover destrin and α-SM mRNA and protein expression in HDMECs of HSP children significantly decreased when exposure to extracellular acidosis .However blockers of ASICs increased destrin and α-SM mRNA and protein expression in vascular endothelial cells of HSP children .Conclusions These findings showed that activation of ASIC 1a could be involved in the vascular endothelial cell injury of HSP children .Blocking ASIC1a may have a significant protective effect on the inflammatory injury of vascular endothelial cells .

Sinomenine protects against ischemic injury in rat hippocampal neurons / 中国药理学通报

Aim To observe the neuroprotective effect of sinomenine on hippocampal neurons from injury in-duced by oxygen glucose deprivation ( OGD ) and its underlying mechanism. Methods Hippocampal neu-rons were exposed to OGD for 4 h followed by 24 h re-oxygenation ( OGD-R) . Then cell viability was detec-ted by MTT. LDH release was detected by LDH kit. Cell apoptosis was detected by Hoechst stain. The ex-pression of Bax, Bcl-2 and caspase-3 were detected by Western blot. [ Ca2+] i of hippocampal neurons was detected by calcium imaging. Acid-sensing ion chan-nels ( ASICs ) current was detected by patch clamp technique. Results SN increased cell viability and reduced LDH release. SN also inhibited neuron apop-tosis and increased ratio of Bcl-2/Bax and reduced the expression of caspase-3 . OGD-induced increase of [ Ca2+] i was inhibited by SN. Furthermore, SN inhib-ited ASIC1 a current and also inhibited OGD induced increase of ASICs current in hippocampal neurons. Conclusion SN protects hippocampal neurons against OGD-R-induced injury. The inhibitory effect of SN on ASIC1 a and calcium overload was involved in the pro-tective effect of SN.

Growing insights into acid-sensing ion channels / 中国药理学通报

Acid-sensing ion channels( ASICs )are ubiquitously expressed both in periphery nervous system, where they are involved in nociception,mechanosensation,inflammation ,cardiac angina, and in central nervous system,where they are essential to a variety of physiologic and pathophysiologic processes,such as synaptic plasticity ,learning ,memory and ischemic brain injury. Here in the article, we present a collection of key points about ASICs, ranging from molecular identity and expression, regulatory mechanisms responsible for channel gating to their multiple functions. Finally, a future prospect for the investigation of ASICs is outlined.