人胰淀素(hAmylin)是由分泌胰岛素的胰岛B细胞释放,作用于靶组织,维持细胞的兴奋性和葡萄糖在体内的稳态。hAmylin分泌异常会引起人类的疾病,特别是阿尔茨海默氏病(Alzheimer's disease,AD)。目前对于hAmylin通过激活什么样的受体...人胰淀素(hAmylin)是由分泌胰岛素的胰岛B细胞释放,作用于靶组织,维持细胞的兴奋性和葡萄糖在体内的稳态。hAmylin分泌异常会引起人类的疾病,特别是阿尔茨海默氏病(Alzheimer's disease,AD)。目前对于hAmylin通过激活什么样的受体从而产生脑神经元的神经毒性仍然不清楚。已知烟碱乙酰胆碱受体(nicotinic acetylcholine receptors,nAChRs)是引发多种神经性疾病的关键因素。本研究通过记录hAmylin和烟碱对基底前脑神经元的全细胞电流和膜电位的影响,来确定hAmylin受体和烟碱受体两者之间的相互作用。在酶解分离的基底前脑Broca区(diagonal band of Broca,DBB)胆碱能神经元上进行全细胞膜片钳记录,结果显示,hAmylin或烟碱单独应用,均引起剂量(1nmol/L^20μmol/L)依赖性膜电位的去极化和DBB神经元放电频率增加。hAmylin受体拮抗剂AC253,不仅阻断hAmylin的兴奋作用,而且也阻断烟碱对神经元的兴奋作用;同样,使用nAChR竞争性拮抗剂二氢-β-刺桐啶碱(dihydro-β-erythroidine,DHβE),可以阻断烟碱和hAmylin对DBB神经元的兴奋作用。以上结果提示,hAmylin受体和nAChRs受体在DBB神经元可能是功能偶联的,协同影响DBB神经元的兴奋性。展开更多
Nicotinic acetylcholine receptors(nAChRs) play important roles in intercellular communications of nerve cells. α-Bungarotoxins(αBtx) is a moderator for the nAChRs. Chemical synthesis provides a promising way to acce...Nicotinic acetylcholine receptors(nAChRs) play important roles in intercellular communications of nerve cells. α-Bungarotoxins(αBtx) is a moderator for the nAChRs. Chemical synthesis provides a promising way to access aBtx and their analogues. Here, we reported a new method for a-bungarotoxin by combining Fmoc-SPPS and peptide hydrazide based ligation strategy. The two-segment ligation method may enable efficient synthesis of aBtx analogues. These synthetic toxin peptides are useful tools for development of imaging or therapeutic reagents.展开更多
Olfactory bulbectomy (OBX) causes cognitive dysfunction by degeneration of cholinergic neurons in the medial septum. Here, we define an involvement of nicotinic acetylcholine receptor (nAChR) in neuroprotective effect...Olfactory bulbectomy (OBX) causes cognitive dysfunction by degeneration of cholinergic neurons in the medial septum. Here, we define an involvement of nicotinic acetylcholine receptor (nAChR) in neuroprotective effect of donepezil in the septum neurons of OBX mice. Neuroprotective effects on the medial septal cholinergic neurons were assessed after chronic donepezil administration in OBX mice. We also measured Akt and ERK phosphorylation to define the neuroprotective mechanism of donepezil. We found that treatment with donepezil (1 - 3 mg/kg) for 15 consecutive days completely rescued cholinergic neurons in the OBX mice with concomitant improved memory. Reduction of both protein kinase B (Akt) and extracellular signal-regulated kinase (ERK) phosphorylation were restored by chronic donepezil administration (1 - 3 mg/kg) in OBX mouse medial septum. Both phosphorylated Akt and ERK immunoreactivities were localized in cell bodies of choline acetyltransferase (ChAT)-positive cholinergic cells in the medial septum. Enhancement of Akt and ERK phosphorylation seen following donepezil administration was totally blocked by pre-administration of mecamylamine (10 μM), a nicotinic acetylcholine receptor antagonist. Donepezil increases phosphorylation of Akt and ERK via nAChR stimulation in the medial septum cholinergic neurons. The Akt and ERK stimulation by donepezil is associated with its ability of neuroprotection in the medial septum and memory improvement.展开更多
Nicotine, the major addictive substance in tobacco, interacts with nicotinic acetylcholine receptors (nAChRs) located in neuronal and glial cells, modulating synaptic transmission and memory. Here, we show that nAChRs...Nicotine, the major addictive substance in tobacco, interacts with nicotinic acetylcholine receptors (nAChRs) located in neuronal and glial cells, modulating synaptic transmission and memory. Here, we show that nAChRs agonists, including nicotine, acetylcholine, and choline, increase the intracellular Ca2+ concentration ([Ca2+]i) in cultured hippocampal astrocytes, indicating the involvement of nAChRs. Interestingly, inhibition of nAChRs, with a cocktail of antagonists (mecamylamine, methyllycaconitine plus dihydro-β- erythroidine), does not prevent the astrocytic [Ca2+]i increases generated by nicotine. This last effect would be attributable to inhibition of K+ currents by nicotine in these cells, as previously we showed using patch- clamp recordings. Furthermore, the application of tetraethylammonium, an inhibitor of K+ currents, also increases the [Ca2+]i. Together, these results indicate that nicotine increases [Ca2+]i in hippocampal astrocytes through two pathways: by activation of nAChRs, and likely by direct inhibition of K+ currents.展开更多
Theα7 nicotinic acetylcholine receptors(nAChRs)are widely expressed in the central and peripheral nervous systems and are important drug targets for the treatment of neurological diseases.However,differentiation of t...Theα7 nicotinic acetylcholine receptors(nAChRs)are widely expressed in the central and peripheral nervous systems and are important drug targets for the treatment of neurological diseases.However,differentiation of the agonists and antagonists of the nAChR is difficult.In this study we aimed to develop a reliable and efficient computational approach for differentiation of the agonists from the antagonists of the nAChR based on a systematical analysis of 123 ligands(87 agonists,12 partial agonists,and 24 antagonists)binding with the extracellular domain of theα7 n AChR chimera.Our results suggest that the ligand size and ligand binding affinity cannot differentiate the agonists from the antagonists of the nAChR.The ligand efficiency that considers both ligand binding affinity and size for the agonists is overall more left shifted in comparison to the antagonists,but the values of the ligand efficiency still cannot differentiate the agonists from the antagonists unless the values are either relatively high(more than-0.3 kcal mol^-1)or relatively low(less than-0.45 kcal mol^-1).Our results suggest that accurate prediction of the agonist or antagonist of the nAChR is challenging and the ligand innate configuration has to be considered as an extra for differentiation of the agonists from the antagonists of the nAChR.展开更多
Addiction to nicotine, and possibly other tobacco constituents, is a major factor that contributes to the difficulties smokers face when attempting to quit smoking. Amongst the various subtypes of nicotinic acetylchol...Addiction to nicotine, and possibly other tobacco constituents, is a major factor that contributes to the difficulties smokers face when attempting to quit smoking. Amongst the various subtypes of nicotinic acetylcholine receptors (nAChRs), the α4β2 subtype plays an important role in mediating the addiction process. The characterization of human α4β2-ligand binding interactions provides a molecular framework for understanding ligand-receptor interactions, rendering insights into mechanisms of nicotine addiction and may furnish a tool for efficiently identifying ligands that can bind the nicotine receptor. Therefore, we constructed a homology model of human α4β2 nAChR and performed molecular docking and molecular dynamics (MD) simulations to elucidate the potential human α4β2-ligand binding modes for eleven compounds known to bind to this receptor. Residues V96, L97 and F151 of the α4 subunit and L111, F119 and F121 of the β2 subunit were found to be involved in hydrophobic interactions while residues S153 and W154 of the α4 subunit were involved in the formation of hydrogen bonds between the receptor and respective ligands. The homology model and its eleven ligand-bound structures will be used to develop a virtual screening program for identifying tobacco constituents that are potentially addictive.展开更多
Neonicotinoids, such as imidacloprid, are key insecticides extensively used for control of Nilaparvata lugens. However, imidacloprid resistance has been reported in many Asian countries in recent years. To understand ...Neonicotinoids, such as imidacloprid, are key insecticides extensively used for control of Nilaparvata lugens. However, imidacloprid resistance has been reported in many Asian countries in recent years. To understand the roles of the chlorine atom of pyridyl group on insecticidal activity and resistance, the atom was removed to generate an imidacloprid analogue DC-Imi （DesChlorine Imidacloprid）. DC-Imi showed significantly higher toxicity than imidacloprid in the susceptible strain of N. lugens, but had medium level cross-resistance in an imidacloprid-resistant strain. In Xenopus oocyte expressed nico- tinic acetylcholine receptors （nAChRs） Nlu 1/r/32, the inward currents evoked by DC-Imi were detected and could be blocked by typical nAChRs antagonist dihydro-β-erythroidine （DHβE）, which demonstrated that DC-Imi acted as an agonist on insect nAChRs. The efficacy of DC-Imi on Nlα 1/rβ2 was 1.8-fold higher than that ofimidacloprid. In addition, the influence of an imidacloprid resistance associated mutation （Y 151 S） on agonist potencies was evaluated. Compared with the wild-type receptor, the mutation reduced maximal inward current of DC-Imi to 55.6% and increased half maximal effective concentration （EC50） to 3.53-fold. Compared with imidacloprid （increasing EC50 to 2.38-fold of wild- type receptor）, Y151 S mutation decreased DC-Imi potency more significantly. The results indicated that the selective and possibly high toxicities could be achieved through the modification of 6-chloro-3-pyridyl group in imidacloprid and other neonicotinoids.展开更多
基金supported by the Natural Science Foundation of the Education Department of Henan Province, China (No. 2011C180007)the Science Foundation of Luohe Medical College (No. 2010S1)
文摘人胰淀素(hAmylin)是由分泌胰岛素的胰岛B细胞释放,作用于靶组织,维持细胞的兴奋性和葡萄糖在体内的稳态。hAmylin分泌异常会引起人类的疾病,特别是阿尔茨海默氏病(Alzheimer's disease,AD)。目前对于hAmylin通过激活什么样的受体从而产生脑神经元的神经毒性仍然不清楚。已知烟碱乙酰胆碱受体(nicotinic acetylcholine receptors,nAChRs)是引发多种神经性疾病的关键因素。本研究通过记录hAmylin和烟碱对基底前脑神经元的全细胞电流和膜电位的影响,来确定hAmylin受体和烟碱受体两者之间的相互作用。在酶解分离的基底前脑Broca区(diagonal band of Broca,DBB)胆碱能神经元上进行全细胞膜片钳记录,结果显示,hAmylin或烟碱单独应用,均引起剂量(1nmol/L^20μmol/L)依赖性膜电位的去极化和DBB神经元放电频率增加。hAmylin受体拮抗剂AC253,不仅阻断hAmylin的兴奋作用,而且也阻断烟碱对神经元的兴奋作用;同样,使用nAChR竞争性拮抗剂二氢-β-刺桐啶碱(dihydro-β-erythroidine,DHβE),可以阻断烟碱和hAmylin对DBB神经元的兴奋作用。以上结果提示,hAmylin受体和nAChRs受体在DBB神经元可能是功能偶联的,协同影响DBB神经元的兴奋性。
基金supported by the Science and Technological Fund of Anhui Province for Outstanding Youth(No. 1808085J04)the Innovative Program Development Foundation Hefei Center Physical Science Technology(No. 2017FXCX002)
文摘Nicotinic acetylcholine receptors(nAChRs) play important roles in intercellular communications of nerve cells. α-Bungarotoxins(αBtx) is a moderator for the nAChRs. Chemical synthesis provides a promising way to access aBtx and their analogues. Here, we reported a new method for a-bungarotoxin by combining Fmoc-SPPS and peptide hydrazide based ligation strategy. The two-segment ligation method may enable efficient synthesis of aBtx analogues. These synthetic toxin peptides are useful tools for development of imaging or therapeutic reagents.
文摘Olfactory bulbectomy (OBX) causes cognitive dysfunction by degeneration of cholinergic neurons in the medial septum. Here, we define an involvement of nicotinic acetylcholine receptor (nAChR) in neuroprotective effect of donepezil in the septum neurons of OBX mice. Neuroprotective effects on the medial septal cholinergic neurons were assessed after chronic donepezil administration in OBX mice. We also measured Akt and ERK phosphorylation to define the neuroprotective mechanism of donepezil. We found that treatment with donepezil (1 - 3 mg/kg) for 15 consecutive days completely rescued cholinergic neurons in the OBX mice with concomitant improved memory. Reduction of both protein kinase B (Akt) and extracellular signal-regulated kinase (ERK) phosphorylation were restored by chronic donepezil administration (1 - 3 mg/kg) in OBX mouse medial septum. Both phosphorylated Akt and ERK immunoreactivities were localized in cell bodies of choline acetyltransferase (ChAT)-positive cholinergic cells in the medial septum. Enhancement of Akt and ERK phosphorylation seen following donepezil administration was totally blocked by pre-administration of mecamylamine (10 μM), a nicotinic acetylcholine receptor antagonist. Donepezil increases phosphorylation of Akt and ERK via nAChR stimulation in the medial septum cholinergic neurons. The Akt and ERK stimulation by donepezil is associated with its ability of neuroprotection in the medial septum and memory improvement.
文摘Nicotine, the major addictive substance in tobacco, interacts with nicotinic acetylcholine receptors (nAChRs) located in neuronal and glial cells, modulating synaptic transmission and memory. Here, we show that nAChRs agonists, including nicotine, acetylcholine, and choline, increase the intracellular Ca2+ concentration ([Ca2+]i) in cultured hippocampal astrocytes, indicating the involvement of nAChRs. Interestingly, inhibition of nAChRs, with a cocktail of antagonists (mecamylamine, methyllycaconitine plus dihydro-β- erythroidine), does not prevent the astrocytic [Ca2+]i increases generated by nicotine. This last effect would be attributable to inhibition of K+ currents by nicotine in these cells, as previously we showed using patch- clamp recordings. Furthermore, the application of tetraethylammonium, an inhibitor of K+ currents, also increases the [Ca2+]i. Together, these results indicate that nicotine increases [Ca2+]i in hippocampal astrocytes through two pathways: by activation of nAChRs, and likely by direct inhibition of K+ currents.
基金supported by the Fundamental Research Funds for the Central Universities (No. 201762011 for R. Y.)National Laboratory Director Fund from the Qingdao National Laboratory of Marine Science and Technology (No. QNLM201709)the NSFC-Shandong Joint Fund (No. U1406402)
文摘Theα7 nicotinic acetylcholine receptors(nAChRs)are widely expressed in the central and peripheral nervous systems and are important drug targets for the treatment of neurological diseases.However,differentiation of the agonists and antagonists of the nAChR is difficult.In this study we aimed to develop a reliable and efficient computational approach for differentiation of the agonists from the antagonists of the nAChR based on a systematical analysis of 123 ligands(87 agonists,12 partial agonists,and 24 antagonists)binding with the extracellular domain of theα7 n AChR chimera.Our results suggest that the ligand size and ligand binding affinity cannot differentiate the agonists from the antagonists of the nAChR.The ligand efficiency that considers both ligand binding affinity and size for the agonists is overall more left shifted in comparison to the antagonists,but the values of the ligand efficiency still cannot differentiate the agonists from the antagonists unless the values are either relatively high(more than-0.3 kcal mol^-1)or relatively low(less than-0.45 kcal mol^-1).Our results suggest that accurate prediction of the agonist or antagonist of the nAChR is challenging and the ligand innate configuration has to be considered as an extra for differentiation of the agonists from the antagonists of the nAChR.
文摘Addiction to nicotine, and possibly other tobacco constituents, is a major factor that contributes to the difficulties smokers face when attempting to quit smoking. Amongst the various subtypes of nicotinic acetylcholine receptors (nAChRs), the α4β2 subtype plays an important role in mediating the addiction process. The characterization of human α4β2-ligand binding interactions provides a molecular framework for understanding ligand-receptor interactions, rendering insights into mechanisms of nicotine addiction and may furnish a tool for efficiently identifying ligands that can bind the nicotine receptor. Therefore, we constructed a homology model of human α4β2 nAChR and performed molecular docking and molecular dynamics (MD) simulations to elucidate the potential human α4β2-ligand binding modes for eleven compounds known to bind to this receptor. Residues V96, L97 and F151 of the α4 subunit and L111, F119 and F121 of the β2 subunit were found to be involved in hydrophobic interactions while residues S153 and W154 of the α4 subunit were involved in the formation of hydrogen bonds between the receptor and respective ligands. The homology model and its eleven ligand-bound structures will be used to develop a virtual screening program for identifying tobacco constituents that are potentially addictive.
文摘Neonicotinoids, such as imidacloprid, are key insecticides extensively used for control of Nilaparvata lugens. However, imidacloprid resistance has been reported in many Asian countries in recent years. To understand the roles of the chlorine atom of pyridyl group on insecticidal activity and resistance, the atom was removed to generate an imidacloprid analogue DC-Imi （DesChlorine Imidacloprid）. DC-Imi showed significantly higher toxicity than imidacloprid in the susceptible strain of N. lugens, but had medium level cross-resistance in an imidacloprid-resistant strain. In Xenopus oocyte expressed nico- tinic acetylcholine receptors （nAChRs） Nlu 1/r/32, the inward currents evoked by DC-Imi were detected and could be blocked by typical nAChRs antagonist dihydro-β-erythroidine （DHβE）, which demonstrated that DC-Imi acted as an agonist on insect nAChRs. The efficacy of DC-Imi on Nlα 1/rβ2 was 1.8-fold higher than that ofimidacloprid. In addition, the influence of an imidacloprid resistance associated mutation （Y 151 S） on agonist potencies was evaluated. Compared with the wild-type receptor, the mutation reduced maximal inward current of DC-Imi to 55.6% and increased half maximal effective concentration （EC50） to 3.53-fold. Compared with imidacloprid （increasing EC50 to 2.38-fold of wild- type receptor）, Y151 S mutation decreased DC-Imi potency more significantly. The results indicated that the selective and possibly high toxicities could be achieved through the modification of 6-chloro-3-pyridyl group in imidacloprid and other neonicotinoids.
