AIM: To investigate whether bis (7)-tacrine, a multifunctional drug, inhibits N-methyl-D-aspartate (NMDA) -activated current in retinal ganglion cells (RGC) and provides neuroprotection against retinal cell damage. ME...AIM: To investigate whether bis (7)-tacrine, a multifunctional drug, inhibits N-methyl-D-aspartate (NMDA) -activated current in retinal ganglion cells (RGC) and provides neuroprotection against retinal cell damage. METHODS: Purified RGC cultures were obtained from retinas of 1-3 days old Sprague-Dawley (SD) rats, following a two-step immunopanning procedure. After 7 days of cultivation, the inhibition of NMDA-activated current by bis(7) -tacrine was measured by using patch-clamp recording techniques. In animal experiments, RGCs were damaged after intravitreal injection of NMDA (5 mu L, 40nmol) in adult rats. Bis (7)-tacrine(0.05, 0.1, 0.2mg/kg) or memantine(20mg/kg) was intraperitoneal administered to the rats fifteen minutes before intravitreally injection of NMDA. RGC damage was analyzed by histologic techniques, TUNEL and retrograde labeling techniques. RESULTS: Whole-cell patch-clamp recordings demonstrated that NMDA (30 mu mol/L) resulted in approximately -50 pA inward currents that were blocked by bis (7)-tacrine (1 mu mol/L). Histological examination and retrograde labeling analysis revealed that bis (7)-tacrine induced a significant neuroprotective effect against NMDA-induced cell damage 7 days after NMDA injection. TUNEL staining showed that pretreatment with bis(7)-tacrine was effective in ameliorating NMDA-induced apoptotic cell loss in the retinal ganglion cell layer 18 hours after injection. CONCLUSION: Bis (7)-tacrine possesses remarkable neuroprotective activities against retinal excitotoxicity through inhibition of NMDA receptors.展开更多
目的:观察双七他克林对青光眼模型大鼠的视神经保护作用。方法:选取雄性成年SD大鼠24只,随机分成对照组、手术组、双七他克林组和美金刚胺组,通过右眼巩膜上静脉注射高渗盐水(对照组大鼠右眼仅进行上巩膜静脉穿刺)制作青光眼模型后,对...目的:观察双七他克林对青光眼模型大鼠的视神经保护作用。方法:选取雄性成年SD大鼠24只,随机分成对照组、手术组、双七他克林组和美金刚胺组,通过右眼巩膜上静脉注射高渗盐水(对照组大鼠右眼仅进行上巩膜静脉穿刺)制作青光眼模型后,对照组和手术组大鼠给予正常饮水,双七他克林组和美金刚胺组大鼠饮用水中每天分别添加0.5mg/kg双七他克林和5mg/kg美金刚胺,持续5wk。定期测量眼压,造模后5wk处死大鼠,取右侧视网膜进行免疫荧光染色,检测视网膜神经节细胞数目和视网膜神经纤维层厚度。结果:造模后模型大鼠右眼眼压均显著升高,至造模后1mo,均高于28mmHg。手术组大鼠右眼视网膜神经节细胞数较对照组明显减少(79.83±9.58个vs 119.50±8.26个,P<0.01),神经纤维层厚度明显变薄(6.64±0.50μm vs 13.40±0.60μm,P<0.01),而双七他克林(109.00±7.04个)和美金刚胺(107.33±8.57个)能够抑制青光眼所致的视网膜神经节细胞减少,且双七他克林能够抑制青光眼所致的视网膜神经纤维层萎缩(12.26±0.78μm)。结论:双七他克林能够抑制青光眼所致视网膜神经节细胞数目减少及神经纤维层萎缩。展开更多
In normal rat forebrain, the NR1/NR2A and NR1/NR2B dimmers are the main constitutional forms of NMDA receptors. The present study was carried out to determine the functional properties of the heteromeric NMDA receptor...In normal rat forebrain, the NR1/NR2A and NR1/NR2B dimmers are the main constitutional forms of NMDA receptors. The present study was carried out to determine the functional properties of the heteromeric NMDA receptor subunits and their inhibition by bis(7)-tacrine (B7T). Rat NR1, NR2A and NR2B cDNAs were transfected into human embryonic kidney 293 cells (HEK-293).The inhibition of NMDA-activated currents by B7T was detected in HEK-293 cell expressing NR1/NR2A or NR1/NR2B receptors by using whole-cell patch-clamp techniques. The results showed that in HEK-293 cells expressing NR1/NR2A receptor, 1μmol/L B7T inhibited 30μmol/L NMDA- and 1000μmol/L NMDA-activated steady-state currents by 46% and 40%, respectively (P>0.05; n=5), suggesting that the inhibition of B7T on NR1/NR2A receptor doesn’t depend on NMDA concentration, which is consistent with a non-competitive mechanism of inhibition. But for the NR1/NR2B receptor, 1μmol/L B7T inhibited 30μmol/L NMDA- and 1000 μmol/L NMDA-activated steady-state currents by 61% and 13%, re-spectively (P<0.05; n=6), showing that B7T appears to be competitive with NMDA. In addition, simultaneous application of 1μmol/L B7T and 1000μmol/L NMDA produced a moderate inhibition of peak NMDA-activated current, followed by a gradual decline of the current to a steady state. However, the gradual onset of inhibition produced by B7T applied simultaneously with NMDA was eliminated when B7T was given 5s before NMDA. These results suggested that B7T inhibition of NMDA current mediated by NR1/NR2B receptor was slow onset, and it did not depend on the presence of the agonist. With holding potentials ranging from -50 to +50 mV, the B7T inhibition rate of NMDA currents didn’t change significantly, and neither did the reversal potential. We are led to conclude that the NR1/NR2B recombinant receptor can serve as a very useful model for studying the molecular mechanism of NMDA receptor inhibition by B7T.展开更多
The effects ofbis(7)-tacrine, a novel acetylcholinesterase inhibitor, on cognitive impairment and neuronal degeneration induced by permanent ligation of bilateral common carotid arteries (2VO) were investigated using ...The effects ofbis(7)-tacrine, a novel acetylcholinesterase inhibitor, on cognitive impairment and neuronal degeneration induced by permanent ligation of bilateral common carotid arteries (2VO) were investigated using the Morris water maze in rats. Once daily oral administration ofbis(7)-tacrine (0.025, 0.05 and 0.1 mg?kg?1) was started 14 days after 2VO operation. Over a three-week treatmentbis(7)-tacrine effectively reversed 2VO-induced spatial memory deficits in a dose-dependent fashion. Furthermore, histological observation showedbis(7)-tacrine decreased the neuropathological changes in the 2VO rats brain. These results suggest thatbis(7)-tacrine has therapeutic potential for the treatment of dementia caused by chronic cerebral hypoperfusion.展开更多
The effects of bis(7) tacrine, a novel dimeric acetylcholinesterase (AChE) inhibitor, on glutamate induced cell injury were investigated in primary cerebral cortical neurons of rats. Exposure of cultured neurons (1...The effects of bis(7) tacrine, a novel dimeric acetylcholinesterase (AChE) inhibitor, on glutamate induced cell injury were investigated in primary cerebral cortical neurons of rats. Exposure of cultured neurons (12 days after plating) to 0.5 mmol/L glutamate for 30 min resulted in significant cell damage. Pretreatment with bis(7) tacrine (0.03 1.0 μmol/L) reduced the glutamate induced neurotoxicity in a concentration dependent manner and the maximal response was seen at 1 μmol/L with approximately 30% protection. A receptor binding assay showed that bis(7) tacrine can completely displace MK 801 binding to rat cortical membrane with an IC 50 of 0.57 μmol/L. These findings suggest that bis(7) tacrine can directly interact with N methyl D aspartate receptor channel complex, which may contribute to the inhibitor's protective effects against glutamate induced excitotoxicity. Thus, it is possible that anti glutamate/anti AChE synergism is responsible for potentially better Alzheimer's therapy of bis(7) tacrine relative to tacrine.展开更多
基金National Natural Science Foundation of China (No.81000380H1204)Natural Science Foundation of Hubei Province,China (No.2008CDA053)Scientific Research Fund of the Ministry of Health,Hubei Province,China (No.QJX2010-53)
文摘AIM: To investigate whether bis (7)-tacrine, a multifunctional drug, inhibits N-methyl-D-aspartate (NMDA) -activated current in retinal ganglion cells (RGC) and provides neuroprotection against retinal cell damage. METHODS: Purified RGC cultures were obtained from retinas of 1-3 days old Sprague-Dawley (SD) rats, following a two-step immunopanning procedure. After 7 days of cultivation, the inhibition of NMDA-activated current by bis(7) -tacrine was measured by using patch-clamp recording techniques. In animal experiments, RGCs were damaged after intravitreal injection of NMDA (5 mu L, 40nmol) in adult rats. Bis (7)-tacrine(0.05, 0.1, 0.2mg/kg) or memantine(20mg/kg) was intraperitoneal administered to the rats fifteen minutes before intravitreally injection of NMDA. RGC damage was analyzed by histologic techniques, TUNEL and retrograde labeling techniques. RESULTS: Whole-cell patch-clamp recordings demonstrated that NMDA (30 mu mol/L) resulted in approximately -50 pA inward currents that were blocked by bis (7)-tacrine (1 mu mol/L). Histological examination and retrograde labeling analysis revealed that bis (7)-tacrine induced a significant neuroprotective effect against NMDA-induced cell damage 7 days after NMDA injection. TUNEL staining showed that pretreatment with bis(7)-tacrine was effective in ameliorating NMDA-induced apoptotic cell loss in the retinal ganglion cell layer 18 hours after injection. CONCLUSION: Bis (7)-tacrine possesses remarkable neuroprotective activities against retinal excitotoxicity through inhibition of NMDA receptors.
文摘目的:观察双七他克林对青光眼模型大鼠的视神经保护作用。方法:选取雄性成年SD大鼠24只,随机分成对照组、手术组、双七他克林组和美金刚胺组,通过右眼巩膜上静脉注射高渗盐水(对照组大鼠右眼仅进行上巩膜静脉穿刺)制作青光眼模型后,对照组和手术组大鼠给予正常饮水,双七他克林组和美金刚胺组大鼠饮用水中每天分别添加0.5mg/kg双七他克林和5mg/kg美金刚胺,持续5wk。定期测量眼压,造模后5wk处死大鼠,取右侧视网膜进行免疫荧光染色,检测视网膜神经节细胞数目和视网膜神经纤维层厚度。结果:造模后模型大鼠右眼眼压均显著升高,至造模后1mo,均高于28mmHg。手术组大鼠右眼视网膜神经节细胞数较对照组明显减少(79.83±9.58个vs 119.50±8.26个,P<0.01),神经纤维层厚度明显变薄(6.64±0.50μm vs 13.40±0.60μm,P<0.01),而双七他克林(109.00±7.04个)和美金刚胺(107.33±8.57个)能够抑制青光眼所致的视网膜神经节细胞减少,且双七他克林能够抑制青光眼所致的视网膜神经纤维层萎缩(12.26±0.78μm)。结论:双七他克林能够抑制青光眼所致视网膜神经节细胞数目减少及神经纤维层萎缩。
基金supported by grants from the National Natural Science Foundation of China(No. 30970927)the Natural Science Foundation of Hubei Province, China(No.2008CDA053)the Wuhan Science and Technology Foundation(Nos.200970634270,201250499145-27 and 20115069-9189-23)
文摘In normal rat forebrain, the NR1/NR2A and NR1/NR2B dimmers are the main constitutional forms of NMDA receptors. The present study was carried out to determine the functional properties of the heteromeric NMDA receptor subunits and their inhibition by bis(7)-tacrine (B7T). Rat NR1, NR2A and NR2B cDNAs were transfected into human embryonic kidney 293 cells (HEK-293).The inhibition of NMDA-activated currents by B7T was detected in HEK-293 cell expressing NR1/NR2A or NR1/NR2B receptors by using whole-cell patch-clamp techniques. The results showed that in HEK-293 cells expressing NR1/NR2A receptor, 1μmol/L B7T inhibited 30μmol/L NMDA- and 1000μmol/L NMDA-activated steady-state currents by 46% and 40%, respectively (P>0.05; n=5), suggesting that the inhibition of B7T on NR1/NR2A receptor doesn’t depend on NMDA concentration, which is consistent with a non-competitive mechanism of inhibition. But for the NR1/NR2B receptor, 1μmol/L B7T inhibited 30μmol/L NMDA- and 1000 μmol/L NMDA-activated steady-state currents by 61% and 13%, re-spectively (P<0.05; n=6), showing that B7T appears to be competitive with NMDA. In addition, simultaneous application of 1μmol/L B7T and 1000μmol/L NMDA produced a moderate inhibition of peak NMDA-activated current, followed by a gradual decline of the current to a steady state. However, the gradual onset of inhibition produced by B7T applied simultaneously with NMDA was eliminated when B7T was given 5s before NMDA. These results suggested that B7T inhibition of NMDA current mediated by NR1/NR2B receptor was slow onset, and it did not depend on the presence of the agonist. With holding potentials ranging from -50 to +50 mV, the B7T inhibition rate of NMDA currents didn’t change significantly, and neither did the reversal potential. We are led to conclude that the NR1/NR2B recombinant receptor can serve as a very useful model for studying the molecular mechanism of NMDA receptor inhibition by B7T.
文摘The effects ofbis(7)-tacrine, a novel acetylcholinesterase inhibitor, on cognitive impairment and neuronal degeneration induced by permanent ligation of bilateral common carotid arteries (2VO) were investigated using the Morris water maze in rats. Once daily oral administration ofbis(7)-tacrine (0.025, 0.05 and 0.1 mg?kg?1) was started 14 days after 2VO operation. Over a three-week treatmentbis(7)-tacrine effectively reversed 2VO-induced spatial memory deficits in a dose-dependent fashion. Furthermore, histological observation showedbis(7)-tacrine decreased the neuropathological changes in the 2VO rats brain. These results suggest thatbis(7)-tacrine has therapeutic potential for the treatment of dementia caused by chronic cerebral hypoperfusion.
文摘The effects of bis(7) tacrine, a novel dimeric acetylcholinesterase (AChE) inhibitor, on glutamate induced cell injury were investigated in primary cerebral cortical neurons of rats. Exposure of cultured neurons (12 days after plating) to 0.5 mmol/L glutamate for 30 min resulted in significant cell damage. Pretreatment with bis(7) tacrine (0.03 1.0 μmol/L) reduced the glutamate induced neurotoxicity in a concentration dependent manner and the maximal response was seen at 1 μmol/L with approximately 30% protection. A receptor binding assay showed that bis(7) tacrine can completely displace MK 801 binding to rat cortical membrane with an IC 50 of 0.57 μmol/L. These findings suggest that bis(7) tacrine can directly interact with N methyl D aspartate receptor channel complex, which may contribute to the inhibitor's protective effects against glutamate induced excitotoxicity. Thus, it is possible that anti glutamate/anti AChE synergism is responsible for potentially better Alzheimer's therapy of bis(7) tacrine relative to tacrine.
