Investigation of Mechanisms Involved in (−)‐Borneol‐Induced Vasorelaxant Response on Rat Thoracic Aorta

Abstract: The monoterpene (?)‐borneol is present in essential oils of several medicinal plants. The aim of this study was to evaluate (?)‐borneol effects on rat thoracic aorta artery rings. The cumulative addition of (?)‐borneol (10^?9–3 × 10^?4 M) on a phenylephrine‐induced pre‐contraction (10^?6 M) promoted a vasorelaxant effect in a concentration‐dependent manner and independent of vascular endothelium. A similar effect was obtained on KCl‐induced pre‐contractions (80 mM). (?)‐Borneol (10^?5–3 × 10^?4 M) inhibited contractions induced by cumulative addition of CaCl₂ (10^?6–3 × 10^?2 M) in depolarizing medium without Ca²⁺ in a concentration‐dependent manner. On S‐(?) Bay K 8644‐induced pre‐contractions (10^?7 M), (?)‐borneol did not induce significant changes compared with KCl‐induced pre‐contractions. In a Ca²⁺‐free medium, (?)‐borneol (10^?5, 10^?4 or 10^?3 M) interfered in calcium mobilization from phenylephrine (10^?6 M)‐ or caffeine (20 mM)‐sensitive intracellular stores. The involvement of K⁺ channels was evaluated by tetraethylammonium (3 mM), 4‐aminopyridine (1 mM) and glibenclamide (10^?5 M) pre‐treatment, and (?)‐borneol‐induced vasorelaxation was markedly attenuated. Thus, this vasorelaxant effect can probably be attributed to calcium influx blockade through voltage‐operated calcium channels (Ca_VL), calcium mobilization from intracellular stores and potassium channels activation.     

Effects of the Chinese herb component phellopterin on the increase in cytosolic free calcium in PC12 cells

The present study investigated the effects of the Chinese Herb component, phellopterin on high K⁺ and glutamate‐induced extracellular calcium influx and caffeine or cyclopiazonic acid (CPA)‐induced calcium release from internal stores in attached PC12 cells. Attached cells were loaded with the calcium fluorescent indicator Fluo‐3/AM with the final concentration of 5 µM for 50 min at 37°C and cytosolic free Ca²⁺ measured as fluorescent intensity (FI) (excitation: 488 nm; emission: 535 nm). When PC12 cells were exposed to extracellular Ca²⁺([Ca²⁺]₀) 2.0 mM, the FI for resting [Ca²⁺]_i was 1,188±163, high K⁺ (75 mM) and glutamate (10 mM) induced an increase in [Ca²⁺]_i with peak values of 4,270±982 and 3,096±402, respectively. Phellopterin (0.1–100 µM) had no apparent effect on resting [Ca²⁺]_i, but inhibited high K⁺ and glutamate induced the increase in [Ca²⁺]_i in a dose‐dependent manner. When PC12 cells were exposed to Ca²⁺‐free solution, the FI for resting [Ca²⁺]_i was 804±77. Caffeine (40 mM) and CPA (30 µM) stimulated Ca²⁺ release from caffeine‐ryanodine and inositol 1,4,5‐tris‐phosphate (InsP₃₎‐sensitive internal calcium stores, inducing an increase in [Ca²⁺]_i to 2,938±362 and 1,816±291, respectively. Phellopterin (0.1–100 µmol/L) inhibited caffeine and CPA stimulated intracellular calcium release in a dose‐dependent manner. In summary, phellopterin, a novel component isolated from Changii radix, inhibited Ca²⁺ influx induced by stimulation of voltage‐gated and receptor‐dependent calcium channels with a greater inhibition of receptor‐dependent calcium channels. It also inhibited Ca²⁺ release from caffeine‐ryanodine and InsP₃‐sensitive internal stores, being more potent for caffeine stimulation. Phellopterin may be a promising candidate for the development of new classes of calcium antagonists. Drug Dev Res 68:79–83, 2007. © 2007 Wiley‐Liss, Inc.     

Relationship between intracellular Ca2+ and ROS during fluoride‐induced injury in SH‐SY5Y cells

The mechanisms underlying the neurotoxicology of endemic fluorosis still remain obscure. To explore lactate dehydrogenase (LDH) leakage, intracellular Ca²⁺ concentration ([Ca²⁺]_i) and reactive oxygen species (ROS) production induced by fluoride, human neuroblastoma (SH‐SY5Y) cells were incubated with sodium fluoride (NaF, 20, 40, 80 mg/L) for 24 h, with 40 mg/L NaF for 3, 6, 12, 18, 24 h, and N‐acetyl‐L ‐cysteine (NAC), ethyleneglycol‐bis‐(β‐aminoethyl ether)‐N,N,N′,N′‐tetraacetic acid (EGTA), 1,2‐bis(O‐aminophenoxy)ethane‐N,N,N′,N′‐tetraacetic acid tetra(acetoxymethyl) ester (BAPTA‐AM) alone or combined with fluoride (40 mg/L) respectively for 12 h in vitro. The results showed that the LDH levels in the 40 and 80 mg/L fluoride‐treated groups were significantly higher than that of the control group (in the test level of 0.05, the difference were statistical significance). [Ca²⁺]_i and ROS reached a peak at 3 h and 12 h respectively after exposure to 40 mg/L fluoride. Fluoride coincubated with NAC (antioxidant) dramatically decreased ROS and LDH levels compared with the fluoride only group (in the test level of 0.05, the difference were statistical significance). However, fluoride‐induced increase in [Ca²⁺]_i was not affected by NAC. BAPTA‐AM (intracellular calcium chelator) markedly lowered fluoride‐induced increase of [Ca²⁺]_i, ROS and LDH levels while EGTA (extracellular calcium chelator) have no effects on them. These results indicate that fluoride‐related Ca²⁺ release from the site of intracellular calcium storage causes the elevation of ROS contributing to the cytotoxicity in SH‐SY5Y cells. © 2011 Wiley Periodicals, Inc. Environ Toxicol, 2013.     

超低分子肝素对原代培养大鼠大脑皮质神经元化学诱导损伤的保护作用

目的探讨超低分子肝素(ULMWH)对不同化学诱导损伤大脑皮质神经元的保护作用。方法谷氨酸、叠氮钠、KCl和咖啡因诱导损伤原代培养的大鼠大脑皮质神经元,观察神经元存活率、培养液中乳酸脱氢酶(LDH)漏出量及细胞内游离钙离子浓度([Ca2+]i)。结果ULMWH(0.01～1.0mg.L-1)预处理24h可显著提高谷氨酸损伤神经元的存活率,降低细胞LDH的漏出量和[Ca2+]i,高浓度(1.0mg.L-1)时对叠氮钠引起的神经元损伤也有一定的保护作用,但对咖啡因和KCl所致的神经元损伤无影响。结论ULMWH对谷氨酸和叠氮钠所致大鼠大脑皮质神经元损伤有一定的保护作用,可能与其抑制[Ca2+]i升高有关;但不能对抗KCl和咖啡因所致的皮质神经元损伤。     

环维黄杨星D升高心肌细胞内游离钙浓度实验研究

观察了环维黄杨星D（CVB－D）对急性分离心肌细胞内游离Ca^2 浓度的影响。应用特异性荧光指示剂Fluo-3/AM负载细胞,用激光共聚焦显微镜检测胞内游离钙的变化。结果表明,CVB－D在10^-5,10^-4mol/L时均可升高心肌细胞内游离钙离子浓度,此作用随剂量增加而增加。因此,CVB－D具有升高心肌细胞内游离钙离子浓度的作用。     

Activation of cardiac M3 muscarinic acetylcholine receptors has cardioprotective effects against ischaemia-induced arrhythmias

相似文献   

Glutamate protects against Ca2+ paradox‐induced injury and inhibits calpain activity in isolated rat hearts

This study determined the effects of glutamate on the Ca²⁺ paradoxical heart, which is a model for Ca²⁺ overload‐induced injury during myocardial ischaemia and reperfusion, and evaluated its effect on a known mediator of injury, calpain. An isolated rat heart was retrogradely perfused in a Langendorff apparatus. Ca²⁺ paradox was elicited via perfusion with a Ca²⁺‐free Krebs‐Henseleit (KH) solution for 3 minutes followed by Ca²⁺‐containing normal KH solution for 30 minutes. The Ca²⁺ paradoxical heart exhibited almost no viable tissue on triphenyltetrazolium chloride staining and markedly increased LDH release, caspase‐3 activity, cytosolic cytochrome c content, and apoptotic index. These hearts also displayed significantly increased LVEDP and a disappearance of LVDP. Glutamate (5 and 20 mmol/L) significantly alleviated Ca²⁺ paradox‐induced injury. In contrast, 20 mmol/L mannitol had no effect on Ca²⁺ paradox. Ca²⁺ paradox significantly increased the extent of the translocation of μ‐calpain to the sarcolemmal membrane and the proteolysis of α‐fodrin, which suggests calpain activation. Glutamate also blocked these effects. A non‐selective inhibitor of glutamate transporters, dl ‐TBOA (10 μmol/L), had no effect on control hearts, but it reversed glutamate‐induced cardioprotection and reduction in calpain activity. Glutamate treatment significantly increased intracellular glutamate content in the Ca²⁺ paradoxical heart, which was also blocked by dl ‐TBOA. We conclude that glutamate protects the heart against Ca²⁺ overload‐induced injury via glutamate transporters, and the inhibition of calpain activity is involved in this process.     

IBUDILAST REDUCES INTRACELLULAR CALCIUM ELEVATION INDUCED BY IN VITRO ISCHAEMIA IN GERBIL HIPPOCAMPAL SLICES

1. A microfluorometry was carried out to investigate the effect of 3-isobutyryl-2-isopropylpyrazolo[1,5-a]pyridine (ibudilast) on changes in levels of intracellular calcium concentration ([Ca²⁺]_i) induced by in vitro ischaemia in the CA1 field of gerbil hippocampal slices. 2. When slices, loaded with a calcium ion sensitive dye (rhod-2) were exposed to a glucose-free physiological medium equilibrated with a 95% N₂/5% CO₂ gas mixture (standard in vitro ischaemia), a large [Ca²⁺]_i elevation was detected approximately 5 min after the beginning of in vitro ischaemia. 3. When slices were perfused with the in vitro ischaemic medium containing 43 μmol/L ibudilast, a [Ca²⁺]_i elevation was still observed; however, the extent of the increase in [Ca²⁺]_i was significantly depressed in all subregions of the hippocampal slices. 4. The extent of this inhibitory effect of ibudilast on the in vitro ischaemia-induced [Ca²⁺]_i elevation was in a similar range as those of Ca²⁺ blockers, including (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cycloheptan-5,10-imine maleate (MK-801), flunarizine and dantrolene. 5. Similar [Ca²⁺]_i increases in the CA1 field were induced by a Ca²⁺-free in vitro ischaemia, a high concentration of KCl or by specific agonists for glutamate receptor subtypes (N-methyl-d -aspartate (NMDA), (s)-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) and kainate); these increases were also depressed with 43 μmol/L ibudilast present in the perfusion medium. 6. These results indicate that ibudilast may act by depressing the Ca²⁺ accumulation during and shortly after ischaemia, a possible pharmacological action of ibudilast that leads to the amelioration of ischaemic injury in the central nervous system.     

Mechanism of the vasorelaxant effect induced by trans‐4‐methyl‐β‐nitrostyrene,a synthetic nitroderivative,in rat thoracic aorta

Mechanisms underlying the vasorelaxant effects of trans‐4‐methyl‐β‐nitrostyrene (T4MeN) were studied in rat aortic rings. In endothelium‐intact preparations, T4MeN fully and similarly relaxed contractions induced by phenylephrine (PHE) (IC₅₀ = 61.41 [35.40‐87.42] μmol/L) and KCl (IC₅₀ = 83.50 [56.63‐110.50] μmol/L). The vasorelaxant effect of T4MeN was unchanged by endothelium removal, pretreatment with L‐NAME, indomethacin, tetraethylammonium, ODQ or MDL‐12,330A. Under Ca²⁺‐free conditions, T4MeN significantly reduced with a similar potency: (i) phasic contractions induced by PHE, but not by caffeine; (ii) contractions due to CaCl₂ in aortic preparations stimulated with PHE (in the presence of verapamil) or high KCl; (iii) contractions evoked by the restoration of external Ca²⁺ levels after depletion of intracellular Ca²⁺ stores in the presence of thapsigargin. In contrast, T4MeN was more potent at inhibiting contractions evoked by the tyrosine phosphatase inhibitor, sodium orthovanadate, than those induced by the activator of PKC, phorbol‐12,13‐dibutyrate. These results suggest that T4MeN induces an endothelium‐ independent vasorelaxation that appears to occur intracellularly through the inhibition of contractions that are independent of Ca²⁺ influx from the extracellular milieu but involve phosphorylation of tyrosine residues.     

nNOS抑制剂亚胺基烯丁基-L-鸟氨酸对心肌缺血再灌注损伤的影响及机制

目的 探讨nNOS选择性抑制剂亚胺基烯丁基-L-鸟氨酸（L-VNIO）对心肌缺血再灌注（I/R）损伤的影响及机制。方法 构建SD大鼠离体心脏I/R模型和H9c2细胞缺氧/复氧（H/R）模型；nNOS抑制剂L-VNIO（10 μmol·L^-1）持续给药整个再灌注或复氧过程。TTC染色测定心肌梗死面积；流式细胞术检测H9c2细胞凋亡率；Fluo-3/AM Ca²⁺荧光探针通过流式细胞仪检测H9c2细胞内Ca²⁺浓度；试剂盒法测定离体心脏灌流液乳酸脱氢酶（LDH）、丙二醛（MDA）水平以及H9c2细胞MDA水平和超氧化物歧化酶（SOD）活性；离体心脏提取肌浆网，试剂盒法检测肌浆网Ca²⁺-ATP酶（SERCA）活性，Western blotting检测肌浆网SERCA蛋白表达；Western blotting检测离体心脏中受磷蛋白（PLB）和兰尼碱受体2（RyR2）蛋白表达水平和磷酸化水平。结果 与I/R或H/R模型组相比，L-VNIO显著降低细胞凋亡率，减少心肌梗死面积，降低LDH、MDA水平，提高SOD活性，差异均有统计学意义（P<0.05）；此外，与I/R或H/R模型组相比，L-VNIO组明显降低细胞内Ca²⁺超载，增高PLB磷酸化水平，降低RyR2磷酸化水平，增强SERCA活性（P<0.05）。结论 nNOS抑制剂L-VNIO可以减轻I/R损伤，机制与调节Ca²⁺转运相关蛋白而降低I/R引起的Ca²⁺超载相关。     

Vasorelaxant effects of 2‐nitro‐1‐phenyl‐1‐propanol in rat aorta

2‐Nitro‐1‐phenyl‐1‐propanol (NPP) is a nitro alcohol that is known as an intermediate in the synthesis of sympathomimetic agents, such as norephedrine. The present study investigated the vasoactive effects of NPP on rat aorta. In endothelium‐intact aortic rings, NPP fully relaxed contractions that were induced by phenylephrine, KCl, and U‐46619. The relaxant effects of NPP on phenylephrine‐elicited contractions remained unaffected by NG‐nitro‐l ‐arginine methyl ester (l ‐NAME), indomethacin, propranolol, tetraethylammonium, 4‐aminopyridine, and glibenclamide. Conversely, pretreatment with 1H‐[1,2,4]oxadiazolo[4,3‐a]quinoxalin‐1‐one (ODQ), cis‐N‐(2‐phenylcyclopentyl)‐azacyclotridec‐1‐en‐2‐amine hydrochloride (MDL‐12,330A), and N‐[2‐(P‐bromocinnamylamino)ethyl]‐5‐isoquinolinesulfonamide dihydrochloride (H‐89) reduced the ability of NPP to relax contractions that were elicited by phenylephrine. NPP inhibited the vasoconstrictor response that was induced by Ca²⁺ in aortic rings that were stimulated by pharmacomechanical or electromechanical coupling with phenylephrine and 60 mmol/L KCl, respectively, and after the depletion of intracellular Ca²⁺ stores. Such effects of NPP were significantly reversed by pretreatment with the guanylyl cyclase inhibitor ODQ and weakly influenced by the adenylyl cyclase inhibitor MDL‐12,330A. In Ca²⁺‐free medium, NPP inhibited transient contractions that were induced by phenylephrine but not caffeine. In homogenates of aortic rings, NPP increased cyclic guanosine 3′,5′‐monophosphate (cGMP) and cyclic adenosine 3′‐5′‐monophosphate levels, but this effect was statistically significant only for cGMP. In conclusion, in contrast to the vasoconstrictor amine norephedrine, NPP is a vasodilator in rat aorta, and its relaxant effects are likely attributable to cGMP production.     

AMG-1对突触体内游离钙水平及大鼠尾动脉收缩力的影响

观察了AMG-1对高钾所致大鼠脑突触体内游离钙浓度[Ca²⁺]i升高,及去甲肾上腺素引起的离体大鼠尾动脉环收缩力的影响。结果表明,AMG-110和100μmol·L^-1可对抗高钾(30mmol·L^-1)引起的[Ca²⁺]i升高,使分别降低19±11%及57±12%;在无钙Krebs-Hensleleit液中,AMG-1能抑制去甲肾上腺素引起大鼠尾动脉收缩力的作用。     

3‐butyl‐6‐fluoro‐1(3H)‐isobenzofuranone (6‐F‐NBP), a derivative of dl‐n‐butylphthalide,inhibits glutamate‐induced cytotoxicity in PC12 cells

It is widely recognized that glutamate (Glu)‐induced cytotoxicity, intracellular calcium overload and the excessive free radical production are key events in the development and progression of ischemic brain injury. dl‐3‐n‐butylphthalide (NBP), an anti‐ischemic agent, has therapeutic effects in animal models of vascular dementia. The aim of the present study was to investigate the protective effect of 3‐butyl‐6‐fluoro‐1(3H)‐isobenzofuranone (6‐F‐NBP), a derivative of NBP on Glu‐induced cytotoxicity in rat pheochromocytoma (PC12) cells, and to compare this action with NBP. The results showed that after 24‐h incubation with Glu (5 mM), cell viability and mitochondrial membrane potential (MMP) were decreased. In contrast, the content of reactive oxygen species (ROS), activity of nitric oxide synthase (NOS), and apoptosis rate, as well as intracellular accumulation of [Ca²⁺]_i, were increased, 6‐F‐NBP inhibited the damage induced by Glu in a dose‐dependent manner and exerted a more potent effect than NBP, indicating that 6‐F‐NBP exhibited a protective effect against Glu‐induced cytotoxicity in cultured PC12 cells. Drug Dev Res 73: 11–17, 2012. © 2011 Wiley Periodicals, Inc.     

Adenosine A3 receptor-mediated cardioprotection against doxorubicin-induced mitochondrial damage

Cardiotoxicity associated with doxorubicin (DOX) treatment limits the therapeutic efficiency of this drug against cancer. 2-Chloro-N(6)-(3-iodobenzyl)adenosine-5′-N-methyluronamide (Cl-IB-MECA), a selective agonist of A₃ adenosine receptor (A₃R), reduces DOX toxicity in newborn rat cultured cardiomyocytes. The study's aim was to determine whether the protection demonstrated by Cl-IB-MECA attenuates cardiac depression in vivo. In addition, we wished to examine whether this protective pathway affects the sarcoplasmic reticulum (SR) calcium uptake and release, as well as intramitochondrial Ca²⁺ accumulation induced by DOX.Rats were injected every alternate day (6 times) with (1) saline, (2) 2.5 mg/kg i.p. DOX, (3) 33 μg/kg i.v. Cl-IB-MECA, (4) DOX + Cl-IB-MECA. Left ventricular functions were assessed by invasive (pressure) and non-invasive (echocardiography) techniques at the end of the injection period and 4 weeks later. Cytosolic and intramitochondrial calcium levels were measured with indo-1 and rhod-2 probes. SR Ca²⁺ content was determined by exposing cultured rat cardiomyocytes to caffeine.Echocardiography data demonstrate left ventricular wall thinning (23%), an increase in the end systolic dimension (170%) and decreased fractional shortening (35 ± 5% vs. 54 ± 5%, p < 0.01) in DOX-treated animals, compared to the control group. DOX increased Ca²⁺ levels in the cytosol and in mitochondria by diminishing the SR Ca²⁺ uptake. Pretreatment with Cl-IB-MECA attenuated left ventricular dysfunction, improved SR calcium storage capacity and prevented mitochondrial Ca²⁺ overload.We conclude that the adenosine A₃ receptor agonist is effective in vivo against DOX cardiotoxicity via the restoration of Ca²⁺ homeostasis and prevention of mitochondrial damage that occurs as a result of Ca²⁺ overload.     

Lowering Intracellular Calcium Concentration May Reduce the Cytotoxicity of Triamcinolone on Human Retinal Pigment Epithelial (ARPE19) Cells

1. The present study investigated the use of drugs that affect calcium (Ca^{2 +}) levels and thus reduction of triamcinolone (TA)‐induced cytotoxicity on human retinal epithelial (ARPE19) cells. 2. Four groups were compared: ARPE19 cells alone, cells exposed to TA (0.1 mg/mL), cells that have been pretreated with one of the testing agents for 30 min before the addition of TA, and cells that have only been treated with one of the testing agents. Pinacidil (PIN) and its analogue, P1060, were used to test the effect of potassium (K⁺) channel opening on TA‐induced toxicity. Verapamil (VP) and diltiazem (DZ) were used to test their Ca^{2 +} channel blocking effect. The cell viability under different settings was assessed using 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assay. Ca^{2 +}‐imaging was used to determine the changes in intracellular Ca^{2 +} levels [(Ca^{2 +})_i] upon different treatments. 3. Both PIN and P1060 reduced TA‐induced toxicity. Verapamil and DZ increased the viability of cells treated with TA significantly, suggesting that the excessive influx of Ca^{2 +} was one of the main contributory factors to the TA‐induced toxicity. 4. The results suggest that the prevention of Ca^{2 +} entry may be effective in the reduction of cell necrosis in the presence of TA.     

The negative inotropic action of canrenone is mediated by L-type calcium current blockade and reduced intracellular calcium transients

Background and purpose:

Adding spironolactone to standard therapy in heart failure reduces morbidity and mortality, but the underlying mechanisms are not fully understood. We analysed the effect of canrenone, the major active metabolite of spironolactone, on myocardial contractility and intracellular calcium homeostasis.

Experimental approach:

Left ventricular papillary muscles and cardiomyocytes were isolated from male Wistar rats. Contractility of papillary muscles was assessed with force transducers, Ca²⁺ transients by fluorescence and Ca²⁺ fluxes by electrophysiological techniques.

Key results:

Canrenone (300–600 µmol·L⁻¹) reduced developed tension, maximum rate of tension increase and maximum rate of tension decay of papillary muscles. In cardiomyocytes, canrenone (50 µmol·L⁻¹) reduced cell shortening and L-type Ca²⁺ channel current, whereas steady-state activation and inactivation, and reactivation curves were unchanged. Canrenone also decreased the Ca²⁺ content of the sarcoplasmic reticulum, intracellular Ca²⁺ transient amplitude and intracellular diastolic Ca²⁺ concentration. However, the time course of [Ca²⁺]_i decline during transients evoked by caffeine was not affected by canrenone.

Conclusion and implications:

Canrenone reduced L-type Ca²⁺ channel current, amplitude of intracellular Ca²⁺ transients and Ca²⁺ content of sarcoplasmic reticulum in cardiomyocytes. These changes are likely to underlie the negative inotropic effect of canrenone.     

升陷汤及单味药材水提物对缺氧/复氧致心肌损伤的保护作用

目的 通过观察升陷汤及单味药材水提物对离体培养的大鼠心肌细胞缺氧/复氧损伤的影响,并对其作用机制进行初步探讨。方法 培养H9C2大鼠心肌细胞,共分成8组：空白对照组,缺氧/复氧组（模型组）,缺氧复氧损伤后药物干预组（升陷汤全方及5个单味药材水提物组）。分别对心肌细胞凋亡率、心肌细胞的活力、细胞内活性氧（ROS）活性、细胞内钙离子浓度（Ca²⁺）等指标进行检测。结果 升陷汤全方及黄芪、知母等药材干预能明显降低细胞凋亡率、细胞内ROS活性和Ca²⁺浓度（P<0.05）,其中,全方的作用最强。与缺氧/复氧组细胞内ROS活性和Ca²⁺浓度增加至空白对照组的2.49倍及1.71倍相比,全方能使细胞内ROS活性和Ca²⁺浓度增加率降至缺氧/复氧组的41.37%和15.20%。结论 升陷汤及单味药材对缺氧/复氧致心肌损伤具有保护作用,该作用的机制可能通过抑制细胞凋亡、降低细胞内ROS以及Ca²⁺的浓度所致。     

Effects of Apigenin on Glutamate-induced [Ca2+]i Increases in Cultured Rat Hippocampal Neurons

Flavonoids have been shown to affect calcium signaling in neurons. However, there are no reports on the effect of apigenin on glutamate-induced calcium signaling in neurons. We investigated whether apigenin affects glutamate-induced increase of free intracellular Ca²⁺ concentration ([Ca²⁺]_i) in cultured rat hippocampal neurons, using fura-2-based digital calcium imaging and microfluorimetry. The hippocampal neurons were used between 10 and 13 days in culture from embryonic day 18 rats. Pretreatment of the cells with apigenin (1 µM to 100 µM) for 5 min inhibited glutamate (100 µM, 1 min) induced [Ca²⁺]_i increase, concentration-dependently. Pretreatment with apigenin (30 µM) for 5 min significantly decreased the [Ca²⁺]_i responses induced by two ionotropic glutamate receptor agonists, alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic (AMPA, 10 µM, 1 min) and N-methyl-D-aspartate (NMDA, 100 µM, 1 min), and significantly inhibited the AMPA-induced peak currents. Treatment with apigenin also significantly inhibited the [Ca²⁺]_i response induced by 50 mM KCl solution, decreased the [Ca²⁺]_i responses induced by the metabotropic glutamate receptor agonist, (S)-3,5-dihydroxyphenylglycine (DHPG, 100 µM, 90 s), and inhibited the caffeine (10 mM, 2 min)-induced [Ca²⁺]_i responses. Furthermore, treatment with apigenin (30 µM) significantly inhibited the amplitude and frequency of 0.1 mM [Mg²⁺]_o-induced [Ca²⁺]_i spikes. These data together suggest that apigenin inhibits glutamate-induced calcium signaling in cultured rat hippocampal neurons.     

Alpha‐lipoic acid reduces methylmercury‐induced neuronal injury in rat cerebral cortex via antioxidation pathways

Methylmercury (MeHg), an extremely dangerous environmental pollutant, accumulating preferentially in central nervous system, causes a series of cytotoxic effects. The present study explored the mechanisms which contribute to MeHg‐induced neurotoxicity focusing on the oxidative stress in rat cerebral cortex. In addition, the protective effects of alpha‐lipoic acid (LA), a potent antioxidant on MeHg‐mediated neuronal injury, was also investigated in current study. A MeHg poisoning model was established as 64 rats randomly divided into 4 groups of which saline control group, MeHg‐treated groups (4 and 12 μmol kg^?1), and LA pretreatment (35 μmol kg^?1) group, respectively. After administration of 12 μmol kg^?1 MeHg for 4 weeks, it was found that obvious pathological changes and apoptosis in neuronal cells. Meanwhile, total Hg levels elevated significantly, superoxide dismutase (SOD) and gluthathione peroxidase (GSH‐Px) activities were inhibited, and ROS formation elevated, which might be critical to aggravate oxidative stress in cerebral cortex. In addition, NF‐E2‐related factor 2 (Nrf2) pathways were activated, as heme oxygenase‐1 (HO‐1) and γ‐glutamylcysteine synthetase heavy subunit (γ‐GCSh) expressions were up‐regulated obviously by MeHg exposure. Moreover, activities of Na⁺‐K⁺‐ATPase and Ca²⁺‐ATPase were inhibited, leading to intracellular calcium (Ca²⁺) overload. LA pre‐treatment partially reduced MeHg neurotoxic effects via anti‐oxidation pathways. In conclusion, these findings clearly indicated that MeHg aggravated oxidative stress and Ca²⁺ overload in cerebral cortex. LA possesses the ability to prevent MeHg neurotoxicity through its anti‐oxidative properties. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 931–943, 2017.