苦味受体7TM

哺乳动物有酸、咸、甜、苦4种味觉。近年来,人们又认识了其第5种形式umami(即谷氨酸钠)的味道。味觉受体细胞(TRCs)位于味乳头的上皮层,味觉信号可与嗅觉和躯体感受器接受的信号相融合,TRCs通过传入神经元将此信号传入大脑以形成特有的味觉。尽管味觉带给人们诸多美妙的享受,但对其机制却知之甚少。研究味觉信号传导途径有助于揭示其中的奥秘。酸味与咸味可能直接通过离子介导,而苦味与甜味则有赖于G蛋白复合受体7TM(7-跨膜蛋白)传递信号。支持这一假说的有力证据为:去除味素(G蛋白的一种),可导致小鼠无法辨别苦甜味。去年,Ryba等人将推测的两种7TM分别命名为味觉受体1、2(TR1、TR2),并证实它们在某些TRCs上表达,当时暂定为“舌受体”。     

EXPRESSION OF BAX AND BCL－2 IN MOUSE OFFSPRING BRAIN AFIER MATERNAL ORAL ADMINISTRATION OF MONOSODIUM GLUTAMATE

Objective:To analyze the excitotoxicity of monosodium glutamate(MSG)in the offspring crebral cortex and hippocampal subresions after maternal oral administration of MSG.Methods:Kunming mice were given per os MSG(4.0g/kg)at 17-21 days of pregnancy and their offspring behaviors were studied at 10,20,30days postnatally.By using inmunohistochemical means,the involvment of Bcl-2 and bax in the glutamate-induced cell death in cortical and hippocampal neurons were examined.Cell damage was assessed by direct cell counting.Results:administration of monosodium glutamate during the fetal period in mice resulted in a moderate increase in the expression of Bax in principal neurons in CA1,CA2,CA3,CA4 and in the cerebral cortex at postpartum 10,20,30 days in the offspring mice,whereas Bcl-2 protein expressions were reduced significantly in the same regions as compared with those of controls.Conclusion:These findings suggest that glutamate toxicity results in cellular death via an apoptotic mechanism in which the Bcl-2/Bax-alpha molecular complex may be involved.The glutamate-induced apoptosis appears to be related to the modulation of Bcl-2 family gene products such as Bcl-2 and Bax.     

Harmful Effects of MSG on Function of Hypothalamus—Pituitary—Target Gland System

It has been demonstrated that neonatal administration of monosodium glutamate(MSG)results in a clearly defined lesion of the arcuate nucleus(AN)of the hypothalamus.The present study shows that fat was accumulated in the abdomen of male rats treated with MSG;weights of the body,pituitary and testis were lower;β-EP content in hypothalamus decreased while L-EnK content increased;serum LH,FSH,TSH,GH and TS levels all decreased in varying degrees while serum PRL level significantly increased.The cAMP content lowered in pituitary,but nor in testes;clear histological changes occurred in testicular tissue;Se-GSH-Px activity in both testis and adrenal gland lowered while LPO level significantly increased.Both Se-GSH-Px activity and LPO level in liver increased.These results indicate that MSG is harmful to the function of the hypothalamus-pituitarytarget system of neonatal rats.     

IL-1β对谷氨酸钠致痫大鼠海马代谢型谷氨酸受体5的表达的影响

目的：探讨IL-1β对谷氨酸钠(GluNa)致痫大鼠海马代谢型谷氨酸受体(mGluR)5的表达变化的影响。方法：把大鼠随机分为生理盐水组、GluNa组、IL-1β GluNa组、人重组IL-1受体拮抗剂(rhIL-1ra) IL-1β GluNa组及D-AP-5(非竞争性NMDA受体拮抗剂) IL-1β GluNa，利用免疫组织化学并结合图像分析进行研究。结果：Glu-Na注射后的大鼠均出现严重癫痫发作。mGluR5表达在生理盐水组大鼠海马中丰富，GluNa致痫组则明显下调，IL-1β GluNa组比GluNa组明显下调，rhIL-1ra IL-1β GluNa组和D-AP-5 IL-1β GluNa组比IL-1β十GluNa组明显增加。同时观察到3个组的mGluR5的表达主要集中在细胞膜上。结论：mGluR5在癫痫发作后表达下降可能在癫痫诱导过程方面具有重要作用，其与IL-1β受体之间可能存在相互作用。     

白细胞介素-1β对谷氨酸钠致痫大鼠海马Gs蛋白表达的影响

目的 探讨白细胞介素-1β(Interleukin-1，IL-1β)在谷氨酸钠致痫大鼠中对海马兴奋性G-蛋白α亚基(stimulated G-protein α subunit，Gsα)蛋白表达的影响，为阐明IL-1β在致痫中的作用机制提供线索。方法 免疫组织化学方法结合行为观察(SD大鼠随机分为对照组、GluNa组、IL-1β GluNa组、rhIL-1ra IL1β GluNa组和D-AP-5 IL-1β GluNa组)。结果 行为观察显示，IL-1β GluNa组大鼠痫性发作潜伏期(平均2min)较其他组(平均6min)明显缩短，且发作程度(Ⅲ～Ⅳ级)较其他组(Ⅰ～Ⅲ级)严重；对照组无痫性发作。免疫组织化学染色显示，Gsα蛋白在海马各区均有表达，IL-1β GluNa组大鼠在齿状回、CAl区和CA3区Gsa表达较其他组明显增强。结论 IL-1β参与致痫，且在谷氨酸致痫中可能通过Gs蛋白介导发挥作用。     

对侧网状巨细胞核对大鼠脊髓背表面电位的影响

以浅麻醉和麻痹大鼠为对象,利用计算机平均技术记录强电流刺激腓肠神经诱发的脊髓背表面电位(CDP),观察对侧网状三细胞核(NGC)微量注射L一谷氨酸钠,使神经细胞兴奋后对CDP的影响.实验发现,对侧NGC神经细胞兴奋后,Aβ和Aσ纤维引起的P_1波及Aσ和C类纤维引起的N_3波减小,C类纤维引起的P_2波明显减小,N_4 波消失.以上结果提示:对侧NGC对细纤维诱发的CDP成分有抑制作用.     

谷氨酸树突处局部给药所引起的前额皮层锥体细胞爆发式放电：NM …

AIM: To investigate whether in the prefrontal cortical (PFC) pyramidal cells, focal glutamate application to the apical dendrite induces bursting and whether the effect of glutamate involves activation of both NMDA and non-NMDA receptors. METHODS: Pyramidal cells in layers V and VI of the PFC were visualized in rat brain slices using infrared videomicroscopy and recorded with whole-cell electrodes. Glutamate and its agonists were focally applied to the apical dendrite and the soma using microiontophoresis. RESULTS: Dendritic glutamate application (0-20 nA, 10 mmol/L) induced repetitive bursts in most cells tested (12/17). In the same cells, somatic glutamate (5-20 nA, 10 mmol/L) induced only regular spiking. The bursting effect is likely to be direct since applications 5 microns away from the dendrite resulted in either a much reduced effect or no effect. Both CGP 37849 1 mumol/L and NBQX 1 mumol/L reduced the effect, suggesting an involvement of both NMDA and non-NMDA receptors. However, when non-NMDA receptors were selectively activated using AMPA (2-50 nA, 10 mmol/L), only regular spiking was observed. In contrast, selective NMDA receptor activation (NMDA 1.3-25 nA, 100 mmol/L) reliably induced bursting. CONCLUSION: In most PFC pyramidal cells tested, dendritic glutamate application induces repetitive bursting, whereas somatic glutamate application induces only regular spiking. Both NMDA and non-NMDA receptors are activated during dendritic glutamate application. However, bursting is primarily mediated by NMDA receptors.     

石菖蒲对谷氨酸钠致惊厥小鼠的作用

石菖蒲味辛性温 ,具芳香之气 ,行散之力较强 ,为宣气通窍之佳品 ,既能芳香化湿、醒脾健胃 ,又可化浊祛痰、开窍宁神 ,颇适用于中风神昏失语、癫痫、多寐、耳鸣等脑神诸病 ,是芳香宁神 ,涤痰开窍之要药 ,从古至今应用十分广泛。《神农本草经》谓“开心孔 ,补五脏 ,通九窍 ,明耳目 ,出声音。”《名医别录》亦谓其能“聪耳明目 ,益心智” ,而其开心、通窍、聪耳、明目、发声之功效 ,实与脑密切相关 ,因此 ,凡脑病多宜选用。本研究系列主要探讨石菖蒲不同部位对中枢神经系统作用 ,为进一步开发石菖蒲提供科学依据。本文报告石菖蒲不同部位对谷氨…     

石菖蒲不同部位镇静抗致惊厥作用实验研究

目的 :实验研究石菖蒲不同部位对士的宁、谷氨酸钠所致惊厥小鼠的作用。方法 :石菖蒲不同部位提取物灌胃小鼠3d后 ,用士的宁及谷氨酸钠造模 ,观察并记录小鼠惊厥潜伏期、惊厥次数、惊厥持续时间、死亡率和死亡时间等指标。结果 :石菖蒲的总挥发油和水提液是中枢镇静作用的主要有效部位     

附子对谷氨酸钠致癫痫大鼠脑电图的影响

目的研究附子提取液对癫痫大鼠发作的影响.方法以大鼠为实验对象,用谷氨酸钠致癫痫,采用脑电图,观察附子提取液对癫痫模型大鼠大脑皮层放电的影响.结果腹腔注射附子提取液后可使癫痫发作次数及发作持续时间明显减少,发作间隔时间明显延长(P＜0.05).结论附子提取液具有抑制谷氨酸钠诱发癫痫的作用.