急性低血压对清醒大鼠前庭神经内侧核区谷氨酸和牛磺酸含量的影响

目的：利用脑部微量透析法和高效液相色谱分析法，测定静脉注射硝普钠诱发急性低血压后清醒大鼠前庭神经内侧核区细胞外液标本中谷氨酸和牛磺酸含量的变化。 方法：实验于2005-02／09在延边大学基础医学院生理学教研室进行。选用Wistar系雄性大鼠，查随机数表法随机分为正常组、单侧迷路破坏损伤同侧组、单侧迷路破坏损伤对侧组，每组6只。单侧迷路破坏组左侧中耳注入对氨基苯胂酸盐损伤外周前庭器官，2周后进行实验。正常组左侧中耳注入生理盐水。腹腔注射水合氯醛麻醉，行股动静脉插管，用于血压监测和静脉给药，动、静脉插管经皮下向后背穿到头部。经股静脉注射硝普钠使动脉血压下降约30％左右。参照Paxinos＆Watson大鼠脑图谱将透析膜的外套管插入到前庭神经核，透析膜的外套管内插八自制的透析导管，利用脑部微量透析法收集样本。参照Jin等方法配制诱导剂，高效液相色谱分析法观察静脉注射硝普钠诱发急性低血压后，前庭神经内侧核区细胞外液标本中谷氨酸和牛磺酸含量的变化。 结果：实验纳入18只大鼠中，18只是透析探针准确进入预定区域的动物。正常组动物，静脉注射硝普钠使血压平均下降30％时，前庭神经内侧核区谷氨酸含量明显增加（P〈0．01），而牛磺酸含量却明显降低（P〈0．05）；单侧迷路破坏损伤同侧组，诱发急性低血压后前庭神经内侧核区谷氨酸含量则无明显变化（P〉0．05），牛磺酸含量明显下降（P〈0．05）；单俱十迷路破坏损伤对侧组，诱发急性低血压后谷氨酸和牛磺酸含量都明显增加（P〈0．05）；诱发急性低血压后，损伤侧前庭神经内侧核区谷氨酸无显著性变化，而牛磺酸含量却明显下降，与正常组动物诱发急性低血压时前庭神经内侧核区两种氨基酸含量变化值相比谷氨酸含量变化差异显著（P〈0．05），牛磺酸含量变化则不明显（P〉0．05）。 结论：清醒动物急性低血压影响前庭神经内侧核功能活动的过程中可能有兴奋性氨基酸一谷氨酸神经递质参与。     

牛磺酸对谷氨酸诱导大鼠视网膜神经节细胞凋亡的抑制

目的:视网膜谷氨酸兴奋毒性可引起视网膜内层神经元尤其是视网膜神经节细胞的凋亡,牛磺酸作为神经保护剂,本研究观察其是否可以减少削弱大鼠视网膜神经节细胞兴奋毒性损伤,减少视网膜神经节细胞凋亡.方法:实验于2003-03/09在第三军医大学营养与食品卫生学教研室完成.通过玻璃体注射谷氨酸建立大鼠视网膜谷氨酸兴奋毒性损伤模型,实验分为正常对照组、玻璃体注射磷酸盐缓冲液对照组,牛磺酸干预高、低剂量组及MK-801干预阳性对照组.牛磺酸干预采用腹腔注射,其高、低剂量分别为25 mg/kg体质量及5 mg/kg体质量.通过Thy-1免疫组化、原位缺口末端标记法观察谷氨酸兴奋毒性及牛磺酸干预对大鼠视网膜神经节细胞的Thy-1蛋白表达及细胞凋亡的影响.结果:玻璃体注射谷氨酸使视网膜Thy-1免疫反应下降、内核层及神经节细胞层出现大量凋亡细胞.谷氨酸组平均每张视网膜切片节细胞层有(200&;#177;12)个原位缺口末端标记阳性细胞,牛磺酸干预使视网膜Thy-1免疫反应增强、节细胞层凋亡细胞数显著下降[高、低剂量组分别为(68&;#177;6)个及(163&;#177;10)个],以高剂量牛磺酸的效果显著.结论:一定剂量的牛磺酸在体内可有效抑制谷氨酸兴奋毒性引起的大鼠视网膜神经节细胞损伤及凋亡.     

牛磺酸对谷氨酸诱导大鼠视网膜神经节细胞凋亡的抑制

目的:视网膜谷氨酸兴奋毒性可引起视网膜内层神经元尤其是视网膜神经节细胞的凋亡,牛磺酸作为神经保护剂,本研究观察其是否可以减少削弱大鼠视网膜神经节细胞兴奋毒性损伤,减少视网膜神经节细胞凋亡。方法:实验于2003-03/09在第三军医大学营养与食品卫生学教研室完成。通过玻璃体注射谷氨酸建立大鼠视网膜谷氨酸兴奋毒性损伤模型,实验分为正常对照组、玻璃体注射磷酸盐缓冲液对照组,牛磺酸干预高、低剂量组及MK-801干预阳性对照组。牛磺酸干预采用腹腔注射,其高、低剂量分别为25mg/kg体质量及5mg/kg体质量。通过Thy-1免疫组化、原位缺口末端标记法观察谷氨酸兴奋毒性及牛磺酸干预对大鼠视网膜神经节细胞的Thy-1蛋白表达及细胞凋亡的影响。结果:玻璃体注射谷氨酸使视网膜Thy-1免疫反应下降、内核层及神经节细胞层出现大量凋亡细胞。谷氨酸组平均每张视网膜切片节细胞层有(200±12)个原位缺口末端标记阳性细胞,牛磺酸干预使视网膜Thy-1免疫反应增强、节细胞层凋亡细胞数显著下降高、低剂量组分别为(68±6)个及(163±10)个,以高剂量牛磺酸的效果显著。结论:一定剂量的牛磺酸在体内可有效抑制谷氨酸兴奋毒性引起的大鼠视网膜神经节细胞损伤及凋亡。     

神经元谷氨酸转运体反义寡核苷酸对急性脑缺血损伤大鼠的神经保护作用

目的:测定神经元谷氨酸转运体(excitaforyaminoacidcarrierl,EAAC1)反义寡核苷酸对急性脑缺血损伤大鼠的神经功能缺损评分、梗死体积和海马数密度值的影响,探讨脑缺血神经保护新方法。方法:将大鼠分为假手术组、模型组、反义寡核苷酸组(简称反义组)和正义寡核苷酸组(简称正义组),用插线法建立大鼠局灶性脑缺血模型(MCAO)。运用Westernblot法、神经功能缺损评分、TTC染色、尼氏染色观察缺血区EAAC1表达和EAAC1反义寡核苷酸对缺血大鼠神经功能缺损评分、梗死体积和海马数密度值的影响。结果:模型组缺血区EAAC1表达(0.61±0.03)明显高于假手术组(0.20±0.01),差异有显著性意义(F=49.49,P<0.01),而反义组表达(0.31±0.01)低于模型组,差异有显著性意义(F=49.33,P<0.05)。反义组大鼠梗死体积(101.33±15.08)mm3显著小于模型组(140.5±20.27)mm3,差异有显著性意义(F=6.66,P<0.01),反义组大鼠神经功能缺损评分(3.33±0.41)分,显著高于模型组(1.42±0.34)分,差异有显著性意义(F=48.51,P<0.01),海马各区数密度值均高于模型组(P<0.01和P<0.05)。结论:EAAC1反义寡核苷酸对急性脑缺血损伤有神经保护作用。     

大鼠前庭神经核群向动眼神经核的投射特征

目的:观察大鼠前庭神经核群向动眼神经核的投射纤维特征。方法:实验于1997年在青岛大学医学院解剖教研室实验室进行。选择6～8周龄SD大鼠20只,将辣根过氧化物酶注射到大鼠的动眼神经核,其中5只注射0.01μL其余15只注射0.05μL。经过48h的逆行轴突运输后用组织化学的方法在脑干中显示被标记的神经元。按实际注射结果将20只大鼠分为6组:①辣根过氧化酶注射到动眼神经核的外侧,没有累及动眼神经核及内侧纵束。②注射到动眼神经核的外部累及内侧纵束和动眼神经核的少部分。③注射部分靠近中线影响双侧动眼神经核。④注射部位在动眼神经核的背侧,没有影响动眼神经核的腹侧。⑤以动眼神经核为中心辣根过氧化物酶的吸收区在它的边界以外。⑥注射部位在动眼神经核胞体部分的中心,推测有效吸收区完全在动眼神经核胞体部分边界内。观察各组及不同剂量的实验动物的标记细胞分布和神经纤维走行。结果:20只大鼠进入结果分析。前庭神经上核、内侧核、下核、外侧核及Y核、膝上核和膝旁核都有标记细胞。上核在前庭神经核的最吻端,主要在同侧标记,多数为中小型细胞;内侧核、下核双侧标记,但以对侧标记为主,两核吻侧形成一体,内侧核标记细胞密集,由中小型神经元组成,下核标记细胞稍大,比较分散;外侧核双侧有少量标记标记细胞;膝上核、膝旁核在注射对侧有明显的标记细胞,并同展神经核核间神经元相连续,环绕面膝形成庞大的神经纤维束进入对侧内侧纵束,在展神经核尾侧200μm仍可以看到前庭神经核群发出的交叉纤维。结论:大鼠前庭神经核发出纤维投向动眼神经核,前庭神经内侧核、部分前庭神经下核主要投射向动眼神经核内直肌亚核,推测这部分纤维和双眼协同运动有关。     

牛磺酸对局灶性脑缺血大鼠神经干细胞巢蛋白表达的影响

【目的】研究牛磺酸治疗对成年大鼠脑缺血后缺血侧神经干细胞巢蛋白(nestin)表达的影响,探讨牛磺酸治疗缺血性脑损伤的作用机制。【方法】采用开颅热凝闭法制作大脑中动脉阻塞(MCAO)模型,随机分为正常组、假手术组、模型组与牛磺酸组,采用腹腔注射每天给予牛磺酸,采用巢蛋白免疫组化法观察脑缺血后3d,7d,14d与21d四个不同时相巢蛋白表达阳性细胞的数量。【结果】脑缺血后不同时相缺血侧皮质、海马齿状回和纹状体均有巢蛋白表达阳性细胞,其中7d时各区的阳性细胞数量明显增加(均P<0.05);而牛磺酸组在不同时相的巢蛋白阳性细胞数量均较同时相模型组有明显的增加(P<0.05)。【结论】牛磺酸可促进缺血后相关脑区巢蛋白阳性细胞数量的增加,提示这种作用可能是牛磺酸治疗脑缺血的重要作用机制之一。     

牛磺酸复合液对运动员运动性疲劳的影响研究

[目的]通过观察牛磺酸复合液对专业运动员血液肝肾功能、相关酶学等生化指标的变化,探讨牛磺酸复合液抗运动性疲劳的效果.[方法]随机选取射击、射箭队男、女运动员各30名,分别分为对照组,实验组,对照组为空白对照,实验组服用"牛磺酸复合液",服法:口服,2次/天,1支/次.连续服用30 d.实验过程中,所有对象均按训练计划进行正常训练.运动员实验前均抽取清晨餐前静脉血,测定血中血尿素氮(BUN)、肌肝(CR)、肌酸激酶(CK)、超氧化物歧化酶(SOD)、尿酸(UA)、肌酸激酶同工酶(CK-MB)、乳酸脱氢酶(LDH)、乳酶脱氢酶同工酶1(LDH-1)、脂质过氧化物丙二醛(MDA)、天冬氨酸转氨酶(AST)、丙氨酸转氨酶(ALT)、等各项指标,30 d后按同法抽取血样进行同样的测试.[结果]运动员服用本方剂后,血中SOD值的水平升高,而BUN、CR、CK、CK-MB、LDH、MDA则显著下降.[结论]牛磺酸复合液可通过清除组织自由基,来延缓运动性疲劳的发生,促进其恢复的作用.     

后循环缺血时前庭神经内侧核5-羟色胺的变化

目的:本实验利用微透析技术研究椎基底动脉缺血动物模型前庭神经内侧核5-羟色胺(5-HT)的变化,探讨5-HT在后循环缺血眩晕发生中的作用.方法:纯白红目豚鼠12只,采用穿线法阻断基底动脉制作椎基底动脉供血不足动物模型.采用自身对照法进行研究,利用微透析技术动态监测12只豚鼠在椎基底动脉供血障碍前、后前庭神经内侧核5-HT的变化.结果:豚鼠椎基底动脉缺血前前庭内侧核5-HT 基础水平为(22.5±1.6) fmol/10 μl,椎基底动脉缺血显著地引起前庭内侧核5-HT 水平的升高,在10 min后升到最高,达到基础值的(195±19)%.然后略有下降,在30 min 5-HT 水平降至基础值的(155±24)%,缺血后30 min内各测试点与缺血前比较差异有显著性(P<0.05).结论:前庭神经内侧核5-HT的显著性升高可能与椎基底动脉短暂缺血性眩晕的产生有关.     

大鼠小脑蚓垂小结毁损对前庭核神经元自发性放电活动的影响

目的:研究小脑传入神经纤维对成年大鼠中枢耳石器神经元生理特性的影响。方法:用外科吸引术毁损小脑蚓垂和小结,观察中枢耳石器神经元自发性放电活动的变化。结果:小脑蚓垂小结毁损后,规则型放电神经元的比例增加,C神经元呈现出规则的和不规则的两种放电类型,而少数I神经元表现出规则型放电。同时,各类神经元的自发性放电均值或增强或减弱,与正常对照组相比,其间的差异均具有显著性意义。结论:小脑蚓垂小结毁损后,中枢耳石器神经元的自发性放电活动受到了明显影响。提示当动物处于正常生理状态下,具有功能特性的中枢耳石器神经元的自发性放电活动受小脑蚓垂和小结的调控。     

大鼠前庭神经核群向动眼神经核的投射特征

目的：观察大鼠前庭神经核群向动眼神经核的投射纤维特征.方法：实验于1997年在青岛大学医学院解剖教研室实验室进行.选择6～8周龄SD大鼠20只,将辣根过氧化物酶注射到大鼠的动眼神经核,其中5只注射0.01μL其余15只注射0.05μL.经过48 h的逆行轴突运输后用组织化学的方法在脑干中显示被标记的神经元.按实际注射结果将20只大鼠分为6组：①辣根过氧化酶注射到动眼神经核的外侧,没有累及动眼神经核及内侧纵束.②注射到动眼神经核的外部累及内侧纵束和动眼神经核的少部分.③注射部分靠近中线影响双侧动眼神经核.④注射部位在动眼神经核的背侧,没有影响动眼神经核的腹侧.⑤以动眼神经核为中心辣根过氧化物酶的吸收区在它的边界以外.⑥注射部位在动眼神经核胞体部分的中心,推测有效吸收区完全在动眼神经核胞体部分边界内.观察各组及不同剂量的实验动物的标记细胞分布和神经纤维走行.结果：20只大鼠进入结果分析.前庭神经上核、内侧核、下核、外侧核及Y核、膝上核和膝旁核都有标记细胞.上核在前庭神经核的最吻端,主要在同侧标记,多数为中小型细胞;内侧核、下核双侧标记,但以对侧标记为主,两核吻侧形成一体,内侧核标记细胞密集,由中小型神经元组成,下核标记细胞稍大,比较分散;外侧核双侧有少量标记标记细胞;膝上核、膝旁核在注射对侧有明显的标记细胞,并同展神经核核间神经元相连续,环绕面膝形成庞大的神经纤维束进入对侧内侧纵束,在展神经核尾侧200 μm仍可以看到前庭神经核群发出的交叉纤维.结论：大鼠前庭神经核发出纤维投向动眼神经核,前庭神经内侧核、部分前庭神经下核主要投射向动眼神经核内直肌亚核,推测这部分纤维和双眼协同运动有关.     

Hyperresponsiveness of sympathoadrenal system in conscious DOCA-NaCl and SHR rats in response to acute hemorrhagic hypotension.

The sympathoadrenal basal tone and reactivity were evaluated by the measure of plasma norepinephrine (NE) and epinephrine (EPI) levels in chronically cannulated awake and unrestrained animals under basal conditions and following an acute withdrawal of blood volume necessary to decrease the mean arterial pressure (MAP) by 50 mmHg in normotensive, in deoxycorticosterone acetate (DOCA) and salt (NaCl) hypertensive and in spontaneously hypertensive (SHR) (10-11 weeks) rats. In DOCA-NaCl and SHR rats the basal sympathoadrenal tone was found to be increased as was reflected by the higher plasma levels of both catecholamines. Moreover, an enhanced reactivity of the sympathoadrenal system was also observed in DOCA-NaCl hypertensive rats as well as a slight sympathetic hyperreactivity in SHR in response to the hemorrhagic hypotension suggesting the possibility of alterations in the baroreflex functions or in the local modulatory mechanisms. In addition, the acute hemorrhagic hypotension triggered compensatory mechanisms which permitted a rapid return of the MAP to the baseline values in normotensive rats and in the SHR. However, in DOCA-NaCl hypertensive rats, the return of the MAP was delayed and remained below initial levels even 60 min after the hemorrhagic hypotension, suggesting a less efficient compensatory mechanism in these animals despite a markedly potentiated sympathoadrenal response. To explain such a discrepancy, it may be hypothesized that the potentiated sympathoadrenal reactivity could induce a decrease in vascular reactivity by an acute desensitization of the vascular alpha-adrenoceptors in DOCA-NaCl hypertensive rats.     

Central metabotropic glutamate receptors differentially participate in interleukin-1beta-induced mechanical allodynia in the orofacial area of conscious rats.

The present study investigated the role of central metabotropic glutamate receptors (mGluRs) in interleukin-1beta (IL-1beta)-induced mechanical allodynia and mirror-image mechanical allodynia in the orofacial area. Experiments were carried out on male Sprague-Dawley rats weighing 230 to 280 g. After administration of 0.01, 0.1, 1, or 10 pg of IL-1beta into a subcutaneous area of the vibrissa pad, we examined the withdrawal behavioral responses produced by 10 successive trials of an air-puff ramp pressure applied ipsilaterally or contralaterally to the IL-1beta injection site. Subcutaneous injection of IL-1beta produced mechanical allodynia and mirror-image mechanical allodynia in the orofacial area. Intracisternal administration of CPCCOEt, a mGluR1 antagonist, or MPEP, a mGluR5 antagonist, reduced IL-1beta-induced mechanical allodynia and mirror-image mechanical allodynia. Intracisternal administration of APDC, a group II mGluR agonist, or L-AP4, a group III mGluR agonist, reduced both IL-1beta-induced mechanical allodynia and mirror-image mechanical allodynia. The antiallodynic effect, induced by APDC or L-AP4, was blocked by intracisternal pretreatment with LY341495, a group II mGluR antagonist, or CPPG, a group III mGluR antagonist. These results suggest that groups I, II, and III mGluRs differentially modulated IL-1beta-induced mechanical allodynia, as well as mirror-image mechanical allodynia, in the orofacial area. PERSPECTIVE: Central group I mGluR antagonists and groups II and III mGluR agonists modulate IL-1beta-induced mechanical allodynia and mirror-image mechanical allodynia in the orofacial area. Therefore, the central application of group I mGluR antagonists or groups II and III mGluR agonists might be of therapeutic value in treating pain disorder.     

Antagonism by naltrexone of the hypotension and bradycardia induced by alpha-methyldopa in conscious normotensive rats

The possible role of the endogenous opioid system in the central hypotensive mechanism of action of alpha-methyldopa was investigated. Conscious normotensive Wistar rats were used in this study and all treatments were given intracisternally. Pretreatment with the opiate receptor antagonist naltrexone resulted in a parallel shift to the right of the dose-response curve for alpha-methyldopa, both for blood pressure and heart rate. In addition, when increasing doses of naltrexone and a constant dose of alpha-methyldopa were used the opiate receptor antagonist inhibited dose-dependently alpha-methyldopa-induced hypotension but not the bradycardia. Administration of naltrexone after the injection of alpha-methyldopa failed to reverse or inhibit alpha-methyldopa-induced hypotension, indicating that the interaction between alpha-methyldopa and the endogenous opioid system occurs at the start of the action of alpha-methyldopa. An antiserum against endorphins also inhibited the fall in blood pressure after alpha-methyldopa. These findings indicate that stimulation of opiate receptors, probably by an endorphin, is involved in the mechanism of action of alpha-methyldopa and that this stimulation seems to occur at the start of the action of alpha-methyldopa.     

Role of peripheral group I and II metabotropic glutamate receptors in IL-1beta-induced mechanical allodynia in the orofacial area of conscious rats

The present study investigated the role of peripheral group I and II metabotropic glutamate receptors (mGluRs) in interleukin-1beta (IL-1beta)-induced mechanical allodynia in the orofacial area. Experiments were carried out on Sprague-Dawley rats weighing between 230 and 280 g. After subcutaneous administration of 0.01, 0.1, 1, or 10 pg of IL-1beta, we examined withdrawal behavioral responses produced by 10 successive trials of a ramp of air-puffs pressure applied ipsilaterally or contralaterally to the IL-1beta injection site. The thresholds of air puffs were measured 10, 30, 60, 120, or 180 min after 25 microl of IL-1beta was administered through an implanted tube. Subcutaneous injection of IL-1beta produced bilateral mechanical allodynia. While the IL-1beta-induced mechanical allodynia was blocked by pretreatment with an IL-1 receptor antagonist, the IL-1beta-induced mirror-image mechanical allodynia was not blocked by an IL-1 receptor antagonist injected into the contralateral side. Subcutaneous administration of CPCCOEt or LY367385, an mGluR1 antagonist, or MPEP or SIB1893, an mGluR5 antagonist, 10 min prior to injection of IL-1beta abolished IL-1beta-induced mechanical allodynia. Pretreatment with APDC or DCG4, a group II mGluR agonist, blocked the IL-1beta-induced mechanical allodynia. The anti-allodynic effect induced by APDC was inhibited by pretreatment with LY341495, a group II mGluR antagonist. These results suggest that peripheral group I and II mGluRs participate in IL-1beta-induced mechanical allodynia in the orofacial area. Peripheral group I mGluR antagonists blocked the IL-1beta-induced mechanical allodynia, while peripheral group II mGluR agonists produced anti-allodynic effects on IL-1beta-induced mechanical allodynia in the orofacial area of rats.     

Antinatriuretic effect of acute morphine administration in conscious rats

The renal response to the acute administration of morphine was examined in conscious, chronically catheterized, nonhydrated rats. After control clearance periods, morphine sulfate was injected i.v. at 4 mg/kg followed by an infusion of 2 mg/kg X hr. Morphine caused an increase in urine flow which was variable in magnitude and duration. The initial diuresis was not maintained despite continued morphine administration and replacement of lost fluid. Compared to vehicle treatment morphine also induced marked sodium and chloride retention which was sustained throughout the 2-hr infusion period. There were no changes in blood pressure or heart during the clearance periods, although an initial transient hypotension and bradycardia were observed with morphine injection. There were no changes in glomerular filtration rate which could account for the antinatriuresis. Naloxone pretreatment blocked all of the observed renal responses. The results indicate that morphine exerts its effects on electrolyte excretion by enhancing renal tubular sodium or chloride reabsorption rather than changes in systemic hemodynamics or glomerular filtration rate. In a separate series of experiments, urine osmolality, osmolar clearance and free water clearance were estimated. All rats receiving morphine transiently excreted a hypotonic urine (minimum 183 +/- 23 mOsmol/kg of H2O) with a reduction in osmolar clearance and a sharp increase in free water clearance. These findings are consistent with a temporary inhibition of vasopressin release by morphine.     

Effect of estrogens on blood glutamate levels in relation to neurological outcome after TBI in male rats

Purpose  

Estrogen has been shown to possess neuroprotective properties both in vitro and in vivo. Traumatic brain injury (TBI) in ovulating females results in favorable neurological outcomes when compared to males with similar insults. The brain-to-blood glutamate gradient removes excess glutamate from brain extracellular fluids (ECF). Enhancing this gradient leads to improved neurological outcomes following TBI. In this study we investigate the effect of female gonadal steroids on blood glutamate levels and neurological outcomes.