孤束核参与室旁核加压素能神经元对大鼠胃缺血-再灌注损伤的调控作用

目的：探讨孤束核（NTS）在下丘脑室旁核（PVN）加压素能神经元对大鼠胃缺血-再灌注损伤（GI-RI）调控中的作用。方法：复制夹闭大鼠腹腔动脉30 min，松开动脉夹血流复灌1 h的GI-RI模型，观察核团内微量注射、电刺激、损毁等对其影响。结果：PVN内注射精氨酸加压素（AVP）能明显减轻GI-RI，且具有剂量-效应依赖关系（r=-0.477, P<0.05）；损毁双侧NTS或NTS内给予AVP受体阻断剂均能取消电刺激PVN对GI-RI的减轻作用；NTS内注射AVP的作用与PVN内注射AVP的效应相似。结论：NTS参与下丘脑室旁核加压素神经元对大鼠胃缺血-再灌注损伤的调控作用，并且是通过其中的AVP受体来实现的。     

电刺激大鼠下丘脑室旁核对胃缺血-再灌注损伤的影响

采用夹闭大鼠腹腔动脉30min，松开动脉夹血流复灌1h的胃缺血－再灌注损伤模型，观察了电刺激和电损毁下丘脑室旁核（paraventricular nucleus,PVN)对大鼠胃缺血－再灌注损伤（gastric ischemia-reperfusion injury,GI-RI的影响，并对其作用机制进行了初步探讨。结果表明：电刺激PVN后GI－RI显著减轻，且有强度－效应依赖关系；PVN内注射胞体兴奋剂L－谷氨酸后，与电刺激PVN的效应相同；电解损毁双侧PVN则能加重GI－RI；电刺激PVN能显著降低GI－RI大鼠的胃粘膜丙二醛（MDA）含量及胃液酸度和胃蛋白酶活性，但对其超氧化物歧化酶（SOD）的活性及胃液量、总酸排出量、胃整结合粘液量无显著影响。提示PVN对GI－RI具有保护作用，其作用机制可能与降低GI－RI大鼠的胃粘膜MDA含量、胃蛋白酶活性、胃液酸度有关，而与胃液量、总酸排出量、胃壁结合粘液量等因素无明显关系。     

幼龄厌食大鼠食欲中枢神经元兴奋性的改变

观察幼龄厌食大鼠摄食中枢(下丘脑外侧区lateral hypothalamic area,LHA)和饱中枢(下丘脑腹内侧核ventromedialhy-pothalamic nuclear,VMN)神经元兴奋性的改变。用特制饲料喂养幼龄大鼠3周制备厌食模型,然后用细胞外记录法,记录大鼠LHA和VMN神经元的自发放电,观察其对电刺激胃迷走神经和静脉注射葡萄糖的反应,比较对照组和模型组间的差异。结果显示:模型组大鼠LHA神经元对胃迷走神经刺激的反应特征与对照组无显著性差异,而VMN神经元对胃迷走神经刺激的兴奋性反应时程延长(P<0.01),刺激强度降低(P<0.01)。模型大鼠中对胃迷走神经刺激有反应的LHA神经元的血糖敏感率降低,而那些对胃迷走神经刺激有反应的VMN神经元的血糖敏感率增加(P<0.01)。以上结果表明:特制饲料改变LHA和VMN神经元对外周传入的摄食负反馈信号的敏感性,从而使LHA和VMN神经元共同作用,发出抑制摄食信号,从而导致了厌食的发生。     

迷走神经电刺激对大鼠肠缺血再灌注后肠损伤的影响

目的:观察迷走神经电刺激对大鼠肠缺血再灌注（I/R）后肠损伤的影响。 方法:30只雄性Wistar大鼠，双侧颈迷走神经切断后，随机分为3组（n=10）：（1）肠缺血再灌注（I/R）组：暴露腹腔后夹闭肠系膜上动脉（SMA）1 h，开放再灌注2 h；（2）迷走神经刺激（VNS）组：在夹闭前及再灌注开始均以5 V、2 ms和1 Hz强度的电能持续刺激左颈部迷走神经远端20 min；（3）假手术对照(SC)组：仅暴露腹腔，不行SMA夹闭及电刺激。颈动脉插管监测平均动脉压（MAP）。所有动物在再灌注2 h后处死，取小肠组织行光学、电子显微镜观察肠粘膜损伤程度并行改良的Chiu’s评分；检测血浆丙二醛（MDA）、肿瘤坏死因子（TNFα）含量。 结果:各组大鼠MAP在缺血期基本保持平稳。而在再灌注期，I/R组的MAP随时间延长明显低于SC组（P＜0.05），而VNS组能明显拮抗MAP下降（P＜0.05）。光学、电子显微镜观察显示I/R后肠组织出现不同程度的损伤，I/R组最为严重，而VNS组相对较轻；但两组的改良Chiu’s评分值显著高于SC组（P＜0.01），VNS组的评分值明显低于I/R组（P＜0.01）。I/R组血浆MDA、TNFα含量明显高于SC组和VNS组（P＜0.05，P＜0.01）；VNS组血浆MDA含量高于SC组（P＜0.05），VNS组血浆TNFα与SC组无显著差异（P＞0.05）。 结论:电刺激迷走神经能显著减轻I/R肠粘膜结构的病理改变并使再灌注期的循环血压得到一定改善，其保护效应可能与减少脂质过氧化、下调TNFα生成有关。     

缺血预处理对大鼠缺血视网膜的保护性研究

<正> 缺血预处理(Rreconditioning,PC)是近年来提出的保护组织缺血性损伤的新概念.被认为组织在间断短暂的缺血后,不会导致损伤的加重,反而会增加组织对缺血的耐受性.研究缺血预处理的意义在于探明其机制,发展药物模拟缺血预处理,达到缺血组织的保护.本研究实验组采用5min间断缺血2次,5min间断性再灌注2次,然后持续阻断双侧颈总动脉(2VO)血流90min,造成视网膜不全性缺血,再灌注4d通过视网膜的组织学变化,对照组则不做缺血预处理,从而观察缺血预处理对缺血性视网膜损伤是否有保护作用.结果显示:实验组与对照组相比,内视网膜层、内同层厚度变薄(P<0.05).节细胞数实验组比对照组显著增多(P<0.05).结果提示:(1)缺血再灌注导致内视网膜层、内同层的组织水肿,通过缺血预处理可能使缺血再灌注所导致的组织水肿减轻.(2)对照组比实验组的节细胞显著减少,可能是缺血预处理减少了节细胞由于缺血及再灌注所导致的细胞死亡.(3)缺血预处理对缺血性损害的视网膜有保护作用,缺血预处理保护机制在其它器官研究发现:热体蛋白[HSP70]在预处理的保护相中的延迟相中起作用;腺苷短暂缺血后大量产生通过A1受体调解兴奋性氨基酸的释放,减轻细胞内Ca~(2+)超载;自由基产生减少而减轻细胞的损伤;无氧糖酵解的增强,避免ATP的过分减少     

小鼠脑缺血时自噬相关基因5的抗损伤作用

 目的: 观察自噬相关基因5(Atg5)在小鼠脑缺血再灌注损伤中的抗损伤作用。方法: 将雄性BALB/c小鼠随机分为假手术(sham)组、缺血再灌注(I/R)组、Atg5 siRNA组和control siRNA组。I/R组采用大脑中动脉阻塞(MCAO)60 min后再灌注24 h。Atg5 siRNA组和control siRNA组将5 μL Atg5 siRNA或scrambled siRNA在MCAO前24 h侧脑室注射。实时荧光定量PCR和Western blot检测Atg5的表达;2,3,5-氯化三苯基四氮唑(TTC)染色法检测抑制Atg5对缺血再灌注损伤后脑梗死面积和水肿率的影响;神经行为学评分法检测抑制Atg5对缺血再灌注损伤后神经症状的影响。结果: MCAO后再灌24 h,缺血半影区Atg5 mRNA和蛋白水平显著增高(P<0.05);Atg5 siRNA明显降低缺血再灌后Atg5 mRNA和蛋白的表达(P<0.05);侧脑室给予Atg5 siRNA能显著增加脑梗死面积和水肿率,并加重神经行为学损伤(P<0.05)。结论: 沉默Atg5加重小鼠脑缺血再灌损伤,提示MCAO后诱导的 Atg5 可减轻小鼠局灶性脑缺血再灌注损伤。     

预处置对急性缺血再灌注肝脏

目的:探讨预处置对缺血再灌注损伤肝脏的防护及其机制。方法:随机将家兔分为对照组、缺血再灌注组和预处置组,复制肝缺血再灌注损伤(HIRI)模型,观察反复3次缺血5 min再灌注5 min(预处置)后再缺血45 min再灌注45 min,对血浆、肝组织一氧化氮(NO)和丙二醛(MDA)水平、谷丙转氨酶(ALT)值及肝细胞形态学改变的影响。结果:肝缺血再灌注期间,预处置组血浆及肝组织NO水平明显高于缺血再灌注组(P＜0.05);而MDA水平和血浆ALT均显著低于缺血再灌注组(P＜0.05和P＜0.01);且与仅行游离、不阻断肝血流的对照组比较均无明显差异;肝细胞形态学异常改变也明显减轻。结论:预处置可通过提高体内NO水平及降低体内氧自由基水平而减轻HIRI。     

肾神经在缺血再灌注性肾损伤室旁核电活动变化中的作用

目的:观察保留和去除大鼠肾神经后,肾缺血再灌注性肾损伤过程中室旁核电活动的变化,了解肾神经在缺血再灌注性肾损伤时室旁核电活动变化中的作用。方法:20只SD大鼠(250±30g)随机分为二组(n=10):①神经组:分离出左侧肾神经,夹闭肾动脉缺血30min,再灌注30min。②去肾神经组:分离并剪断左侧肾神经,夹闭肾动脉缺血30min,再灌注30min。参照大鼠脑立体定位图谱(George Paxinos,Charles Watson),用微电极全程记录各组肾缺血30min,再灌注30min室旁核放电活动。结果:保留肾神经组大鼠缺血和再灌注瞬间室旁核电活动明显减少(P<0.05)。随着缺血和再灌注时间的延长,室旁核放电活动逐渐增强(P<0.05)。去肾神经组大鼠缺血和再灌注瞬间时室旁核放电未出现快速性变化。在缺血和再灌注过程中,室旁核放电进行性增加,与保留肾神经组比较,去神经组缺血和再灌注期间各观察时间点室旁核放电均显著性增强(P<0.05)。结论:急性肾缺血再灌注可引起室旁核放电活动增强;肾缺血再灌注过程中室旁核放电活动的快速性变化与肾神经有关;肾神经具有抑制肾缺血再灌注时室旁核紧张性的作用。     

黄芪对大鼠肾缺血再灌注损伤的保护作用

目的 :研究中药黄芪注射液对大鼠肾缺血再灌注损伤的保护作用。方法 :复制大鼠肾缺血再灌注损伤模型 ,用药治疗 ,观察肾组织病理变化 ,测定血清和肾组织超氧化物歧化酶 (SOD )、丙二醛(MDA)含量。结果 :肾缺血 1h灌注 15min后 ,肾组织出现明显病理改变 ;血清和肾组织SOD活性下降 ,MDA含量升高。应用黄芪注射液治疗后 ,血清和肾组织SOD活性升高 ,MDA含量下降 ,肾组织病理变化有所改善。结论 :黄芪注射液具有减轻脂质过氧化反应、清除自由基的作用 ,这可能是黄芪注射液减轻肾缺血再灌注损伤的作用机制之一。     

尼古丁对大鼠局灶性脑缺血再灌注损伤的神经保护作用

目的:研究尼古丁对大鼠局灶性脑缺血再灌注损伤是否具有神经保护作用。方法:在大鼠大脑中动脉堵塞(MCAO)前30min给予腹腔注射尼古丁酒石酸盐溶液,观察局灶性脑缺血2h再灌注24h后,大鼠神经行为学评分及脑梗死容积的变化。结果:再灌注24h后,与单纯缺血再灌注组相比,给予尼古丁酒石酸盐溶液注射可以改善动物的神经行为学评分、减少脑梗死容积百分比(P0.05)。结论:尼古丁对大鼠局灶性脑缺血再灌注损伤具有神经保护作用。     

Lateral hypothalamic area mediated the protective effects of microinjection of glutamate into interpositus nucleus on gastric ischemia-reperfusion injury in rats

We investigated the protective effects of chemical stimulation of cerebellar interpositus nucleus (IN) on gastric ischemia-reperfusion injury (GI-RI) and its possible regulatory mechanisms in rats. Gastric mucosal damage index (GMDI) indicated the severity of gastric mucosal injuries. Transferase dUTP nick end labeling (TUNEL) staining and proliferating cell nuclear antigen (PCNA) were performed to assess gastric mucosal cell apoptosis and proliferation. Microinjection of glutamate into IN markedly attenuated GI-RI. Either chemical lesion of IN or electrical ablation of the decussation of superior cerebellar peduncle (DSCP) obviously aggravated GI-RI. The protective effects of IN were reversed with the pretreatments of microinjection of 3-mercaptopropionic acid into IN or Bicuculline into lateral hypothalamic area (LHA), individually. The discharge frequency and intensity of greater splanchnic nerve (GSN) decreased and gastric mucosal blood flow increased after chemical stimulation of IN. The apoptosis of positive cells of gastric mucosa was decreased by chemical stimulation of IN, whereas proliferation increased. The gastric juice volume, acidity, and total acid output were all decreased after the chemical stimulation of IN. These results indicated that IN participates in regulation of GI-RI and is a specific area in central nervous system for exerting protective effects on GI-RI. DSCP, LHA and GSN may involve in this process. Apoptosis and proliferation may mediate this protective process in rats too.     

Reflex suppression and initiation of gastric contractions by electrical stimulation of the hepatic vagus nerve

In the rat, electrical stimulation of the cranial end of the cut hepatic branch of the vagus nerve modulated gastric contractions. When the gastric contraction rate reached approximately one per min, nerve stimulation caused total suppression. When the stomach was free of contraction, nerve stimulation initiated one. The amplitude of the stimulation-initiated contractions was frequency related. These contractions were vagal-muscarinic mediated since vagotomy of the gastric branches or i.v. atropine (100 micrograms/kg) eliminated them. The results suggested that the hepatic nerve relayed both excitatory and inhibitory sensory inputs to the central nervous system that modulated the vagal excitatory cholinergic efferent nerve activities.     

Parameters of optic nerve electrical stimulation affecting neuroprotection of axotomized retinal ganglion cells in adult rats

We previously showed the enhancement of survival of retinal ganglion cells (RGCs) by electrical stimulation (ES) of the optic nerve (ON) stump in adult rats. To elucidate the mechanisms underlying the survival enhancement, we determined whether the neuroprotective effect of ES is affected by the following parameters: stimulation time, frequency of current pulses and starting of ES. ES for 10 min immediately after ON transection was not effective in increasing the number of surviving RGCs 7 days after the transection, but that for 30 min was effective. ES at 20 Hz was the most effective, when applied just after axotomy. When the starting of ES to the ON was shifted either 3 h after or 4 h before the axotomy, the neuroprotective effect of ES was not observed. These results suggest that the electrical activation of RGCs and/or the transected ON interfere with early events after axotomy that leads to RGC death.     

Electrical stimulation of paralyzed vibrissal muscles reduces endplate reinnervation and does not promote motor recovery after facial nerve repair in rats

The outcome of peripheral nerve injuries requiring surgical repair is poor. Recent work has suggested that electrical stimulation (ES) of denervated muscles could be beneficial. Here we tested whether ES has a positive influence on functional recovery after injury and surgical repair of the facial nerve. Outcomes at 2 months were compared to animals receiving sham stimulation (SS). Starting on the first day after end-to-end suture (facial–facial anastomosis), electrical stimulation (square 0.1 ms pulses at 5 Hz at an ex tempore established threshold amplitude of between 3.0 and 5.0 V) was delivered to the vibrissal muscles for 5 min a day, 3 times a week. Restoration of vibrissal motor performance following ES or SS was evaluated using the video-based motion analysis and correlated with the degree of collateral axonal branching at the lesion site, the number of motor endplates in the target musculature and the quality of their reinnervation, i.e. the degree of mono- versus poly-innervation. Neither protocol reduced collateral branching. ES did not improve functional outcome, but rather reduced the number of innervated motor endplates to approximately one-fifth of normal values and failed to reduce the proportion of poly-innervated motor endplates. We conclude that ES is not beneficial for recovery of whisker function after facial nerve repair in rats.     

Stimulation of Vagus Nerve Modifies Negative Chronotropic and Hypotensive Effects of Adenosine

The effects of electrical stimulation of the vagus nerve on the negative chronotropic and hypotensive effects of adenosine were studied on adult rats. Intravenous injection of adenosine to control rats significantly reduced the heart rate and induced a transient blood pressure drop followed its increase. Preliminary electrical stimulation of the right vagus nerve reduced the magnitude and duration of adenosine-induced bradycardia and changed the dynamics of adenosine-induced arterial pressure perturbations.     

Inhibition of the development of collagen-induced arthritis in Wistar rats through vagus nerve suspension: a 3-month observation

OBJECTIVE AND DESIGN: In this study, we have investigated the effects of vagus nerve suspension in a rat model of collagen-induced arthritis (CIA) . MATERIALS AND TREATMENT: CIA was induced in male Wistar rats and vagus nerve suspension or sham operation was performed on day 10 after the second immunization. All rats were monitored for macroscopic signs of clinical arthritis and cytokine titres within 2 months after the second immunization. Radiological and histological examination were performed 3 months after the second immunization. RESULTS: Rats subjected to vagus nerve suspension (the test group) showed nerve activities that resemble electrical stimulation of the vagus nerve in the control group. Compared to control, the test group had reduced soft-tissue swelling, arthritic scores, TNF-alpha level and Collagen-II antibody titre, throughout the course of the experiment. Sham operation produced similar suppression on the CIA symptoms as the test group but most of the effects produced by sham operation subsided after 27 or 35 days. CONCLUSION: Vagus nerve suspension is a novel approach to achieve sustained long-term stimulation of the vague nerve. This procedure can suppress the development of CIA in rats.     

Effects of taste stimuli on the efferent activity of the gastric vagus nerve in rats

The effect of taste stimuli on the efferent discharges in the gastric branch of the vagus nerve was studied in rats anesthetized with urethane-chloralose. An increase in discharge rate following taste stimulation with 5% NaCl over the tongue for 5 min, and a decrease of it following an application of 10% sucrose for the same duration were observed in normal as well as in decerebrated rats. The results indicate the existence of a pathway from the taste receptors to the gastric vagus nerve via the brainstem. The reflex effects of taste stimuli on gastric vagal outflow may be related to gastric acid output.     

Modulation of peripheral inflammation by locally administered endomorphin-1

OBJECTIVES: Neurogenic inflammation is mediated via sensory peptides released from the peripheral terminals of sensory nerves and can be modulated by locally released opioid peptides at the site of injury. Endomorphins are recently discovered endogenous opioid peptides with high selectivity and affinity for the mu-opioid receptor. The aim of this study was to examine the ability of endomorphin-1 (EM-1) to modulate the inflammatory response under different injury conditions. METHODS: A vacuum-induced blister model in anaesthetised rats (nembutal 60 mg/kg i.p.) was used to examine the effect of EM-1 on the acute inflammatory response induced by; (1) electrical stimulation (ES) of the distal portion of the exposed/cut sciatic nerve at 20 V, 5 Hz, 2 ms for 1 min or; (2) superfusion of substance P (SP) over the blister base. In addition, the effect of EM-1 on the inflammatory response to SP was examined under acute, recurrent (repeated blister induction) and chronic (chronic sciatic nerve lesion) injury conditions. RESULTS: Prior and concomitant perfusion of EM-1 (100 microM) significantly inhibited the vascular response to ES by 58% compared to controls. EM-1 also inhibited the inflammatory response to SP (both vasodilatation and plasma extravasation) in a dose-dependent manner. Significant inhibition was achieved at 100 microM and 1 mM concentrations of EM-1. Naloxone (1 mg/kg i.v.) reversed the inhibitory effect of EM-1 on the inflammatory response to SP. EM-1 (100 microM) was equally potent in inhibiting the inflammatory response to SP under acute (34% inhibition) recurrent (39%) and chronic (42%) injury conditions. CONCLUSIONS: The current results demonstrate a greater inhibitory effect of EM-1 on the inflammatory response to electrical nerve stimulation (58% inhibition) compared to SP (34% inhibition) suggesting the involvement of both pre- and post-terminal mechanisms in the inhibitory modulatory actions of EM-1. Evidence is provided for the involvement of opioid receptors in this inhibitory effect. The results also suggest that EM-1 is equipotent in inhibiting the inflammatory response under different injury conditions.