Effects of ginkgolide B on neuronal discharges in paraventricular nucleus of rat hypothalamic slices

Objective To study the central role of ginkgolide B （BN52021） in regulating cardiovascular function of nerve center by examining the effects of ginkgolide B on the electrical activity of rat paraventricular nucleus （PVN） neurons in hypothalamic slice preparation and to elucidate the mechanism involved. Methods Extracellular single-unit discharge recording technique. Results （1） In response to the application of ginkgolide t3 （0.1, 1, 10 μmol/L; n = 27） into the perfusate for 2 rain, the spontaneous discharge rates （SDR） of 26 （26/27, 96.30%） neurons were significantly decreased in a dose-dependent manner. （2） Pretreatment with L-glutamate （L-Glu, 0.2 mmol/L） led to a marked increase in the SDR of all 8 （100%） neurons in an epileptiform pattern. The increased discharges were suppressed significantly after ginkgolide B （1 μmol/L） was applied into the perfusate for 2 min. （3） In 8 neurons, perfusion of the selective L-type calcium channel agonist, Bay K 8644 （0.1 μmol/L）, induced a significant increase in the discharge rates of 8 （8/8, 100%） neurons, while ginkgolide B （1μmol/L） applied into the perfusate, could inhibit the discharges of 8 （100%） neurons. （4） In 8 neurons, the broad potassium channels blocker, tetraethylammonium （TEA, 1 mmol/L） completely blocked the inhibitory effect of ginkgolide B （1 μmol/L）. Conclusion These results suggest that ginkgolide B can inhibit the electrical activity of paraventricular neurons. The inhibitory effect may be related to the blockade of L-type voltage-activated calcium channel and potentially concerned with delayed rectifier potassium channel （KDR）.

Mechanism of hypothalamic paraventricular nucleus in regulating asthmatic attack

BACKGROUND:It has been confirmed that c-fos expression increased markedly in hypothalamic paraventricular nucleus(PVN)during asthmatic attack in rats,and PVN has extensive physiological functions,involving in the regulation of respiratory system,etc.OBJECTIVE:To observe the alteration of electroencephalogram(EEG)and power spectra in PVN during the asthmatic attack,and the alteration of lung function and diaphragmatic muscle discharge after bilateral PVN lesion in asthmatic rats.DESIGN:A randomized control study.SETTING:Laboratory of Physiology and Pharmacology,School of Basic Medical Sciences,Southeast University.MATERIALS:Forty-eight male adult SD rats of 260-300 g were used.The rats were randomly divided into 6 groups(n=8):control group,asthma group,electrolytic lesion of PVN group,KA-induced lesion of PVN group,sham electrolytic lesion of PVN group and sham kainic acid(KA)-induced lesion of PVN group.KA,chicken ovalbumin and aluminum hydroxide were purchased from American Sigma Company.Bordetella pertussis vaccine(Institute of Biological Products of Shanghai);stereotaxic apparatus(JiangwanⅡ,China);lesion-producing device(YC-2 programmable stimulato,Chengdu Instrument Company);MD2000 signal processing system(Nanjing Medical School);data acquisition system(RM6240B,Chengdu Instrument Company).METHODs:The experiments were carried out in the Laboratory of Physiology and Pharmacology,School of Basic Medical Sciences,Southeast University from January to August in 2006.①Rats except for control group were sensitized with an intraperitoneal injection of 100 mg chicken ovalbumin and 100 mg aluminum hydroxide and Bordetella pertussis vaccine containing 5×10^(9) heat-killed in 1 mL of sterile saline.From the fifteenth to seventeenth days rats received three times aerosolized ovalbumin challenge.In rats of the control group and asthma group three steel electrodes were placed into the left PVN(AP-1.8 mm,LR 0.4 mm,OH-7.9 mm),parietal cortex and subcutaneous tissue in lower limb.Lung function tests were carried out simultaneously.Small holes were drilled in the skull to introduce a concentric bipolar electrode in the direction of the PVN in order to perform electrolytic lesion.The electrodes were connected to a lesion-producing device and a current of 1.0-1.5 mA was passed over a period of 10-15 s on each side of the PVN.The rats received 0.5μg/0.5μL of KA in phosphate buffer(0.1 mol/L,pH 7.4),and the speed of infusion was 0.1μL per minute in order to perform KA-induced lesion of PVN.②Three days after operation of lesion,lung function tests were carried out.All the electrode and transducer were connected with data acquisition system.This technique yielded airway resistance(Raw),dynamic compliance(Cdyn),the expiratory time(Te)/the inspiratory time(Ti),minute ventilation volume(MVV),EMGdi frequency and EMGdi integral.③The differences of the measurement data were compared using the t test.MAIN OUTCOME MEASURES:①The alteration of EEG and power spectrum of PVN during asthmatic attack in sensitized rats;②The effects of electrolytic lesion or KA-induced lesion of PVN on lung function in asthmatic rats.RESULTS:All the 48 rats were involved in the analysis of results.①Alteration of EEG and power spectrum:Five minutes after injection of ovalbumin into caudal vena,the breathing rate of the rat was obviously speeded up and the total power spectrum was increased[(18476.71±2140.94),(13838.75±2983.26)mV^(2),P<0.01],the percentage of theδpower andθpower decreased significantly(P<0.01),while the percentage ofαpower andβ1 power were enhanced(P<0.05,0.01).Ten minutes after injection,the EEG power spectrum of PVN further shifted rightward,the total power gradually increased(P<0.01)which suggesting that the intensive hypersynchrony activities of PVN neurons.The percentage ofδpower was decreased significantly(P<0.01),but theα,β1 andβ2 were increased(P<0.01).Twenty-five minutes later,the breathing movements became steady,and the EEG power spectrum of PVN returned to the control level step by step.②The alteration of lung function was detected during asthmatic attack after electrolytic lesion or KA-induced lesions of PVN respectively.It was found that EMGdi frequency,Te/Ti and RL were all decreased(P<0.01),EMGdi integral,MVV and Cdyn were all enhanced(P<0.01),while there were no significant changes in the sham surgery group(P>0.05).CONCLUSION:The excitability of PVN is increased during the asthmatic attack.PVN plays a key role in the regulation of asthma.Both electrolytic and KA lesions of PVN can significantly relieve the asthmatic symptoms of rats,and improve their lung function.

Inhibitory effects of ketamine and L--NAME on expression of c-fos and NOS in hypothalamic paraventricular nucleus after acute hypothermia and hypoxia in rats

Objective: To determine whether NMDA receptor activation mediates the expression of c--fos and NOS and study the relationship between the expression of c--fos and NOS in the hypothalamic paraventricularnucleus (PVN) following acute hypothermia and hypoxia. Methods: Fos immunohistochemistry, NADPH--d histochemistry and Fos/NADH--d double labeling were used. Results: Acute hypothermia and hypoxia induced the overexpression of on fos and NOS in PVN in rats. Pretreatment with ketamine, a NMDA receptor antagonist, resulted in partial inhibition of the expression of c--fos and NOS and that with blocker of NOS resulted in significant inhibition of the expression of c--fos. Conclusion: The activation of NMDA receptor is involved in the expression of c- fos and NOS in PVN in the rats subjected to acute hypothermia and hypoxia.Meanwhile, hypothalamic endogenous NO participates in adaptive reaction to hypothermia and hypoxia,which might be related to the modulation of c- fos expression.

Fos expression incatecholaminergic medullary neu-rons induced by chemical stimulation of stomach projecting to the paraventricular nucleus of hypothalamus in rats

AIM To determine whether medullary catecholaminergic neurons expressing Fos induced by chemical stimulation of the stomach project to the paraventricular nucleus of hypothalamus (PVH) in rats. METHODS A triple labeling method of horseradish peroxidase (HRP) retrograde tracing combined with Fos (ABC method) and tyrosin hydroxylase (TH) (PAP method) immunohistochemical stainings was used in the present study. RESULTS Seven kinds of labeled neurons were found in the nucleus tractus solitarii (NTS), the ventrolateral medulla (VLM) and the reticular formation of the medulla (RF): Fos like immunoreactive (LI) neurons, TH LI neurons and HRP retrogradely single labeled neurons, Fos/HRP, Fos/TH and HRP/TH double labeled neurons, and Fos/HRP/TH triple labeled neurons. CONCLUSION Ascending projections from the NTS, VLM and RF to the PVH might be involved in the transmitting process of the visceral noxious stimulation.

Ginsenoside Rg1 promotes non-rapid eye movement sleep via inhibition of orexin neurons of the lateral hypothalamus and corticotropin releasing hormone neurons of the paraventricular hypothalamic nucleus

Objective:This study investigates the sleep-modulating effects of ginsenoside Rg1(Rg1,C_(42)H_(72)O_(14)),a key bioactive component of ginseng,and elucidates its underlying mechanisms.Methods:C57BL/6J mice were intraperitoneally administered doses of Rg1 ranging from 12.5 to100 mg/kg.Sleep parameters were assessed to determine the average duration of each sleep stage by monitoring the electrical activity of the brain and muscles.Further,orexin neurons in the lateral hypothalamus(LH)and corticotropin-releasing hormone(CRH)neurons in the paraventricular hypothalamic nucleus(PVH)were ablated using viral vector surgery and electrode embedding.The excitability of LH^(orexin)and PVH^(CRH)neurons was evaluated through the measurement of cellular Finkel-Biskis-Jinkins murine osteosarcoma viral oncogene homolog(c-Fos)expression.Results:Rg1(12.5–100 mg/kg)augmented the duration of non-rapid eye movement(NREM)sleep phases,while reducing the duration of wakefulness,in a dose dependent manner.The reduced latency from wakefulness to NREM sleep indicates an accelerated sleep initiation time.We found that these sleep-promoting effects were weakened in the LH^(orexin)and PVH^(CRH)neuron ablation groups,and disappeared in the orexin and CRH double-ablation group.Decreased c-Fos protein expression in the LH and PVH confirmed that Rg1 promoted NREM sleep by inhibiting orexin and CRH neurons.Conclusion:Rg1 increases the duration of NREM sleep,underscoring the essential roles of LH^(orexin)and PVH^(CRH)neurons in facilitating the sleep-promoting effects of Rg1.Please cite this article as:Wang YY,Wu Y,Yu KW,Xie HY,Gui Y,Chen CR,Wang NH.Ginsenoside Rg1 promotes non-rapid eye movement sleep via inhibition of orexin neurons of the lateral hypothalamus and corticotropin-releasing hormone neurons of the paraventricular hypothalamic nucleus.J Integr Med.2024;22(6):719–728.

PVN和脑刺激镇痛关系初探

用４％水合氯醛麻醉大鼠，在下丘脑室旁核（ＰＶＮ）、中脑导水管周围灰质（ＰＡＧ）埋藏双极刺激电极或不锈钢管，以便刺激、损毁或电泳药物，并暴露脊髓背角，利用微电极记录脊髓背角神经元对伤害刺激坐骨神经单位反应。实验观察到：（１）电刺激ＰＶＮ或注射盐酸吗啡可使大鼠痛阈显著升高。微量注射纳络酮可翻转盐酸吗啡的作用，（２）电刺激ＰＶＮ可抑制脊髓背角神经元伤害反应，其作用持续２０ｍｉｎ，在刺激后３ｍｉｎ作用最显著。（３）电解损毁ＰＡＧ后，刺激ＰＶＮ抑制脊髓背角神经元伤害反应仍然存在。实验结果表明：ＰＶＮ是脑内镇痛的主要核团之一，其作用通过ＰＡＧ实现，也可通过ＰＶＮ—脊髓背角直接投射的途径。

刺激大鼠 PVN 影响痛感受下行途径的研究

在大鼠腰脊髓背角泳入辣根过氧化酶（ＨＲＰ），下丘脑室旁核（ＰＶＮ）找到逆行标记细胞；在ＰＶＮ泳入ＨＲＰ，脊髓内均有顺行标记纤维和终末分布于脊髓背角第Ⅰ、Ⅱ、和Ⅳ、Ⅴ板层。可见大鼠ＰＶＮ－脊髓背角间存在直接纤维联系。用行为测痛法观察到电刺激ＰＶＮ或注射谷氨酸钠、盐酸吗啡，痛阈均显著升高。纳络酮可翻转盐酸吗啡的作用。电刺激ＰＶＮ的同时，电针双侧“足三里”痛阈升高更显著，说明刺激ＰＶＮ可使痛阈升高，电针“足三里”有协同作用。用微电极记录脊髓背角神经元伤害单位活动，其反应可被电刺激ＰＶＮ所抑制。分别电解中脑导水管周围灰质（ＰＡＧ）和中缝大核（ＮＲＭ）后，ＰＶＮ对脊髓背角神经元伤害反应的抑制仍存在。实验结果表明，ＰＶＮ参与了痛觉下行的调制过程。

糖尿病诱导的小鼠室旁核催产素和加压素阳性神经元FOS表达

目的:探索糖尿病(DM)不同状态下小鼠下丘脑室旁核(PVN)催产素和加压素阳性神经元的FOS表达变化。方法:腹腔注射溶媒或链脲佐菌素(STZ)制备对照组或糖尿病小鼠模型,根据机械痛测试区分糖尿病痛(DNP组)与非痛组(DWP组)。采用免疫组化和免疫荧光染色技术检测PVN内FOS、催产素(OXT)和加压素(VP)阳性神经元的分布及双标情况,并进行计数和比较。结果:7 d时三组(Control组、DNP组和DWP组)小鼠PVN内均有较多的FOS表达,而28 d时DWP和DNP组FOS的表达几近于无,与7 d组相比差异显著(P<0.05或0.001)。与对照组相比,DNP组和DWP组动物的VP和OXT荧光染色同样存在随着造模时间延长染色强度减弱的趋势(P<0.05)。VP、OXT与FOS的双标染色计数结果显示,在DWP 7 d组,VP/FOS双标细胞数为74.33±22.10,占VP阳性细胞数的(56.64±7.52)%,而OXT/FOS的双标率则仅为(10.44±3.14)%。在DNP 7 d组,OXT/FOS双标细胞数为51.00±31.80,占OXT阳性细胞数的(18.50±9.51)%,而VP/FOS的双标率仅为(9.34±3.27)%。与此相对,28 d组FOS的表达锐减,几乎无双标细胞。结论:下丘脑PVN内的VP和OXT阳性神经元在糖尿病痛与非痛,疾病发展的不同阶段存在明显不同的可塑性变化特点,理解这些变化对于揭示糖尿病及其并发症的神经机制具有重要意义。

Electroacupuncture preconditioning alleviates myocardial ischemia-reperfusion injury through the hypothalamic paraventricular nucleus-interposed nucleus nerve pathway

OBJECTIVE:To explore whether the paraventricular nucleus(PVN)participates in regulation of the antimyocardial ischemia-reperfusion injury(MIRI)effect of electroacupuncture(EA)and whether this is achieved through the PVN-interposed nucleus(IN)neural pathway.METHODS:The modeling method of myocardial ischemia reperfusion injury was achieved by ligating the left anterior descending coronary artery in SpragueDawley rats.We used the Powerlab multi-channel physiological recorder system to record electrocardiograms and analyze the changes in ST segment displacement;2,3,5-Triphenyltetrazolium chloride staining was used to observe the percentage of myocardial infarction areas.Detecting cardiac troponin I(cTnI),lactate dehydrogenase(LDH)in serum was done with an enzyme-linked immunosorbent assay kit.Morphological changes in the myocardium were detected in each group with hematoxylin-eosin staining of paraffin sections.Detection of c-fos protein expression in the PVN of the hypothalamus was done with the immuneofluorescence method.The Plexon multi-channel acquisition system recorded PVN neuron discharges and local field potentials in each group of rats.Offline Sorter software was used for cluster analysis.Neuro Explorer software was used to perform autocorrelation,raster and frequency characteristics and spectral energy analysis of neuron signals in each group.RESULTS:Compared with the MIRI model group,the areas of myocardial infarction in the EA group were significantly reduced;the expression of cTnI,LDH in serum was decreased significantly.The firing frequency of pyramidal cells in the PVN was significantly increased and the spectrum energy map showed energy was reduced,c-fos expression in PVN was reduced,this indicated that neuronal activity in the PVN participates in the effect of EA improving myocardial injury.In addition,we used the kainic acid method to lesion the IN and observed that the effect of EA was weakened.For example,the area of myocardial infarction of lesion IN+EA group in rats was significantly increased compared with that resulting from EA group,the expression of cTnI,LDH in serum was significantly increased,the firing frequency of pyramidal cells in the PVN was significantly reduced.A spectral energy diagram shows that the energy after damage was higher than that of EA group.At the same time,the expression of c-fos in the PVN increased again.CONCLUSION:Our results indicated that the PVN-IN nerve pathway may participate as an effective pathway of EA to improve the effect of myocardial injury.

Glutamatergic neurons in the paraventricular nucleus of the hypothalamus participate in the regulation of visceral pain induced by pancreatic cancer in mice

Background:Visceral pain induced by pancreatic cancer seriously affects patients’quality of life,and there is no effective treatment,because the mechanism of its neural circuit is unknown.Therefore,the aim of this study is to explore the main neural circuit mechanism regulating visceral pain induced by pancreatic cancer in mice.Methods:The mouse model of pancreatic cancer visceral pain was established on C57BL/6N mice by pancreatic injection of mPAKPC-luc cells.Abdominal mechanical hyperalgesia and hunch score were performed to assess visceral pain;the pseudorabies virus(PRV)was used to identify the brain regions innervating the pancreas;the c-fos co-labeling method was used to ascertain the types of activated neurons;in vitro electrophysiological patch-clamp technique was used to record the electrophysiological activity of specific neurons;the calcium imaging technique was used to determine the calcium activity of specific neurons;specific neuron destruction and chemogenetics methods were used to explore whether specific neurons were involved in visceral pain induced by pancreatic cancer.Results:The PRV injected into the pancreas was detected in the paraventricular nucleus of the hypothalamus(PVN).Immunofluorescence staining showed that the majority of c-fos were co-labeled with glutamatergic neurons in the PVN.In vitro electrophysiological results showed that the firing frequency of glutamatergic neurons in the PVN was increased.The calcium imaging results showed that the calcium activity of glutamatergic neurons in the PVN was enhanced.Both specific destruction of glutamatergic neurons and chemogenetics inhibition of glutamatergic neurons in the PVN alleviated visceral pain induced by pancreatic cancer.Conclusions:Glutamatergic neurons in the PVN participate in the regulation of visceral pain induced by pancreatic cancer in mice,providing new insights for the discovery of effective targets for the treatment of pancreatic cancer visceral pain.

Effects of needling acupoints at different nerve segments on oxytocin neurons in rat’s hypothalamic paraventricular nucleus and intragastric pressure

Objective:To compare and explore the effects of needling acupoints at different nerve segments on the oxytocin(OT)neurons in the paraventricular nucleus of hypothalamus(PVN)and the intragastric pressure,and discuss the possible mechanisms.Methods:Thirty-two healthy adult Sprague-Dawley(SD)rats were numbered and divided into 4 groups according to the random number table,a Zusanli(ST 36)group,a Neiguan(PC 6)group,a Weishu(BL 21)group and a control group,with 8 rats in each group.Except the control group,rats in the other three groups received acupuncture at the corresponding acupoints.To observe the differences in double-labeled OT neurons and c-fos neurons of the hypothalamic PVN and the intragastric pressure after acupuncture among the three groups of needling acupoints at different nerve segments.Results:Compared with the control group,the numbers of double-labeled cells in the PVN of the Zusanli(ST 36)group and the Neiguan(PC 6)group decreased significantly,while the intragastric pressure increased significantly(all P<0.05),and the inter-group differences were statistically significant(P<0.05).The intragastric pressure in the Weishu(BL 21)group decreased significantly,and the inter-group difference was statistically significant(P<0.05).Compared with the Weishu(BL 21)group,the numbers of OT/c-fos double-labeled cells in PVN of the Zusanli(ST 36)group and the Neiguan(PC 6)group decreased significantly,and the intragastric pressure increased significantly,the inter-group differences were statistically significant(all P<0.01).Conclusion:Acupoints at different nerve segments have different regulation effects on intragastric pressure.The difference may be related to the different nerve conduction pathways by acupoints at different nerve segments in regulating the intragastric pressure.The PVN may be one common integration center for the regulation of gastric function in the three acupoints[Zusanli(ST 36),Neiguan(PC 6)and Weishu(BL 21)]at different nerve segments.

淫羊藿苷对去卵巢大鼠骨和下丘脑不同核团ERβ mRNA表达的影响

目的观察淫羊藿苷对去卵巢大鼠骨和下丘脑不同核团ERβmRNA表达的影响,探讨其治疗绝经后骨质疏松的作用机制。方法将10～11月龄SD♀大鼠60只,随机分为假手术组、去卵巢模型组、淫羊藿苷小、中、大剂量组(每组12只)。以双侧卵巢切除法建立大鼠骨质疏松模型。分别用淫羊藿苷小、中、大剂量给药4个月,采用RT-PCR法,观察各组大鼠骨和下丘脑室旁核、视上核、弓状核ERβmRNA表达的变化。结果大鼠卵巢切除后,血清E2水平、椎骨骨密度、子宫湿重、胫骨和下丘脑弓状核ERβmRNA表达明显降低(P<0.01),下丘脑室旁核、视上核ERβmRNA表达均明显升高(P<0.01)。与去卵巢模型组比较,淫羊藿苷50.0和100.0 mg.kg-1组治疗后,血清E2水平、椎骨骨密度、胫骨和下丘脑弓状核ERβmRNA表达明显升高(P<0.01),下丘脑室旁核、视上核ERβmRNA表达均明显降低(P<0.01),子宫湿重无明显改变(P>0.05)。结论淫羊藿苷可以改善切除卵巢所致的骨质疏松大鼠的骨密度,对子宫无不良反应。其机制可能与其选择性调节去卵巢骨质疏松大鼠下丘脑不同核团ERβmRNA表达水平有关,调节下丘脑功能活动是其途径之一。

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 (paraventricularnucleus,PVN)对大鼠胃缺血 再灌注损伤 (gastricischemia reperfusioninjury ,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、胃壁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。

下丘脑室旁核对大鼠胃缺血-再灌注损伤调控的神经机制

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 ,观察了电和化学刺激以及电损毁下丘脑室旁核 (paraventricularnucleus,PVN)对大鼠胃缺血 再灌注损伤 (gastricischemia reperfusioninjury ,GI RI)的影响 ,并对其调控的神经机制进行了初步探讨。结果表明 :①电刺激PVN或PVN内注射L 谷氨酸后 ,GI RI均显著减轻 ;②电解损毁双侧PVN则能加重GI RI;③损毁双侧孤束核 (nucleustractussolitarius,NTS)后 ,能取消电刺激PVN对GI RI的减轻作用 ;④去除脑垂体后不影响电刺激PVN对GI RI的作用 ;⑤分别切断膈下迷走神经和切除腹腔交感神经节后 ,电刺激PVN使GI RI较单纯电刺激PVN组明显减轻。提示 :PVN是对GI RI具有保护作用的特异性中枢部位 ,孤束核以及外周迷走神经、交感神经均参与了PVN对GI RI的调控 ,而与室旁核

下丘脑室旁核参与脑刺激镇痛的实验研究

目的 :探讨下丘脑室旁核 (PVN )的镇痛与脑刺激镇痛间的关系及作用途径。方法 :用 4%水合氯醛麻醉大鼠 ,在PVN埋藏双极刺激电极或不锈钢管 ,在中缝大核 (NRM )埋藏损毁电极 ,并暴露脊髓用玻璃微电极记录脊髓背角神经元对伤害刺激坐骨神经的反应 ,信号由计算机采集处理。结果 :电解中缝大核 (NRM )后 ,刺激PVN可抑制脊髓背角神经元伤害反应 ,其作用时间持续 15～18min ,其中 3～ 6min抑制作用最强 ;向PVN微量注射吗啡 10 μg ,脊髓背角神经元伤害单位放电明显减少 ,纳洛酮可反转吗啡的抑制作用。结论 :PVN除通过已知的内源性镇痛系统中的NRM中继外 ,也可能通过PVN 脊髓背角间的直接神经投射等途径参与脑刺激镇痛 ,此作用过程中在PVN可能有吗啡参与。本工作对痛觉生理及镇痛的研究具有重要意义。

Blockade of c-Src Within the Paraventricular Nucleus Attenuates Inflammatory Cytokines and Oxidative Stress in the Mechanism of the TLR4 Signal Pathway in Salt-Induced Hypertension

Toll-like receptor 4 (TLR4) and cellular Src (cSrc) are closely associated with inflammatory cytokines and oxidative stress in hypertension, so we designed this study to explore the exact role of c-Src in the mechanism of action of the TLR4 signaling pathway in salt-induced hypertension. Salt-sensitive rats were given a high salt diet for 10 weeks to induce hypertension. This resulted in higher levels of TLR4, activated c-Src, pro-inflammatory cytokines, oxidative stress, and arterial pressure. Infusion of a TLR4 blocker into the hypothalamic paraventricular nucleus (PVN) decreased the activated c-Src, while microinjection of a c-Src inhibitor attenuated the PVN levels of nuclear factor-kappa B, pro-inflammatory cytokines, and oxidative stress. Our findings suggest that a longterm high-salt diet increases TLR4 expression in the PVN and this promotes the activation of c-Src, which upregulates the expression of pro-inflammatory cytokines and results in the overproduction of reactive oxygen species.Therefore, inhibiting central c-Src activity may be a new target for treating hypertension.

NERP-1对大鼠下丘脑室旁核MNCs活动的影响机制

目的分析神经内分泌调节肽(NERP)-1对大鼠下丘脑室旁核(PVN)神经分泌大细胞(MNCs)活动的影响及其对PVN MNCs活动调节的突触机制。方法实验动物选用出生2~3周龄的雄性Wistar系大鼠,异氟烷麻醉后立即断头取出脑,随后用振动切片机制备厚度为250μm的含PVN的下丘脑切片。在室温(24~25℃)条件下,将切片置于持续充有混合气体(95%O_(2)和5%CO_(2))的人工脑脊液中孵育1 h以上。电极的阻抗为5~7 MΩ。使用膜片钳放大器(Axopatch-200B)及Clampex数据采集软件记录PVN神经分泌细胞的电活动,NERP-1、河豚毒素(TTX)和犬尿喹啉酸(KYC)经蠕动泵灌流给药。在电生理记录结束后,用4%多聚甲醛溶液将脑片行固定24 h后,进行二氨基联苯胺(DAB)染色、显微照相,观察所记录神经分泌细胞的组织形态学特点,确认所记录细胞为PVN NMCs。使用Clampfit10.4和MiniAnalysis(6.0)软件进行电生理实验数据分析。结果在电流钳记录模式下,PVN MNCs对去极化电流刺激表现出明显的外向整流电流。给予NERP-1(100 nmol/L)可导致PVN神经分泌大细胞的放电频率显著降低并伴随膜电位超极化,冲洗后恢复到给药前水平。给予非选择性离子型谷氨酸受体拮抗剂犬KYC可阻断NERP-1引起的PVN MNCs放电频率降低和膜超极化作用。NERP-1对PVN MNCs的自发性放电活动的抑制作用不受GABAA受体阻断剂的影响。在电压依存性钠通道阻断剂TTX的存在下,NERP-1显著降低NMCs的微小兴奋性突触后电流(mEPSCs)的发生频率,但对mEPSCs的振幅没有显著影响。结论NERP-1下调下丘脑PVN MNCs兴奋性谷氨酸能传入效能,降低PVN MNCs的兴奋性,提示NERP-1通过间接方式调节PVN缩宫素和血管紧张素神经元的分泌活动。

Effects of the aqueous extract of Schizandra chinensis fruit on ethanol withdrawal-induced anxiety in rats

Background We previously demonstrated that the aqueous extract of the Schizandra chinensis fruit （AESC） ameliorated Cd-induced depletion of monoamine neurotransmitters in the brain through antioxidant activity.In the present study,we investigated the effect of AESC on anxiety-like behavior and the levels of norepinephrine and 3-methoxy-4-hydroxyphenylglycol （a metabolite of norepinephrine） in different brain regions during ethanol withdrawal in rats.Methods Male Sprague-Dawley rats were treated with 3 g/kg of ethanol （20％,w/v） or saline by daily intraperitoneal injection for 28 days followed by three days of withdrawal.During withdrawal,rats were given AESC （100 mg.kg 1.d-1 or 300 mg.kg 1·d1,P.O.） once a day for three days.Thirty minutes after the final dose of AESC,the anxiogenic response was evaluated using an elevated plus maze,and the plasma corticosterone levels were examined by radioimmunoassay.Meanwhile,the concentrations of norepinephrine and 3-methoxy-4-hydroxy-phenylglycol in the hypothalamic paraventricular nucleus and hippocampus were also measured by high performance liquid chromatography.Results Rats undergoing ethanol withdrawal exhibited substantial anxiety-like behavior,which was characterized by both the decrease in time spent in the open arms of the elevated plus maze and the increased level of corticosterone secretion,which were greatly attenuated by doses of AESC in a dose-dependent manner.The high performance liquid chromatography analysis revealed that ethanol withdrawal significantly increased norepinephrine and 3-methoxy-4-hydroxy-phenylglycol levels in the hypothalamic paraventricular nucleus,while not significantly altering them in the hippocampus.Similar to the results from the elevated plus maze test,the AESC significantly inhibited the elevation of norepinephrine and its metabolite in the hypothalamic paraventricular nucleus in a dose-dependent manner.Conclusions These results suggest that AESC attenuates anxiety-like behavior induced by ethanol withdrawal through modulation of the hypothalamic norepinephrine system in the brain.

Electrical Stimulation of Deep Peroneal Nerve Mimicking Acupuncture Inhibits the Pressor Response via Capsaicin-lnsensitive Afferents in Anesthetized Rats

Objective： To assess the inhibitory modulation of blood pressure by stimulation of the deep peroneal nerve （DPN） and to determine the involvement of nociceptive fibers in the modulation. Methods： All the animals were divided into six groups （A-F）. The rats in groups A and B received no pretreatment. The rats in groups C and D received subcutaneous injection of capsaicin or control vehicle, respectively, near the DPN for 2 days. Those in groups E and F had the DPN exposed to capsaicin or control vehicle, respectively, for 20 min. Subsequently, pressor responses were induced by stimulation of paraventricular nucleus （PVN） either electrically （groups A and C-F） or chemically via injection of glutamate （group B）. After two stable pressor responses （baseline）, all groups were subject to 5-min DPN stimulation followed by PVN stimulation for 10 s. Arterial blood pressure, heart rate, and electrocardiogram were recorded. The pressor response was calculated as the difference in the mean arterial pressure （MAP） before and after PVN stimulation, and changes from baseline in pressor response after DPN stimulation were compared between the groups. Results： Increases of MAP of 22.88 ＋ 2.18 mm Hg and 20.32 ＋ 5.25 mm Hg were induced by electrical （group A） or chemical （group B） stimulation of the PVN, respectively. These pressor responses were inhibited by stimulation of the DPN, and the MAP was reduced to 12.00 _＋ 2.10 mm Hg in group A （n=6, P〈0.01） and 7.00 ＋ 2.85 mm Hg in group B （n=6, P〈0.01）. Subcutaneous injection of capsaicin （125 mg/kg） near the DPN in group C （n=7） had no effect on the inhibitory effect of DPN stimulation compared with the group D （n=9）, and neither did blockade of nociceptive fibers with capsaicin in group E （n=6） compared with group F （n=8）. Conclusion： Stimulation of the DPN mimicking acupuncture has an inhibitory effect on the pressor response, and the effect is mediated by capsaicin-insensitive afferent fibers in the DPN.