大鼠脑桥臂旁核味觉神经元的生理学特性

采用微电极细胞外记录技术,观察和分析了大鼠脑桥臂旁核(Parabrachial nuclei,PbN)味觉神经元的反应特征.记录到的55个PbN味觉神经元中,绝大部分位于脑桥味区并有自发放电.大部分PbN味觉神经元对多种基本味觉刺激起反应,其中对氯化钠反应的频率最高.PbN味觉神经元对蔗糖的反应和对其他味觉反应的相关性都较低.根椐最适刺激,PbN味觉神经元可分为:氯化钠优势反应、盐酸优势反应、奎宁优势反应和蔗糖优势反应神经元.结果提示,PbN中存在不同类型的神经元,它们可能在味觉的传递和编码中发挥着重要作用.     

电刺激大鼠杏仁中央核对脑桥臂旁核味觉神经元的影响

利用电生理学方法观察了电刺激杏仁中央核对脑桥臂旁核味觉神经元的影响.结果表明:电刺激杏仁中央核抑制大部分臂旁核味觉神经元的活动,并且提高臂旁核味觉神经元对五种基本味觉刺激反应的特异性.电刺激杏仁中央核对臂旁核的抑制作用以对盐酸和奎宁刺激的反应尤为明显(P＜0.01),并且对这两种厌味刺激反应的抑制作用是基本一致的.本研究的结果提示,杏仁中央核可能通过抑制脑干味觉神经元对厌味刺激的反应,从而参与对摄食行为的调控.     

电刺激大鼠杏仁中央核对脑桥臂旁核味觉神经元的影响(英文)

利用电生理学方法观察了电刺激杏仁中央核对脑桥臂旁核味觉神经元的影响。结果表明 :电刺激杏仁中央核抑制大部分臂旁核味觉神经元的活动 ,并且提高臂旁核味觉神经元对五种基本味觉刺激反应的特异性。电刺激杏仁中央核对臂旁核的抑制作用以对盐酸和奎宁刺激的反应尤为明显 (P <0 .0 1) ,并且对这两种厌味刺激反应的抑制作用是基本一致的。本研究的结果提示 ,杏仁中央核可能通过抑制脑干味觉神经元对厌味刺激的反应 ,从而参与对摄食行为的调控     

电刺激大鼠杏仁中央核对脑桥臂弯核味觉神经元的影响

利用电生理学方法观察了电刺激杏仁中央核对脑桥臂旁核味觉神经元的影响。结果表明：电刺激杏仁中央核抑制大部分臂旁核味神经元的活动，并且提高臂旁核味觉神经元对五种基本味觉刺激反应的特异性。电刺激杏仁中央核对臂旁核的抑制作用以对盐酸和奎宁刺激的反应尤为明显（P＜0．01），并且对这两种厌味刺激反应的抑制作用是基本一致的。本研究的结果提示，杏仁中央核可能通过抑制脑干味觉神经元对厌味刺激的反应，从而参与对摄食行为的调控。     

癫痫持续发作对大鼠海马神经元的影响

目的 研究实验性癫痫大鼠在癫痫发作持续不同时间对海马神经元的影响。方法24只SD大鼠随机分成4组：诱发火鼠瘢痫持续状态（status cpilepticus，SE）〈10、10～30、〉30min组及正常对照组。于电镜下观察各组海马神经元超微结构变化；采用免疫组化方法检测凋亡相关基因bcl-2、bax的蛋白表达及通过流式细胞技术检测细胞凋亡情况。结果SE〈10min组海马神经元所受影响不大．SE10～30min组海马神经元具有明显凋亡特征．SE〉30min组多数海马神经元呈坏死性改变。结论大鼠SE对海马神经元损伤有凋亡和坏死两种不同形式．这与癫痫发作的持续时间密切相关。     

一种改良的胚胎大鼠颞叶海马区神经元的培养方法

目的:探索胚胎大鼠颞叶海马区神经元的改良培养方法。方法:在无血清培养基础上,采用改良的分离纯化法获取单细胞悬液,接种后在不同阶段通过加入不同配方的培养基进行培养,并进行免疫组化鉴定。结果:用该方法培养的颞叶海马区神经元细胞存活率高,生长状态良好,且βⅢ-tublin免疫染色为阳性,神经元细胞纯度可达90%以上。结论:改良分离、结合分阶段的不同培养条件是一种简单、高效的颞叶海马区神经元的纯化培养方法。     

下丘脑神经元NMDA受体通道特性研究

目的通过对正常和缺氧条件下N-甲基-D-天冬氨酸(NMDA)受体通道特性进行研究,探讨下丘脑神经元缺氧损伤的机理,为临床防治脑缺血/缺氧损伤提供实验依据。方法取材于新生SD大鼠下丘脑视前区/下丘脑前区(PO/AH)神经元,应用膜片钳单通道记录技术对缺氧和非缺氧两种状态下NMDA受体特性进行研究,观察其在缺氧和非缺氧条件下的翻转电位、电流幅度、电导特性的变化。结果神经元缺氧后其通道内向电流幅值由平均(4.501±0.980) pA(n=20,40 mV)上升为(6.000±1.750) pA(n=16,40 mV),优势电导由非缺氧组的(45.693±1.850) pS (n=16)上升为(60.206±1.750) pS(n=10),而翻电位极为接近。结论缺氧是使NMDA受体通道过度激活和Ca2+大量内流的一外因条件。神经元缺氧时,同一钳制电压下其内向电流幅度明显高于对照组,优势电导也有明显上升,可以解释为缺氧引起了神经元Ca2+超载,从而介导了细胞的损伤和死亡。     

纳洛酮对大鼠额叶皮层神经元兴奋性的影响

纳洛酮对昏迷患者具有显著的促醒作用，一般认为纳洛酮可拮抗内源性阿片肽。纳洛酮促醒的机制并非这样简单。我们研究了纳洛酮对大鼠额叶皮质(FCX)锥体细胞兴奋性的影响，进而阐明纳洛酮促醒的神经药理机制。     

帕金森病大鼠模型神经元型一氧化氮合酶(nNOS)阳性神经元的实验研究

目的 观察研究帕金森病(PD)大鼠模型纹状体神经元型一氧化氮合酶(nNOS)阳性神经元，探讨一氧化氮(NO)在PD发病机制中所起作用。方法 应用立体定向技术建立6-OHDA毁损的大鼠PD模型，通过多巴胺受体激动剂阿扑吗啡(APO)测试大鼠旋转行为，免疫组化方法观察黑质酪氨酸羟化酶(TH)阳性神经元和纹状体nNOS阳性神经元的变化。结果 大鼠6-OHDA损毁侧黑质TH阳性神经元数目较对侧明显减少，双侧纹状体nNOS阳性神经元数目无显著差异。结论 6-OHDA对TH阳性神经元有损伤作用，而NOS阳性神经元对其具有抵抗作用。NO可能参与了PD发病机制。     

大鼠导水管周围灰质注射谷氨酸可使Barrington核神经元表达Fos

形态学研究已发现大鼠内侧视前区（ＭＰＯ）和导水管周围灰质（ＰＡＧ）发出大量轴突,投射至与排尿反射密切相关的Ｂａｒｒｉｎｇｔｏｎ 核。本研究试图通过注射谷氨酸钠到ＭＰＯ或ＰＡＧ后,观察Ｂａｒｒｉｎｇｔｏｎ 核内的Ｆｏｓ表达情况,来了解以上两通路的性质。将谷氨酸钠注射到ＭＰＯ后,只有少量Ｆｏｓ阳性神经元出现在Ｂａｒｒｉｎｇ－ｔｏｎ 核。而将谷氨酸钠注射到ＰＡＧ后,Ｂａｒｒｉｎｇｔｏｎ 核内出现大量的Ｆｏｓ阳性神经元。此结果提示,ＰＡＧ可能对大鼠脑桥排尿反射活动具有兴奋性调节作用。     

Axon collaterals of pontine taste area neurons project to the posterior ventromedial thalamic nucleus and to the gustatory neocortex

Retrograde axonal transport of fluorescent dyes was used to demonstrate collateral projections from neurons of the pontine taste area (PTA) to gustatory-responsive areas of the posterior ventromedial thalamic nucleus (VPM), and to the gustatory neocortex (GN) of the rat. Dual-labeled PTA neurons were reliably observed following application of two different fluorescent dyes to the GN and to VPM thalamus. Dye injections into the GN and into thalamic regions surrounding the VPM nucleus, the bed nucleus of stria terminalis or the infralimbic neocortex, did not result in dual-labeled cells within the PTA. This finding suggests that gustatory information may be relayed simultaneously and specifically to VPM thalamus and to the GN via collateral axons of PTA neurons.     

Coding of gustatory information in the pontine parabrachial nuclei of the rabbit: Temporal patterns of neural response

An electrophysiological analysis was carried out on 82 neurons in the parabrachial nuclei to study coding of gustatory stimuli. The magnitude of neural discharge evoked by two concentrations of each of 4 basic taste stimuli were subjected to two types of analyses to evaluate neuronal specificity and across-element spatial patterning in the coding of taste quality. Results were compared and contrasted to those in rodents. Profiles of taste response of individual neurons were analyzed mathematically by Q-technique principal components analysis and cluster analysis to identify basic neuronal patterns of response. Four distinct patterns emerged which, based on the average profiles of response, were characterized as: NaCl-dominant, NaClHCl, sucrose-dominant, and nonspecific. Analysis of the NaCl- and sucrose-dominant types of neurons indicated that neurons with the most narrowly tuned patterns of response to the taste stimuli could not effectively code specific taste qualities. Comparison of interstimulus correlations in magnitude of response across neurons between qualitatively different tastants and intrastimulus correlations between intensities of given tastants also revealed difficulties with the spatial pattern model of coding. The discrepant findings raise questions about an assumption utilized in the analysis of the model, viz., that all elements contribute homogeneously to the patterning code.     

Location and taste responses of parabrachio-thalamic relay neurons in rats

Thirty of the 55 taste units in the parabrachial nucleus were activated antidromically by stimulation of either or both of the ipsi- or contralateral thalamic taste areas. Such parabrachio-thalamic taste relay neurons produced bilateral thalamic afferent fibers (B type, N = 14), exclusively ipsilateral thalamic afferent fibers (I type, N = 12), or exclusively contralateral thalamic afferent fibers (C type, N = 4). Most of the B-type neurons were excited best by NaCl among the four basic taste stimuli; approximately one-half the I-type neurons by HCl. Most of the NaCl-best neurons were located in the medial part of the parabrachial nucleus but most of the HCl-best neurons were in the lateral part. In addition, NaCl-best neurons had shorter ipsilateral latencies (modal value = 1.0 to 3.0 ms) from the ipsilateral thalamic taste area, whereas HCl-best neurons had longer latencies (modal value = 4.0 to 6.0 ms).     

Direct connectivity between pontine taste areas and gustatory neocortex in rat

Horseradish peroxidase histochemistry was used to determine the course and extent of neuronal projections from the pontine taste area (PTA) to the gustatory neocortex (GN) in rat. Two distinct findings were encountered: (1) thalamocortical projections from posterior ventromedial thalamus to GN were confirmed, and (2) direct projections from cells located in the PTA to the GN were described. This novel anatomical finding supports previous suggestions that some gustatory information may be relayed to forebrain areas without making synaptic connection in the diencephalon.     

Localization of corticotropin-releasing factor, somatostatin, and vasoactive intestinal polypeptide in the parabrachial nuclei of the human brain

The immunocytochemical localizations of corticotropin-releasing factor (CRF), somatostatin (SRIF), and vasoactive intestinal polypeptide (VIP) were studied in the human parabrachial nuclei (PBN) using the avidin-biotin complex (ABC) technique. The brains were obtained from seven adult male human subjects of 38-74 years. In three cases, the brains were fixed within 2 hr, in four cases within 5 hr, postmortem. All of these peptides were detected in fibers through the orocaudal extent of the lateral PBN, whereas the medial nucleus contained only CRF immunoreactive fibers. Immunoreactive fibers were distributed unevenly within the lateral nucleus with the highest density in the dorsal and much fewer in the ventral part of the lateral subdivision. The highest to lowest density of immunostained processes were detected using CRF, SRIF, and VIP antisera, respectively. Since NPB is known as an important relay nucleus for the central autonomic pathway, the presence of the above noted neuropeptides in nerve fibers in this area may suggest a neurotransmitter or neuromodulatory role of CRF, somatostatin, and VIP in certain autonomic nervous mechanism of the human brain.     

Lateral parabrachial nucleus lesions in the rat: neophobia and conditioned taste aversion

The present study investigated the hypothesis that the conditioned taste aversion (CTA) deficit consequent to lesions of the lateral parabrachial nucleus (LPBN) may be due to a disruption of neophobia. In Experiment 1, subjects were tested with one of three taste stimuli (alanine, saccharin, or quinine) and two nontaste stimuli (capsaicin and almond odor). Ibotenic acid lesions of the LPBN eliminated neophobia to alanine and saccharin but had no influence on the neophobic response to quinine, capsaicin, or almond odor. In Experiment 2, all the LPBN-lesioned (LPBNX) rats failed to develop a CTA. These results do not support the experimental hypothesis. Not only was the lesion-induced disruption of neophobia restricted to taste stimuli, the deficit was selective within that category. It is already known that LPBNX rats are unable to acquire conditioned aversions to capsaicin as well as alanine. Thus, the absence of a conditioned ingestional aversion in LPBNX rats is not predicated upon the absence of a neophobic response to the target stimulus. The present results, although exposing a stimulus selective disruption of neophobia, suggest that this deficit is independent of, rather than responsible for, the absence of conditioned ingestional aversions in rats with LPBN lesions.     

Corticofugal effects on the activity of thalamic taste cells

To examine corticofugal influences on afferent thalamic cell responses in the gustatory system, effects of cortical conditioning stimuli on the responses of thalamic taste cells to peripheral stimulation were examined in the rat. Two types of excitability change of thalamic cells were observed; one is inhibitory (for about 60 msec) (20%) and the other is inhibitory (for about 10 msec)-facilitatory (for about 60 msec) (40%) to conditioning stimulus applied to the ventral gustatory area, and half of the cells belonging to the latter type also showed a similar pattern with more marked and prolonged excitability changes to conditioning stimulus applied to the dorsal gustatory area. It was suggested that some of the response characteristics of thalamic and cortical taste cells were attributed to the corticofugal feedback loop.