小鼠脊神经节内P2X2、P2X3受体与降钙素基因相关肽和植物凝集素结合位点的共存

目的:研究小鼠脊神经节内ATP受体P2X2、P2X3与降钙素基因相关肽(CGRP)、植物凝集素IB4(IB4)结合位点的共存。方法:在成年c57/6小鼠脊神经节,用免疫组织化学荧光三标方法结合激光共聚焦显微镜技术观察。结果:脊神经节内可见大量P2X2、P2X3阳性细胞和纤维;P2X2阳性细胞多为大型和小型神经元,P2X3阳性细胞多为小型神经元;有34.2%±3.9%P2X2阳性细胞含有CGRP;但只有4.6%±1.1%P2X3阳性神经元含有CGRP。许多感觉神经元结合IB4;有62.4%±4.3%P2X2和89.5%±4.1%P2X3阳性神经元分别结合IB4。未观察到P2X2/CGRP/IB4或P2X3/CGRP/IB4三标神经元。结论:小鼠脊神经节内P2X2、P2X3的表达与IB4结合位点之间密切相关,部分P2X2受体与CGRP共存。     

VR1与CGRP和IB4在大鼠结状神经节和岩神经节内的共存

应用免疫荧光组织化学三标方法结合激光共聚焦显微镜技术研究了辣椒素受体(VR1)在大鼠舌咽神经和迷走神经内脏感觉神经节结状神经节(NG)和岩神经节(PG)内的表达,以及与降钙素基因相关肽(CGRP)、植物凝集素(IB4)的共存。结果显示:VR1在NG和PG内中、小型神经元胞体和神经纤维存在广泛的表达。许多VR1阳性神经元呈IB4阳性或与CGRP共存。在NG,CGRP阳性神经元数量较少,约有71.4%±3.8%VR1阳性神经元与IB4共存,只有7.1%±1.2%VR1阳性细胞与CGRP共存。PG内CGRP阳性神经元胞体数量较多,有55.7%±3.1%VR1阳性神经元与IB4共存;有38.7%±2.7%VR1阳性细胞同时呈CGRP阳性。两个神经节内IB4/CGRP双标神经元或VR1/CGRP/IB4三标神经元数量稀少。上述结果提示舌咽神经和迷走神经内脏感觉神经节内存在VR1/IB4和VR1/CGRP两种不同的与伤害性刺激相关的VR1阳性神经元亚群。     

大鼠咬肌内P2X_3受体阳性神经纤维来自三叉神经节神经元

目的:观察咬肌内是否有表达P2X3受体的神经纤维,并追踪这些P2X3受体阳性神经纤维的来源。方法:将10只SD大鼠随机分为免疫组化组和HRP示踪组,每组5只。免疫组化组用于分别观察咬肌和三叉神经节(TG)内P2X3受体阳性纤维和神经元的分布;HRP示踪组用于观察将HRP注入咬肌后P2X3受体/HRP双标神经元在TG内的分布。结果:咬肌内有少量神经纤维表达P2X3受体;TG内P2X3受体阳性神经元的数量约占细胞总数的50.4%±1.3%;TG内有21.7%的HRP标记神经元表达P2X3受体,P2X3受体/HRP双标神经元的胞体主要定位于TG的外侧部。结论:P2X3受体可能参与咬肌疼痛信息向中枢的传递。     

香草酸受体亚型Ⅰ与降钙素基因相关肽和植物凝集素结合位点在大鼠脊神经节内感觉神经元的共存

目的:研究香草酸受体亚型Ⅰ(VR1)在大鼠脊神经节(DRG)内感觉神经元的表达.及与降钙素基因相关肽(CGRP)、植物凝集素(IB4)结合位点的共存,为探讨VR1在伤害性感觉刺激信号传导中的作用提供形态学依据.方法:应用免疫荧光组织化学三标方法结合激光共聚焦扫描显微镜技术观察VR1与CGRP和IB4结合位点在DRG的分布及相互关系.结果:背根节内可见大量中、小型神经元胞体和神经纤维表达VR1,一群独特的VR1阳性特小神经元胞体(直径8～11 μm)呈荧光强阳性.荧光双标显示背根节内许多VR1阳性神经无与CGRP共存或结合IB4,而CGRP/IB4双标神经元数量稀少.有41.1%±3.2%VR1阳性细胞呈CGRP阳性,有54.9%±3.8%VR1阳性神经元结合IB4.VR1强荧光特小神经元胞体未见CGRP阳性标记或结合IB4.VR1/CGRP/IB4三标神经元数量较少,只有1.5%±1.1% VR1阳性神经元同时呈CGRP阳性并结合IB4.结论:背根节内可能存在VR1/CGRP与VR1/IB4两种不同的与伤害性刺激相关的VR1阳性神经元亚群.     

内脏伤害性传入信息向三叉神经脊束间质核的投射

舌咽、迷走神经向三叉神经脊束间质核的投射纤维除传递非伤害性内脏信息者外是否也含内脏伤害性传入？尚未见报道。本文综合应用：（1）福尔马林刺激舌咽、迷走神经支配的一些内脏诱导FOS蛋白表达；（2）抽除外周神经节观察三叉神经脊束间质核内一些与伤害性信息传递有关的神经递质的变化；（3）运用荧光金逆行追踪与免疫组化相结合的双重反应等方法，对大鼠投射至三叉神经脊束间质核的舌烟、迷走神经初级传入纤维中是否含传递伤害性刺激信息的成分进行了研究。结果证明：(1)2％福尔马林刺激大鼠软腭、咽、食道和胃后，三叉神经脊束间质核内有大量FOS阳性神经元表达，这些阳性神经元与舌咽、迷走神经初级传入分布区基本一致。（2）抽除一侧舌咽、谈走神经报及其神经节后，术侧三叉神经脊束间质核内SP、CGRP等和痛传递有关的神经肽及BSI-B_4阳性终末与对侧比较明显减少。（3）荧光金微量注入三叉神经脊束间质核后，在舌咽、迷走神经节的下节内发现被荧光金逆标的细胞中分别有10％和12％呈SP、CGRP阳性，此两种双重阳性细胞分别占SP、CGRP阳性细胞的33．3%和278％。以上结果提示，三叉神经脊束间质核接受舌咽、迷走神经的传入纤维中有一部分传递内脏伤害性信息。     

表达在爪蟾卵母细胞上的大鼠P2X_4受体介导的ATP-激活电流特征

本研究应用显微注射和双电极电压钳技术对P2X4受体介导的三磷酸腺苷(ATP)-激活电流(IATP)的特征进行了研究。结果显示:(1)大鼠P2X4受体可高效表达于非洲爪蟾卵母细胞;(2)外加1μmol/L、10μmol/L和100μmol/LATP,IATP激活相的时间常数τon分别是3.58s±0.20s、2.30s±0.21s和1.3s±0.14s。IATP快失敏相的时间常数τdes分别是11.74s±0.11s、7.52s±0.24s和4.11s±0.18s。IATP慢失敏相的时间常数τoff分别为14.25s±2.30s、25.42s±4.45s和35.71s±5.92s;(3)ATP作用的量-效关系:EC50为(16.03±1.81)μmol/L,Hill系数为1.02±0.09;(4)100μmol/L的PPADS和suramin不改变IATP的幅值;(5)IATP呈电压依赖性和内向整流特性;(6)加药时间分别为20s、30s、45s和60s的情况下,IATP幅值并无显著性差异。以上结果说明了P2X4受体介导的ATP-激活电流的特征,为进一步研究P2X4受体的功能和调控机制奠定了基础。     

大鼠咽黏膜内ATP受体P2X3阳性感觉纤维的分布

目的 研究大鼠咽黏膜内三磷酸腺苷(ATP)受体P2X₃阳性感觉纤维的分布,为探究ATP在咽黏膜感觉信号传导中的作用提供形态学依据。 方法 成年Wistar大鼠12只,应用免疫荧光组织化学双标技术结合激光扫描共焦显微镜。 结果 1.在咽黏膜各部位均可观察到P2X₃阳性感觉纤维,纤维分为两类：一类为串珠样游离神经纤维;另一类纤维在黏膜内发出分支并形成复杂的树枝状末梢,纤维分支在黏膜内形成神经丛。2.可见许多降钙素基因相关肽（CGRP）阳性纤维缠绕在P2X₃阳性树枝状末梢周围,并有少量的串珠样P2X₃阳性纤维与CGRP共存。3.在岩神经节内可观察到许多P2X₃或CGRP免疫阳性神经元,其中有少量神经元同时呈P2X₃/CGRP免疫阳性。 结论 大鼠咽黏膜内不同类型的感觉纤维均表达ATP受体P2X₃阳性,提示ATP可能与咽黏膜伤害性刺激和其他生理性刺激向中枢的传递有关。     

囊泡膜谷氨酸转运体与ASIC3或TRPV1在大鼠结状神经节内的共存研究(英文)

为了探讨囊泡膜谷氨酸转运体(VGluTS)与酸敏感离子通道亚基3(ASIC3)或瞬时感受器电位香草酸亚型1(TRPV1)样阳性产物在大鼠迷走神经结状神经节(nodoseganglia,NG)内的分布和共存,本研究采用免疫荧光组织化学双重标记技术,在激光共聚焦显微镜下观察了大鼠NG内VGluT1或VGluT2分别与ASIC3或TRPV1的共存情况。结果显示:(1)在NG内,VGluT2、ASIC3和TRPV1主要见于中、小型神经元的胞浆内,大型神经元少见,而VGluT1阳性神经元数量较少,主要见于大型或中型神经元;(2)部分VGluT2阳性神经元同时显示ASIC3或TRPVl免疫活性,其中VGluT2/ASIC3双标神经元分别占VGluT2阳性神经元的43.06%,占ASIC3阳性神经元的58.74%;而VGluT2/TRPVl双标神经元分别占VGluT2或TRPVl阳性神经元的5617%和51.12%;(3)VGluTI与ASIC3或TRPV1双标神经元的数量很少,不到1%。以上结果提示,VGluT2主要存在于NG内中、小型神经元,这些神经元通常被认为是内脏伤害性信息的初级感受神经元,因而VGluT2分别与ASIC3或TRPVl的共存表明它们可能与内脏伤害性信息的产生和传递密切相关。     

β—淀粉样蛋白31—35和载脂蛋白E4对大鼠海马神经元存活和生长的影响

目的 :研究 β 淀粉样蛋白 (Betaamyloidpritein ,Aβ)与载脂蛋白E4(ApolipoproteinE ,ApoE4)对神经元的共同作用 ,探讨老年性痴呆发病的细胞分子机制。材料与方法 :体外培养神经细胞 ,采用MTT比色法和免疫组化标记 ,结合图像分析技术 ,研究Aβ3 1 3 5和ApoE4对海马神经元存活和生长的作用。结果 :(1 )Aβ3 1 3 5(1 0 0 μmol/L) +ApoE4(1 0 μg/ml)和Aβ3 1 3 5(2 0 μmol/L) +ApoE4(1 0 μg/ml)的OD值 ,分别为 0 .1 97± 0 .0 2 1和 0 .1 91± 0 .0 2 4,明显低于对照组 0 .2 2 9± 0 .0 0 3 μm(P <0 .0 5 )。 (2 )这两组神经元胞体的最长径分别为 1 0 .0 7± 1 .98μm和 1 0 .0 1± 1 .68μm ;最短径分别为 6.40± 0 .77μm ,6.2 8± 0 .89μm ,明显低于对照组 1 2 .73± 3 .0 0 μm、7.0 5± 1 .0 4μm ,Aβ3 1 3 5组 1 2 .0 9± 2 .45 μm、7.0 1± 1 .0 2 μm ,最长径和最短径 (P <0 .0 5 ) ;(3 )两组神经元突起平均长度分别为 2 6.3 6± 7.73 μm和2 3 .86± 7.2 9μm ,明显低于对照组 3 0 .88± 9.79μm、2 8.3 4± 4.40 μm ,P <0 .0 5。 (4 )Aβ3 1 3 5(2 0 μmol/L)组的平均突起长度 (2 6.81± 5 .42 μm) ,明显低于对照组和ApoE4组 3 0 .60± 7.3 0 μm(P <0 .0 5 )。ApoE4对海马神经元的存     

P2X_2和P2X_3受体在小鼠咽粘膜味蕾内的分布

应用免疫组织化学双标记技术研究ATP受体的P2X2和P2X3受体亚型在小鼠咽部粘膜味蕾和邻近组织内的分布,探究ATP在咽部味觉及一般感觉信号传导中的作用。在咽部各水平粘膜味蕾内均可观察到许多P2X2受体阳性味细胞和基细胞,未见P2X2受体阳性的神经纤维。许多降钙素基因相关肽(CGRP)阳性神经纤维围绕在味蕾周围,并发出分支与P2X2受体阳性味细胞和基细胞形成密切接触。P2X3受体多在咽部粘膜上皮味蕾内的神经终末表达,P2X3受体阳性纤维在粘膜基底部形成纤维束并与粘膜下P2X3受体阳性纤维相连,其分支在味蕾基底部形成神经丛,由神经丛发出神经终末到达顶部的味孔和味蕾各部,未见味蕾细胞表达P2X3受体。在无味蕾的粘膜上皮内,也观察到少量P2X3受体阳性神经终末。CGRP阳性纤维缠绕在味蕾周围,并发出分支与味蕾内的P2X3受体阳性纤维形成密切接触。上述结果表明ATP可能是咽粘膜内味觉信号感受与传导的神经递质。     

P2X receptors in peripheral neurons

P2X receptors are a family of ligand-gated ion channels, activated by extracellular ATP. The seven subunits cloned (P2X1-7) can assemble to form homomeric and heteromeric receptors. Peripheral neurons of neural crest origin (e.g. those in dorsal root, trigeminal, sympathetic and enteric ganglia) and placodal origin (e.g. those in nodose and petrosal ganglia) express mRNAs for multiple P2X subunits. In this review, we summarize the molecular biological, electrophysiological and immunohistochemical evidence for P2X receptor subunits in sensory, sympathetic, parasympathetic, pelvic and myenteric neurons and adrenomedullary chromaffin cells. We consider the pharmacological properties of these native P2X receptors and their physiological roles. The responses of peripheral neurons to ATP show considerable heterogeneity between cells in the same ganglia, between ganglia and between species. Nevertheless, these responses can all be accounted for by the presence of P2X2 and P2X3 subunits, giving rise to varying proportions of homomeric and heteromeric receptors. While dorsal root ganglion neurons express predominantly P2X3 and rat sympathetic neurons express mainly P2X2 receptors, nodose and guinea-pig sympathetic neurons express mixed populations of P2X2 and heteromeric P2X2/3 receptors. P2X receptors are important for synaptic transmission in enteric ganglia, although their roles in sympathetic and parasympathetic ganglia are less clear. Their presence on sensory neurons is essential for some processes including detection of filling of the urinary bladder. The regulation of P2X receptor expression in development and in pathological conditions, along with the interactions between purinergic and other signalling systems, may reveal further physiological roles for P2X receptors in autonomic and sensory ganglia.     

Gene expression for peptides in neurons of the petrosal and nodose ganglia in rat

Summary In situ hybridization was used to determine whether genes for neuropeptides [substance P/neurokinin A (SP/NKA), calcitonin gene-related peptide (CGRP), somatostatin (SOM), neuropeptide tyrosine (NPY) and cholecystokinin (CCK)] are expressed in inferior ganglia of the vagus (nodose) and glossopharyngeal (petrosal) nerves. Synthetic oligodeoxyribonucleotides, complementary to the cognate, mRNAs were labeled with [³²P] or [³⁵S], and hybridized to 10 m thick sections of unperfused tissue which were then processed for film and emulsion autoradiography. We found numerous, clustered neuronal perikarya throughout the nodose and petrosal ganglia that expressed preprotachykinin A (SP/NKA) and CGRP mRNAs to varying degrees. Neurons expressing preproSOM mRNA were less abundant and more scattered throughout both ganglia. Notably, we found mRNA for NPY in cells (usually 5–10 per section) in both ganglia. To our knowledge, this is first evidence for NPY in these sensory ganglia. In contrast to previous immunohistochemical findings, we found no evidence for expression of preproCCK in either the nodose or petrosal ganglia. The present findings demonstrate that cells of the nodose and petrosal ganglia express the genes for a number of neuropeptides that are presumably involved with transmission of visceral sensory afferent information to higher order neurons of the central nervous system.     

Immunohistochemical study of neuropeptides in vagal and glossopharyngeal afferent neurons in the rat

The presence and distribution of multiple neuropeptides in vagal and glossopharyngeal afferent ganglia of the rat were studied using immunohistochemistry. Substance P-, calcitonin-gene related peptide-, cholecystokinin-, neurokinin A-, vasoactive intestinal polypeptide-, and somatostatin-immunoreactive neurons were detected in each visceral afferent ganglion. Neurotensin-immunoreactive cells were not observed. In the nodose ganglion (inferior ganglion of the vagus nerve) occasional immunoreactive cells were scattered throughout the main (caudal) portion of the ganglion with small clusters of cells seen in the rostral portion. The pattern of distribution of the various peptides in the nodose ganglion was similar, with the exception of vasoactive intestinal polypeptide-immunoreactive neurons which exhibited a more caudal distribution. The relative numbers of immunoreactive cells varied, with the greatest numbers being immunoreactive for substance P or vasoactive intestinal polypeptide, and the lowest numbers being immunoreactive for neurokinin A and somatostatin. A build-up of immunoreactivity for each of the peptides, except somatostatin and neurotensin, was detected in vagal nerve fibers of colchicine-injected ganglia. Numerous peptide-immunoreactive cells were also found in the petrosal (inferior ganglion of the glossopharyngeal nerve) and jugular (superior ganglion of the vagus nerve) ganglia. No specific intraganglionic distribution was noted although the relative numbers of cells which were immunoreactive for the different peptides varied considerably. Substance P and calcitonin-gene related peptide were found in large numbers of cells, cholecystokinin was seen in moderate numbers of cells, and neurokinin A, vasoactive intestinal polypeptide and somatostatin were seen in fewer cells. These data provide evidence for the presence and non-uniform distribution of multiple peptide neurotransmitters in vagal and glossopharyngeal afferent neurons. In general, relatively greater numbers of immunoreactive cells were located in the rostral compared with caudal nodose ganglion, and in the petrosal and jugular ganglia compared with the nodose ganglion. Thus, multiple neuropeptides may be involved as afferent neurotransmitters in the reflexes mediated by vagal and glossopharyngeal sensory nerves.     

Calcitonin gene-related peptide immunoreactive sensory neurons in the vagal and glossopharyngeal ganglia innervating the larynx of the rat

We have examined whether calcitonin gene-related peptide-immunoreactive (CGRP-ir) neurons in the vagal and glossopharyngeal ganglia innervate the larynx. Many CGRP-ir neurons were located mostly in the superior glossopharyngeal–jugular ganglion complex that was fused the superior glossopharyngeal ganglion and the jugular ganglion in the cranial cavity. When Fluorogold was applied to the cut end of the superior laryngeal nerve (SLN) or the recurrent laryngeal nerve (RLN), many Fluorogold-labeled neurons were found in the superior glossopharyngeal–jugular ganglion complex and the nodose ganglion. Double-labeling for CGRP and Fluorogold showed that about 80% of Fluorogold-labeled neurons in the superior glossopharyngeal–jugular ganglion complex expressed CGRP-like immunoreactivity in the case of application to the SLN, and about 50% of Fluorogold-labeled neurons expressed CGRP-like immunoreactivity in the case of the RLN. Only a few double-labeled neurons were found in the nodose ganglion. The number of the Fluorogold-labeled neurons and double-labeled neurons in the superior glossopharyngeal–jugular ganglion complex in the case of the SLN was larger than that in the case of the RLN. These results indicate that sensory information from the larynx might be conveyed by many CGRP-ir neurons located in the superior glossopharyngeal–jugular ganglion complex by way of the SLN and the RLN.     

Localization of P2X2 and P2X3 receptors in rat trigeminal ganglion neurons

Purine receptors have been implicated in central neurotransmission from nociceptive primary afferent neurons, and ATP-mediated currents in sensory neurons have been shown to be mediated by both P2X3 and P2X2/3 receptors. The aim of the present study was to quantitatively examine the distribution of P2X2 and P2X3 receptors in primary afferent cell bodies in the rat trigeminal ganglion, including those innervating the dura. In order to determine the classes of neurons that express these receptor subtypes, purine receptor immunoreactivity was examined for colocalization with markers of myelinated (neurofilament 200; NF200) or mostly unmyelinated, non-peptidergic fibers (Bandeiraea simplicifolia isolectin B4; IB4). Forty percent of P2X2 and 64% of P2X3 receptor-expressing cells were IB4 positive, and 33% of P2X2 and 31% of P2X3 receptor-expressing cells were NF200 positive. Approximately 40% of cells expressing P2X2 receptors also expressed P2X3 receptors and vice versa. Trigeminal ganglion neurons innervating the dura mater were retrogradely labeled and 52% of these neurons expressed either P2X2 or P2X3 or both receptors. These results are consistent with electrophysiological findings that P2X receptors exist on the central terminals of trigeminal afferent neurons, and provide evidence that afferents supplying the dura express both receptors. In addition, the data suggest specific differences exist in P2X receptor expression between the spinal and trigeminal nociceptive systems.     

Intraepithelial vagal sensory nerve terminals in rat pulmonary neuroepithelial bodies express P2X(3) receptors

The neurotransmitters/modulators involved in the interaction between pulmonary neuroepithelial bodies (NEBs) and the vagal sensory component of their innervation have not yet been elucidated. Because P2X(3) purinoreceptors are known to be strongly expressed in peripheral sensory neurons, the aim of the present study was to examine the localization of nerve endings expressing P2X(3) purinoreceptors in the rat lung in general and those contacting pulmonary NEBs in particular. Most striking were intraepithelial arborizations of P2X(3) purinoceptor-immunoreactive (IR) nerve terminals, which in all cases appeared to ramify between calcitonin gene-related peptide (CGRP)- or calbindin D28k (CB)-labeled NEB cells. However, not all NEBs received nerve endings expressing P2X(3) receptors. Using CGRP and CB staining as markers for two different sensory components of the innervation of NEBs, it was revealed that P2X(3) receptor and CB immunoreactivity were colocalized, whereas CGRP-IR fibers clearly formed a different population. The disappearance of characteristic P2X(3) receptor-positive nerve fibers in contact with NEBs after infranodosal vagal crush and colocalization of tracer and P2X(3) receptor immunoreactivity in vagal nodose neuronal cell bodies in retrograde tracing experiments further supports our hypothesis that the P2X(3) receptor-IR nerve fibers contacting NEBs have their origin in the vagal sensory nodose ganglia. Combination of quinacrine accumulation in NEBs, suggestive of the presence of high concentrations of adenosine triphosphate (ATP) in their secretory vesicles, and P2X(3) receptor staining showed that the branching intraepithelial P2X(3) receptor-IR nerve terminals in rat lungs were exclusively associated with quinacrine-stained NEBs. We conclude that ATP might act as a neurotransmitter/neuromodulator in the vagal sensory innervation of NEBs via a P2X(3) receptor-mediated pathway. Further studies are necessary to determine whether the P2X(3) receptor-expressing neurons, specifically innervating NEBs in the rat lung, belong to a population of P2X(3) receptor-IR nociceptive vagal nodose neurons.     

Intraganglionic laminar endings in the rat esophagus contain purinergic P2X2 and P2X3 receptor immunoreactivity

Intraganglionic laminar endings (IGLEs) represent the most prominent vagal afferent terminal structures throughout the gastrointestinal tract. They are most prominent in the esophagus and stomach, but can be found down to the distal colon. Their role as mechanosensors as proposed on anatomical grounds was recently substantiated in elegant functional experiments. There is evidence that vagal mechanosensors in the esophagus and stomach respond to ATP. Thus, the present study aimed at detecting purinergic receptors on IGLEs. IGLEs in the rat esophagus were identified by immunohistochemistry for calretinin and sections were co-incubated with antibodies directed against P2X₂ or P2X₃ receptors. Also, double label immunocytochemistry for purinergic receptors and calcitonin gene-related peptide as a marker for spinal afferents was performed. Terminal nerve fibers immunoreactive for P2X₂ and P2X₃, respectively, were observed between outer and inner layers of the tunica muscularis, covering myenteric ganglia totally or partly. Both P2X₂ and P2X₃ receptor immunoreactivities were highly co-localized with calretinin positive IGLEs as shown by confocal laser scanning microscopy. Numerous calcitonin gene-related peptide immunostained fibers were found to closely approach and intermingle with P2X immunopositive IGLEs. However, there was never co-staining for either of the purinergic receptors and calcitonin gene-related peptide within the same fibers. P2X₃ but not P2X₂ immunoreactivity was also observed within nerve fiber arborizations in the mucosa of the pharynx. In the nodose ganglion, 8.9±1.1% of P2X₂ and 7.2±1.3% of P2X₃ immunopositive neurons, respectively, co-stained for calretinin. On the other hand, 63.4±4.6% and 60.1±5.3% of calretinin positive cell bodies contained P2X₂ and P2X₃ receptor immunoreactivity, respectively. These results indicate that IGLEs are equipped with both P2X₂ and P2X₃ receptors. Thus, they may act as chemosensors or their mechanosensory properties may be modulated by ATP. It is also suggested that spinal afferents innervating the esophagus are equipped with neither P2X₂ nor P2X₃ purinergic receptors.     

Occipital artery injections of 5-HT may directly activate the cell bodies of vagal and glossopharyngeal afferent cell bodies in the rat

The primary objective of this study was to determine whether circulating factors gain direct access to and affect the activity of vagal afferent cell bodies in the nodose ganglia and glossopharyngeal afferents cell bodies in the petrosal ganglia, of the rat. We found that the occipital and internal carotid arteries provided the sole blood supply to the nodose ganglia, and that i.v. injections of the tracer, Basic Blue 9, elicited strong cytoplasmic staining in vagal and glossopharyngeal afferent cell bodies that was prevented by prior ligation of the occipital but not the internal carotid arteries. We also found that occipital artery injections of 5-HT elicited pronounced dose-dependent reductions in heart rate and diastolic arterial blood pressure that were (1) virtually abolished after application of the local anesthetic, procaine, to the ipsilateral nodose and petrosal ganglia, (2) markedly attenuated after transection of the ipsilateral vagus between the nodose ganglion and brain and virtually abolished after subsequent transection of the ipsilateral glossopharyngeal nerve between the petrosal ganglion and the brain, (3) augmented after ipsilateral transection of the aortic depressor and carotid sinus nerves, and (4) augmented after transection of all ipsilateral glossopharyngeal and vagal afferent nerves except for vagal cardiopulmonary afferents. These findings suggest that blood-borne 5-HT in the occipital artery gains direct access to and activates the cell bodies of vagal cardiopulmonary afferents of the rat and glossopharyngeal afferents of undetermined modalities.