Coexistence of peptide immunoreactivity in sensory neurons of the cat

The coexistence of the neuropeptides substance P, cholecystokinin, somatostatin and vasoactive intestinal polypeptide in cat sensory neurons has been examined using peroxidase-anti-peroxidase immunocytochemistry. Attempts were also made to locate cells containing bombesin, neurotensin, [Met]enkephalin and [Leu]enkephalin but no immunoreactivity was found when antisera to these peptides was used. Cells in the dorsal root ganglia were studied by cutting 5 microns serial wax sections or 15 microns cryostat sections. Coexistence was established by applying the antiserum to each peptide to serially adjacent 5 microns sections and establishing the presence of peptide-like immunoreactivity in each of 4 different sections through a single cell. Results showed that the distribution and combinations of coexistence of these neuropeptides in the cat is extremely complex; three and sometimes all four antisera showing immunoreactivity with a single cell. About 21% of all ganglion cells contained some immunoreactivity but there were certainly some small cells which did not contain any immunoreactivity. The coexistence of these peptides differed markedly from that previously reported in the rat suggesting that interspecific differences in the neuropeptide content of cells might be much greater than they are for classical neurotransmitters. The results are discussed in relation to the possible role of neuropeptides and the regulation of their production by sensory neurons.     

Immunohistochemical studies of substance P, cholecystokinin-octapeptide and somatostatin in dorsal root ganglia of the rat

Immunofluorescence histochemistry was used to determine the distribution of substance P, somatostatin and cholecystokinin-octapeptide-immunoreactive perikarya in C6, T6, T10, L2 and S1 dorsal root ganglia of rat. Five different categories of immunoreactive primary afferent neurons were distinguished on the basis of cell size, cytology and peptide immunoreactivities. The population of small cells (diameter less than 20 microns) included three groups which were identified as containing somatostatin, substance P, or substance P + cholecystokinin-octapeptide. Two groups of cells were identified in an intermediate size range (diameter 21-43 microns) as containing cholecystokinin-octapeptide or cholecystokinin-octapeptide + substance P. These categories may reflect four distinct populations of primary afferent neurons. The relative abundance of dorsal root ganglion cells containing substance P, cholecystokinin-octapeptide or somatostatin immunoreactivities was significantly different within segmental levels. More neurons were immunoreactive for cholecystokinin-octapeptide than substance P in ganglia C6, T6 and T10. Somatostatin-containing cells were fewest in number regardless of level. The number of immunoreactive cells also varied among spinal ganglia. L2 contained the greatest number of immunoreactive cells; S1 contained the fewest. These studies are relevant to our understanding of dorsal root ganglia in two ways. Firstly, the data document significant variation in the distribution of peptide-containing neurons among spinal ganglia associated with various cord levels. The variation in peptide-containing cell populations among spinal ganglia may reflect differences in populations of modality-specific primary afferent fibers as well as in populations of somatic and visceral primary afferent fibers at each level. Furthermore, the data indicate that the relative abundance of a population of peptide-containing primary afferent neurons cannot be extrapolated from the examination of spinal ganglia from a single level. Secondly, substance P and cholecystokinin-octapeptide did not co-exist in all spinal ganglion cells as previously reported. In conjunction with immunostaining characteristics and cell size, the differential distribution of the two peptides defined four cell types, raising the possibility that each cell type may mediate a different modality.     

Ultrastructural cytochemical localization of carbonic anhydrase activity in rat peripheral sensory and motor nerves, dorsal root ganglia and dorsal column nuclei

Some of the myelinated axons in rat peripheral nerves possess marked axoplasmic carbonic anhydrase activity [Riley, Ellis and Bain (1982) J. Histochem. Cytochem. 30, 1275-1288; Riley and Lang (1984) J. Hand Surg. 9A, 112-120]. A mixture of reactive and nonreactive neurons was a general observation in cervical, thoracic and lumbar ganglia. Nonmyelinated axons in lumbar dorsal roots were nonreactive; this was consistent with the lack of carbonic anhydrase in small sensory neurons. The carbonic anhydrase cytochemical method marked the larger afferent or sensory neurons and distinguished them from the smaller sensory neurons which were devoid of carbonic anhydrase activity. Nonmyelinated axons in the lumbar ventral roots were also nonreactive. Examination of muscle spindle innervation revealed staining of the primary sensory and gamma motor endings. This was strongly suggestive that some of the reactive sensory neurons were primary afferents and a portion of the reactive ventral root axons were gamma motor. The reactive central processes of spinal neurons sent collaterals into the grey matter of the spinal cord, entered the dorsal funiculi, and terminated in synaptic glomeruli in the cuneate and gracilis nuclei. Oligodendroglial cells appeared to be the only intrinsic cellular elements of the brain stem and spinal cord that exhibited high carbonic anhydrase activity. Both oligodendroglial and Schwann cells exhibited intense carbonic anhydrase activity in thin pockets of cytoplasm internal to compact myelin. The subcellular distribution of reaction product within sensory neurons and oligodendroglial cells agreed with biochemical reports of cytosol and membrane-bound forms of carbonic anhydrase. A general staining of the cytoplasm was suggestive of soluble carbonic anhydrase fixed in situ by the glutaraldehyde. Clumps of reaction product on the cytoplasmic surface of the endoplasmic reticulum possibly represented membrane-bound enzyme. Most of the membrane-bound carbonic anhydrase was associated with the internal membranes rather than the axolemma or limiting plasma membrane of the axon. In contrast to biochemical reports, a small fraction of neuronal mitochondria exhibited staining in the intracristal spaces. We suggest that the association of carbonic anhydrase with endoplasmic reticulum and mitochondria implicates the enzyme in regulating intracellular calcium because both organelles are known to sequester calcium.     

Actions of opiates, substance P, and serotonin on the excitability of primary afferent terminals and observations on interneuronal activity in the neonatal rat's dorsal horn in vitro

Approximately 5 segments of lumbo-thoracic spinal cord together with connected dorsal root ganglia were removed from 1-11-day-old rats and maintained in vitro. Dorsal root afferents, recorded from the ganglion and stimulated at the root entry zone, had conduction velocities typical of unmyelinated fibers (less than 2 m/s). The spinal terminals of individual afferents showed increased excitability with bath application of substance P and serotonin and decreased excitability with morphine sulfate, [D-ala2]methionine-enkephalinamide, manganese ions and magnesium ions. Naloxone by itself elicited no change in excitability, although it appeared to reduce the ongoing effect of opiates. Neurons recorded extracellularly in the dorsal horn responded to afferent volleys with one or more of 3 distinct phases: an excitation roughly coincident with the volley's arrival, a 50-300 ms period of inhibition, and a late excitation of 150-300 ms latency. The excitability results are accounted for by a model in which substance P, gamma-aminobutyric acid and possibly other depolarizing agents are contained in interneurons which synapse on afferent terminals. These interneurons could receive inhibitory enkephalinergic input, and, in the neonate but not the adult, excitatory serotoninergic input. An alternate scheme would have enkephalin and serotonin acting directly on afferent terminals, although perhaps by non-synaptic diffusion since the appropriate synapses have not been seen in histochemical studies. Such an action for enkephalin might explain the existence of opiate receptor on afferent terminals. The interneuronal responses to afferent volleys are parallel in most aspects to those found in the dorsal horns of adult mammals in vivo.     

Local application of capsaicin to one sciatic nerve of the adult rat induces a marked depletion in the peptide content of the lumbar dorsal horn

In an earlier study we have shown that local application of capsaicin directly to one sciatic nerve induces a decrease of substance P and cholecystokinin octapeptide (CCK8)-like peptide from the dorsal spinal cord using immunocytochemical analysis.¹ Here the effect of locally applied capsaicin on seven peptides known to be present in the L4 segment was assessed by radioimmunoassay and immunocytochemistry. The peptides investigated were substance P, somatostatin and CCK8-like peptide (which are present in small diameter primary afferent fibres), neurotensin, enkephalin (which are intrinsic to the spinal cord), neurophysin (of supraspinal origin) and bombesin (whose origin is unknown). Fourteen days after a single application of 49 mM solution of capsaicin a significant depletion of substance P and somatostatin was detected. These results were confirmed by parallel immunocytochemical analysis which localised the dramatic decreases of substance P and somatostatin to lamina 1 and lamina 2. In addition a depletion of CCK8-like immunoreactivity was observed by immunocytochemistry in this area, but quantitative radioimmunoassay of CCK8-like peptide did not detect this depletion. The capsaicin-induced changes were dose-dependent and reversible. Small decreases were noted with concentrations of capsaicin as low as 0.1 mM. The changes were apparent from day 9 onwards, maximal depletion seen by day 14. By 200 days post-operatively, a recovery to normal peptide levels in the ipsilateral dorsal horn was observed. In addition, a significant depletion of cutaneous substance P was noted in the area of the skin innervated by the capsaicin-treated nerve. These changes were accompanied by a significant increase in noxious thermal response (hind paw immersion test, T = 49°C, ipsilateral leg 9.11 ± 1.3 seconds, contralateral leg: 5.1 ± 1.3 seconds, P = < 0.005). The peptides neurotensin, enkephalin, neurophysin and bombesin were not affected by capsaicin treatment.These findings suggest that local application of capsaicin induces an indiscriminate depletion of peptide-containing primary sensory afferent fibres which is dose-dependent, long-lasting, but reversible.     

脊髓背角和背根神经节ERK1/2磷酸化表达在鞘内注射高乌甲素抗大鼠神经病理性疼痛中的作用

目的探讨鞘内注射高乌甲素对神经病理性疼痛大鼠脊髓背角和背根神经节ERK1/2磷酸化(p-ERK1/2)表达的影响。方法将90只SD大鼠随机分为假手术组(S组)、手术组(O组)和高乌甲素(L组)(n=30),建立坐骨神经慢性压迫(chronic constriction injury of sciatic nerve,CCI-SN)模型,术后L组鞘内注射高乌甲素20μg/kg,S组和O组以同样方式注射等体积生理盐水,末次给药后每组又分为术后第4、7和10天三个亚组(n=10);分别于相应时间点测定大鼠机械刺激缩足阈值(paw withdrawal mechanical threshold,PWMT),并采用Western blot技术检测脊髓背角和背根神经节p-ERK1/2的表达。结果与S组相比,O组术后第4、7和10天PWMT值均显著降低(第4、7天:P0.001;第10天:P0.01)。与O组相比,L组术后第4、7和10天PWMT值均明显升高(第4、7天:P0.05;第10天:P0.01)。在脊髓背角和背根神经节中,O组术后第4、7和10天p-ERK1/2表达均明显高于相应S组(脊髓背角:第4、7天,P0.001;第10天,P0.01;背根神经节:第4、10天,P0.01;第7天,P0.001);与O组相比,L组p-ERK1/2水平明显降低(脊髓背角:第4、10天,P0.05;第7天,P0.01;背根神经节:第4、7天,P0.05;第10天,P0.01)。结论鞘内注射高乌甲素能有效缓解CCI-SN大鼠神经病理性疼痛,其机制可能与其抑制脊髓背角和背根神经节中p-ERK1/2的表达有关。     

前列腺酸性磷酸酶在慢性痛大鼠脊髓背角和背根神经节的表达变化

目的:观察前列腺酸性磷酸酶(prostatic acid phosphatase,PAP)在多种慢性痛大鼠脊髓背角(spinaldorsal horn,SDH)和背根神经节(dorsal root ganglion,DRG)内的表达变化。方法:应用免疫组织化学染色法以及免疫荧光多重染色技术在多种慢性痛模型大鼠观察PAP的表达变化。结果:在正常大鼠,PAP阳性反应产物主要位于DRG的中、小型的非肽能神经元,PAP阳性神经元约占DRG神经元总数的64±4.3%;在脊髓背角,PAP阳性纤维和终末主要位于Ⅱ层。在神经病理性痛模型大鼠,术侧脊髓背角Ⅱ层的PAP阳性初级传入终末较对侧减少甚至消失,DRG内PAP阳性神经元较对侧明显减少。在慢性炎性痛模型大鼠,双侧脊髓背角和DRG内PAP的表达未见明显改变。结论:PAP特异地定位于DRG神经元以及脊髓背角Ⅱ层,可能与神经病理性痛信号的传递和加工密切相关。     

大鼠慢性背根节压迫诱致DRG大神经元兴奋性增强和I_h电流显著上调

目的:探讨大鼠CCD模型模拟的腰背痛诱致的DRG大神经元兴奋性改变及其离子通道机制。方法:建立大鼠慢性压迫腰膨大L4/L5 DRG的CCD模型,模拟临床常见的腰背痛的触诱发痛表现。制备整节L4/L5 DRG标本,应用全细胞膜片钳技术记录去极化电流刺激诱致的DRG大型神经元的兴奋性改变及其离子通道机制。结果:对直径50μm的健康的DRG大神经元进行全细胞膜片钳记录。结果显示:给予去极化方波电流刺激可以诱致CCD模型大鼠DRG大神经元呈现兴奋性增强的表现,具体表现为相同刺激强度的电流注射在CCD模型DRG大神经元上诱致的动作电位的频率显著高于对照组神经元。同样的细胞放电增强也见于给予细胞斜波电流刺激。进一步的机制研究分析显示CCD模型大鼠上DRG大神经元的I_h电流明显高于对照组大鼠。结论:CCD模型可以诱致DRG大神经元呈现超兴奋状态,该兴奋性增强的状态主要由I_h电流增强来介导,为认识神经损伤诱致的病理性痛觉敏化尤其是触诱发痛的神经机制提供了实验证据。     

ClC-3在神经病理性痛大鼠脊髓背角及背根神经节的表达及其参与痛行为调控的研究

目的:观察电压门控性氯通道(voltage-gated chloride channel,ClC)3型在腓总神经结扎神经病理性痛模型大鼠脊髓背角(spinal dorsal horn,SDH)和背根神经节(dorsal root ganglion,DRG)内的表达变化及阻断氯离子通道后痛行为的改变。方法:应用免疫组织化学染色法、蛋白印迹法以及痛行为检测观察ClC-3在神经病理性痛大鼠SDH和DRG的变化和作用。结果:在正常大鼠,ClC-3主要位于DRG神经元胞膜;在SDH,ClC-3阳性纤维主要位于Ⅰ层。在腓总神经结扎大鼠,1周内结扎侧背角Ⅰ层及DRG的ClC-3表达增加,2～4周表达逐渐减少,在DRG也观察到相同的现象。给予氯离子通道阻断剂后,腓总神经结扎大鼠的痛阈下降。结论:ClC-3在神经病理性痛早期表达上调,随病程发展逐渐下降;阻断ClC-3可使大鼠痛阈下降。     

Effects of neonatal capsaicin administration on the numbers and volumes of neurons in left and right T10 dorsal root ganglia in the rat

The long-term effects of neonatal capsaicin were studied in left and right dorsal root ganglia (T10) from control and capsaicin-treated groups of Wistar rats. At 12 hours post partum, 5 females per group were injected subcutaneously with capsaicin or vehicle solution and killed at 6 months of age. Tissues were perfusion-fixed, embedded in resin and serially sectioned. A Nissl stain was used to distinguish between A and B neurons and systematic random sampling schemes were employed to obtain stereological estimates of numbers of neurons and mean volumes of their perikarya. Numbers were calculated from ganglion volumes (estimated via the Cavalieri principle) and neuron packing densities (estimated using physical disectors). Mean perikaryal volumes were calculated from packing densities and volume densities (estimated by point counting). Data were analysed to isolate main and interaction effects of neuron subtype, laterality and treatment. There was no evidence of lateral asymmetry or interaction effects. Control ganglia contained 3320 (coefficient of variation, CV, 8%) neurons. Most (73%) were B cells with a mean volume of 13,100 µm³ (CV 17%) of which the nucleus accounted for 1,800 µm³ (CV 18%). About 22% were A cells with a mean volume of 79,800 µm³ (CV 24%) and a nucleus of 6,100 µm³ (CV 26%). After capsaicin, over half the original population of cells was destroyed and B cell loss was significantly greater than that of A cells (about 80% of all cells lost were B cells). The mean size of A cells was greater after capsaicin due to selective loss of smaller cells and a greater volume of cytoplasm. B cell perikaryal volume was not affected but nuclear volume declined. The findings show that capsaicin destruction of peripheral sensory neurons is bilaterally symmetrical. In general, smaller neurons are selectively destroyed but this operates differently in A and B cells. It is size-dependent in A cells but size-independent (possibly random) in B cells.     

TNF-α在CCD模型大鼠背根神经节中的表达及机制

目的:探讨TNF-α和NF-κB在背根神经节慢性压迫(CCD)模型大鼠背根神经节(DRG)中的表达变化及其对疼痛学行为的影响。方法:建立CCD大鼠模型,采用von Frey纤维丝监测机械痛阈的改变;通过Western blotting检测TNF-α和NF-κB在DRG中的表达变化趋势,分析其与疼痛行为之间的相关性;并采用免疫荧光双染技术研究TNF-α在DRG中的表达位置。结果:CCD组的50%机械缩足阈值在术后1 d即开始明显下降(P0.01),7~14 d达到高峰,其后逐渐上升,直至术后35 d仍明显低于术前及sham组(P0.01)。而DRG上的TNF-α及NF-κB于造模后各时点均显著增多(P0.01),且TNF-α的表达趋势与50%机械缩足阈值显著相关(P0.05)。结论:DRG慢性压迫可促进其上的TNF-α和NF-κB的合成和分泌,进而诱发机械痛觉过敏。因此,TNF-α/NF-κB信号通路可能是CCD模型疼痛形成的重要通路之一。     

Immunohistochemical Localization of Substance P And Cholecystokinin in the Dorsal Root Ganglia and Spinal Cord of the Bottlenose Dolphin (Tursiops truncatus)

The presence of substance P (SP) and cholecystokinin (CCK) immunoreactive neurons was examined in the bottlenose dolphin dorsal root ganglia (DRGs) and spinal cord by immunohistochemical techniques. SP‐positive and CCK‐immunoreactive neurons were respectively ～50% and 1% of the total number of ganglion cells examined and especially belonged to small and medium‐sized cell populations. Using double labeling techniques we observed that SP‐ and CCK‐immunoreactivity coexisted in a very low number of primary afferent neurons (2.7%). Few SP‐immunoreactive (IR) neurons (2.7%) were also CCK‐positive. On the contrary, 65% of CCK‐immunoreactive neurons contained SP. Interestingly, we observed CCK‐immunoreactive satellite glial cells located around large cell class somata. Virtually no SP‐IR and CCK‐positive neurons were surrounded by peripheral CCK‐immunoreactive satellite glial cells. The SP‐IR and CCK‐positive nerve fibers were particularly conspicuous in the superficial layers of the spinal cord. The present study indicates that SP and CCK only partially overlap in the thoracic, lumbar, and caudal DRGs of the bottlenose dolphin, suggesting that the majority of SP‐IR ganglion neurons are lacking in CCK‐immunoreactivity. The role of SP‐containing DRG neurons is discussed also in relation to the huge vascular spinal retia mirabilia typical of cetaceans. Anat Rec, 293:477–484, 2010. © 2010 Wiley‐Liss, Inc.     

Cholecystokinin-like immunoreactivity in the dorsal horn of the spinal cord of the rat: a light and electron microscopic study

Cholecystokinin-like immunoreactivity was investigated with an indirect immunoperoxidase technique in the whole spinal cord with the light microscope and in the dorsal horn with the electron microscope. Intraparenchymal injections of colchicine were performed to allow the detection of cholecystokinin-like immunoreactive cell bodies. Rats treated at birth with capsaicin were also studied at the light microscope. Numerous cholecystokinin-like immunoreactive fibres and varicosities were found in the two superficial layers of the dorsal horn and in the intermedio-medial nucleus; cholecystokinin-like immunoreactive cell bodies were also present in these two regions. After neonatal capsaicin treatment, the number of cholecystokinin-like immunoreactive fibres and varicosities was strongly reduced in the dorsal horn. At the electron microscope level, cholecystokinin-like immunoreactivity was localized in numerous neurites often filled with vesicles (axon terminals and dendrites containing vesicles) and in few cell bodies and dendrites. The immunoreaction was found mainly associated with ribosomes, granular reticulum, neurotubules and vesicles. Large granular vesicles were filled with the reaction product whereas small and medium-sized vesicles showed a varying degree of immunoprecipitate around their membrane. In addition dense "granules" of precipitate were observed in numerous presynaptic neurites. Cholecystokinin-like immunoreactive axons were of small calibre and mostly unmyelinated. Cholecystokinin-like immunoreactive axon terminals made asymmetric synaptic contacts with generally unlabelled dendrites or dendritic spines. A single labelled nerve terminal could contact several different dendrites in structures resembling glomeruli. Few axo-somatic synapses but a relatively high number of axo-axonic contacts were seen. About half of these axo-axonic contacts involved pre- and postsynaptic profiles. Both light and electron microscopic observations led us to the conclusion that some of the cholecystokinin-like immunoreactive fibres of the dorsal horn originate in the spinal ganglia via capsaicin-sensitive C afferents; and some from intrinsic neurons, particularly islet cells. Other fibres may come from supraspinal centres, other local neurons or capsaicin-insensitive afferents from the spinal ganglia. The results are discussed with regard to data in the literature, particularly those concerned with the specificity of the cholecystokinin antibodies; it is hypothesized that several types of cholecystokinin-like immunoreactive peptides may be present in the dorsal horn, depending on their origin (supraspinal, intrinsic or peripheral).(ABSTRACT TRUNCATED AT 400 WORDS)     

Substance P in Dorsal Root Ganglion Neurons in Young and Adult Rats,after Nociceptive Stimulation during the Neonatal Period

The nervous system is highly plastic during the neonatal period, being sensitive to noxious stimuli, which may cause short‐ and long‐term pain responsivity changes. Understanding plasticity in peripheral pain pathways is crucial, particularly when the nervous system is still under development and remodeling process. Substance P (SP) is widely used as a marker for peripheral neurons with unmyelinated and small myelinated fibers. We investigated the number of SP immunoreactive neurons in the dorsal root ganglion (DRG) of male and female Wistar rats, 15 and 180 days after nociceptive stimulation during the neonatal period. Right and left 5th lumbar (L5) DRG were incubated in rabbit polyclonal anti‐substance P primary followed by biotinylated donkey anti‐rabbit secondary antibodies. Reaction was revealed with a nickel‐diaminobenzidine solution. Labeled neurons were counted and compared between ages, genders and groups. Gender differences were present in both ages, with the number of SP‐positive DRG neurons being larger in 15‐days‐old males on both sides. After 180 days, males showed a larger number of SP‐positive neurons than females only on the nociceptive stimulated side. An increased number of SP‐positive neurons in the DRG on the stimulated side was present in females, immediately after nociceptive stimulation, but not after 180 days. In conclusion, neonatal noxious stimulation caused a permanent increase in SP‐positive DRG neurons in males that was not observed in females, suggesting that differences in pain processing/responsivity between genders could be related to morphological alterations of the nervous system. Anat Rec, 301:849–861, 2018. © 2017 Wiley Periodicals, Inc.     

高频电刺激大鼠丘脑底核抑制背侧中缝核5-羟色胺表达

本研究探讨高频电刺激丘脑底核对大鼠背侧中缝核5-羟色胺(5-HT)表达的影响。实验动物分两组,刺激组给予高频电流(130Hz,100μA,60μs)刺激大鼠右侧丘脑底核,对照组大鼠右侧丘脑底核植入电极,但无电流输出。刺激结束后,用免疫组织化学方法染色背侧中缝核5-HT能神经元,检测背侧中缝核5-HT能神经元的数量和平均灰度值。结果显示电刺激组背侧中缝核5-HT阳性神经元数目与对照组比明显减少(t(13)=3.786,P=0.002),并且神经递质5-HT表达量减少,平均灰度值显著增高(t(13)=7.917,P<0.001)。本实验结果表明高频电刺激丘脑底核对背侧中缝核5-HT能神经元有抑制作用,在应用高频电刺激丘脑底核治疗Parkison病运动障碍时出现的情绪障碍可能与其有关。     

1,8-桉叶素对背根神经节内P2X3受体介导神经病理痛的作用

目的:探讨1,8-桉叶素对大鼠背根神经节(DRG)神经元P2X3受体介导神经病理痛的作用。方法:建立大鼠坐骨神经慢性压迫性损伤模型(CCI)。SD大鼠随机分为假手术(Sham)组,坐骨神经慢性压迫性损伤(模型组,CCI)组、低剂量1,8-桉叶素治疗组、高剂量1,8-桉叶素治疗组、二甲亚砜对照组。检测大鼠术后7、14 d机械缩足反射(MWT)及热缩足反射潜伏期(TWL),观察大鼠行为学变化。免疫组织化学和原位杂交观察神经病理痛大鼠第4~5腰(L_(4-5))DRG神经元P2X3受体表达变化。结果:术后第7和14天,模型组大鼠MWT和TWL明显低于假手术组,低、高剂量治疗组较模型组明显升高,二甲亚砜组与模型组比较无差别;L_(4-5)DRG内P2X3受体表达模型组明显高于假手术组,低、高剂量治疗组较模型组均明显降低,二甲亚砜组与模型组比较无明显区别。结论:1,8-桉叶素抑制CCI大鼠L_(4-5)DRG神经元P2X3受体过表达,从而缓解神经病理性疼痛症状。     

Gender dependent effect of DHCR24 polymorphism on the risk for Alzheimer's disease

Although neuroimmune interactions associated with the development of pain sensitization in models of neuropathic pain have been widely studied, there are some aspects that require further investigation. Thus, we aimed to evaluate whether the local intraneural or perineural injections of dexamethasone, an efficacious anti-inflammatory and immunosuppressant drug, delays the development of both thermal hyperalgesia and mechanical allodynia in an experimental model of neuropathic pain in rats. Hargreaves and electronic von Frey tests were applied. The chronic constriction injury (CCI) of right sciatic nerve was performed. Single intraneural dexamethasone administration at the moment of constriction delayed the development of sensitization for thermal hyperalgesia and mechanical allodynia. However, perineural administration of dexamethasone, at the highest dose, did not delay experimental pain development. These results show that inflammation/immune response at the site of nerve lesion is an essential trigger for the pathological changes that lead to both hyperalgesia and allodynia. In conclusion, this approach opens new opportunities to study cellular and molecular neuroimmune interactions associated with the development of pain derived from peripheral neuropathies.     

Presence of serotonin in the rat vas deferens: its influence on contractile responses

Serotonin has been detected in the rat vas deferens. Increase in the serotonin concentration by exposure of the rat vas deferens to L-tryptophan occurs in vitro. p-chlorophenylalanine partly blocks the increase in serotonin concentration induced by tryptophan in vitro but not in vivo. Chronic sympathetic denervation induces an increase in 5-HT concentration. Responses of the vas deferens to transmural stimulation are depressed by pretreatment of rats with p-chlorophenylalanine, and the depression is reversed by incubation in vitro with 5-hydroxytryptophan or serotonin. Serotonin can enhance the response to transmural stimulation at low concentrations but has no effect at higher concentrations. Physostigmine-induced enhancement of the response to stimulation is depressed only by higher concentrations of serotonin. The results raise the question whether endogenous serotonin can act as a modulator of neurotransmission in the rat vas deferens.