大鼠桡神经、尺神经感觉纤维在脊髓胶状质的定位投射——酸性磷酸酶法研究

本实验按照跨神经节溃变的原理,以酸性磷酸酶(AcP)法研究了大鼠桡神经、尺神经感觉纤维在脊髓胶状质内的定位投射。大鼠桡神经感觉纤维纵向投射,主要至脊髓C_6上段至T_1中段胶状质,尺神经主要投射至C_6中段至T_1中段胶状质。其横向投射,桡神经主要位于整个胶状质的中1/3区域;尺神经則均在胶状质中线以内,主要位于胶状质内侧半的外侧1/2～3/4区域。桡神经投射区居外,尺神经投射区居内。     

大鼠腋神经感觉纤维在脊髓胶状质的定位投射——酸性磷酸酶法研究

按照跨神经节溃变的原理,以酸性磷酸酶法,研究了大鼠腋神经感觉纤维在脊髓胶状质的定位投射。大鼠腋神经感觉纤维纵向投射,主要至脊髓C_0上段至C_8下段胶状质,少数动物还投射至C_5下段及T_1上段。其横向投射均在胶状质中线以外,主要位于胶状质外侧半内侧和中1/3区域,部分动物C_7至C_8节段的投射区,占据胶状质外侧半内侧1/2范围。投射柱从上至下有向外扩展趋势。     

大鼠正中神经感觉纤维在脊髓胶状质的定位投射——酸性磷酸酶法研究

本实验按照跨神经节溃变的原理,以酸性磷酸酶法研究了大鼠正中神经感觉纤维在脊髓胶状质内的定位投射。大鼠正中神经感觉纤维纵向投射主要至脊髓C_6上段至T_1中段胶状质;少数动物还投射至C_4中、下段及T_1下段。与解剖学专著的记载及HRP法研究的结果相比,有“前置”的趋势。其横向投射均在胶状质中线以内,且主要位于胶状质内侧半的内侧1/4～1/2区域;少数动物C_7～T_1上段的投射区占居胶状质内侧半全部范围。投射柱从上至下有向外扩展的趋势。     

大鼠正中神经感觉纤维在脊髓胶状质定位投射的定量分析

目的　对大鼠正中神经感觉秒纤维在脊髓胶状质 (SG)的定量投射进行定量分析。方法　按照跨神经节溃变的原理 ,用抗氟化物酸性磷酸酶 (FRAP)法和显微测量。结果　大鼠正中神经向SG的纵向投射主要为C5～T1。C5～T1各节段SG水平向眉毛状反应带所测均值 (mm)分别为 0 888、0 935、0 95 7、0 90 5和 0 776 ,而正中神经向C5～T1各节段SG水平向投射所测均值 (mm)分别在 0～ 0 2 0 4、0～ 0 30 3、0～ 0 4 0 9、0～ 0 4 32和 0～ 0 336的范围。结论　结果显示正中神经投射区均位于SG的内侧带和部分中间带     

大鼠腓浅、腓深神经纤维对脊髓胶状质投射的节段和区域定位——酸性磷酸酶法的研究

本实验根据跨神经节溃变的机理,利用酸性磷酸酶(AcP)法研究了大鼠腓浅、腓深神经纤维对脊髓胶状质投射的节段和区域定位。大鼠腓浅、腓深神经纤维向胶状质投射的节段,都是L_(2～5),在每节段都投至胶状质的中间部。在L_2节段,腓浅神经投到胶状质中线的外侧;腓深神经投到中线两旁内外侧对称。在L_3节段,腓浅神经也投到胶状质中线外侧,但紧靠中线;腓深神经投到中线内侧。在L_(4,5)节段,腓浅神经投到胶状质的中线两旁,其内区大于外区;腓深神经投到胶状质内侧半的中间部。从L_2至L_5,腓浅、腓深神经纤维对胶状质的投射区都逐渐内移。两神经相比,腓深神经纤维的投射区在腓浅神经者的内侧。     

大鼠腓浅神经传入纤维在脊髓胶状质的定位投射--FRAP法

为了解大鼠腓浅神经传入纤维在脊髓胶状质的投射定位投射按照跨神经节溃变原理，用抗氟化物酶性酸酶法和显微测量进行定量研究。结果显示：大鼠腓浅神经向ＳＧ的纵向投射主要为为Ｌ２－６，Ｌ２－６各节段ＳＧ水平切面“眉毛状反应带”弧形长均值分别为０．７９５、０．８４９、０．９１３、０．９２１、０．８５２ｍｍ；而腓浅神经向Ｌ２－６各节段ＳＧ水平切面投射均值分别为０．４４７－０．５３３、０．３８４－０．５６１、０．     

大白鼠颈丛皮神经对脊髓胶状质投射的节段及区域定位—ACP法研究

本实验按照超节溃变机理,切除颈丛皮神经5～9天后,利用Gomori酸性磷酸酶改良法(AcP法),研究颈丛皮神经纤维对脊髓胶状质的节段(纵向)和区域(横向)投射。结果如下:1.切除耳大、枕小神经,见投射到脊髓C_1～C_4节段,AcP最大消失区在C_2及C_3节段胶状质的中外侧部,分两处存在,在C_3上段占41.5％±4.7。2.切除颈前皮神经,见投射到脊髓C_2～C_5节段。AcP最大消失区在C_3及C_4节段胶状质的中外侧部,在C_3中段占46.3％±4.98。3.切除锁骨上神经,见投射到脊髓C_1～C_5节段,AcP最大消失区在C_3及C_4节段胶状质的中外侧部,在C_3下段占40.0％±7.74。     

Neurons with asymmetrical dendritic arbors in the substantia gelatinosa of the rat spinal cord

Summary Two types of neurons were observed in the substantia gelatinosa (SG) of the rat spinal cord which exhibit wide variations in dendritic symmetry. As demonstrated with the Golgi technique, islet cells with short dendritic arbors and type III stalk cells display dendritic patterns which vary from a bipolar type arrangement with two dendritic arbors of nearly equal dimensions to a unipolar arrangement with a dendritic arbor which extends in only one direction. Examination of the morphology and dendritic development of these neurons shows that they are unique compared with other SG neurons in that they have short, longitudinal dendritic arbors which undergo maturation relatively late in the postnatal period. As is discussed, variations in dendritic symmetry are probably dependent on the location of the terminal fields of primary and/or other types of afferents which are formed earlier in development.     

大鼠桡神经钳夹伤后背根节和脊髓nNOS免疫阳性神经元的变化

目的研究大鼠桡神经钳夹伤后背根神经节(DRG)和脊髓nNOS免疫阳性神经元的变化,探讨NO是否参与大鼠桡神经钳夹伤后的DRG和脊髓水平的痛觉调制。方法用辣根过氧化物酶追踪大鼠桡神经的由来;大鼠桡神经钳夹伤结合免疫组化法,研究桡神经钳夹伤后DRG鄄和脊髓的nNOS免疫阳性结构变化。结果(1)大鼠桡神经的组成范围在C5～T1;(2)大鼠桡神经钳夹伤后,DRG内nNOS免疫阳性神经元的变化难以分析:脊髓后角nNOS免疫阳性结构数量减少、免疫强度下降。结论大鼠桡神经钳夹伤后,脊髓nNOS免疫阳性结构发生可塑性变化,NO在桡神经钳夹伤后的痛觉调制中有一定的作用。     

Ascending propriospinal afferents to area X (substantia grisea centralis) of the spinal cord in the rat

Area X (the tenth area) of the spinal cord is a region surrounding the central canal and extending throughout the spinal cord length. Using anterograde and retrograde labeling techniques, ascending propriospinal projections to area X were examined in the rat. For anterograde tracing of axons, biotinylated dextran was injected into middle-thoracic, lumbar, or sacral-caudal segments. Unilateral injections resulted in bilateral labeling of terminals in area X of all segments rostral to the injections. The distribution of labeled terminals was conspicuous in regions dorsal and lateral to the central canal. The labeled axons were derived from the ventrolateral and the lateral cord. They coursed through lamina VII, giving off terminal axons. While giving off terminal axons in area X, they coursed further rostrally or caudally along the central canal or crossed over the central canal to terminate in the contralateral area X. Possible cells of origin of these ascending afferents were examined after injections of wheat germ agglutinin-horseradish peroxidase into regions surrounding the central canal (area X) at the cervical or thoracic level. Retrogradely labeled neurons were consistently seen in area X, and laminae VII and VIII of the thoracic and lumbar segments. The present study shows that ascending propriospinal axons project to area X of all spinal levels rostral to the cells of origin and suggests that some of these afferents may originate from neurons in area X and laminae VII and VIII. Based on previous data, it is surmised that area X functions, through these intricate interconnections, as a site for integration or modulation of somatic or nociceptive and visceroceptive sensation. Received: 3 July 1997 / Accepted: 8 October 1997     

1,25(OH)2 vitamin D3 sites of action in spinal cord and sensory ganglion

Summary Autoradiographic studies revealed concentration of ³H 1,25(OH)₂ vitamin D₃ in nuclei of certain neurons in the spinal cord of adult and neonatal mice, fed a normal or a vitamin D deficient diet. Nuclear uptake and retention was strongest in motor neurons in lamina IX. Nuclear concentration also existed in neurons of lamina II, lamina VIII, lamina X and intermediate nucleus of the lateral column. The results indicate that these neurons are target neurons which contain nuclear receptors for 1,25(OH)₂ vitamin D₃. this suggests that 1,25(OH)₂ vitamin D₃ has direct genomic actions on the innervation of skeletal muscle by exerting related trophic, secretory, and electrophysiological effects. In addition, these data point to direct genomic actions of 1,25(OH)₂ vitamin D₃ on spinal sensory perception, and on certain autonomic functions. Nuclear binding in certain neurons in the peripheral ganglion of the trigeminal nerve further suggests that sensory perception is influenced by 1,25(OH)₂ vitamin D₃ not only at the level of the substantia gelatinosa, but also at the level of spinal ganglia.Supported in part by USPHS grants NS 09914 and HD 03110     

Distribution and identity of neurons expressing the oxytocin receptor in the mouse spinal cord

Oxytocin can influence various spinal functions. However, little is known about the spinal neuronal networks responsible for oxytocin effects. The aim of this study was to localize and characterize spinal neurons expressing oxytocin receptors. We used an oxytocin receptor-reporter mouse in which the fluorescent protein Venus is expressed under the control of the oxytocin receptor gene promoter. At all segmental levels, Venus-expressing neurons were most numerous in the substantia gelatinosa, mingled with protein kinase Cγ interneurons in the innermost layer of the inner lamina II, which, in contrast to the outer two thirds of this layer, does not receive nociceptive input. Venus-expressing neurons were also observed in the intermediolateral and sacral parasympathetic nuclei, where they represented about 5% of presumed preganglionic neurons identified by choline acetyltransferase immunoreactivity. Finally, Venus immunoreactivity was detected in lumbar and sacral dorsal gray commissures as well as in isolated neurons scattered in different regions of the dorsal horn. Altogether, our results establish the location of neurons putatively involved in oxytocin modulation of spinal functions, in particular of sexual functioning and nociception.     

Influences of contralateral nerve and skin stimulation on neurones in the substantia gelatinosa of the rat spinal cord

Stimulation of high threshold A delta and C fibre peripheral afferents inhibits dorsal horn cells on the other side of the spinal cord. The substantia gelatinosa (SG) is an area full of interneurones known to have commissural connections across the spinal cord. The role of SG in this contralateral inhibitory pathway is investigated here. Forty-three SG cells were recorded in the lumbar dorsal horn of decerebrate spinal rats. Their ipsilateral excitatory receptive fields and responses to sciatic nerve stimulation were recorded. Repetitive electrical stimulation was then applied to the contralateral sciatic nerve. Eight (19%) units were excited by such stimulation. A brief tetanus was followed by an increase of ongoing activity lasting 30 s to 10 min. These cells did not, however, have excitatory contralateral fields. A small separate group of 4 cells (9%) were mildly inhibited by heating or pinching the contralateral limb. The significance of contralateral excitation of some SG cells is discussed in the light of the predominantly inhibitory contralateral effect on dorsal horn cells in laminae 4 and 5. It is suggested that some SG cells may be inhibitory interneurones in their effect on deeper cells.     

Excitatory synaptic transmission in the spinal substantia gelatinosa is under an inhibitory tone of endogenous adenosine

Exogenous adenosine produces potent synaptic inhibition in spinal substantia gelatinosa (SG), a region involved in nociceptive and thermoreceptive mechanisms. To examine the possibility that endogenous adenosine tonically modulates excitatory synaptic transmission in spinal SG, whole-cell, voltage-clamp recordings were made from SG neurons in adult rat spinal cord slices. In all SG neurons sensitive to exogenous adenosine, the adenosine uptake inhibitor, NBTI, mimics adenosine's inhibitory actions on dorsal root evoked EPSCs (eEPSCs) and miniature spontaneous EPSCs (mEPSCs). These inhibitory effects were antagonized by A1 adenosine receptor antagonist, DPCPX. DPCPX also potentates eEPSCs in those SG neurons in which adenosine or adenosine A1 receptor agonists (CHA, CCPA) suppressed eEPSCs. DPCPX often increases mEPSC frequency without altering mEPSC amplitude, suggesting presynaptic action on adenosine A1 receptors. Selective A2 (DMPX) and A2a (ZM 241385) adenosine receptor antagonists had no or minimal effects upon either eEPSCs or mEPSCs. The adenosine degrading enzyme, adenosine deaminase, mimicked the effects of DPCPX on the mEPSC frequency. We conclude that the excitatory synaptic transmission in the spinal SG is under an inhibitory tone of endogenous adenosine through the activation of A1 receptors. The present results suggested that the background activity of A1 receptors in the spinal SG might be contributed to setting the physiological “noceceptive thresholds”.