GAP-43 expression in the developing rat lumbar spinal cord.

The expression of the growth-associated protein GAP-43, detected by immunocytochemistry, has been studied in the developing rat lumbar spinal cord over the period E11 (embryonic day 11), when GAP-43 first appears in the spinal cord, to P29 (postnatal day 29) by which time very little remains. Early GAP-43 expression in the fetal cord (E11-14) is restricted to dorsal root ganglia, motoneurons, dorsal and ventral roots and laterally positioned and contralateral projection neurons and axons. Most of the gray matter is free of stain. The intensity of GAP-43 staining increases markedly as axonal growth increases, allowing clear visualization of the developmental pathways taken by different groups of axons. Later in fetal life (E14-19), as these axons find their targets and new pathways begin to grow, the pattern of GAP-43 expression changes. During the period, GAP-43 staining in dorsal root ganglia, motoneurons, and dorsal and ventral roots decreases, whereas axons within the gray matter begin to express the protein and staining in white matter tracts increases. At E17-P2 there is intense GAP-43 labelling of dorsal horn neurons with axons projecting into the dorsolateral funiculus and GAP-43 is also expressed in axon collaterals growing into the gray matter from lateral and ventral white matter tracts. At E19-P2, GAP-43 is concentrated in axons of substantia gelatinosa. Overall levels decline in the postnatal period, except for late GAP-43 expression in the corticospinal tract, and by P29 only this tract remains stained.     

The effect of site and type of nerve injury on the expression of brain-derived neurotrophic factor in the dorsal root ganglion and on neuropathic pain behavior

A number of rat neuropathy models have been developed to simulate human neuropathic pain conditions, such as spontaneous pain, hyperalgesia, and allodynia. In the present study, to determine the relative importance of injury site (proximal or distal to the primary afferent neurons) and injury type (motor or sensory), we examined pain-related behaviors and changes of brain-derived neurotrophic factor expression in the dorsal root ganglion in sham-operated rats, and in the L5 dorsal rhizotomy, L5 ventral rhizotomy, L5 dorsal rhizotomy+ventral rhizotomy, and L5 spinal nerve transection models. L5 ventral rhizotomy and spinal nerve transection produced not only mechanical and heat hypersensitivity, but also an increase in brain-derived neurotrophic factor mRNA/protein in the L5 dorsal root ganglion at 7 days after surgery. In contrast, rats in the L5 dorsal rhizotomy and dorsal rhizotomy+ventral rhizotomy groups did not show both pain behaviors at 7 days after surgery, despite brain-derived neurotrophic factor upregulation in medium- and large-size neurons in the L5 dorsal root ganglion. On the other hand, L5 spinal nerve transection, but not dorsal rhizotomy, dorsal rhizotomy+ventral rhizotomy or ventral rhizotomy, increased the expression of brain-derived neurotrophic factor in the L4 dorsal root ganglion at 7 days after surgery. Taken together, these findings suggest that the upregulation of brain-derived neurotrophic factor expression in the L4 and L5 dorsal root ganglion neurons may be, at least in part, involved in the pathophysiological mechanisms of neuropathic pain and that the selective nerve root injury models may be useful for studying the underlying mechanisms of chronic pain after nerve injury.     

Peripheral targets influence sensory-motor connectivity in the neonatal spinal cord: sciatic nerve axotomy in Bax-deficient mice

In neonatal animals, peripheral nerve axotomy induces cell death in the corresponding dorsal root ganglion neurons and motoneurons, indicating that trophic interactions between these neurons and their targets control neuronal survival at this age. However, axotomy-induced cell death masks the role of peripheral tissues in regulating the central connections between these neurons in neonates. Since we have shown in Bax-deficient mice (Bax-/-) that transection of the sciatic nerve at postnatal day (P) 0 rarely induced apoptosis in motoneurons, we examined whether peripheral nerve axotomy eliminates synaptic connections between group Ia afferents and motoneurons in Bax-/-. After the axotomy, we observed in P7 Bax-/- that many axons survived in the fourth lumber (L4) dorsal root and that primary afferent projections to L4 motor pools also remained. Sciatic nerve stimulation evoked synaptic responses in L4 ventral roots in these mice although the amplitudes were considerably smaller and the onset latencies longer compared with the controls. Our results suggest that the monosynaptic connection between group Ia afferents and motoneurons is morphologically and functionally preserved following axotomy. Peripheral tissues may modulate synaptic connectivity but do not contribute to the maintenance of primary afferent projections in the stretch reflex pathway at an immature stage.     

Effect of peripheral nerve cut on neuropeptides in dorsal root ganglia and the spinal cord of monkey with special reference to galanin

Summary Using the indirect immunofluorescence method andin situ hybridization, the localization and levels of immunoreactivities and mRNAs for several neuropeptides were studied in lumbar dorsal root ganglia and spinal cord of untreated monkeys (Macaca mulatto) and after unilateral transection of the sciatic nerve. Immunoreactive galanin, calcitonin gene-related peptide, substance P and somatostatin and their mRNAs were found in cell bodies in dorsal root ganglia of untreated monkeys and on the contralateral side of the monkeys with unilateral sciatic nerve lesion. After axotomy there was a marked decrease in the number of calcitonin gene-related peptide-, substance P- and somatostatin-positive neurons in dorsal root ganglia ipsilateral to the lesion, whereas the number of galanin positive cells strongly increased. A few neuropeptide tyrosine-positive cells were seen in after axotomy, whereas no such neurons were found in controls. No vasoactive intestinal polypeptide-, peptide histidine isoleucine-, cholecystokinin-, dynorphin-, enkephalin-, neurotensin-or thyrotrophin releasing hormone-positive cell bodies were seen in dorsal root ganglia of any of the groups studied. In the dorsal horn of the spinal cord all peptide immunoreactivities described above, except thyrotropin releasing hormone, were found in varying numbers of nerve fibres with a similar distribution in untreated monkeys and in the contralateral dorsal horn in monkey with unilateral sciatic nerve lesion. Two cholecystokinin antisera were used directed against the C- and N-terminal portions, respectively, showing a distinctly different distribution pattern in the dorsal horn. Somatostatin- and dynorphin-like immunoreactivities were also observed in small neurons in the dorsal horn. No certain effect of axotomy on these interneurons could be seen. However, marked changes were observed after this type of lesion for some peptide containing fibres in the ipsilateral dorsal horn. Thus, there was a marked increase in galanin-like immunoreactivity, whereas calcitonin gene-related peptide-, substance P-, somatostatin-, peptide histidine isoleucine neurotensin- and cholecystokinin-like immunoreactivities decreased. No changes could be observed in neuropeptide tyrosine or enkephalin-positive fibres. The present results demonstrate marked ganglionic and transganglionic changes in peptide levels after peripheral axotomy. When compared to published results on the effect of axotomy on peptides in dorsal root ganglia and spinal cord of rat, both similarities and differences were encountered. Thus, in contrast to rat there was no marked upregulation of vasoactive intestinal polypeptide/peptide histidine isoleucine or neuropeptide tyrosine after axotomy in the monkey, whereas galanin was increased in both species. Both in monkey and rat, calcitonin gene-related peptide, substance P and somatostatin decreased. The decrease in neurotensin, peptide histidine isoleucine, and genuine cholecystokinin seen in monkey after axotomy has not been reported in the rat. Experimental studies on rat suggest that galanin may be an endogenous analgesic compound, active particularly after peripheral nerve lesions. We have therefore recently proposed that galanin agonists may be used in treatment of chronic pain, and the present demonstration that galanin is regulated in a similar fashion in a primate gives further support to the proposal to test galanin as an analgesic in human.     

Survival and regeneration of cutaneous and muscular afferent neurons after peripheral nerve injury in adult rats

Peripheral nerve injury induces the retrograde degeneration of dorsal root ganglion (DRG) cells, which affects predominantly the small-diameter cutaneous afferent neurons. This study compares the time-course of retrograde cell death in cutaneous and muscular DRG cells after peripheral nerve transection as well as neuronal survival and axonal regeneration after primary repair or nerve grafting. For comparison, spinal motoneurons were also included in the study. Sural and medial gastrocnemius DRG neurons were retrogradely labeled with the fluorescent tracers Fast Blue (FB) or Fluoro-Gold (FG) from the homonymous transected nerves. Survival of labeled sural and gastrocnemius DRG cells was assessed at 3 days and 1–24 weeks after axotomy. To evaluate axonal regeneration, the sciatic nerve was transected proximally at 1 week after FB-labeling of the sural and medial gastrocnemius nerves and immediately reconstructed using primary repair or autologous nerve grafting. Twelve weeks later, the fluorescent tracer Fluoro-Ruby (FR) was applied 10 mm distal to the sciatic lesion in order to double-label sural and gastrocnemius neurons that had regenerated across the repair site. Counts of labeled gastrocnemius DRG neurons did not reveal any significant retrograde cell death after nerve transection. In contrast, sural axotomy induced a delayed loss of sural DRG cells, which amounted to 22% at 4 weeks and 43–48% at 8–24 weeks postoperatively. Proximal transection of the sciatic nerve at 1 week after injury to the sural or gastrocnemius nerves neither further increased retrograde DRG degeneration, nor did it affect survival of sural or gastrocnemius motoneurons. Primary repair or peripheral nerve grafting supported regeneration of 53–60% of the spinal motoneurons and 47–49% of the muscular DRG neurons at 13 weeks postoperatively. In the cutaneous DRG neurons, primary repair or peripheral nerve grafting increased survival by 19–30% and promoted regeneration of 46–66% of the cells. The present results suggest that cutaneous DRG neurons are more sensitive to peripheral nerve injury than muscular DRG cells, but that their regenerative capacity does not differ from that of the latter cells. However, the retrograde loss of cutaneous DRG cells taking place despite immediate nerve repair would still limit the recovery of cutaneous sensory functions.     

The effects of delayed nerve repair on neuronal survival and axonal regeneration after seventh cervical spinal nerve axotomy in adult rats

It has been proposed clinically that delayed surgery after traumatic brachial plexus injury may adversely affect functional outcome. In the present experimental study the neuroprotective and growth-promoting effects of early and delayed nerve grafting following proximal seventh cervical spinal nerve (C7) axotomy were examined. The ventral branch of C7 spinal nerve was transected and axons projecting out of the proximal nerve stump were labelled with Fast Blue (FB). At the same time, the biceps brachii muscle was denervated by transecting the musculocutaneous nerve at its origin. Neuronal survival and muscle atrophy were then assessed at 1, 4, 8 and 16 weeks after permanent axotomy. In the experimental groups, a peripheral nerve graft was interposed between the transected C7 spinal nerve and the distal stump of the musculocutaneous nerve at 1 week [early nerve repair (ENR)] or 8 weeks [delayed nerve repair (DNR)] after axotomy. Sixteen weeks after nerve repair had been performed, a second tracer Fluoro-Ruby (FR) was applied distal to the graft to assess the efficacy of axonal regeneration. Counts of FB-labelled neurons revealed that axotomy did not induce any significant cell loss at 4 weeks, but 15% of motoneurons and 32% of sensory neurons died at 8 weeks after injury. At 16 weeks, the amount of cell loss in spinal cord and dorsal root ganglion (DRG) reached 29 and 50%, respectively. Both ENR and DNR prevented retrograde degeneration of spinal motoneurons and counteracted muscle atrophy, but failed to rescue sensory neurons. Due to substantial cell loss at 8 weeks, the number of FR-labelled neurons after DNR was significantly lower when compared to ENR. However, the proportion of regenerating neurons among surviving motoneurons and DRG neurons remained relatively constant indicating that neurons retained their regenerative capacity after prolonged axotomy. The results demonstrate that DNR could protect spinal motoneurons and reduce muscle atrophy, but had little effect on sensory DRG neurons. However, the efficacy of neuroprotection and axonal regeneration will be significantly affected by the amount of cell loss already presented at the time of nerve repair.     

Intraspinal non-neuronal cellular responses to peripheral nerve injury

The accumulation of non-vascular, non-neuronal cells (designated herein as reactive cells) in association with perikarya of axotomized motor neurons has been described by many investigators. Recently Gilmore ('75) found that sciatic axotomy in immature rats resulted in the occurrence of reactive cells not only in the spinal ventral gray matter but also in the dorsal gray matter. To determine if the presence of these cells in the dorsal gray matter, a finding not reported by others, was related to the immaturity of the animal, sciatic axotomy was performed in rats ranging in age from 17 days to 16 months in the present study. Light microscopic evaluation of the spinal cords three or seven days post-operatively showed that the reactive cells occurred consistently in both dorsal and ventral gray matter irrespective of age. Transection of tibial nerve or the nerve to the medial head of the gastrocnemius muscle elicited a cellular response in both dorsal and ventral gray matter, although transection of the latter nerve resulted in a much less obvious response. Crushing of the sciatic nerve was followed by a response of reactive cells not qualitatively different from that noted following transection. Transection of the sural nerve, primarily a sensory nerve, resulted in the presence of reactive cells in dorsal gray matter but not in the environs of motor neurons in the ventral gray matter. These findings suggest that the reactive cells in the dorsal gray matter of the spinal cord are associated with altered central processes of dorsal root ganglion cells.     

Intraspinal non-neuronal cellular responses to peripheral nerve injury.

The accumulation of non-vascular, non-neuronal cells (designated herein as reactive cells) in association with perikarya of axotomized motor neurons has been described by many investigators. Recently Gilmore ('75) found that sciatic axotomy in immature rats resulted in the occurrence of reactive cells not only in the spinal ventral gray matter but also in the dorsal gray matter. To determine if the presence of these cells in the dorsal gray matter, a finding not reported by others, was related to the immaturity of the animal, sciatic axotomy was performed in rats ranging in age from 17 days to 16 months in the present study. Light microscopic evaluation of the spinal cords three or seven days post-operatively showed that the reactive cells occurred consistently in both dorsal and ventral gray matter irrespective of age. Transection of tibial nerve or the nerve to the medial head of the gastrocnemius muscle elicited a cellular response in both dorsal and ventral gray matter, although transection of the latter nerve resulted in a much less obvious response. Crushing of the sciatic nerve was followed by a response of reactive cells not qualitatively different from that noted following transection. Transection of the sural nerve, primarily a sensory nerve, resulted in the presence of reactive cells in dorsal gray matter but not in the environs of motor neurons in the ventral gray matter. These findings suggest that the reactive cells in the dorsal gray matter of the spinal cord are associated with altered central processes of dorsal root ganglion cells.     

Increased neuropeptide Y (NPY)-like immunoreactivity in rat sensory neurons following peripheral axotomy.

The effects of peripheral axotomy (sciatic nerve transection) on the presence and distribution of neuropeptide Y (NPY) in rat dorsal root ganglion (DRG) and spinal grey matter were examined using immunocytochemistry. In normal rats and on the sham-operated side of experimental rats, NPY-like immunoreactivity (NPYir) was observed in all laminae of the lumbar spinal cord, with an especially dense concentration of immunostained axons and axonal varicosities in laminae I-II of the dorsal horn. There was no detectable NPYir in L4-L5 DRG cells from normal rats or from the sham-operated side of experimental rats. At 14 days after axotomy, there was a large ipsilateral increase in the density of NPYir axons and varicosities in the lumbar spinal cord on the side of the nerve injury; this was especially apparent in laminae III-V. In the same rats, NPYir was observed in many small, medium, and large neurons in the L4-L5 DRGs on the side of the severed nerve.     

The growth-associated protein GAP-43 appears in dorsal root ganglion cells and in the dorsal horn of the rat spinal cord following peripheral nerve injury

When adult dorsal root ganglion cells are dissociated and maintained in vitro, both the small dark and the large light neurons show increases in the growth-associated protein GAP-43, a membrane phosphoprotein associated with neuronal development and plasticity. Immunoreactivity for GAP-43 appears in the cytoplasm of the cell bodies as early as 3.5 h post axotomy and is present in neurites and growth cones as soon as they develop. At early stages of culture (4 h to eight days) satellite/Schwann cells are also immunoreactive for GAP-43. Neurons in isolated whole dorsal root ganglion maintained in vitro become GAP-43-immunoreactive between 2 and 3 h after axotomy. It takes three days however, after cutting or crushing the sciatic nerve in adult rats in vivo, for GAP-43 immunoreactivity to appear in the axotomized dorsal root ganglion cells. GAP-43 immunoreactivity can be detected in the central terminals of primary afferent neurons in the superficial laminae of the dorsal horn of the lumbar enlargement four days after sciatic cut or crush. The intensity of the GAP-43 staining reaches a peak at 21 days and becomes undetectable nine weeks following crush injury and 36 weeks following sciatic nerve cut. The pattern of GAP-43 staining is identical to the distribution of sciatic small-calibre afferent terminals. Little or no staining is present in the deep dorsal horn, but GAP-43 does appear in the ipsilateral gracile nucleus 22 days after sciatic injury. In investigating the mechanism of GAP-43 regulation, blockade of axon transport in the sciatic nerve with vinblastine (10(-5) M-10(-4) M) or capsaicin (1.5%) was found to produce a pattern of GAP-43 immunoreactivity in the dorsal horn identical to that found with crush, while electrical stimulation of the sciatic nerve had no effect. Axotomy of primary sensory neurons or the interruption of axon transport in the periphery therefore acts to trigger GAP-43 production in the cell body. The GAP-43 is transported to both the peripheral and the central terminals of the afferents. In the CNS the elevated GAP-43 levels may contribute to an inappropriate synaptic reorganization of afferent terminals that could play a role in the sensory disorders that follow nerve injury.     

抗BDNF血清对小鼠坐骨神经损伤后脊髓前角运动神经元内GAP-43表达的影响

小鼠坐骨神经压榨损伤后 ,腹腔注射抗 BDNF血清 ,动物存活 2周。用组织原位杂交技术与免疫组织化学方法观察生长相关蛋白 ( GAP-4 3)在脊髓腰骶膨大部前角运动神经元的表达 ,并对实验结果进行图像分析。结果发现 ,注射抗 BDNF血清后坐骨神经损伤侧脊髓前角 GAP-4 3m RNA的阳性神经元与 GAP-4 3免疫反应阳性神经元的数目减少 ,阳性神经元的光密度也降低 ,上述改变在统计学上均有显著意义。结果提示 ,小鼠坐骨神经损伤后内源性 BDNF可能参与脊髓前角运动神经元 GAP-4 3的表达     

大鼠坐骨神经损伤与再生中GAP－43表达的实验研究

用免疫组化技术对６０只大鼠坐骨神经切断、卡压和再卡压损伤后不同时期的ＧＡＰ－４３表达作了观察．观察结果：（１）大鼠坐骨神经卡压或切断后，前角运动神经元、后根神经节细胞和坐骨神经纤维均产生免疫反应阳性，其中７ｄ组近段和１４ｄ组远段坐骨神经纤维为强阳性，（２）３０ｄ组各部免疫反应减弱，６０ｄ组基本恢复正常；（３）３０和６０ｄ组的再卡压损伤的各部均较同期其他损伤组免疫反应为强；（４）伤侧腰骶髓前角运动神经元染色逐渐减弱．ＧＡＰ－４３免疫反应结果显示，神经元胞体部分随再生期延长而逐渐减弱，周围部由近至远逐渐增强，又逐渐恢复至正常水平．结果提示ＧＡＰ－４３主要由神经元胞体所产生，随轴突逐渐转运至损伤和再生处，表明了此种蛋白参与神经再生，在神经再生过程中一直起着重要的作用．     

神经损伤与再生中神经元GAP-43mRNA表达的原位杂交研究

目的：研究周围神经损伤过程中生长相关蛋白（GAP-43）mRNA表达的变化规律。方法：建立大鼠坐骨神经中段钳夹损伤模型，用原位杂交技术对大鼠的腰髓和背根神经节的GAP-43mRNA表达进行观察。结果：大鼠坐骨神经损伤2d后，腰髓腹角运动神经元和背根节感觉神经元可检测到GAP-43mRNA杂交信号；术后4、7和14d明显增强；术后30d减弱，60d已恢复正常。结论：周围神经损伤诱导神经元胞体GAP-43mRNA表达显著增强，表明GAP-43在神经再生过程中起重要作用。     

Dynamic changes in Robo2 and Slit1 expression in adult rat dorsal root ganglion and sciatic nerve after peripheral and central axonal injury

Robos are transmembrane receptors that mediate Slit signaling to repel growth cone outgrowth and neural migration in the developing central nervous system. Their distribution and function in the peripheral nervous system remains unclear. In the present study, we examined expression of Slit1 and Robo2 in adult rat dorsal root ganglion (DRG), spinal cord and sciatic nerve after peripheral nerve injury (axotomy). In control rats, Slit1 and Robo2 mRNA and protein were expressed at basic levels in the L5 and L6 DRGs. Sciatic transection resulted in a significant up-regulation of both Robo2 and Slit1 mRNA and protein (p<0.05 versus control). The peak of Slit1 and Robo2 expression occurred at days 7 and 14, respectively, and returned to control levels at days 28 and 21 post-axotomy, respectively. By contrast, injury to the central axons of the DRG by dorsal rhizotomy did not up-regulate Slit1 and Robo2 expression. Robo2 staining was stronger in small diameter neurons than in large diameter neurons in control DRG. Interestingly, post-axotomy, Robo2 immunostaining increased in the large diameter neurons and the number of Robo2 positive large diameter neurons increased significantly relative to controls. Non-neuronal cells surrounding the primary sensory neurons, including the satellite cells, were Slit1-positive, and Slit1 protein was expressed in the myelin sheath and non-neural cells in both intact and degenerating sciatic nerve axons. Sciatic nerve transection also led to an accumulation of Slit1 protein in peripheral region of the traumatic neuroma. In conclusion, we report an altered expression and redistribution of Robo2 and Slit1 in the DRG and sciatic nerve trunk after peripheral axotomy. Our results indicate that Slit1 and Robo2 likely play an important role in regeneration after peripheral nerve injury.     

Phosphorylation of extracellular signal-regulated kinases 1/2 is predominantly enhanced in the microglia of the rat spinal cord following dorsal root transection

The present study was initiated to investigate the role of extracellular signal-regulated kinases (ERK) 1/2 signaling pathway in the early response of spinal cord and associated dorsal root ganglion (DRG) to rhizotomy by using Western blotting and immunohistochemical techniques in a rat model of L3 and L4 dorsal root transection. The results showed that there were a considerable amount of total and phosphorylated ERK 1/2 protein in both spinal cord and DRG in normal animals killed under pentobarbital anesthesia. The total ERK 1/2 distributed in both glia and neurons, while phosphorylated ERK 1/2 dominantly existed in the latter in the gray matter of spinal cord, as demonstrated with double immunofluorescent staining. Twenty-four and forty-eight hours after axotomy, the phosphorylation level of ERK 1/2 in the operation side of dorsal spinal cord was much higher than that in the contralateral side, while the total ERK 1/2 level seemed unchanged. The increased expression of Fos protein was also seen in the dorsal spinal cord at lesion side twelve and twenty-four hours after axotomy. Double fluorescent staining proved that the phosphorylated ERK 1/2 positive cells in the ipsilateral dorsal spinal cord after axotomy predominantly were microglia and small portion was oligodendrocytes, whereas the Fos expression was mainly in neurons. In normal DRG, most neurons, especially the medium and small-sized ones, and the satellite cells contained total ERK 1/2-like immunoreactivity, whereas only a small portion of neurons and satellite cells contained phosphorylated ERK 1/2. After unilateral dorsal rhizotomy, there were no detectable changes for the phosphorylation of ERK 1/2 in either neurons or satellite cells in DRG.Collectively, the present results suggest that both ERK and Fos signal pathways involve the cellular activation in the spinal cord following dorsal rhizotomy, with ERK mainly in microglia and Fos in neurons. The increase of phosphorylation of ERK 1/2 in microglia of spinal cord after rhizotomy implicates that ERK signaling pathway involves intracellular activity of microglia responding to the experimental injury.     

Time-dependent differences in the increase in GAP-43 expression in dorsal root ganglion cells after peripheral axotomy.

Peripheral axotomy of primary afferent neurons results in the up-regulation of the growth-associated phosphoprotein GAP-43, by dorsal root ganglion cells. We have studied the temporal sequence of GAP-43 expression in those dorsal root ganglion neurons with unmyelinated axons (the small dark cells) and in those with myelinated axons (the large light cells) after sciatic nerve section in the adult rat. Immunoreactivity for the RT 97 neurofilament epitope, which is detectable only in large light dorsal root ganglion cells, was used to differentiate the two types of dorsal root ganglion cell. Within two days of a sciatic nerve section the number of GAP-43-immunoreactive profiles in the ipsilateral ganglion had increased five-fold and this increase persisted for 80 days post-section. While 50% of the small numbers of GAP-43-positive cells in control ganglia were RT 97 positive, only 8% of the large number of GAP-43-immunoreactive cells four days post-section, were RT 97 positive. By 14 days the number of RT 97-positive/GAP-43-positive cells had increased to 29%. This was paralleled by an increase in GAP-43 immunoreactivity in large diameter profiles at 14 days. The signals that alter GAP-43 expression in unmyelinated (small, RT 97 -ve) and myelinated (large, RT 97 +ve) afferents after peripheral nerve injury appear to operate with different time-courses.     

Expression of leukemia inhibitory factor receptor mRNA in sensory dorsal root ganglion and spinal motor neurons of the neonatal rat

Previous studies have shown that the application of leukemia inhibitory factor to the proximal nerve stump prevents the degeneration of axotomized sensory neurons in the dorsal root ganglion and motor neurons in the spinal cord of newborn rats. This study investigated the expression of leukemia inhibitory factor receptor mRNA in these neurons using in situ hybridization. Leukemia inhibitory factor receptor mRNA was detected both in sensory neurons within the dorsal root ganglion and motor neurons of the cervical spinal cord. Twenty-four hours after axotomy these neurons continue to express leukemia inhibitory factor receptor mRNA. This pattern of leukemia inhibitory factor receptor expression provides a mechanism by which endogenous and exogenous leukemia inhibitory factor could act on injured sensory and motor neurons.     

Sciatic nerve injury in the adult rat: comparison of effects on oligosaccharide, CGRP and GAP43 immunoreactivity in primary afferents following two types of trauma

Summary Using immunocytochemical and morphometric techniques, the localisation of three neuronal oligosaccharide antigens (two lactoseries and one globoseries oligosaccharide) were studied in the spinal cord and dorsal root ganglia of adult rats following unilateral crushing or transection of the sciatic nerve. The expression of CGRP and GAP43 was also studied for comparison. We found that following transection of the nerve the expression of lactoseries oligosaccharides and CGRP was permanently depressed, whilst that of the globoseries antigen (SSEA4) was unaffected. However following crush trauma and subsequent regeneration after 2 months, only the expression of one lactoseries antigen, LA4 remained significantly depressed. Our results suggest that different subsets of sensory neurons vary in the rate of reaction to injury and that one subset of neurons expressing a lactoseries oligosaccharide antigen is particularly susceptible to axotomy-induced changes. Furthermore neurons expressing the globoseries oligosaccharide antigen SSEA4 appear to be relatively unaffected by peripheral axotomy.     

银杏酮酯对大鼠坐骨神经损伤后生长相关蛋白43表达的影响

目的:研究银杏酮酯对大鼠坐骨神经损伤后生长相关蛋白43(GAP-43)表达的影响。方法:SD大鼠78只,随机分成正常组、损伤对照组与实验组,给予不同处理,后两组切断右侧坐骨神经并缝合。实验组给予银杏酮酯200mg·kg-1.d-1溶于1ml生理盐水中灌胃,损伤对照组给予生理盐水1ml灌胃,正常组不做处理。分别于术后1、3、7、14、21及28d取吻合口远段的神经、相应节段的脊神经节及脊髓,应用免疫组织化学和图像分析的方法研究所取组织中GAP-43蛋白的表达并进行定量分析。结果:实验组坐骨神经、脊神经节及脊髓中GAP-43蛋白免疫阳性区域面积和平均光密度值在术后7、14和21d明显高于对照组。结论:大鼠坐骨神经损伤后用银杏酮酯治疗,在早期可促使坐骨神经及相应节段脊神经节和脊髓组织中的GAP-43蛋白表达增加。