Temporal changes of neuronotrophic activities accumulating in vivo within nerve regeneration chambers

The presence of neuronotrophic factors (NTFs) in noninjured sciatic nerve extract and the course of their accumulation from 3 h to 30 days after nerve transection was examined. Rat sciatic nerves were transected and their proximal and distal stumps sutured into the openings of cylindrical silicone chambers leaving a 10-mm interstump gap. Previous studies had shown that regeneration occurs in chambers containing both stumps but is absent in chambers lacking the distal stump. Chambers became completely filled with fluid 10 to 12 h after implantation. Fluid from chambers without nerve stumps (open-ended) implanted adjacent to nerve-containing chambers had markedly lower trophic activities than those containing one or both stumps. In fluid collected from chambers containing both proximal and distal nerve stumps, the highest titers of NTFs directed to sensory neurons were measured at 3 h posttransection whereas the highest titers of NTFs directed to sympathetic and spinal cord neurons were detected at 1 and 3 days, respectively. Chambers containing only the proximal or only the distal stumps showed similar temporal dynamics for sensory and sympathetic NTFs. Sensory and sympathetic neuronotrophic activity in extracts of proximal and distal stumps followed a similar temporal course to those in chamber fluid. Extracts of nonlesion nerve segments 5 mm from the transection site contained higher sensory and lower sympathetic trophic activity than extracts including the transection site. Spinal cord activity was undetectable in all extracts. Antiserum to nerve growth factor had no effect on fluid or extracts containing high sensory or sympathetic activities. These observations suggested that (i) some NTFs may be present in normal nerves and others may be synthesized or accumulated in response to nerve injury, (ii) sensory, sympathetic, and spinal cord NTFs are separate agents and immunochemically distinct from nerve growth factor, (iii) NTFs predominantly originate from nerve stumps rather than from surrounding fluid, and (iv) proximal and distal nerve stumps accumulate and release NTFs at similar rates.     

Suppression of the cell body response in axotomized frog spinal neurons does not prevent initiation of nerve regeneration

Frog spinal neurons, in animals maintained at environmental temperatures above 20 degree C, show the classic features of the cell body response following peripheral axotomy. In contrast, axotomized spinal neurons in frogs held at an ambient temperature of 15 degree C showed no apparent cell body response. The 15 degree C neurons retained normal morphology, continued to synthesize and transport normal levels of acetylcholinesterase activity, and sustained normal reflex connections. Despite the apparent absence of a cell body response, the proximal nerve stump began to regenerate. The apparent latency to the initiation of axonal growth was increased at 15 degree C; regeneration began 3.8 days after axotomy at 25 degree C, but 4.5 days following nerve section at 15 degree C. The rate of axon regeneration was also considerably slower at 15 degree C: 0.6 mm/day compared to 2.4 mm/day at 25 degree C. Nonetheless, these data imply that initiation of axonal sprouting and regeneration may not depend on alterations in the cell body. Additional data indicated that the appearance of the cell body response may not be linked to the elimination of a normal, peripherally-derived, constituent of the retrograde transport system. Injured motor axons at 15 degree C were able to acquire and transport horseradish peroxidase from the point of transection to the cell body. Material normally in transit to the cell body should also be drained from the injured axons over time. Yet, the elimination of this "trophic' supply did not induce the appearance of the cell body response.     

Uptake and retrograde transport of proteins by regenerating axons

Summary It is well known that the ends of normal axons can absorb exogenous tracer proteins, which are then transported intra-axonally to the neuronal perikarya. The object of this investigation was to determine whether the same phenomenon occurs in regenerating nerve fibres. Horseradish peroxidase (HRP) was applied to the hypoglossal nerves of rats immediately or at intervals of 12 h to 14 days after crushing. The enzyme was detected histochemically, 24 h later, in the neurones of the hypoglossal nucleus. The numbers of HRP-containing neurones declined abruptly after the 4th postoperative day. By this time most of the regenerating axons extended further distally in the nerve than the region permeated by the topically applied HRP, though some growth cones were still present near the site of injury even after 14 days. It is deduced that the growing tips of the regenerating axons, but not their more proximal parts, absorbed HRP for subsequent retrograde transport to their cell bodies.In some of the rats a fluorescent tracer protein (thodamine B-labelled bovine serum albumin) was injected i.v. 1 h before death. Abnormal permeability of the endoneurial blood vessels was observed distal to the sites of crushing. The zone of increased permeability advanced distally at the same rate as that of the tips of the regenerating axons. It is suggested that the growth cones of regenerating axons may absorb proteins derived from the blood plasma. The retrograde axoplasmic transport of such substances to the cell bodies might be important in initiating and maintaining the neuronal metabolic changes necessary for the regeneration of severed axons.     

Neurite-promoting factors and extracellular matrix components accumulating in vivo within nerve regeneration chambers

The outgrowth of neurites from cultured neurons can be induced by the extracellular matrix glycoproteins, fibronectin and laminin, and by polyornithine-binding neurite-promoting factors (NPFs) derived from culture media conditioned by Schwann, or other cultured cells. We have examined the occurrence of fibronectin, laminin and NPFs during peripheral nerve regeneration in vivo. A previously established model of peripheral nerve regeneration was used in which a transected rat sciatic nerve regenerates through a silicone chamber bridging a 10 mm interstump gap. The distribution of fibronectin and laminin during regeneration was assessed by indirect immunofluorescence. Seven days after nerve transection the regenerating structure within the chamber consisted primarily of a fibrous matrix which stained with anti-fibronectin but not anti-laminin. At 14 days, cellular outgrowths from the proximal and distal stumps (along which neurites grow) had entered the fibronectin-containing matrix, consistent with a role of fibronectin in promoting cell migration. Within these outgrowths non-vascular as well as vascular cell stained with anti-fibronectin and anti-laminin. Wihtin the degenerated distal nerve segment, cells characteristics of Bungner bands (rows of Schwann cells along which regenerating neurites extend) stained with anti-fibronectin and laminin. The fluid surrounding the regenerating nerve was found to contain NPF activity for cultured ciliary ganglia neurons which markedly increased during the period of neurite growth into the chamber. In previous studies using this particular neurite-promoting assay, laminin but to a much lesser extent fibronectin also promoted neurite outgrowth. Affinity-purified anti-laminin antibody failed to block chamber fluid NPF activity while completely blocking the neurite-promoting activity of laminin. These two results suggested that chamber fluid NPF activity did not consist of individual molecules of either fibronectin or laminin. The spatial and temporal distribution of insoluble fibronectin and laminin and the temporal correlation between chamber fluid NPF accumulation and neurite outgrowth support the possibility that these agents influence regenerative events including axonal elongation in vivo.     

Axonal transport in mdx mouse sciatic nerve

Anterograde and retrograde flows of acetylcholinesterase (AChE) in sciatic nerves of adult mdx mice were compared with those of normal mice. Specific molecular forms of AChE were resolved by high-performance liquid chromatography such that slow anterograde (G1 + G2), fast anterograde and fast retrograde (G4 and A12) flows could be simultaneously studied. Although we found no difference in the total AChE activity and the molecular forms in non-ligated nerves between mdx and the normal mice, ligated nerves showed significant differences. The total AChE activity accumulated at the proximal segment of ligated nerve was higher in mdx mice than in normal mice after 24 h ligation. The G1 + G2 molecular forms were accumulated more in the proximal segment of mdx than the normal. A12, on the other hand, was more abundant in both segments of mdx mice than the normal. No statistically significant difference in the accumulated amount of G4 molecular form was present between mdx and the normal mice at either proximal or distal segment. These results indicated that axonal flow in sciatic nerve likely plays a role in muscle regeneration, and that the transport machinery in dystrophin-deficient mdx neuron is probably normal.     

Re-expression of Nerve Growth Factor Receptor after Axonal Injury Recapitulates a Developmental Event in Motor Neurons: Differential Regulation when Regeneration is Allowed or Prevented

Motor neurons in the brainstem and spinal cord transiently express nerve growth factor receptors (NGFr) during development, but not in normal adult animals. In this study, NGFr was immunohistochemically identified in hypoglossal motor neurons after different types of peripheral axonal injury in adult rats. NGFr is re-expressed in motor neurons 7 days after a nerve crush injury, and has disappeared again by 28 days. These times correspond, respectively, to the active phase of regeneration, and a time by which regeneration has largely been completed, as determined by electrical activation of tongue muscle twitch. In contrast, 7 days after nerve transection and ligation of the proximal stump to prevent regeneration, there is no re-expression of NGFr, but 28 days after such treatment NGFr is present in a few neurons. By this time, neuroma formation has begun proximal to the end of the cut and ligated nerve. Together, these findings suggest that motor neurons transiently re-express NGFr during regeneration and not in response to axonal transection per se. The signal triggering re-expression thus seems more likely to be the introduction of a message from the site of injury, rather than the loss of a target-derived message. Although the function of NGFr in developing and regenerating motor neurons is not known, its expression appears to be associated with periods of axonal growth and maturation.     

Electromagnetic fields influence NGF activity and levels following sciatic nerve transection

Pulsed electromagnetic fields (PEMF) have been shown to increase the rate of nerve regeneration. Transient post‐transection loss of target‐derived nerve growth factor (NGF) is one mechanism proposed to signal induction of early nerve regenerative events. We tested the hypothesis that PEMF alter levels of NGF activity and protein in injured nerve and/or dorsal root ganglia (DRG) during the first stages of regeneration (6–72 hr). Rats with a transection injury to the midthigh portion of the sciatic nerve on one side were exposed to PEMF or sham control PEMF for 4 hr/day for different time periods. NGF‐like activity was determined in DRG, in 5‐mm nerve segments proximal and distal to the transection site and in a corresponding 5‐mm segment of the contralateral nonoperated nerve. NGF‐like activity of coded tissue samples was measured in a blinded fashion using the chick DRG sensory neuron bioassay. Overall, PEMF caused a significant decrease in NGF‐like activity in nerve tissue (P < 0.02, repeated measures analysis of variance, ANOVA) with decreases evident in proximal, distal, and contralateral nonoperated nerve. Unexpectedly, transection was also found to cause a significant (P = 0.001) 2‐fold increase in DRG NGF‐like activity between 6 and 24 hr postinjury in contralateral but not ipsilateral DRG. PEMF also reduced NGF‐like activity in DRG, although this decrease did not reach statistical significance. Assessment of the same nerve and DRG samples using ELISA and NGF‐specific antibodies confirmed an overall significant (P < 0.001) decrease in NGF levels in PEMF‐treated nerve tissue, while no decrease was detected in DRG or in nerve samples harvested from PEMF‐treated uninjured rats. These findings demonstrate that PEMF can affect growth factor activity and levels, and raise the possibility that PEMF might promote nerve regeneration by amplifying the early postinjury decline in NGF activity. J. Neurosci. Res. 55:230–237, 1999. Published 1999 Wiley‐Liss, Inc.     

Best time window for the use of calcium‐modulating agents to improve functional recovery in injured peripheral nerves—An experiment in rats

Peripheral nerve injury can have a devastating effect on daily life. Calcium concentrations in nerve fibers drastically increase after nerve injury, and this activates downstream processes leading to neuron death. Our previous studies showed that calcium‐modulating agents decrease calcium accumulation, which aids in regeneration of injured peripheral nerves; however, the optimal therapeutic window for this application has not yet been identified. In this study, we show that calcium clearance after nerve injury is positively correlated with functional recovery in rats suffering from a crushed sciatic nerve injury. After the nerve injury, calcium accumulation increased. Peak volume is from 2 to 8 weeks post injury; calcium accumulation then gradually decreased over the following 24‐week period. The compound muscle action potential (CMAP) measurement from the extensor digitorum longus muscle recovered to nearly normal levels in 24 weeks. Simultaneously, real‐time polymerase chain reaction results showed that upregulation of calcium‐ATPase (a membrane protein that transports calcium out of nerve fibers) mRNA peaked at 12 weeks. These results suggest that without intervention, the peak in calcium‐ATPase mRNA expression in the injured nerve occurs after the peak in calcium accumulation, and CMAP recovery continues beyond 24 weeks. Immediately using calcium‐modulating agents after crushed nerve injury improved functional recovery. These studies suggest that a crucial time frame in which to initiate effective clinical approaches to accelerate calcium clearance and nerve regeneration would be prior to 2 weeks post injury. © 2017 Wiley Periodicals, Inc.     

Conduction studies in peripheral cat nerve using implanted electrodes: II. The effects of prolonged constriction on regeneration of crushed nerve fibers

Arrays of chronically implanted electrodes were used to examine the time course of elongation and maturation of peripheral nerve fibers in the cat after crush of the tibial nerve in the proximal calf. Regeneration after crush alone was compared with crush 5 mm proximal to a tight constriction of the nerve. Regeneration was monitored by the progression of excitability along the electrode arrays on the tibial and plantar nerves. The sensitivity was sufficient to record the averaged activity in single nerve fibers allowing detection of the earliest regeneration. The diameters of the fastest regenerating fibers were estimated from the conduction velocity proximal to the site of crush. Both after crush alone, and after crush constriction, small myelinated fibers regenerated in front of large fibers. The rate of elongation after crush alone was 3.2 mm/day, whereas it was slower (P less than 0.02) distal to crush + constriction (2.2 mm/day). In both lesions, the extrapolated delay to onset of regeneration was 8 days. In observations up to 300 days after crush, maturation was delayed or impaired by the constriction, and the compound nerve action potential had a smaller amplitude and a dispersed shape. Transverse sections of nerves after crush + constriction showed a diminished number of large and an increased number of small fibers compared with crush alone, possibly due to persistent branching of regenerated fibers. After both crush alone and crush + constriction, regenerated fibers had similar g ratios, suggesting that myelination developed fully in fibers of diminished diameters.     

Local nitric oxide synthase activity in a model of neuropathic pain

A local inflammatory reaction may play an important role in the development of neuropathic pain following peripheral nerve injury. One important participant in the inflammatory response of injured peripheral nerve may be nitric oxide (NO). In this work, we examined physiological and morphological evidence for nitric oxide synthase (NOS) activation in the chronic constriction injury model of neuropathic pain in rats. Physiological evidence of local NO action was provided by studying NO-mediated changes in local blood flow associated with the injury site. Immunohistochemistry was used to localize isoforms of NOS that might generate NO. Sciatic nerve injury associated with behavioural evidence of neuropathic pain had substantial rises in local blood flow. The NOS inhibitor N^G-nitro-l -arginine methyl ester (L-NAME), but not N^G-nitro-d -arginine methyl ester (D-NAME), reversed the hyperaemia in a dose-dependent fashion proximal to the constriction at 48 h and distally at 14 days post-operation when applied systemically or topically. Aminoguanidine, a NOS inhibitor with relatively greater selectivity for the inducible NOS (iNOS) isoform, reversed nerve hyperaemia distal to the constriction only at 14 days. NOS-like immunoreactivity of the neuronal and endothelial isoforms was identified just proximal to the constriction at 48 h. iNOS-like immunoreactivity was observed at 7 and 14 days at the constriction and distal sites, respectively. This work provides evidence for local NOS expression and NO action in the chronic constriction injury model of neuropathic pain. NO has local physiological actions that include vasodilatation of microvessels and that may be important in the development of pain sensitivity.     

Orthograde and retrograde axonal transport of labeled protein in motoneurons

After injection of 3H-l-leucine into the vicinity of rat lumbosacral motoneurons, a wave of labeled protein traveled along the sciatic nerve with a velocity of 428 mm/day. Subsequent events were followed by crushing the sciatic nerve at intervals after injection and measuring the accumulation of label at crushes over a 3-hr period. The 3-hr accumulation at the proximal side of a crush declined rapidly over the first 10 hr after precursor administration. Over the period 10 to 99 hr proximal accumulations declined more slowly. Three hour accumulations at the distal side of a crush were initially low but rose to a peak at 44 to 47 hr, when distal accumulation was 180% of proximal accumulation. Thereafter distal accumulation declined.After intravenous injection of leucine, accumulations of activity which occurred at nerve crushes were only 3 to 6% of the accumulation observed when leucine was injected into the lumbosacral cord. Injury currents were not responsible for conveying material to the crush region. It was concluded that accumulation represented the damming-up of material derived from the motoneuron and in transit along the axon.The pattern of accumulation at the nerve crushes was interpreted thus: after precursor administration there was a 6-hr phase of orthograde protein transport containing large amounts of activity, followed by a more sustained phase containing smaller amounts of activity. Some of the transported protein was returned to the cell body after spending about 30 hr in the terminals. During the period 4 to 99 hr after precursor administration, the quantity of label returning to the cell body was half the amount transported into the axons.     

Prevention of optic nerve regeneration in the frog Hyla moorei transiently delays the death of some ganglion cells

We have previously reported that a proportion of ganglion cells die during optic nerve regeneration in the adult frog Hyla moorei (Humphrey and Beazley, '85). Here we assess the effect of preventing optic nerve regeneration on this cell loss. The optic nerve was crushed unilaterally and regeneration was allowed to progress unimpeded in one experimental series but was prevented by ligating or capping the nerve in another. We estimated total cell numbers in the ganglion cell layer from cresyl-stained wholemounts, comparing each experimental retina with its unoperated partner. At 70-78 days postcrush, mean cell numbers had fallen by 31.5% for frogs with unimpeded regeneration (N = 9), a significantly greater reduction than the 21.5% (N = 8) loss for the impeded regeneration series (p less than 0.001). Thereafter, cell numbers were stable for frogs with unimpeded regeneration. Cell death continued in the series with impeded regeneration, and losses exceeded those of frogs with unimpeded regeneration from 110 days postcrush. When regeneration was impeded, ganglion cell somas underwent an intense cell soma reaction and became arranged in rows radiating from the optic nerve head. Our findings indicate that some ganglion cells are transiently spared when regeneration of their axons is prevented. The abnormally extensive contacts formed between somas may delay ganglion cell loss. However, the eventual death of most ganglion cells shows them to be target-independent in the long term.     

Distribution of nerve fibers in the basilar papilla of normal and sound-damaged chick cochleae

Epifluorescent light microscopy and confocal laser scanning microscopy were employed to visualize the distribution of nerve fibers in whole-mount preparations of normal and sound-damaged chick basilar papillae (BP). In normal cochleae, we identified a consistent pattern of nerve processes that ran transversely across the BP. The transverse processes increase in number from the proximal to the distal ends of the epithelium. However, when the processes are separated into populations of thin fibers and thick bundles, the thin fibers are more prevalent in distal regions whereas thick bundles are more extensive in proximal regions. Furthermore, the thick bundles form an elaborate longitudinal network in the border cell and hyaline cell region. Based on these data and on other previous studies, the thin fibers appear to be afferent nerves and the thick bundles represent efferent nerves. When birds are exposed to acoustic trauma, the normal pattern and number of nerve processes is not altered by levels of sound that produce moderate levels of damage, i.e., damage that leads to hair cell loss and regeneration. However, the nerve pattern is disrupted by severe levels of damage that destroy both hair cells and supporting cells. These findings indicate that the level of sound exposure that induces hair cell regeneration may damage the synaptic endings associated with the lost hair cells, but that the nerve processes that give rise to these endings remain intact within the sensory epithelium. In contrast, severe damage destroys both the hair cells and their associated nerve fibers. © 1996 Wiley-Liss, Inc.     

Spatiotemporal progress of nerve regeneration in a tendon autograft used for bridging a peripheral nerve defect

We have previously shown that a tendon autograft from the rat tail can support regeneration across a gap in the continuity of the rat sciatic nerve. In this study, we characterized the spatiotemporal progress of regeneration in such a graft bridging a 10-mm defect in the sciatic nerve of the rat. Regeneration was assessed 7, 10, 14, or 18 days postoperatively, by immunocytochemistry for axons, Schwann cells, and macrophages and histochemistry for blood vessels. Axonal regrowth into the grafts showed an initial delay period of 6.8 days, whereafter axons grew at a rate of 1.0 mm/day. Schwann cells grew into the grafts from both the proximal and distal nerve segments, proximally just ahead of the axonal front. Macrophages were initially preferentially located at the periphery of the grafts, but gradually increased inside the grafts. Blood vessels entered the grafts from both the proximal and distal aspects of the severed nerve. The onset of vascularization appeared to coincide with axonal regeneration into the grafts.     

Evidence for selective loss of brain dopamine- and histamine-stimulated adenylate cyclase activities in rabbits with aging

Dopamine-stimulated adenylate cyclase activity in striatum and both dopamine-and histamine-stimulated adenylate cyclase activity in hypothalamus, frontal cortex and anterior limbic cortex declined by about 50% as rabbits aged from 5.5 months to 5.5 years of age. These changes were primarily in maximal response to amine although an additional component involving decreased affinity in the case of dopamine may also be present. In contrast, dopamine-stimulated adenylate cyclase of retina and both basal and guanyl-5′-yl-imidodiphosphate (Gpp(NH)p)-stimulated activity in these regions were not altered with age. There was no measurable decrease in the old animals in either dopamine or norepinephrine concentration in striatum, anterior limbic cortex or retina, or in choline acetylase activity or [³H]quinuclidinylbenzilate binding in striatum, anterior limbic cortex or frontal cortex. It is proposed that selective age-dependent decreases in transmitter receptors coupled to adenylate cyclase occur in the absence of or independent from neuronal cell loss, as evidenced by the retention of the other biochemical markers.     

ACTH-like neurotropic peptides: possible regulators of rat brain cyclic AMP

The influence of behaviorally active, N-terminal fragments of ACTH on the accumulation of cAMP in rat brain investigated in broken cell preparations of subcortical tissue, in slices of neostriatum and in vivo. ACTH1--24 has a biphasic effect on the activity of adenylate cyclase in broken cell preparations of rat brain subcortical tissue: concentrations below 25 micrometer stimulated, whereas concentrations of 0.1 mM and higher inhibited adenylate cyclase activity. The magnitude of the stimulation was dependent on the concentrations of ATP and Mg2+ in the incubation medium. Structure activity studies revealed that at a concentration of 10(-4) M ACTH1--16-NH2 and ACTH4--7 also inhibited the activity of adenylate cyclase, whereas ACTH11--24, ACTH1--10, ACTH4--10, [D-Phe7]ACTH1--10 and [D-Phe7]ACTH4--10 were inactive in this respect. Addition of 0.8 mM EGTA but not of 0.25 mM Ca2+ prevented the inhibition by 10(-4) M ACTH1--24. GMP-N-P (10(-5) M), naltrexone (10(-3) M) and ergometrine (10(-3) M) did not influence the inhibitory effect. ACTH1--24 enhanced the accumulation of cAMP in slices from rat brain neostriatum in a dose-dependent manner. This effect was already maximal 7.5 min after the addition of the peptide and was potentiated by isobutylmethylxanthine, a potent inhibitor or phosphodiesterase. Intraventricular injection of 1 microgram ACTH1--16-NH2 in rats significantly elevated (+ 27%) the concentration of cAMP in the septal region 60 min after the injection of the peptide. The results are discussed in terms of a possible involvement of cAMP as a second messenger in the central nervous system for N-terminal fragments of ACTH.     

Motoneuron survival is not affected by the proximo-distal level of axotomy but by the possibility of regenerating axons to gain access to the distal nerve stump

The aim of this study was to examine whether axotomy-induced motoneuron death in adult mammals differ: (1) with the distance between the site of injury and the nerve cell body, and (2) if contact between the transected nerve stumps is established after the injury, compared with cases where contact is prevented. The hypoglossal nerve of adult rats was transected either proximally in the neck (proximal injury) or close to the tongue (distal injury). The nerve stumps were then either deflected from each other in order to prevent axon regeneration into the distal nerve stump, or sutured. Three months later, the extent of nerve cell loss was examined bilaterally in cresyl violet-stained sections of the hypoglossal nucleus. In addition, we examined hypoglossal neuron survival twelve months after a proximal nerve transection with prevented regeneration. Our results show that there was no significant difference in neuronal survival after a proximal nerve transection compared with a distal one, neither if contact between the nerve stumps was established nor if it was prevented. However, contact between the transected nerve stumps increased the likelihood of neuronal survival significantly after both proximally and distally located injury compared to nerve injury with prevented regeneration. There was no significant decrease in nerve cell survival after twelve months with prevented reinnervation compared with survival after three months. These observations indicate that the extent of axotomy-induced motoneuron death in adult mammals does not correlate with the proximo-distal level of peripheral injury. Furthermore, early contact with the distal stump and/or target musculature is a significant factor for the survival of axotomized motoneurns. However, more than 50% of the original nerve cell population survives a considerable time even after permanent disconnection from the target. Copyright © 1994 Wiley-Liss, Inc.     

下肢短潜伏期体感诱发电位和F波对糖尿病近端神经病的诊断价值

目的 探讨下肢短潜伏期体感诱发电位(SLSEP)和F波检测在糖尿病近端神经病变的诊断意义.方法 排除脑卒中、腰颈椎病及其他疾病引起的神经-肌肉疾病,对92例2型糖尿病患者:有神经病变体征而神经传导检测正常(Ⅰ组)32例、无神经病变体征神经传导检测正常(Ⅱ组)30例和神经传导异常(Ⅲ组)30例,与30名健康人行下肢SLSEP和F波测定.结果 胫神经SLSEP和F波各参数总异常率以Ⅰ组有神经病变体征肢体亚组(n=43)比例最高[97.7%(42/43)],Ⅰ组Fdur、N13传导速度(CV)、N24CV、N13-N24CV、N9-N24CV平均值与对照组比较差异均有统计学意义(g值分别:5.887和6.780、-4.568和-5.062、-6.799和-6.905、-5.978和-5.609、-5.433和-5.190;均P＜0.01);Ⅱ组Fdur和N13-N24CV异常肢体率[25.0%(15/60),23.3%(14/60)]与对照组[0,1. 7%(1/60)]比较差异有统计学意义(x2值分别:17.143、12.876,均P=0.0050);Ⅲ组各参数异常肢体率与对照组比较,除N9-N24CV、N13波幅及N24波幅外,差异均有统计学意义,其中N9CV异常率最高[76.7%(46/60)].结论 SLSEP可以提供感觉纤维近端信息;SLSEP和F波联合使用可以提高糖尿病近端神经病变的诊断率,对有周围神经损害症状而常规神经传导速度测定正常的糖尿病患者其诊断意义尤为显著.     

Transient neovascularisation of the frog retina during optic nerve regeneration

In conditions such as diabetic retinopathy, degenerative events in the retina are associated with neovascularisation. It is well established that a proportion of retinal ganglion cells die during optic nerve regeneration in the frog. The present study has determined whether neovascularisation takes place during this regenerative process. To do so, the pattern of blood vessels overlying the retinal ganglion cell layer was analysed in the frog Litoria (Hyla) moorei. We examined normal animals and those undergoing optic nerve regeneration following nerve crush. Blood vessels were visualised by perfusion with Indian ink and retinae were prepared as wholemounts. In normal animals, the vascular tree was found to lie superficial to the nerve fibre layer and was more complex in regions overlying the area centralis and visual streak. After nerve crush, abnormal blood vessels transiently formed between the existing branches of the vascular tree. The new vessels were concentrated as an annulus centred on the optic nerve head and over the area centralis in midtemporal retina. The neovascularisation became most extensive between 6 and 10 weeks postcrush and disappeared by 12 weeks. The spatiotemporal sequence of neovascularisation suggests that it is triggered by accumulations of degenerating material formed as a proportion ofthe ganglion cells die during optic nerve regeneration. © 1993 Wiley-Liss, Inc.     

Estrogen receptor-beta colocalizes extensively with parvalbumin-labeled inhibitory neurons in the cortex,amygdala, basal forebrain,and hippocampal formation of intact and ovariectomized adult rats

Some amphibian retinal ganglion cells die during optic nerve regeneration. Here we have investigated whether ganglion cell death in the frog Litoria moorei is associated with the lesion site. For one experimental series, the optic nerve lesion extended for 0.15 mm; in the other, it extended for 1.5 mm. The extent of ganglion cell death was estimated from cresyl violet-stained whole mounts at 24 weeks post lesion. In other animals, individual regenerating axons were visualised in the optic nerve by horseradish peroxidase (HRP) labelling from 1 day to 24 weeks post lesion; counterstaining with cresyl violet allowed examination of cells that repopulated the lesion site. Ganglion cell numbers fell significantly more after an extensive than after a localised lesion, long-term losses being 50% and 34%, respectively (P < 0.05). Regenerating axons were delayed in their passage across the cell-poor extensive lesion compared with the relatively cell-rich localised lesion. The differing rates of regeneration between series were matched by greater delay after extensive lesion in the return of visually guided behaviour as assessed by optokinetic horizontal head nystagmus. We suggest that delays in regeneration after an extensive lesion exacerbate ganglion cell death, indicating that conditions within the lesion are associated with the death of some ganglion cells.