Morphologic changes of the cranial nerves, spinal cord ganglia and roots in botulism

Peripheral nervous system was studied morphologically in 4 patients who had died from botulism. The results indicate considerable alterations in cranial and spinal nerves as well as in spinal cord ganglia. This may explain a neurological symptoms (radiculoneuritis, radiculoganglionitis) in botulism.     

Sexual differences in the topographical distribution of serotonergic fibers in the anterior column of rat lumbar spinal cord

Summary Sexual dimorphism in the topographical organization of immunoreactive serotonergic fibers has been shown for the first time in the anterior column of the rat lumbar cord. A characteristic preferential arrangement of serotonergic fibers on the small cell column composed of anterior horn motoneurons, which have been proved to send their axons to the cremaster muscle, was demonstrated at the lumbar segments (L1–L2) of male rats, using the immunoperoxidase technique with antiserum against serotonin. A similar finding was also observed in female rats, but was less prominent than in males. Comparative analysis of the cell numbers and the size of neuronal somata of the aforementioned nucleus, done using retrograde transport of fluorescent dye (DAPI) via axonal fibers coursing down the genitofemoral nerve to the cremaster muscle, gave significantly larger values in males.The sexual difference in the serotonergic innervation pattern was, in consequence, surmised to be caused by the cytoarchitectonic contrast ascertained in the lumbar anterior column. Furthermore, there may be a striated muscle endowed with some active functions homologous to those of the male cremaster muscle in the female rat.     

Pathological changes of the spinal cord in centenarians

In order to study the changes that occur in the spinal cords of the aged, 19 centenarian spinal cords from two men and 17 women (age range, 100-116 years at death; mean, 103 years) were pathologically examined. Cross-sections at each segmental level of the 19 autopsied spinal cords were examined for histopathological changes. The cross-sectional area and flattening ratio at the level of the C7 segment were measured. The size of the cords had some negative correlation with age, but the individual variation was considerably large. Among the 19 centenarians, macroscopic anteroposterior flattening appeared in the lower cervical cords in six individuals. In these cases, various degrees of neuron loss were observed in the anterior horn. White matter degeneration appeared frequently, especially in the posterior column. In 12 cases, myelin loss in the fasciculus of Goll at the cervical level was observed. The degeneration of the fasciculus of Goll was considered to be upward wallerian degeneration secondary to posterior root damage at the lumbosacral level. These changes seemed to be produced by disorders in the spinal canal or surrounding tissue, such as cervical spondylosis, degeneration of the intervertebral disk and spinal canal stenosis. Argyrophilic structures such as neurofibrillary tangles and neuropil threads were observed in 16 cases; however, this incidence was less than in the brain. Medial thickening of the anterior spinal artery was found in four cords. Amyloidangiopathy was noted in only one cord. Necrosis and hemorrhage due to vascular disturbance were not found.     

Afferent connections of posterior column nuclei of the spinal cord

Brain Institute, All-Union Mental Health Research Center, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR D. S. Sarkisov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 110, No. 9, pp. 229–231, September, 1990.     

胸腰段脊柱手术与脊髓血供损伤的相关性研究

目的：为减少手术中对脊髓血供损伤和设计合理脊柱手术入路提供基础。方法：20俱尸体运用解剖、血管铸型及9例成年人常规进行超选择性脊柱脊髓血管造影等方法，对脊柱脊髓血管应用解剖较系统地研究，了解脊柱脊髓血供及代偿通路。结果：①节段动脉在肋横突关节内侧椎间孔部发出根髓动脉。②胸段毗邻的肋间动脉吻合主要是椎间孔周围和骶棘肌内两处；而腰段还有椎体侧面的髂腰肌和腰大肌中的吻合。③超选择性血管造影显示胸、腰段，毗邻的节段动脉之间及与对侧同名动脉之间有广泛吻合。胸段动脉多见以横向连接吻合，而腰段除此之外还可见明显的动脉上下2～3节段侧支吻合。结论：①脊柱前路矫形应在根髓动脉分支前，结扎多个节段血管，脊髓血供可以通过后方代偿，能避免累及脊髓根髓动脉产生脊髓损伤；②侧前入路应在根髓动脉分支后，经胸、腰段毗邻的动脉之间，椎间盘切除或椎间隙减压伤及根髓动脉出现脊髓损伤机率最小。③后入路截骨选择经过椎弓、椎体中部截骨损伤血管最少。     

Morphofunctional characteristics of the lumbar enlargement of the spinal cord in rats

The topography of the lumbar enlargement of the spinal cord in rats was studied; an immunohistochemical method was used to determine the distribution of synaptophysin — a membrane protein of synaptic vesicles. Synaptophysin-immunoreactive structures were detected in the gray matter of all Rexed laminae, around most neurons and in the neuropil. Previously undescribed subpial synaptic contacts were detected immunohistochemically in the white matter and confirmed by electron microscopy. A non-myelinated component of the corticospinal tract, including axonal varicosities and synaptic contacts, was observed in the dorsal part of the white matter of the lumbar enlargement of the spinal cord. __________ Translated from Morfologiya, Vol. 132, No. 5, pp. 33–37, September–October, 2007.     

Circumferential cells of the developing Rana catesbeiana lumbar spinal cord

Summary Neural elements in the lumbar enlargement of the developing Rana catesbeiana spinal cord were labelled by placing chips of dessicated horseradish peroxidase (HRP) into various lesions of the spinal cord. Of the elements labelled in the lumbar enlargement, a population of cells circumjacent to the gray matter was seen to be distinct from all others on the basis of their morphology, position and their putative embryonic origin. One cell type not previously described was a large circumferential cell (LCC) with primary processes completely circumscribing the gray matter. The ventral process crosses the midline and ascends or descends in the ventral funiculus. The dorsal primary process was observed to extend to the midline and turn ipsilaterally in a rostro-caudal direction in the dorsal funiculus. LCC's were present at early stages of larval development (stage III, Taylor and Kollros 1946) but could not be labelled in juvenile frogs. LCC's were only observed in the lumbar enlargement and could only be labelled through HRP applications at that level. They receive abundant synaptic input from the ipsilateral lateral funiculus. Possible roles for the LCC in the early function and development of the ranid lumbar spinal cord are discussed.     

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.     

Spinoreticular neurons in the second sacral segment of the feline spinal cord.

In continuation of previous electrophysiological studies on the location of ascending tract neurones within the second sacral segment of the feline spinal cord, the spinoreticular projections of these neurones have been investigated. Following electrical stimulation of the axonal terminals of 37 spinoreticular neurons via a tungsten electrode placed stereotactically in the contralateral nucleus reticularis gigantocellularis, antidromic potentials from their cell bodies were recorded with glass microelectrodes both extra- and intracellularly. The axons of these neurones were additionally excited from the dorsolateral funiculi of the contralateral (n = 37) and ipsilateral (n = 30) side at the lowermost thoracic spinal level. The latencies of antidromic excitation from the brainstem to the second sacral segment ranged from 3.2 to 11.8 ms (mean, 5.9 ms), whereas the corresponding axonal conduction velocities were between 27.1 and 100 m/s. The neurones examined in this study were found to be situated in the medial lamina VII of Rexed and the area adjacent to the central canal (n = 13), the medial lamina VIII (n = 12), medial laminae V and VI (n = 10) and in laminae II and III (n = 2). Three medium-sized (40-60 microm) of triangular- or oval-shaped neurones were visualized in medial laminae VII and VIII following the intracellular labelling with horseradish peroxidase.     

State-dependent changes in glutamate, glycine, GABA, and dopamine levels in cat lumbar spinal cord

Recent studies have indicated that the glycine receptor antagonist strychnine and the gamma-aminobutyric acid type A (GABA A) receptor antagonist bicuculline reduced the rapid-eye-movement (REM) sleep-specific inhibition of sensory inflow via the dorsal spinocerebellar tract (DSCT). These findings imply that the spinal release of glycine and GABA may be due directly to the REM sleep-specific activation of reticulospinal neurons and/or glutamate-activated last-order spinal interneurons. This study used in vivo microdialysis and high-performance liquid chromatography analysis techniques to provide evidence for these possibilities. Microdialysis probes were stereotaxically positioned in the L3 spinal cord gray matter corresponding to sites where maximal cerebellar-evoked field potentials or individual DSCT and nearby spinoreticular tract (SRT) neurons could be recorded. Glutamate, glycine, and GABA levels significantly increased during REM sleep by approximately 48, 48, and 14%, respectively, compared with the control state of wakefulness. In contrast, dopamine levels significantly decreased by about 28% during REM sleep compared with wakefulness. During the state of wakefulness, electrical stimulation of the nucleus reticularis gigantocellularis (NRGc) at intensities sufficient to inhibit DSCT neuron activity, also significantly increased glutamate and glycine levels by about 69 and 45%, respectively, but not GABA or dopamine levels. We suggest that the reciprocal changes in the release of glutamate, glycine, and GABA versus dopamine during REM sleep contribute to the reduction of sensory inflow to higher brain centers via the DSCT and nearby SRT during this behavioral state. The neural pathways involved in this process likely include reticulo- and diencephalospinal and spinal interneurons.     

胸髓半横断引起腰髓前角钙网蛋白阳性中间神经元突触联系的变化

为检测大鼠胸髓半横断后后肢运动功能状况和腰髓前角中间神经元的突触联系的变化,并分析其相关关系,本实验通过BBB评分、钙网蛋白(CR)和突触囊泡素(SYN)免疫荧光双标记及相关分析方法进行了研究。结果显示:大鼠胸髓半横断后12 h时,后肢运动功能完全丧失,BBB分值下降,从第3 d开始后肢功能逐渐恢复,BBB分值逐渐增加,至第21 d基本恢复正常;同时观察到腰髓损伤侧12 h时CR免疫反应阳性(CR-IR)神经元周围的SYN-IR降低,第3 d时恢复至正常水平,至第21 d时升高;相关分析显示后肢运动功能BBB评分与CR-IR中间神经元周围的SYN表达水平呈正相关(r=0.45,P<0.05)。上述结果提示大鼠胸髓半横断后,与腰髓CR-IR中间神经元形成的突触联系出现可塑性改变,这种可塑性变化可能是后肢运动功能自发性恢复的形态学基础。     

The consequences of longitudinal division of the lumbar spinal cord in puppies

Summary The results of longitudinal division of the spinal cord at the level of the lumbar and sacral segments were investigated in puppies aged 1.5 to 2.5 months in a long-term experiment. Considerable disturbances in the hind legs were noted immediately after the operation. The puppies could not stand or walk.The functions of standing and walking were not reestablished in puppies operated on at the age of two and two-and-a-half months. When the puppies were operated on at the age of one-and-a-half months — recovery took place in 30 to 40 days after the operation.Presented by Active Member Acad. Med. Sci. USSR V.V. Parin     

Steady-state levels of monoamines in the rat lumbar spinal cord: spatial mapping and the effect of acute spinal cord injury

Monoamines in the spinal cord are important in the regulation of locomotor rhythms, nociception, and motor reflexes. To gain further insight into the control of these functions, the steady-state extracellular distribution of monoamines was mapped in the anesthetized rat's lumbar spinal cord. The effect of acute spinal cord lesions at sites selected for high resting levels was determined over approximately 1 h to estimate contributions to resting levels from tonic descending activity and to delineate chemical changes that may influence the degree of pathology and recovery after spinal injury. Measurements employed fast cyclic voltammetry with carbon fiber microelectrodes to give high spatial resolution. Monoamine oxidation currents, sampled at equal vertical spacings within each segment, were displayed as contours over the boundaries delineated by histologically reconstructed electrode tracks. Monoamine oxidation currents were found in well defined foci, often confined within a single lamina. Larger currents were typically found in the dorsal or ventral horns and in the lateral aspect of the intermediate zone. Cooling of the low-thoracic spinal cord led to a decrease in the oxidation current (to 71-85% of control) in dorsal and ventral horns. Subsequent low-thoracic transection produced a transient increase in signal in some animals followed by a longer lasting decrease to levels similar to or below that with cooling (to 17-86% of control values). We conclude that descending fibers tonically release high amounts of monoamines in localized regions of the dorsal and ventral horn of the lumbar spinal cord at rest. Lower amounts of monoamines were detected in medial intermediate zone areas, where strong release may be needed for descending activation of locomotor rhythms.     

Exercise-induced gene expression changes in the rat spinal cord

There is growing evidence that exercise benefits recovery of neuromuscular function from spinal cord injury (SCI). However, the effect of exercise on gene expression in the spinal cord is poorly understood. We used oligonucleotide microarrays to compare thoracic and lumbar regions of spinal cord of either exercising (voluntary wheel running for 21 days) or sedentary rats. The expression data were filtered using statistical tests for significance, and K-means clustering was then used to segregate lists of significantly changed genes into sets based upon expression patterns across all experimental groups. Levels of brain-derived neurotrophic factor (BDNF) protein were also measured after voluntary exercise, across different regions of the spinal cord. BDNF mRNA increased with voluntary exercise, as has been previously shown for other forms of exercise, contributed to by increases in both exon I and exon III. The exercise-induced gene expression changes identified by microarray analysis are consistent with increases in pathways promoting neuronal health, signaling, remodeling, cellular transport, and development of oligodendrocytes. Taken together these data suggest cellular pathways through which exercise may promote recovery in the SCI population.     

Endogenous peroxidase-like activity in the feline dorsal column nuclei and spinal cord

Summary Endogenous peroxidase-like activity was investigated with a combined light and electron microscopical technique in 15 cats. The lateral cervical nucleus, the dorsal column nuclei, and segments C6 and L5 of the spinal cord were incubated with diaminobenzidine-tetrahydrochloride (DAB) or tetramethylbenzidine (TMB). After histochemical reaction with DAB a considerable amount of activity was found in nerve cells, astrocytes and pericytes. The neuronal labelling was mainly located in mitochondria of axon terminals and in dendrites whereas the astrocytic and pericytic activity was found in cytoplasmic dense bodies. The quantity of stained structures differed considerably between the animals. In TMB reacted tissue endogenous peroxidase-like activity was only sparsely seen. It was found mainly in frozen sections, in which the neuropil and perivascular structures sometimes contained granules and irregular filaments. The significance of the findings is discussed in relation to observations in tracer studies using horseradish peroxidase.