Segmental distribution of thyrotropin releasing hormone in rat spinal cord

The segmental and laminar distribution of thyrotropin releasing hormone (TRH) was determined in the rat spinal cord using radioimmunoassay (RIA) and immunocytochemistry (ICC). Immunoreactive TRH was found in sensory, autonomic, and motor spinal columns. Dorsal horn TRH-containing fibers and cell bodies in lamina II and along the lamina II/III border were seen by ICC in all spinal cord segments. ICC showed dense TRH immunoreactivity in the sympathetic areas of the thoracic cord. Densely staining TRH-containing fibers were seen in the ventral horn of all spinal segments. RIA of whole segment extracts showed high concentrations in C6-T1 and T12-L6. Low levels were seen in C2-C4 and T5-T6. Other segments were intermediate in concentration. RIA and ICC results were comparatively evaluated.     

GABAergic neurons in human spinal cord cultures: a computer-aided analysis of normal and thienyl-phencyclidine-treated cells

γ-Aminobutyric acid (GABA)-containing neurons were studied in dissociated cell cultures of human spinal cords from 6–10-week-old fetuses using immunohistochemistry with anti-GABA antibodies. Light microscopy showed two types of immunoreactive (IR) neurons: (1) IR neurons with short neuritic processes remaining near the cell body (small neuritic tree neurons); and (2) IR neurons with long neuritic processes extending far from the cell body (large neuritic tree neurons). Both types were studied at different ages in vitro, in control and in thienyl phencyclidine (TCP)-treated cultures by means of computer reconstructions and morphometric parameters. A discriminant analysis permitted the recognition of three populations: whatever the age, the control and TCP-treated neurons with small neuritic trees were not discriminated from each other and were considered to be one population whereas the 98 DIV control and both 21 DIV and 98 DIV TCP-treated cells with large neuritic trees were clearly separated from each other and from the small cell population. In all models, an astrocytic labeling, weaker than that of the neurons, was observed. The nature of these neurons (probably interneurons) intrinsic to the spinal cord is discussed in view of previous findings concerning the anatomical distribution and organization of the GABAergic system in the spinal cord.     

Segmental hypersensitivity and spinothalamic function in spinal cord injury pain

The mechanisms underlying central pain following spinal cord injury (SCI) are unsettled. The purpose of the present study was to examine differences in spinothalamic tract function below injury level and evoked pain in incomplete SCI patients with neuropathic pain below injury level (central pain) versus those without such pain. A clinical examination, quantitative sensory testing and magnetic resonance imaging (MRI) were performed in 10 SCI patients with below-level pain and in 11 SCI patients without neuropathic pain. Patients with and without pain had similar reductions of mechanical and thermal detection thresholds below injury level. SCI patients with central pain had sensory hypersensitivity in dermatomes corresponding to the lesion level more frequently than SCI patients without pain, but this may in part be explained by the exclusion of at-level spontaneous pain in the pain-free group. The rostral-caudal extent of the lesion measured by MRI did not differ between the two patient groups, and there were no statistically significant differences in any of the predefined areas of interest on the axial plane images. This study suggests that neuronal hyperexcitability plays a key role in central SCI pain and furthermore - in contrast to previous findings - that loss of spinothalamic functions does not appear to be a predictor for central neuropathic pain in spinal cord injury.     

Segmental organization of sympathetic preganglionic neurons in the mammalian spinal cord

We have used retrograde transport of horseradish peroxidase to determine the distribution of the preganglionic cell bodies whose axons join particular rami of the thoracic spinal cord in a series of guinea pigs, and in a small number of hamsters and cats. In contrast to other recent studies, our results show that the neurons sending axons to a ramus are confined to a single segment at the corresponding spinal level. This segmental organization supports the idea that the rostro-caudal position of preganglionic cell bodies is one determinant of selective synapse formation between preganglionic axons and sympathetic ganglion cells.     

Vasomotion in normal and injured spinal cord

Blood flow in the feline thoracic spinal cord was measured, using a laser-Doppler flowmetry. Rhythmic changes in the spinal cord blood flow were repeatedly observed with a frequency of about three to eight cycles per minute, unrelated to the respiratory or cardiac cycles. These changes were unaffected by hypertension induced by angiotensin II, but disappeared when systemic blood pressure was lowered by trimethaphan or when hypercapnia was induced. CO2 responsiveness of the blood flow and postocclusive reactive hyperemia were also examined, in both the normal and injured spinal cord. CO2 responsiveness was lost 1 h after a 500 gm/cm injury without rhythmic changes, but was partially regained 2 days later, at which time rhythmic changes were frequently observed. Postocclusive hyperemia apparently diminished 1 h after a 500 gm/cm injury, but reappeared 2 days later. Vasomotion in the normal and injured spinal cord is discussed.     

Differential microglial regulation in the human spinal cord under normal and pathological conditions

As the primary intrinsic immune effector cells of the central nervous system, microglia are involved in virtually all pathological processes of the brain and spinal cord including inflammatory, neurodegenerative, traumatic, neoplastic and vascular diseases. Despite this important role, there is a lack of data concerning microglial distribution and protein expression in the human spinal cord. In this study, we immunohistochemically investigated 10 normal human spinal cords to establish reference data and compared these results with 15 pathological human spinal cords deriving from distinct pathologies. Each spinal cord was evaluated at eight different levels for three white and two grey matter areas for both constitutive (MHC-II, CD68, IL-16, AIF-1, LCA, CD4) and reactive (MRP-8, MRP-14) microglial antigens. Whereas previous studies revealed significant regional differences in microglial distribution and protein expression in human brain, normal spinal cord displayed a uniform expression pattern, reaching levels of up to 17% MHC-II positive cells of the total cell population. This datum formed the basis for the further evaluation of microglia expression levels in pathological spinal cords, where levels of up to 45% positive cells were observed. Our results represent important reference values for future neuropathological diagnostic and therapeutical approaches in spinal cord pathologies.     

Spinal cord-notochord relationship in normal human embryos and in a human embryo with double spinal cord

Spinal cord-notochord relationship was analyzed histologically and immunohistochemically in normal human conceptuses between the 4–8 developmental weeks and in an 8-week embryo with double spinal the neural tube along the cranio-caudal body axis was paralleled by the differentiation of the median hindge point cells at the ventral midline of the tube and by its temporary close association with the notochord. During the 5th–8th developmental weeks, the neuroepithelium differentiating into three distinct layers was accompanied by a solid, ventromedially positioned notochord. In the abnormal 8-week embryo, the additional spinal cord was located ventrolaterally from the vertebral column. Both spinal cords appeared bilaterally asymmetric, with their floor and roof plates irregularly formed. An abnormally enhanced pattern of neuroepithelial differentiation characterized their dorsal parts. Furthermore, additional spinal nerves and ganglia and an abnormal bony structure were associated with the spinal cord positioned outside the vertebral column. The underlying vertebral bodies were misshaped and contained scattered supernumerary groups of notochord cells. Our investigation underlines the importance of the notochord-neural tube relationship in the morphogenesis of the spinal cord. We suggest that the double spinal cord was induced by the split notochord.     

Paroxysmal Kinesigenic Segmental Myoclonus due to a spinal cord glioma.

We report an 18-year-old man with paroxysmal jerking movements of the left arm since age 7 years. These were invariably precipitated by startle or sudden movements. He was subsequently diagnosed with a cervical cord anaplastic astrocytoma on MRI. We could not identify previous reports of paroxysmal myoclonus secondary to a spinal cord neoplasm. We have coined the term Paroxysmal Kinesigenic Segmental Myoclonus to describe this entity.     

Neuropeptide Y in human spinal cord

The distribution of a newly described peptide, neuropeptide Y (NPY) within the human spinal cord has been determined using radioimmunoassay and immunocytochemistry. Higher concentrations were found in the lumbar (49.9 +/- 6.8 pmol/g) and sacral (47.0 +/- 10.6 pmol/g) regions than in the cervical (27.6 +/- 2.7 pmol/g) and thoracic spinal cord (33.8 +/- 5.3 pmol/g). Immunocytochemistry revealed numerous nerve fibers containing NPY in the spinal cord; these were particularly concentrated in the substantia gelatinosa of the dorsal horn. In the ventral spinal cord NPY-containing nerves were sparse becoming more abundant in lumbosacral segments.     

Growth of diseased human muscle in combined cultures with normal mouse embryonic spinal cord.

Normal and diseased human muscle cells have been grown in combined cultures with 12-14 day embryonic mouse spinal cord explants. Nerve endings on myotubes were found by light and scanning electron microscopy, and motor end-plates were identified by a histochemical reaction for acetylcholinesterase. Contracting myotubes, never observed in cultures of human muscle alone, were found in a culture from normal muscle. Histochemical studies demonstrated the presence of strongly and weakly reacting myotubes for both ATPase pH 9.4 and NADH-TR, but could not be related to the development of fibre types. No differences in morphology or histochemical reactions were found between normal and diseased muscle cells in these combined cultures.     

择性结扎节段动脉致局灶性脊髓缺血损伤动物模型的建立

背景：以往研究表明采用腹膜后入路结扎兔所有腰动脉的方法能够建立稳定的脊髓缺血损伤动物模型,但动脉的具体结扎部位尚不明确。 目的：采用选择性节段动脉结扎方法建立局灶性脊髓缺血动物模型。 方法：将成年新西兰大白兔16只随机分为对照组和模型组,8只/组。模型组采用腹膜后入路结扎L1~3双侧腰动脉,对照组不结扎血管。建模后第3天,用改良Tarlov评分法评价两组兔神经功能,取结扎血管所对应的脊髓组织并进行苏木精-伊红染色,观察其组织学改变。 结果与结论：模型组后肢出现功能障碍,Tarlov评分低于对照组(P < 0.05)。脊髓组织出现急性炎性改变及神经细胞坏死等脊髓缺血现象。实验结果表明采用腹膜后入路结扎L1~3双侧腰动脉能够建立较稳定的局灶性脊髓缺血损伤模型。     

Estimate of motor conduction in human spinal cord: slowed conduction in spinal cord injury

By using motor evoked potential (MEP) created by transcranial electric stimulation over the motor cortex and F-wave measurement from the peripheral nerve stimulation, it is possible to estimate the spinal cord motor conduction velocity (SCMCV) in the diseased state. Twenty-four patients with spinal cord injury (SCI) between T1 and T11 neurological levels participated in this study. MEP in leg muscle was absent in all neurologically complete paraplegics. In 16 patients with neurologically incomplete SCI, MEP was obtained in 13 patients. The SCMCV estimated from C7 to T12 spinal levels was 32.1 (SD = 9.4) m/s. This was significantly slower than 63.3 (SD = 8.6) m/s in 40 normal controls. This noninvasive, indirect method is measurable, and can provide valuable electrophysiological data in the assessment of motor function in patients with SCI.     

Microscopic analysis of early histopathological spinal cord alterations following trauma in normal and catecholamine-depleted cats

The progressive histopathological sequence over the first 3 hr after a 400 g-cm blunt injury to the spinal cord of catecholamine (CA)-intact and CA-depleted cats is described. Norepinephrine levels were measured in all animals. The experiments were designed to determine the role of CA in progressive hemorrhagic necrosis of the spinal cord by removing CA from one group of animals prior to trauma. A second group of CA-intact animals was subjected to identical experimentally-induced trauma. Upon analysis of the histopathological changes, it appears that the sequential nature of the development of hemorrhagic necrosis is both qualitatively and quantitatively similar in both experimental groups. The general conclusion is drawn that catecholamines in greater than normal amounts are present at the lesion site after trauma, but these catecholamines are probably not involved in the process of central hemorrhagic necrosis.     

Pericapillary rosettes in the human spinal cord

Summary We have found large eosinophilic bodies in the pericapillary regions of the gray and white matter in the human spinal cord. These are entirely different from the previously reported pericapillary inclusion bodies (PIB). We have designated them pericapillary rosettes (PR), since they consist of clusters of round or ovoid structures of various sizes which form rosettes around the transversely sectioned capillaries. Positive staining with silver impregnation and anti-neurofilament antibody, the presence of the myelin around the bodies, and the accumulation of neurofilaments within them indicate that axonal swelling is associated with the formation of PR. These bodies are not observed in individuals aged less than 30 years, and afterwards they increase in proportion to age. Over the age of 80, they are almost always found in the spinal cord, particularly in the gray matter of both the anterior and posterior horns at the thoracic and lumbar levels. Thus, the development of PR is closely related to the aging process.     

Amino acids in autopsied human spinal cord

The distribution of glycine, glutamate, aspartate, glutamine, and taurine was measured at autopsy in 10 normal human spinal cords, and in 4 spinal cords from Friedreich’s Ataxia patients, using sensitive double-isotope microassay of their dansyl derivatives. Transverese sections of spinal cord from cervical, thoracic, and lumbar levels were dissected to afford samples of gray matter, posterior columns, dorsal white matter, and ventral white matter. Levels of glycine, glutamate, and glutamine were found to be elevated in lumbar gray matter, being 2–3 times higher than those found in white matter structures. Aspartate and taurine, on the other hand, were found to be distributed more evenly in autopsied human spinal cord. Selective abnormalities of amino acid distribution in Friedreich’s Ataxia included decreased glutamate and glutamine in lumbar gray matter and posterior columns and increased taurine content of lumbar spinal cord. These changes may be of pathophysiological significance in this hereditary neurodegenerative disease.     

Pathway-specific plasticity in the human spinal cord

The aim of the present study was to artificially induce plasticity in the human spinal cord and evaluate whether this plasticity is pathway specific. For this purpose, a technique called paired associative stimulation (PAS) was applied. Volleys evoked by transcranial magnetic stimulation over the primary motor cortex and peripheral nerve stimulation of the nervus tibialis in the popliteal fossa were timed to coincide at the spinal level. The transmission of different corticospinal projections was assessed before and after PAS using conditioned H-reflexes. Different groups of healthy volunteers (28 ± 5 years) were tested; intervention groups 1 (n = 9) and 2 (n = 8) received spinal PAS (360 paired stimuli) and the induced effects were evaluated using cortical (group 1) or cervicomedullary (group 2) conditioning of musculus soleus H-reflexes. After spinal PAS, the conditioned H-reflexes were significantly facilitated when tested with cortical and cervicomedullary stimulation. The effect of the latter technique is independent of changes in the excitability of cortical neurons. Therefore, the finding that conditioned H-reflexes were increased after spinal PAS when tested with both cortical and cervicomedullary stimulation suggests that neural plasticity was induced within the spinal cord. The facilitation could only be observed for specific inter-stimulus intervals between volleys induced by peripheral nerve stimulation and transcranial magnetic stimulation. As the specific inter-stimulus intervals were assumed to relate to transmission within specific motor pathways, it is argued that changes in the corticospinal transmission were pathway-specific. These findings may be helpful in inducing and assessing neural plasticity in pathological conditions like spinal cord injuries.     

Calcineurin and synaptophysin in the human spinal cord of normal individuals and patients with familial dysautonomia

Summary This report concerns the immunohistochemical demonstration of two neuronal Ca²⁺-binding proteins, calcineurin and synaptophysin, in the spinal cord of normal controls and from patients with familial dysautonomia. In controls, calcineurin immunoreactivity was highly concentrated in small nerve cells and fibers of the substantia gelatinosa. Synaptophysin immunoreactivity was normally distributed throughout the spinal cord gray matter, being highly concentrated in the substantia gelatinosa, the dorsal nucleus of Clarke and the anterior horn. In patients with familial dysautonomia, no apparent changes in calcineurin immunoreactivity were found in the substantia gelatinosa. By contrast, there was a significant depletion of synaptophysin-positive axon terminals in the substantia gelatinosa and in the dorsal nucleus of Clarke of patients with familial dysautonomia.     

Spinal cord reflexes induced by epidural spinal cord stimulation in normal awake rats

Motor responses in hindlimb muscles to epidural spinal cord stimulation in normal awake rats during bipedal standing were studied. Stimulation at L2 or S1 induced simultaneous and bilateral responses in the vastus lateralis, semitendinosus, tibialis anterior, and medial gastrocnemius muscles. Stimulation at S1 evoked an early (ER), middle (MR) and late (LR) response: stimulation at L2 elicited only a MR and LR. Vibration and double epidural stimulation testing suggests that the ER is a direct motor response, whereas the MR and LR are mediated synaptically. MR has properties of a monosynaptic reflex, i.e., inhibited during vibration and depressed during the second pulse of a double stimulation. Some components of the LR seem to be mediated by afferents associated with the flexor reflex and probably involve group II afferents. During bipedal treadmill stepping, the MR was modulated in extensors, whereas the LR was modulated in flexors. These results show differential modulation of monosynaptic and polysynaptic reflexes in flexor and extensor motor pools during locomotion. Monosynaptic responses to stimulation at either L2 or S1 generally were amplified in extensors during the stance phase and in flexors during the swing phase of the step cycle. No correlation was found between the ER and the EMG background during stepping, whereas both the MR and LR were closely correlated with the changes in the EMG activity level of the corresponding muscle. These data demonstrate the feasibility of using epidural stimulation for examining monosynaptic and polysynaptic pathways to motor pools associated with multiple muscles during movement and over a prolonged period.     

Distribution of neuropeptide FF in porcine spinal cord in comparison with other neuropeptides and serotonin

A large number of neurotransmitters and neuropeptides are concentrated in the dorsal horn of the spinal cord, Where they interact in a complex manner and modulate sensory mechanisms. Most studies are carried out in the rat, and little is known of other species. It is relevant to study mammals with a more complex central nervous system, because pain mechanisms are central in both human and veterinary medicine. Immunoreactivity for neuropeptide FF, an amidated octapeptide originally isolated from bovine brain, was found immunocytochemically at all levels of porcine spinal cord. In contrast to other species studied so far, the peptide immunoreactivity in porcine spinal cord was confined to the intermediolateral gray matter, especially to the intermediolateral cell column and lamina X of the gray matter. This distribution was remarkably different from that of substance P, proenkephalin A-derived peptides, thyrotropin-releasing hormone, serotonin, and neuropeptide Y. Pharmacologic administration of neuropeptide FF alters behavior in assays for analgesia. The distribution of neuropeptide FF immunoreactivity as revealed by this study suggests that there may be marked species differences in the distribution and function of the peptide. © 1994 Wiley-Liss, Inc.