Expression of Fos-like immunoreactivity in the brain and spinal cord of rats following middle cerebral artery occlusion

 This study examined c-fos protein expression in the brain and spinal cord of rats following permanent occlusion of the middle cerebral artery (MCA) above the rhinal fissure. At 1 h after right-sided MCA occlusion, Fos-like immunoreactivity (Fos-LI) was detected in neurons not only in the ipsilateral cerebral cortex but also in the spinal cord. In the latter, Fos-LI was localized in the nucleus and perikarya of neurons in the grey matter, notably the large motor neurons in the ventral horn. Fos-LI was most intense at 2–4 h, but became undetectable after 48 h in the cerebral cortex and 72 h in the spinal cord. In sham-operated animals, Fos-LI was almost undetectable or virtually absent. It was also not detected in the core territory supplied by the MCA at any time points after arterial occlusion. When the ischaemia-induced neuronal damage in both the cerebral cortex and spinal cord was evaluated by Nissl staining, some neurons appeared atrophic. We conclude that the induction of Fos-LI in neurons of the cerebral cortex and spinal cord is linked respectively to early onset–short stimulation and persistent excitatory or disinhibition phenomenon as a result of focal ischaemic brain injury. Received: 16 September 1996 / Accepted: 29 November 1996     

Bradykinin preconditioning induces protective effects on the spinal cord ischemic injury of rats

The study was performed to investigate the effects of bradykinin preconditioning on spinal cord ischemic injury using an in vivo transient spinal cord ischemia model in rats. Prior to ischemia, bradykinin was infused continuously via the left femoral artery starting 15min before ischemia. Neurological functions were evaluated for 7 days postoperatively using modified Tarlov's scores. Tarlov's score outcomes showed a marked improvement in the bradykinin group compared to the ischemia group. The blood-spinal cord barrier (BSCB) permeability was also decreased by bradykinin preconditioning after 72 h reperfusion focal spinal cord in rats, which was greatly reversed by B9430 (bradykinin B2 receptor antagonist). Immunohistochemical and Western blot analysis of spinal cords revealed a significant increase in basic fibroblast growth factor protein (bFGF) levels. The study demonstrated that bradykinin preconditioning induces protection against spinal cord ischemic injury, and this protection is likely due to the protection of the vasculature of the spinal cord and the promotion of neuronal survival.     

Neuroprotective effect of afobazole on rats with bilateral local photothrombosis of vessels in the prefrontal cortex

We studied the neuroprotective effect of a new selective anxiolytic afobazole on rats with bilateral focal ischemic stroke in the prefrontal cortex caused by photothrombosis. Intraperitoneal injection of 5 mg/kg afobazole 1 h after surgery and over the next 8 days (daily treatment) produced a neuroprotective effect. Afobazole was far superior to the reference cerebroprotective drug cavinton (4 mg/kg) by neuroprotective activity. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 145, No. 2, pp. 167–169, February, 2008     

Modulation of somatocardiac sympathetic reflexes mediated by opioid receptors at the spinal and brainstem level

This study investigated astroglial responses after focal cerebral ischemia in the rat cortex induced by photothrombosis. Astrocyte activation was studied at various time points by immunocytochemistry for glial fibrillary acidic protein (GFAP) and vimentin (VIM). We found a dual astrocytic response to focal ischemia: In the border zone of the infarct, GFAP-positive astrocytes were present within 2 days and persisted for 10 weeks. These astrocytes additionally expressed VIM. Remote from the ischemic lesion, cortical astrocytes of the entire ipsilateral hemisphere transiently expressed GFAP, but not VIM, beginning on day 3 after photothrombosis. This response had disappeared on day 14. By recording DC potentials, five to seven spreading depressions (SD) could be detected on the cortical surface during the first 2 h after photothrombosis. Treatment with MK801, a non-competitive NMDA-receptor antagonist, completely abolished SD and remote ipsilateral astrocytic activation, while the reaction in the border zone of the infarct remained unchanged. Functionally, persistent astrocytosis around the infarct might be induced by leukocyte-derived cytokines, while NMDA-receptor-mediated SD might cause remote responses.     

Effects of stimulation of cortical motor points in dogs after hemisection of the spinal cord

Summary The effects of electric stimulation of the motor points of the cortex were studied in dogs following laroral hemisection of the spinal cord at the level of 2nd–3rd cervical segments. Chronic experiments were staged on 6 adult dogs without anesthesia. Superficial silver electrodes were implanted into trephined openings in the cranium over the motor area of the cortical representation of the fore limbs; this was done for stimulation of the motor points of the cortex. Stimulation of the cortex was first carried out prior to hemisection of the spinal cord, then 1–5 months later. For the first time it was shown that after the spinal cord hemisection it was possible to provoke movement in the affected extremity by stimulation of the corresponding motor points in the cerebral cortex. Such movement may be induced about 3–4 weeks after spinal cord hemisection, i.e., 2 to 3 days before the extremity begins actively to participate in standing and walking. (Presented by Active Member AMN SSSR N. I. Grashchenkov) Translated from Byulleten éksperimental'noi Biologii i Meditsiny, Vol. 56, No. 11, pp. 64–67, November, 1963     

Effect of dimephosphon on functional recovery of damaged spinal cord

The effect of endolumbar dimephosphon perfusion in dogs with spinal cord contusion was studied by means of transcranial magnetic stimulation and stimulation electromyography. Treatment with dimephosphon contributed to preservation of conduction function of the spinal cord and decrease in excitability of spinal motoneurons in the perifocal zone. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 141, No. 2, pp. 140–143, February, 2006     

Functional characteristics of the input-output correlation in the vestibular nuclear complex of the frog

Experiments on perfused frog brains were used to record focal and intracellular potentials of neurons in the vestibular nuclear complex produced in response to stimulation of the anterior branch of the ispilateral vestibular nerve and the spinal cord. Stimulation of the vestibular nerve evoked mono- and polysynaptic EPSP with orthodromic action potentials. These were accompanied by recordings of antidromic activation (with a mean latent period of 0.75 sec) of neurons which send their axons into the labyrinth. Antidromic action potentials from vestibular neurons arose with latent periods of the order of 1.43 msec in response to stimulation of the cervical thicknening and 2.19 msec in response to stimulation of the lumbar thickening of the spinal cord. Bursts from the spinal cord often evoked EPSP with orthodromic action potentials in vestibular neurons. The characteristics of the functional correlation between the vestibular input and the vestibulospinal system are discussed. Translated from Rossiiskii Fiziologicheskii Zhurnal imeni I. M. Sechenova, Vol. 84, No. 10, pp. 1085–1092, October, 1998.     

Changes in the constant potential in brain structures in rats during focal ischemia and systemic hypoxia

The functional consequences of spreading depression (SD) during the evolution of ischemic damage was studied in two models: focal cortical ischemia induced by photothrombosis of the middle cerebral artery (MCA) and systemic hypoxia induced by 0.8% carbon monoxide (CO). These studies showed that cortical waves of SD, arising spontaneously during MCA thrombosis and after arterial occlusion delayed thrombus formation and promoted the establishment of a collateral blood supply in the perifocal zone of ischemic lesions. The underlying mechanism consisted of episodes of intense vasodilation at the decay phase of every wave of SD. Respiration of 0.8% CO increased the blood carboxyhemoglobin level to 50–60%. In lightly anesthetized rats (pentobarbital 20 mg/kg), cortical and subcortical spontaneous waves of SD were transformed into stable hypoxic depolarization, leading to death of 60% of the animals of severe lesions of the central nervous system, in 20% of animals. Increases in the level of anesthesia (50 mg/kg anesthetic) prevented the spontaneous appearance of SD during long-lasting exposure to CO. In these conditions, experimentally induced waves of SD demonstrated that the hippocampus has a high sensitivity to moderate levels of hypoxia. The duration of hypoxic depolarization of the hippocampus, provoking a single SD wave, reached 30–60 min. Selective neuron damage in field CA1 was seen 30 days after hypoxia. Additionally, the left hippocampus of rats frequently showed profound morphological lesions in the form of “granules.” Cerebrolysine (2.5 ml/kg daily for 10 days) completely prevented the formation of these lesions. Translated from Zhurnal Vysshei Nervnoi Deyatel'nosti imeni I. P. Pavlova, Vol. 48, No. 4, pp. 640–653, July–August, 1998.     

Primary sensory neurons in the central nervous system

Published data and our own results relating to exteroceptor and a variety of interceptor neurons in the brain and spinal cord, such as intraspinal Hesse ocelli and light-sensitive epiphyseal and ependymal neurons, are presented. Light-sensitive ganglion neurons in invertebrates are also described, along with intrinsic spinal cord bipolar sensory neurons within the spinal cord, primary chemo-and thermosensitive neurons, and sensory unipolar neurons associated with the three fine “central nerves” of Motavkin, which perforate the sheath of the spinal cord and ending with bush-like receptors close to vessels or near the ependyma of the central canal. Data on all known intracortical interoceptors in vertebrates are generalized into a single scheme. It is hypothesized that the brains of animals and humans have an intrinsic sensory innervation comparable with the innervation of other organs and containing local primary sensory neurons and their asynaptic dendrites, which can be divided into two groups: interceptor and exteroceptor. __________ Translated from Morfologiya, Vol. 127, No. 3, pp. 75–81, May–June, 2005.     

Projections from the nucleus reticularis magnocellularis to the rat cervical cord using electrical stimulation and iontophoretic injection methods

The aim of this study is to clarify the fiber distribution of the nucleus reticularis magnocellularis (NRMC) and adjacent areas in the rat spinal cord. Biotinylated dextran amine was injected iontophoretically through a glass capillary into the areas, in which a single cell responded to noxious electrical stimulation of the sciatic nerve and to a pinch of the thigh skin with multiple spikes. Labeled fibers descended bilaterally through the ventral funiculi of the medulla oblongata and then through the ventral and lateral funiculi of the cervical cord with an ipsilateral predominance, and terminated in the spinal gray (laminae I–2X). A single fiber sometimes ran through several laminae while bifurcating many short branches with axon varicosities and terminal buttons in one transverse section, that is, through laminae V, VII and X, through laminae V, III–IV and I-II, and through laminae VII to I–II. The present study showed that the wide distribution of a single fiber and a mass of fibers descending from the NRMC and adjacent areas might modulate not only somatic sensory and motor functions but also autonomic functions in the spinal cord.     

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.     

Region-specific sensitivity of the spinal cord to ischemia/reperfusion: the dynamic of changes in catalytic NOS activity

This study was designed in order to consider whether the release of neuronally derived nitric oxide (NO) in the lumbosacral spinal cord during ischemia/reperfusion is region-specific and whether changes in Ca²⁺-dependent NO synthase (cNOS) activity paralell with functional outcome. The cNOS activity was measured in the spinal cord regions after 13-, 15- and 17-min ischemia alone and that followed by 24 h of reperfusion. In addition, the Tarlov’s criteria were applied to define the neurological consequences of ischemia/reperfusion in experimental animals. Based on the results, it is evident that only the 17-min ischemia alone was quite sufficient to cause changes in cNOS activity, however, without alterations in functional outcomes. On the other hand, the ischemic episodes followed by reperfusion caused dynamic, region-specific alterations in cNOS activity and consequently led to deterioration of motor function of hindlimbs in affected animals. Our results indicate that the motoneurons in the ventral horns respond more sensitively to ischemia/reperfusion than do neurons localized in the other spinal cord regions and that changes in cNOS activity may also influence the axonal conductance in the white matter and account for the impairment of motoneuronal activity in affected animals.     

The use of micropolarization in the treatment of spinal cord lesions

Transdermal micropolarization of the spinal cord was performed in patients suffering sequelae of spinal cord trauma and tuberculous spondylitis. Changes in clinical and electrophysiological status were monitored. These studies demonstrated that the use of local direct currents passed via skin electrodes promoted improvements in motor and autonomic functions in these patients, leading to positive changes in measures of the functional state of the spinal cord and heart activity. The possible mechanisms of the action of direct currents acting on the spinal cord are discussed, along with the potential for applying micropolarization in the treatment of spinal cord lesions. Translated from Zhurnal Nevrologii i Psikhiatrii imeni S. S. Korsakova, Vol. 98, No. 12, pp. 22–24, December, 1998.     

局灶脑梗塞小胶质细胞的可塑性变化及谷氨酸转运体表达

为了探讨小胶质细胞在急性局灶脑梗塞的可塑性变化及其谷氨酸转运体的表达 ,运用免疫组织化学和免疫荧光双标记技术对大鼠皮质光化学局灶性脑梗塞后小胶质细胞的反应及其谷氨酸转运体表达进行了研究。结果显示 ,光化学局灶性脑梗死后小胶质细胞明显活化 ,其形态在脑梗塞半暗带区以高分枝状和杆状为主 ,梗塞灶中心为阿米巴形和圆形。脑梗塞的早期以高分枝状和杆状为主 ,脑梗塞的晚期以阿米巴形和圆形小胶质细胞为主。谷氨酸转运体 EAAT2主要在缺血周边的半暗带区表达 ,呈网状环绕在神经元周围 ,共聚焦显微镜扫描见与 OX42标记的小胶质细胞双重标记。结论 :本研究提示急性局灶脑梗塞后发生可塑性变化的小胶质细胞 ,通过增强 EAAT2的表达积极地参与脑梗塞的修复过程。     

Cell death in developing human spinal cord

Cell death in the developing human spinal cord was investigated in 5–12 week human conceptuses using immunohistochemical and TUNEL methods. Expression of pro-apoptotic (Fas-receptor, caspase-3) and anti-apoptotic (bcl-2) markers and marker for internucleosomal fragmentation (TUNEL) were analysed in the cranial and caudal parts of the human spinal cord. In early developmental stages (5–6 weeks) of the cranial spinal cord, bcl-2 positive cells were seen in the ventricular zone and in the roof plate, while in the caudal part they were seen surrounding the central lumen. Subsequently, bcl-2 expression appeared in the basal plates of the grey matter and in the spinal ganglia, and from the seventh week on they also appeared in the intermediate horn of the grey matter. In the fetal period, bcl-2 expression appeared in the dorsal horns of the grey matter (9 weeks) but ceased in the ventricular zone (12 weeks) . In the trunk region, TUNEL-positive cells were found in ventricular and mantle zones along the whole length of the spinal cord. Caspase-3 positive cells and Fas-receptor positive cells appeared only in the grey matter of the cranial segments (head and trunk) of the spinal cord, but they were missing in the caudal parts. Caspase-3 dependant pathway, probably activated by Fas-receptor, seems to operate only in the cranial part of the human spinal cord. In the caudal (sacrococcygeal and tail) parts, cells seem to die by caspase-3 independent pathway. The interplay of pro-apoptotic and anti-apoptotic factors may be associated with cranial spinal cord morphogenesis, adjustment of cells number and selective survival of neurons, while in the caudal regions these factors cause massive cell death associated with regression of the caudal spinal cord.     

Initiation of Locomotion in Decerebrate Cats by Pulsed Magnetic Fields Projected onto Spinal Cord Segments

The motor effects induced by pulsed magnetic fields (PMF) projected onto the lumbar and cervical spinal cord were studied in decerebrate cats. A magnetic coil (inductor) of diameter 8 cm was positioned 1–2 cm above the surface of the spinal cord. Stimulation of the spinal cord with PMF was performed in two regimes: with single impulses with an intensity of 0.5–1 T and with continuous rhythmic stimulation at a frequency of 1 Hz and an intensity of 0.5 T. Application of single stimuli to the lumbar enlargement evoked reflex responses in the proximal and distal hindlimb muscles. Rhythmic stimulation initiated locomotor activity of the limb on a running treadmill, i.e., activated the neural locomotor network of the spinal cord (stepping movement generator). Magnetic stimulation of the lumbar enlargement evoked coordinated stepping movements of the hindlimbs only. Application of PMF to the cervical enlargement induced coordinated stepping movements of all four limbs, hindlimb movements starting before forelimb movements. After cessation of magnetic stimulation, the limbs completed several further coordinated movement cycles. This is the first report of the triggering of limb stepping movement generators with PMF in decerebrate cats. The results obtained here demonstrate that the neural locomotor networks of the spinal cord can be activated noninvasively and open new perspectives for the clinical use of PMF.     

Neurological disorders and neural regeneration, with special reference to Parkinson’s disease and cerebral ischemia

For many years, it was recognized that brain and spinal cord tissues could not be regenerated once they were damaged. Recently, this concept has been challenged and many basic and clinical studies regarding neural regeneration and transplantation have been reported. In this review, we will summarize the clinical studies using cell transplantation for the treatment of Parkinson’s disease and cerebral ischemia. Then, we will report the recent advancement of basic studies using cell lines and neural stem cells as donor tissue. Cell line grafting can be done by encapsulating desired cell line in semipermeable polymer hollow fibers, and neurotransmitter and neurotrophic factors can be delivered into the brain. Neural stem cells, especially those of adult origin, have the advantage that autologous cell transplantation can be done. The biological features of various types of stem cells have been widely investigated and will be applied to the treatment of neurological disorders through cell transplantation. This article is modified from “Neural regeneration: treatment of Parkinson’s disease and cerebral ischemia,” by the same authors, in Jinkozoki 2007;36:130–133     

脊髓血供及其监测研究

本文主要对脊髓的血供及目前的用于监测脊髓血供的方法和未来可能应用的新技术做一个综述,旨在协助临床脊柱外科医生能更好地对脊髓血供进行监测,预防脊髓缺血的发生,减少脊髓缺血所引起的损伤。     

大鼠脊髓缺血再灌注损伤后caspase-12表达与细胞凋亡

目的:观察大鼠脊髓缺血再灌注损伤过程中细胞凋亡、caspase-12的表达变化规律,以探讨其分子机制。方法:采用自制压迫装置制备脊髓压迫缺血再灌注模型。运用形态学、分子生物学等方法,分别于缺血再灌注后3、7、11、23和47h,观察脊髓缺血再灌注损伤后,脊髓的病理变化和内质网的形态学改变、细胞凋亡及caspase-12的表达变化的规律。结果:脊髓缺血再灌注3h后,出现不同程度的细胞肿胀,神经元退行性变及内质网结构变化;随着再灌注时间的延长,神经元和神经胶质细胞凋亡数明显增加,并伴有caspase-12的表达增强;capspase-12表达与细胞凋亡的时空变化规律相一致。结论:在脊髓缺血再灌注过程中神经细胞凋亡是引起脊髓继发性损伤的主要病理因素,caspase-12可能参与了脊髓缺血再灌注损伤所导致的细胞凋亡。     

Induced auxotonic muscle contractions in animals with lateral spinal cord hemisection under various cooling regimens

We studied the effects of long-term moderate hypothermia on induced auxotonic contractions of dog hindlimb extensor muscle after lateral hemisection of the spinal cord at the thoracolumbar region (T_XII-L_I–II) during the early and late postoperative periods (1–2 and 3–5 weeks, respectively). The mechanisms of antispastic effects of moderate hypothermia are different: the immediate effect was due to cold blockade of spinal neurons, while delayed effects resulted from activation of descending bilateral oversegmental motor apparatus. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 128, No. 9, pp. 270–273, September, 1999