Cerebral Palsy

Adenosine A(2A) receptor inactivation consistently protects against acute ischemic brain injury; however, the role of the A(2A) receptor in chronic cerebral ischemia is unknown. To elucidate that, chronic cerebral hypoperfusion model was established by permanent stenosis of bilateral common carotid artery in A(2A) receptor knock-out mice and their wild-type littermates in this study. White matter lesions were observed after stenosis of common carotid arteries in both A(2A) receptor knock-out mice and wild-type mice. The demyelination-related damage and proliferation of astrocytes and microglia in white matter was observed more seriously in A(2A) receptor knock-out mice compared with that in wild-type mice. Working memory was also more seriously impaired in A(2A) receptor knock-out mice relative to wild-type mice. The mRNA expression and protein level of proinflammatory cytokines, including tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), and interleukin-6 (IL-6) increased more remarkably in the corpus callosum in the A(2A) receptor knock-out mice. In conclusion, inactivation of the A(2A) receptor exacerbates the white matter lesions and cognitive deficits induced by chronic cerebral hypoperfusion, and this effect may be associated with increased expression of the proinflammatory cytokines in the white matter.

Apoptotic cell death contributes to neuronal loss in the penumbral region of brain infarction. Activated caspase-3 (ACA-3) cleaves proteins including poly(ADP-ribose) polymerase-1 (PARP-1) important in DNA repair, thus promoting apoptosis. Overactivation of PARP-1 depletes NAD(+) and ATP, resulting in necrosis. These cell death phenomena have been investigated mostly in experimental animals. We studied an autopsy cohort of 13 fatal ischemic stroke cases (symptoms 15 h to 18 days) and 2 controls by immunohistochemical techniques. The number of PARP-1 immunoreactive neurons was highest in the periinfarct area. Nuclear PARP-1 correlated with increasing neuronal necrosis (P = 0.013). Cytoplasmic PARP-1 correlated with TUNEL in periinfarct and core areas (P = 0.01). Cytoplasmic cleaved PARP-1 was inversely correlated with increasing necrotic damage (P = 0.001). PAR-polymers were detected in neurons confirming enzymatic activity of PARP-1. Cytoplasmic ACA-3 correlated with death receptor Fas (r (s) = 0.48; P = 0.005). In conclusion, the confirmation of the same pathways of cell death than previously described in experimental animal models encourages neuroprotective treatments acting on these mediators also in human stroke.

Spinal cord injury (SCI) is an irreversible condition causing damage to myelinated fiber tracts that carry sensation and motor signals to and from the brain. SCI is also associated with gray matter damage and often life-threatening secondary complications. This mini-review aims to provide the nonspecialist reader with a comprehensive description of recent advances made in 2008 using murine models of SCI. A variety of approaches, including advanced genetics and molecular techniques, have allowed a number of key findings in the field of secondary degeneration, repair, regeneration (including insights from peripheral nerve lesion models), metabolic dysfunctions, and pharmacological neuromodulation.

Upon central nervous system injury, the extracellular concentrations of nucleotides and cysteinyl-leukotrienes, two unrelated families of endogenous signalling molecules, are markedly increased at the site of damage, suggesting that they may act as ‘danger signals’ to alert responses to tissue damage and start repair. Here we show that, in non-injured spinal cord parenchyma, GPR17, a P2Y-like receptor responding to both uracil nucleotides (e.g. UDP-glucose) and cysteinyl-leukotrienes (e.g. LTD(4) and LTC(4)), is present on a subset of neurons and of oligodendrocytes at different stages of maturation, whereas it is not expressed by astrocytes. GPR17 immunoreactivity was also found on ependymal cells lining the central canal that still retain some of the characteristics of stem/progenitor cells during adulthood. Induction of spinal cord injury (SCI) by acute compression resulted in marked cell death of GPR17(+) neurons and oligodendrocytes inside the lesion followed by the appearance of proliferating GPR17(+) microglia/macrophages migrating to and infiltrating into the lesioned area. Moreover, 72 h after SCI, GPR17(+) ependymal cells started to proliferate and to express GFAP, suggesting their activation and ‘de-differentiation’ to pluripotent progenitor cells. The in vivo knock down of GPR17 by an antisense oligonucleotide strategy during SCI induction markedly reduced tissue damage and related histological and motor deficits, thus confirming the crucial role played by this receptor in the early phases of tissue damage development. Taken together, our findings suggest a dual and spatiotemporal-dependent role for GPR17 in SCI. At very early times after injury, GPR17 mediates neuronal and oligodendrocyte death inside the lesioned area. At later times, GPR17(+) microglia/macrophages are recruited from distal parenchymal areas and move toward the lesioned zone, to suggest a role in orchestrating local remodelling responses. At the same time, the induction of the stem cell marker GFAP in GPR17(+) ependymal cells suggests initiation of repair mechanisms. Thus, GPR17 may act as a ‘sensor’ of damage that is activated by nucleotides and cysteinyl-leukotrienes released in the lesioned area, and could also participate in post-injury responses. Moreover, its presence on spinal cord pre-oligodendrocytes and precursor-like cells suggests GPR17 as a novel target for therapeutic manipulation to foster remyelination and functional repair in SCI.

The validity of the free radical theory of aging has been recently questioned. Our aim was to test whether there is oxidative stress in tissues critically involved in accelerated aging (senescent accelerated mice, SAM) and whether this correlates with lower glucose consumption in vivo and behavioural tests. Positron emission tomography shows that brains of old SAM prone animals consume less glucose than young ones. Behavioural characteristics, mitochondrial peroxide production, and damage in both the central nervous system and bone marrow stem cells also indicate that SAM prone animals age faster than SAM resistant ones. Our results support the role of the free radical theory of aging in critical tissues involved in aging and that this correlates with glucose consumption.

Phagocytic activity of blood cells and free fatty acids content in rat brain were studied during experimental disturbances of blood supply. It is shown that disturbances of cerebral circulation in rats lead to a depression of a phagocytic part of immunity though during the expressed damage during the early periods its intensification is observed. During disturbances in brain circulation, the most significant changes are seeing in the contents of arachidonic and palmitic fatty acids. The level of changes in fatty acids contents and their dynamics depended on the degree of circulatory disturbances. Correlation communications between activity of phagocyte blood cells and changes in fatty acid content in rat brain during circulatory alterations point to the certain dependence on systemic oxidative stress.

There is growing evidence implicating the kynurenine pathway (KP) and particularly one of its metabolites, quinolinic acid (QUIN), as important contributors to neuroinflammation in several brain diseases. While QUIN has been shown to induce neuronal and astrocytic apoptosis, the exact mechanisms leading to cell death remain unclear. To determine the mechanism of QUIN-mediated excitotoxicity in human brain cells, we measured intracellular levels of nicotinamide adenine dinucleotide (NAD(+)) and poly(ADP-ribose) polymerase (PARP) and extracellular lactate dehydrogenase (LDH) activities in primary cultures of human neurons and astrocytes treated with QUIN. We found that QUIN acts as a substrate for NAD(+) synthesis at very low concentrations (<50 nM) in both neurons and astrocytes, but is cytotoxic at sub-physiological concentrations (>150 nM) in both the cell types. We have shown that the NMDA ion channel blockers, MK801 and memantine, and the nitric oxide synthase (NOS) inhibitor, L-NAME, significantly attenuate QUIN-mediated PARP activation, NAD(+) depletion, and LDH release in both neurons and astrocytes. An increased mRNA and protein expression of the inducible (iNOS) and neuronal (nNOS) forms of nitric oxide synthase was also observed following exposure of both cell types to QUIN. Taken together these results suggests that QUIN-induced cytotoxic effects on neurons and astrocytes are likely to be mediated by an over activation of an NMDA-like receptor with subsequent induction of NOS and excessive nitric oxide (NO(*))-mediated free radical damage. These results contribute significantly to our understanding of the pathophysiological mechanisms involved in QUIN neuro- and gliotoxicity and are relevant for the development of therapies for neuroinflammatory diseases.

OBJECTIVE: To investigate the protective effects of the total base from rhizoma coptis chinensis (CTB) and berberine (Ber) on neurodegeneration induced by aluminum overload in rats. METHODS: The study took place in the Department of Pharmacology, Chongqing Medical University, Chongqing, China, between February 2005 and May 2007. Wistar rats were divided into control group, model group, Ber-treated group, CTB (55 mg/kg and 110 mg/kg)-treated group, and nimodipine-treated group (n=20). A rat brain damage model was established via intragastric administration of 400 mg/kg element aluminum once a day, 5 days a week for 12 weeks. The CTB, Ber, and nimodipine were intragastrically administered 4 hours after each aluminum administration for 12 weeks. The morphological changes of the neurons of the rat hippocampus and the changes of rat learning and memory functions were observed. The superoxide dismutase (SOD), choline acetyltransferase (ChAT), acetylcholinesterase (AchE), and monoamine oxidase-B (MAO-B) activities and malondialdehyde (MDA) content, as well as the MAO-B expression in the rat brain were examined. RESULTS: The CTB, Ber, and nimodipine significantly improved the learning and memory ability impairment and hippocampal neuronal death. The CTB, Ber, and nimodipine also significantly blunted the decrease of SOD and ChAT activities, and the increase of MDA content, AchE activities, and MAO-B expressions and activity in the aluminum-overload rats. CONCLUSION: The CTB and Ber have protective effects on neurodegeneration induced by aluminum overload. The CTB (110 mg/kg) has more powerful neuroprotection than Ber.

Quantitative enzyme immunoassay of glial fibrillary acidic protein of astrocyte intermediate filaments opened new prospects for highly selective diagnosis and monitoring of pathological processes in the CNS. Immunochemical screening of glial fibrillary acidic protein in biological fluids helps to adequately evaluate the permeability of the blood-brain barrier in CNS diseases associated with violation of its functions, such as hypoxic and ischemic disorders, neuroinfections, glial tumors, brain injuries, etc. Wide-scale introduction of enzyme immunoassays into clinical laboratory practice implies the development of biotechnological approaches to the creation of methods for obtaining EIA components. This paper presents a method for creation of a test system for EIA of glial fibrillary acidic protein (GFAP) on the basis of recombinant GFAP and antibodies obtained by immunization with recombinant GFAP. Due to this approach, a highly standardized test system for the analysis of GFAP in human biological fluids was created.

Loss of hand use is considered by many spinal cord injury survivors to be the most devastating consequence of their injury. Functional electrical stimulation (FES) of forearm and hand muscles has been used to provide basic, voluntary hand grasp to hundreds of human patients. Current approaches typically grade pre-programmed patterns of muscle activation using simple control signals, such as those derived from residual movement or muscle activity. However, the use of such fixed stimulation patterns limits hand function to the few tasks programmed into the controller. In contrast, we are developing a system that uses neural signals recorded from a multi-electrode array implanted in the motor cortex; this system has the potential to provide independent control of multiple muscles over a broad range of functional tasks. Two monkeys were able to use this cortically controlled FES system to control the contraction of four forearm muscles despite temporary limb paralysis. The amount of wrist force the monkeys were able to produce in a one-dimensional force tracking task was significantly increased. Furthermore, the monkeys were able to control the magnitude and time course of the force with sufficient accuracy to track visually displayed force targets at speeds reduced by only one-third to one-half of normal. Although these results were achieved by controlling only four muscles, there is no fundamental reason why the same methods could not be scaled up to control a larger number of muscles. We believe these results provide an important proof of concept that brain-controlled FES prostheses could ultimately be of great benefit to paralyzed patients with injuries in the mid-cervical spinal cord.