A Single Dose of Atorvastatin Applied Acutely after Spinal Cord Injury Suppresses Inflammation, Apoptosis, and Promotes Axon Outgrowth, Which Might Be Essential for Favorable Functional Outcome.

The aim of our study was to limit the inflammatory response after a spinal cord injury (SCI) using Atorvastatin (ATR), a potent inhibitor of cholesterol biosynthesis. Adult Wistar rats were divided into five experimental groups: one control group, two Th9 compression (40 g/15 min) groups, and two Th9 compression + ATR (5 mg/kg, i.p.) groups. The animals survived one day and six weeks. ATR applied in a single dose immediately post-SCI strongly reduced IL-1β release at 4 and 24 h and considerably reduced the activation of resident cells at one day post-injury. Acute ATR treatment effectively prevented the excessive infiltration of destructive M1 macrophages cranially, at the lesion site, and caudally (by 66%, 62%, and 52%, respectively) one day post-injury, whereas the infiltration of beneficial M2 macrophages was less affected (by 27%, 41%, and 16%). In addition, at the same time point, ATR visibly decreased caspase-3 cleavage in neurons, astrocytes, and oligodendrocytes. Six weeks post-SCI, ATR increased the expression of neurofilaments in the dorsolateral columns and Gap43-positive fibers in the lateral columns around the epicenter, and from day 30 to 42, significantly improved the motor activity of the hindlimbs. We suggest that early modulation of the inflammatory response via effects on the M1/M2 macrophages and the inhibition of caspase-3 expression could be crucial for the functional outcome

Glial-Neuronal Interactions in Pathogenesis and Treatment of Spinal Cord Injury

Traumatic spinal cord injury (SCI) elicits an acute inflammatory response which comprises numerous cell populations. It is driven by the immediate response of macrophages and microglia, which triggers activation of genes responsible for the dysregulated microenvironment within the lesion site and in the spinal cord parenchyma immediately adjacent to the lesion. Recently published data indicate that microglia induces astrocyte activation and determines the fate of astrocytes. Conversely, astrocytes have the potency to trigger microglial activation and control their cellular functions. Here we review current information about the release of diverse signaling molecules (pro-inflammatory vs. anti-inflammatory) in individual cell phenotypes (microglia, astrocytes, blood inflammatory cells) in acute and subacute SCI stages, and how they contribute to delayed neuronal death in the surrounding spinal cord tissue which is spared and functional but reactive. In addition, temporal correlation in progressive degeneration of neurons and astrocytes and their functional interactions after SCI are discussed. Finally, the review highlights the time-dependent transformation of reactive microglia and astrocytes into their neuroprotective phenotypes (M2a, M2c and A2) which are crucial for spontaneous post-SCI locomotor recovery. We also provide suggestions on how to modulate the inflammation and discuss key therapeutic approaches leading to better functional outcome after SCI

Epidural oscillating field stimulation increases axonal regenerative capacity and myelination after spinal cord trauma

Oscillating field stimulation (OFS) with regular alterations in the polarity of electric current is a unique, experimental approach to stimulate, support, and potentially guide the outgrowth of both sensory and motor nerve fibers after spinal cord injury (SCI). In previous experiments, we demonstrated the beneficial effects of OFS in a 4-week survival period after SCI. In this study, we observed the major behavioral, morphological, and protein changes in rats after 15 minutes of T9 spinal compression with a 40 g force, followed by long-lasting OFS (50 µA), over a 8-week survival period. Three groups of rats were analyzed: rats after T9 spinal compression (SCI group); SCI rats subjected to implantation of active oscillating field stimulator (OFS + SCI group); and SCI rats subjected to nonfunctional OFS (nOFS + SCI group). Histopathological analysis of spinal tissue indicated a strong impact of epidural OFS on the reduction of tissue and myelin loss after SCI in the segments adjacent to the lesion site. Quantitative fluorescent analysis of the most affected areas of spinal cord tissue revealed a higher number of spared axons and oligodendrocytes of rats in the OFS + SCI group, compared with rats in the SCI and nOFS + SCI groups. The protein levels of neurofilaments (NF-l), growth-associated protein-43 (marker for newly sprouted axons), and myelin basic protein in rats were signifiantly increased in the OFS + SCI group than in the nOFS + SCI and SCI groups. This suggests a supporting role of the OFS in axonal and myelin regeneration after SCI. Moreover, rats in the OFS + SCI group showed great improvements in sensory and motor functions than did rats in the nOFS + SCI and SCI groups. All these findings suggest that long-lasting OFS applied immediately after SCI can provide a good microenviroment for recovery of damaged spinal tissue by triggering regenreative processes in the acute phase of injury

Localization of N-type Ca2+ channels in the rat spinal cord following chronic constrictive nerve injury

Previous studies have shown that spinal L-type, N-type, and P-type Ca2+-channel blockers are effective in modulating pain behavior caused nerve injury. In the present work, using the loose ligation of the sciatic nerve model, we characterized the time course of the appearance of tactile and cold allodynia and the corresponding spinal expression of the N-type Ca2+ channel alpha(1B)-subunit after nerve ligation. Within 1 week after ligation, the majority of rats developed a unilateral sensitivity to mechanical stimulation (von Frey filaments), as well as sensitivity to cold, which persisted for 30 days. Immunocytochemical analysis of the spinal cord in sham-operated animals for the alpha(1B)-subunit showed a smooth, moderate staining pattern in the superficial laminae I-II, as well as in ventral alpha-motoneurons. In nerve-ligated animals, an intense, dot-like immunoreactivity in the ipsilateral dorsal horn was observed from 5-20 days after nerve ligation. The most prominent alpha(1B)-subunit upregulation was found in the outer as well as the inner part of lamina II (II(o), II(i)), extending from the medial toward the lateral region of the L4 and L5 spinal segments. The behavioral changes which developed after chronic constriction injury directly correlated with the alpha(1B)-subunit upregulation in the corresponding spinal cord segments. These data suggest that upregulation of the spinal alpha(1B)-subunit may play an important role in the initiation and maintenance of pain state after peripheral nerve injury

A Single Dose of Atorvastatin Applied Acutely after Spinal Cord Injury Suppresses Inflammation, Apoptosis, and Promotes Axon Outgrowth, Which Might Be Essential for Favorable Functional Outcome.

The aim of our study was to limit the inflammatory response after a spinal cord injury (SCI) using Atorvastatin (ATR), a potent inhibitor of cholesterol biosynthesis. Adult Wistar rats were divided into five experimental groups: one control group, two Th9 compression (40 g/15 min) groups, and two Th9 compression + ATR (5 mg/kg, i.p.) groups. The animals survived one day and six weeks. ATR applied in a single dose immediately post-SCI strongly reduced IL-1β release at 4 and 24 h and considerably reduced the activation of resident cells at one day post-injury. Acute ATR treatment effectively prevented the excessive infiltration of destructive M1 macrophages cranially, at the lesion site, and caudally (by 66%, 62%, and 52%, respectively) one day post-injury, whereas the infiltration of beneficial M2 macrophages was less affected (by 27%, 41%, and 16%). In addition, at the same time point, ATR visibly decreased caspase-3 cleavage in neurons, astrocytes, and oligodendrocytes. Six weeks post-SCI, ATR increased the expression of neurofilaments in the dorsolateral columns and Gap43-positive fibers in the lateral columns around the epicenter, and from day 30 to 42, significantly improved the motor activity of the hindlimbs. We suggest that early modulation of the inflammatory response via effects on the M1/M2 macrophages and the inhibition of caspase-3 expression could be crucial for the functional outcome

Thoracic 9 Spinal Transection-Induced Model of Muscle Spasticity in the Rat: A Systematic Electrophysiological and Histopathological Characterization.

The development of spinal hyper-reflexia as part of the spasticity syndrome represents one of the major complications associated with chronic spinal traumatic injury (SCI). The primary mechanism leading to progressive appearance of muscle spasticity is multimodal and may include loss of descending inhibitory tone, alteration of segmental interneuron-mediated inhibition and/or increased reflex activity to sensory input. Here, we characterized a chronic thoracic (Th 9) complete transection model of muscle spasticity in Sprague-Dawley (SD) rats. Isoflurane-anesthetized rats received a Th9 laminectomy and the spinal cord was transected using a scalpel blade. After the transection the presence of muscle spasticity quantified as stretch and cutaneous hyper-reflexia was identified and quantified as time-dependent changes in: i) ankle-rotation-evoked peripheral muscle resistance (PMR) and corresponding electromyography (EMG) activity, ii) Hoffmann reflex, and iii) EMG responses in gastrocnemius muscle after paw tactile stimulation for up to 8 months after injury. To validate the clinical relevance of this model, the treatment potency after systemic treatment with the clinically established anti-spastic agents baclofen (GABAB receptor agonist), tizanidine (α2-adrenergic agonist) and NGX424 (AMPA receptor antagonist) was also tested. During the first 3 months post spinal transection, a progressive increase in ankle rotation-evoked muscle resistance, Hoffmann reflex amplitude and increased EMG responses to peripherally applied tactile stimuli were consistently measured. These changes, indicative of the spasticity syndrome, then remained relatively stable for up to 8 months post injury. Systemic treatment with baclofen, tizanidine and NGX424 led to a significant but transient suppression of spinal hyper-reflexia. These data demonstrate that a chronic Th9 spinal transection model in adult SD rat represents a reliable experimental platform to be used in studying the pathophysiology of chronic spinal injury-induced spasticity. In addition a consistent anti-spastic effect measured after treatment with clinically effective anti-spastic agents indicate that this model can effectively be used in screening new anti-spasticity compounds or procedures aimed at modulating chronic spinal trauma-associated muscle spasticity