Systemic effects induced by intralesional injection of ω-conotoxin MVIIC after spinal cord injury in rats

ω-Conotoxina MVIIC e células-tronco mesenquimais promovem recuperação motora em ratos Wistar após trauma medular agudo

RESUMO O objetivo deste estudo foi avaliar o efeito da ω-conotoxina MVIIC e das células-tronco mesenquimais (CTM) de forma isolada e sua associação nos ratos submetidos ao trauma medular agudo (TMA). Trinta Rattus novergicus, linhagem Wistar, três meses de idade, foram distribuídos igualmente em cinco grupos experimentais: controle negativo (CN), controle positivo (CP), ω-conotoxina MVIIC (MVIIC), células-tronco mesenquimais da medula óssea (CTM-MO) e associação (MVIIC + CTM-MO). O grupo CN foi submetido à laminectomia sem trauma medular, e os grupos CP, MVIIC, CTM-MO e MVIIC + CTM-MO foram submetidos ao trauma medular contusivo. O grupo CP recebeu, uma hora após o TMA, 10μL de PBS estéril, e os grupos MVIIC e MVIIC + CTM-MO receberam 10μL de PBS contendo 20pmol da ω-conotoxina MVIIC, todos por via intratecal. Os grupos CTM-MO e MVIIC + CTM-MO receberam, 24 horas após, 1x106 de CTM via intravenosa. Avaliou-se a recuperação da função locomotora até o sétimo dia pós-trauma. Os animais tratados com MVIIC + CTM-MO obtiveram recuperação motora após o trauma medular agudo (P<0,05). Conclui-se que essa associação apresentou efeito neuroprotetor com melhora na função locomotora em ratos Wistar.

Histological and Biochemical Changes in Adult Male Rat Liver after Spinal Cord Injury with Evaluation of the Role of Granulocyte-Colony Stimulating Factor

Spinal cord injury (SCI) is a devastating disease leading to motor disability. Metabolic dysfunction is another complication of SCI. Thus, we aimed to study the effect of SCI on the histological and biochemical structure of the liver in adult male rats and to delineate the role of post-injury administration of G-CSF. Thirty adult male Sprague-Dawley rats were assigned into three groups: Group I; control (18 rats subdivided equally into three subgroups), and 12 rats underwent SCI and were divided into an SCI group II and G-SCF-treated group III. Twenty-one days post-injury, liver sections were processed for light and electron microscopic examinations and immunohistochemical staining for PCNA and CD68 antibodies. The biochemical assay was carried out for detection of serum levels of ALT, AST, total proteins, albumin, total cholesterol, triglycerides, HDL-c, GSH and MDA. Liver tissue levels of GPx and MDA as well as semiquantitative RT-PCR analysis of hepatic cytokine expression were also conducted. In the SCI group, results showed liver tissue damage in the form of lipid infiltration, blood vessel congestion, vacuolated cells with apoptotic nuclei and increased collagen deposition. Increased CD68-positive macrophages and a decreased number of PCNA-positive cells was detected. Moreover, liver enzymes, total cholesterol and triglycerides were increased while serum albumin, total proteins and HDL-c were decreased in the SCI group. Oxidative stress and increased expression of inflammatory cytokines were detected. Administration of G-CSF induced significant liver improvement with retained liver function by anti-inflammatory, immune-modulatory and antioxidant mechanisms.

Association of riluzole and dantrolene improves significant recovery after acute spinal cord injury in rats

BACKGROUND CONTEXT

Damage to the spinal cord can result in irreversible impairment or complete loss of motor, sensory, and autonomic functions. Riluzole and dantrolene have been shown to provide neuroprotection by reducing neuronal apoptosis after brain and spinal cord injury (SCI) in several animal models of neurologic disorders. As these drugs protect the injured spinal cord through different mechanisms, we investigated the cumulative effects of riluzole and dantrolene.

PURPOSE

This study aimed to investigate the neuroprotective efficacy of the combined administration of riluzole and dantrolene in experimental thoracic SCI.

STUDY DESIGN

Twenty-nine Wistar rats were laminectomized at T12 and divided in five groups. Rats in GI (n=6) underwent laminectomy alone and were treated with placebo. Rats in GII (n=6) underwent laminectomy followed by SCI and were treated with placebo. Rats in GIII (n=5) underwent laminectomy followed by SCI and were treated with riluzole and placebo 15 minutes and 1 hour after laminectomy, respectively. Rats in GIV (n=6) underwent laminectomy followed by SCI and were treated with placebo and dantrolene 15 minutes and 1 hour after laminectomy, respectively. Rats in GV (n=6) underwent laminectomy followed by SCI and were treated with riluzole and dantrolene 15 minutes and 1 hour after laminectomy, respectively. A compressive trauma was performed to induce SCI.

METHODS

Behavioral testing of hind limb function was performed using the Basso Beattie Bresnahan locomotor rating scale, which revealed significant recovery in the group treated with the association of riluzole and dantrolene compared with other groups. After euthanasia, the spinal cord was evaluated using light microscopy and immunochemistry with anti-NeuN and transferase dUTP nick-end-labeling (TUNEL) staining.

RESULTS

Animals treated with the association of riluzole and dantrolene showed a larger number of NeuN-positive neurons adjacent to the epicenter of injury (p≤.05). Furthermore, the TUNEL staining was similar between animals treated with riluzole and dantrolene and those that did not receive spinal cord trauma (p>.05).

CONCLUSIONS

These results showed that riluzole and dantrolene have a synergistic effect in neuroprotection after traumatic SCI by decreasing apoptotic cell death.

Omega-conotoxin MVIIC attenuates neuronal apoptosis in vitro and improves significant recovery after spinal cord injury in vivo in rats

Excessive accumulation of intracellular calcium is the most critical step after spinal cord injury (SCI). Reducing the calcium influx should result in a better recovery from SCI. Calcium channel blockers have been shown a great potential in reducing brain and spinal cord injury. In this study, we first tested the neuroprotective effect of MVIIC on slices of spinal cord subjected to ischemia evaluating cell death and caspase-3 activation. Thereafter, we evaluated the efficacy of MVIIC in ameliorating damage following SCI in rats, for the first time in vivo. The spinal cord slices subjected a pretreatment with MVIIC showed a cell protection with a reduction of dead cells in 24.34% and of caspase-3-specific protease activation. In the in vivo experiment, Wistar rats were subjected to extradural compression of the spinal cord at the T12 vertebral level using a weigh of 70 g/cm, following intralesional treatment with either placebo or MVIIC in different doses (15, 30 and 60 pmol) five minutes after injury. Behavioral testing of hindlimb function was done using the Basso Beattie Bresnahan locomotor rating scale, and revealed significant recovery with 15 pmol (G15) compared to other trauma groups. Also, histological bladder structural revealed significant outcome in G15, with no morphological alterations, and anti-NeuN and TUNEL staining showed that G15 provided neuron preservation and indicated that this group had fewer neuron cell death, similar to sham. These results showed the neuroprotective effects of MVIIC in in vitro and in vivo model of SCI with neuronal integrity, bladder and behavioral improvements.