Effect of a spinal cord photolesion injury on catalase

Monosialoganglioside Increases Catalase Activity in Cerebral Cortex of Rats

Monosialoganglioside (GM1) is a neuroprotective agent that has been reported to scavenge free radicals generated during reperfusion and to protect receptors and enzymes from oxidative damage. However, only a few studies have attempted to investigate the effects of GM1 on enzymatic antioxidant defenses of the brain. In the present study, we evaluate the effects of the systemic administration of GM1 on the activity of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px), and on spontaneous chemiluminescence and total radical-trapping potential (TRAP) in cerebral cortex of rats ex vivo. The effects of GM1 on CAT activity and spontaneous chemiluminescence in vitro were also determined. Animals received two injections of GM1 (50 mg/kg, i.p.) or saline (0.85% NaCl, i.p.) spaced 24 h apart. Thirty minutes after the second injection the animals were sacrificed and enzyme activities and spontaneous chemiluminescence and TRAP were measured in cell-free homogenates. GM1 administration reduced spontaneous chemiluminescence and increased catalase activity ex vivo, but had no effect on TRAP, SOD or GSH-Px activities. GM1, at high concentrations, reduced CATactivity in vitro. We suggest that the antioxidant activity of GM1 ganglioside in the cerebral cortex may be due to an increased catalase activity.

Strategies for regeneration and repair in spinal cord traumatic injury

Spinal cord injury is frequently followed by the loss of supraspinal control of sensory, autonomic and motor functions at the sublesional level. In order to enhance recovery in spinal cord-injured patients, we have developed three fundamental strategies in experimental models. These strategies define in turn three chronological levels of postlesional intervention in the spinal cord. Neuroprotection soon after injury using pharmacological tools to reduce the progressive secondary injury processes that follow during the first week after the initial lesion. This strategy was conducted up to clinical trials, showing that a pharmacological therapy can reduce the permanent neurological deficit that usually follows an acute injury of the central nervous system (CNS). A second strategy, which is initiated not long after the lesion, aims at promoting axonal regeneration by acting on the main barrier to regeneration of lesioned axons: the glial scar. Finally a mid-term substitutive strategy is the management of the sublesional spinal cord by sensorimotor stimulation and/or supply of missing key afferents, such as monoaminergic systems. These three strategies are reviewed. Only a combination of these different approaches will be able to provide an optimal basis for potential therapeutic interventions directed to functional recovery after spinal cord injury.

A mouse model of acute ischemic spinal cord injury

Mice models of spinal cord injury (SCI) should improve our knowledge of the mechanisms of injury and repair of the nervous tissue. They represent a powerful tool for the development of therapeutic strategies in the fields of pharmacological, cellular, and genetic approaches of neurotrauma. We demonstrate here that the photochemical graded ischemic spinal cord injury model, described in rats, can be successfully adapted in mice, in a reliable and reproducible manner. Following the intravenous injection of Rose Bengal, the translucent dorsal surface of the T9 vertebral laminae of C57BL/6 female mice was irradiated with a 560-nm wavelength-light (3-8 min depending on the experimental group). Animals were sacrificed at 1 day or 7 days after injury. Functional tests were performed daily for motor, sensory, autonomic, and reflex responses. Lesion histopathology was assessed for lesion length, percentage of residual white matter, and astrocytic reactivity. Experimental groups demonstrated a functional deficit, which was correlated to the increase of the irradiation time and, therefore, to the severity of the injury. Histopathological and immunocytochemical data were reliable morphological measurements characterizing the degree of injury, which were strongly correlated to the severity of the functional impairment. Despite differences in the mechanism of injury, the wound healing response described in other traumatic SCI mice models was confirmed (no cavitation and, conversely, the formation of a dense connective tissue matrix). In this context, the precise understanding of the mechanisms of healing response after SCI in mice and of neurochemical kinetics appear to be crucial in the development of therapeutic strategies of CNS repair. Thus, the possible use of an increasing collection of transgenic mice offers a new dimension for experimental research in this area. The ischemic photochemical model of SCI in mice represents a relevant model that can play a key role in this new era of neurotrauma research.