Glutamine : A novel and potent therapeutic for acute spinal cord injury

Abstract

Spinal cord injury occurs at a rate of 11.5 - 53.4 per million in developed countries with great emotional and financial consequences. The damage caused by the initial injury is followed by secondary damage, a complex cascade of mechanisms including ischemia, oxidative stress, inflammation and apoptosis. Although nothing can be done to reverse the initial damage to the spinal cord once it occurs, the secondary damage can be targeted by therapeutics to improve recovery. Following injury, concentrations of the potent antioxidant glutathione (GSH) are decreased in the spinal cord which potentiates mechanisms of secondary damage. In an attempt to maintain the GSH concentrations, the non-essential amino acid glutamine was tested as it was shown to increase GSH concentrations both in vivo and in vitro. Glutamine is being used extensively in clinical research in an expansive number of physiological and pathological conditions including brain trauma. To examine the therapeutic potential of glutamine after spinal cord trauma, two compression injury models, the modified aneurysm clip and the modified forceps, were used to induce an injury in male Wistar rats. We have demonstrated the ability of glutamine treatment (1 mmol/kg), given 1 hour after a 30 g aneurysm clip injury to increase GSH not only in whole blood samples but within the spinal tissue at the site of injury. Increasing GSH in this way also resulted in improved locomotor scores and maintenance of white matter tissue at the injury epicenter. Experiments using the forceps model were then performed to determine if the potency of glutamine treatment would be carried over to a different model and at a variety of severities. Glutamine, again, demonstrated the ability to improve maintenance of whole blood GSH, locomotor scores and tissue histology. In our experiments, glutamine has proven to be a potent therapeutic for spinal cord injury with an effect that is matched by few compounds currently being studied and well exceeding the standard therapeutic, methylprednisolone. Given the breadth of knowledge regarding the effects of glutamine clinically in numerous paradigms and the potency of the therapeutic effect seen in these studies, we believe that glutamine is fit for clinical trial and has a high potential for success.