| Abstract No.: | A-C1109 |
| Country: | Canada |
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| Title: | FOCAL DEMYELINATION AND ASSOCIATED NEUROPATHIC PAIN: NOVEL THERAPEUTIC APPROACHES |
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| Authors/Affiliations: | 1 Geoffrey McComb*; 1 Jennifer Fortin; 2 Bernhard Juurlink; 1 Verge Valerie
1 University of Saskatchewan, Saskatoon, SK, Canada
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| Content: | Multiple Sclerosis is characterized by segmental demyelination of axons. This results in symptoms ranging from spasticity, ataxia, visual cognitive or swallowing difficulties, thermal sensitivity, fatigue to pain. However, little MS research addresses pain states despite the high prevalence in MS patients.
Objective 1: To develop a focal CNS demyelination model that has a measurable and reproducible neuropathic pain component.
Once developed we intend to use this model to explore whether a diet rich in glucoraphanin, the precursor of the phase 2 protein inducer sulforaphane, has potent anti-inflammatory actions and promote endogenous mechanisms that can counter oxidative stress. We hypothesize that a diet rich in phase two enzyme inducers will mitigate the CNS damage induced by the demyelinating event and the associated neuropathic pain state.
Objective 2: To perform preliminary and determine if rats fed a broccoli sprout diet high in glucoraphanin have diminished demyelination, reduced mononuclear cell invasion and reduced gliosis 2 weeks following a unilateral injection of lysophosphatidyl choline into dorsal columns at the level of L4, 5, 6 sensory input.
Materials and Methods: A focal demyelinating insult was induced with a 1µl injection of 2% lysophosphatidyl choline with 0.25% Fluorogold into the right dorsal column at a depth of 1mm at two sites between T10 and 12 representing the region of spinal cord where the L4, 5 primary afferents enter the cord. Animals were fed diets supplemented with 400 mg/day of dried broccoli sprouts, control deactivated broccoli sprouts or nothing in addition to the regular diet starting seven days prior to insult and for the duration of the experiment. Mechanical and thermal thresholds were measured every second day for four days before beginning specialized diet and continued for 13 days after insult. Ten µm sections of formaldehyde perfused spinal cords were thaw mounted on microscope slides and processed for immunohistochemistry to detect activated macrophage and microglia (ED1), astrogliosis (GFAP) and myelin (MBP). Accuracy of injection was confirmed by unilateral presence of Fluorogold in the L4,5 DRG. The area of demyelination was confirmed using Black Gold.
Results: Our preliminary results indicate that unilateral focal demyelination of the dorsal columns leads to reproducible mechanical sensitivity resulting in decreased thresholds detectable at 9 days post insult and continuing until day 13 after which thresholds appear to trend back toward baseline levels in some animals. There was no marked change in thermal threshold detected. Beyond the algesic component, we observed the predicted loss of myelin, gliosis and the infiltration of activated macrophages and microglia. Broccoli sprout fed animals showed fewer ED1 and GFAP positive cells than did the other two groups.
Conclusions: We have developed a model of focal demyelination that leads to a reproducible altered mechanical sensitivity. Preliminary results support a role for a diet rich in glucoraphanin in reduction of gliosis and the infiltration of activated macrophages and microglia associated with a demyelinating insult.
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