Treatment with omega-3 polyunsaturated fatty acid docosahexaenoic acid reduces the upregulation of chondroitin sulphate proteoglycans following spinal cord injury
Spinal cord injury (SCI) results in devastating consequences due to the inability of the central nervous system to regenerate. However, plasticity is thought to contribute to functional recovery. Here, we examined the effects of treatment with the omega-3 fatty acid docosahexaenoic acid (DHA) on changes in the expression of chondroitin sulphate proteoglycans (CSPGs) in the extracellular matrix and in perineuronal nets (PNNs), since it is thought that CSPGs are inhibitory to regenerating axons and that PNNs restrict synaptic plasticity. Hemisection was performed at thoracic level 12 in adult rats. Rats received intravenous injections of 500 nmol/kg DHA or saline 30 min post-injury. Spinal cords were dissected out 14 and 56 days later and sections were stained for PNNs, the CSPGs NG2 and neurocan, GFAP, and serotonin (5-HT). DHA treatment resulted in reduced lesion size, a smaller increase in neurocan, NG2, and GFAP expression at the scar border, and reduced neurocan immunoreactivity in PNNs 1 mm rostral and 3.5 and 4 mm caudal to the lesion. The decrease in 5-HT terminals contacting neurons seen caudal to the injury was not affected by DHA treatment. DHA may facilitate functional recovery after SCI by reducing the levels of CSPGs at the scar border, favouring axonal regeneration, and by decreasing neurocan expression within PNNs, which might promote synaptic plasticity.