Docosahexaenoic acid, but not eicosapentaenoic acid, reduces the early inflammatory response following compression spinal cord injury in the rat

Abstract

Docosahexaenoic acid (DHA, 22 : 6) and eicosapentaenoic acid (EPA, 20 : 5) are omega-3 polyunsaturated fatty acids (n-3 PUFAs) with distinct anti-inflammatory properties. Both have neuroprotective effects acutely following spinal cord injury (SCI). We examined the effect of intravenous DHA and EPA on early inflammatory events after SCI. Saline, DHA or EPA (both 250 nmol/kg) were administered 30 min after T12 compression SCI, to female Sprague-Dawley rats. DHA significantly reduced the number of neutrophils to some areas of the injured epicentre at 4 h and 24 h. DHA also reduced C-reactive protein plasma levels, whereas EPA did not significantly reduce neutrophils or C-reactive protein. Laminectomy and SCI elicited a sustained inflammatory response in the liver, which was not reversed by the PUFAs. The chemokine KC/GRO/CINC and the cytokine IL-6 provide gradients for chemotaxis of neutrophils to the epicentre. At 4 h after injury, there was a significant increase in IL-6, KC/GRO/CINC, IL-1β and tumour necrosis factor-α in the epicentre, with a return to baseline at 24 h. Neither DHA nor EPA returned their levels to control values. These results indicate that the acute neuroprotective effects of n-3 PUFAs in rat compression SCI may be only partly attributed to reduction of some of the early inflammatory events occurring after injury.