Objective: To evaluate effects of docosahexaenoic acid-enriched phosphatidylcholine (DHA-PC) on cytokine production induced by lipopolysaccharide (LPS). Methods: The culture supernatants of splenocytes exposed to DHA-PC along with LPS were harvested to determine the production of Th 1 (IFN-γ and IL-2) and Th2 [IL-4, IL-5, IL-6 and IL-12/IL-23(p40)] cytokines. Cytokines were measured using ELISA. Results: Co-administration of DHA-PC with LPS resulted in significantly lower IL-2 expression compared to that observed with administration of only LPS (P<0.01). Treatment with DHA-PC and LPS significantly increased IL-5 expression (P<0.01). Moreover, co-administration of DHA-PC with LPS significantly decreased IL-6 and IL-12/IL-23(p40) expressions compared to that observed with administration of only LPS (P<0.01). Conclusions: Our results suggest that DHA-PC inhibits pro-inflammatory cytokines [IL-2, IL-6 and IL-12/IL-23(p40)] expression on induction of inflammation.

BACKGROUND: Mirror-image allodynia is a mysterious phenomenon that occurs in association with many clinical pain syndromes including complex regional pain syndromes (CRPS). Underlying mechanisms for the development of such pain are still a matter of investigation. Several studies suggest that activation of the N-methyl-D-aspartate (NMDA) receptor is essential for central sensitization as a base for persistent pain. The aim is to assess whether alteration of NMDA receptor expression correlates with the contralateral allodynia in the chronic post-ischemia pain (CPIP) model rats representing CRPS-Type I. METHODS: Application of a tight-fitting tourniquet for a period of 3 hours before reperfusion produced CPIP in male Sprague-Dawley rats. The mechanical paw withdrawal thresholds to von Frey stimuli (using a dynamic plantar aesthesiometer) were measured as pain indicators in ipsilateral and contralateral hindpaws. Phosphorylation of the NMDA receptor 1 subunit (pNR1), assessed with Western blot, was measured in the contralateral L4-6 spinal cord. RESULTS: Ipsilateral and contralateral mechanical allodynia is present at 4 hours after reperfusion, peaked at 3 days, and continued for 7 days after reperfusion. The relative density of pNR1 of CPIP rats significantly decreased in the contralateral L4-6 spinal cord compared to baseline value (P < 0.05). There was significant correlation between paw withdrawal threshold and the relative density of pNR1 (ipsilateral; R2 = 0.75, P < 0.01, contralateral; R2 = 0.60, P < 0.01). CONCLUSIONS: These data suggest that pNR1 is correlated to the contralateral mechanical allodynia in CPIP rats.
Animals ; Blotting, Western ; Central Nervous System Sensitization ; Complex Regional Pain Syndromes ; Humans ; Hyperalgesia ; Inositol Phosphates ; Male ; N-Methylaspartate ; Phosphorylation ; Prostaglandins E ; Rats ; Rats, Sprague-Dawley ; Reperfusion ; Specific Gravity ; Spinal Cord ; Tourniquets