PubMedDate not supplied
BACKGROUND: The effects of fat emulsions containing omega-3 and omega-6 polyunsaturated fatty acids (PUFAs) on fatty acid profile, cytokine production, and delayed type hypersensitivity (DTH) in burned rats receiving total parenteral nutrition (TPN) were investigated. METHODS: A fat emulsion containing only eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) was prepared (omega-3 fat emulsion). Sprague-Dawley rats were fed fat-free chow for 2 weeks and were divided into three groups according to the contents of TPN. Groups C (n = 11) and C' (n = 14) received fat-free TPN. Group omega6 received safflower oil emulsion containing linoleic acid (omega-6 PUFA) (n = 11). Group omega3 (n = 11) received safflower oil emulsion (19% of total caloric intake) and fat emulsion containing only EPA and DHA (1% of total calories). On day 5, all rats except for those in group C' were subjected to a 20% full-thickness burn. Group C' did not receive burns. After 48 hours, the rats were killed. RESULTS: The interleukin (IL)-8 concentration was significantly 45% lower in group omega3 than in group C (p < .05). The IL-10 concentration was significantly 15% lower in group omega3 than in group omega6 (p < .05). The IL-6 concentration was increased in group omega6 but not in group omega3 when compared with group C. The IL-6 and IL-8 were not detected in group C'. Prostaglandin E2 (PGE2) and thromboxane B2 (TXB2) concentrations were increased by burn injury, but there were no significant differences among the burned groups. Cell-mediated immunity was thus significantly decreased in burned groups (groups C, omega6, and omega3; p < .01). However, the decrease of DTH was smaller in group omega3 and significantly greater when compared with groups C and omega6 (p < .05). CONCLUSIONS: omega-6 PUFAs increased serum inflammatory cytokine levels in a stressed state. omega-3 fat emulsion reduced IL-8 and IL-10 levels and prevented immunosuppression in burned rats that were receiving TPN.