Prefeeding with omega-3 fatty acids suppresses inflammation following hemorrhagic shock

Hemorrhagic shock followed by resuscitation stimulates an inflammatory response. This study tests the hypothesis that prefeeding with fish oil rich in ω-3 fatty acids (FAs) will attenuate that response.

Male Sprague-Dawley rats (n = 60; 350 ± 30 g) were randomly but unequally assigned to 3 groups: sham (n = 12), control (n = 24), and fish oil (n = 24). In the fish oil group, rat chow was supplemented with fish oil (600 mg/kg/d, 25% ω-3 FA). Control and sham group diets were supplemented with corn oil. Under fluothane, hemorrhagic shock was induced, and arterial pressure was maintained at 25 to 30 mm Hg for 30 minutes. Resuscitation was carried out by giving 21 mL/kg lactated Ringer's solution and returning shed blood to the animal. Half of each group was killed at 30 minutes and at 4 hours postresuscitation. Liver samples were assayed for indicators of inflammation and heat shock protein 25 (Hsp25). Lung edema was measured.

All animals survived. At 30 minutes postresuscitation, expression of mRNA for inducible nitric oxide synthase (iNOS) was significantly elevated in the control group but normal in the fish oil group. At 4 hours, expression of mRNA for Hsp25 was significantly increased in the fish oil group. Lung edema index was significantly lower in the fish oil group than in either sham or control groups.

Fish oil prefeeding in a rodent model of hemorrhagic shock was associated with increased liver mRNA expression of Hsp25, reduced liver mRNA expression of iNOS, and decreased lung edema. These findings support the validity of the study hypothesis.