Short-term dietary conjugated linoleic acid supplementation does not enhance the recovery of immunodepleted dexamethasone-treated rats

Summary.

Background: Conjugated linoleic acid (CLA) has been reported to decrease fat deposition, and increase lean body mass. This has been broadly inferred to mean that CLA alters protein turnover. However, data to test the effects of CLA on protein turnover are lacking. An enhancement in immune responses by CLA has also been demonstrated. Aim of the study: The objective of this study was to determine the potential for dietary CLA and protein intervention to improve nutritional and functional recovery in an animal model of catabolic stress and immunodepletion. Methods: Diets varying in their protein levels in the presence or absence of CLA were tested for their effects on the recovery of glucocorticoid (intraperitoneal injection of dexamethasone, 120 mg/kg) treated rats. Following steroid injection, rats were fed 4 dietary treatments for 4 d. The diets contained 10 or 20 g/100 g protein with or without 0.5 g/100 g CLA. Results: Dexamethasone treatment resulted in a decreased food intake and loss of weight, independent of dietary treatment. A higher number of blood monocytes occurred in rats fed the high CLA diets. The protein fractional synthesis rate in spleens of rats fed the diets containing either high proteins or CLA were higher compared to those fed diets with low protein content or without CLA, respectively. CLA, consumed post-dexamethasone treatment, did not improve protein turnover in the other tissues studied, including gut mucosa, liver, muscle and thymus. Conclusions: The present study was performed to determine the effect of CLA in acute conditions, as opposed to a preventive approach, on the recovery from a catabolic stress with immunodepletion. Overall, no effect of short-term feeding CLA on the recovery from dexamethasone-mediated immunodepletion was observed.