Effect of an enterally administered glutamine-rich protein on the catabolic response to a zymosan challenge in rats

Determination of the anti-inflammatory and cytoprotective effects of l-glutamine and l-alanine, or dipeptide, supplementation in rats submitted to resistance exercise

We evaluated the effects of chronic oral supplementation with l-glutamine and l-alanine in their free form or as the dipeptide l-alanyl-l-glutamine (DIP) on muscle damage, inflammation and cytoprotection, in rats submitted to progressive resistance exercise (RE). Wistar rats (n 8/group) were submitted to 8-week RE, which consisted of climbing a ladder with progressive loads. In the final 21 d before euthanasia, supplements were delivered in a 4 % solution in drinking water. Glutamine, creatine kinase (CK), lactate dehydrogenase (LDH), TNF-α, specific IL (IL-1β, IL-6 and IL-10) and monocyte chemoattractant protein-1 (MCP-1) levels were evaluated in plasma. The concentrations of glutamine, TNF-α, IL-6 and IL-10, as well as NF-κB activation, were determined in extensor digitorum longus (EDL) skeletal muscle. HSP70 level was assayed in EDL and peripheral blood mononuclear cells (PBMC). RE reduced glutamine concentration in plasma and EDL (P<0·05 v. sedentary group). However, l-glutamine supplements (l-alanine plus l-glutamine (GLN+ALA) and DIP groups) restored glutamine levels in plasma (by 40 and 58 %, respectively) and muscle (by 93 and 105 %, respectively). GLN+ALA and DIP groups also exhibited increased level of HSP70 in EDL and PBMC, consistent with the reduction of NF-κB p65 activation and cytokines in EDL. Muscle protection was also indicated by attenuation in plasma levels of CK, LDH, TNF-α and IL-1β, as well as an increase in IL-6, IL-10 and MCP-1. Our study demonstrates that chronic oral l-glutamine treatment (given with l-alanine or as dipeptide) following progressive RE induces cyprotective effects mediated by HSP70-associated responses to muscle damage and inflammation.

Influence of enteral diets supplemented with key nutrients on lymphocyte subpopulations in Peyer's patches of endotoxin-boostered mice

BACKGROUND AND AIMS

This study was undertaken to compare the effect of different key nutrients on lymphocyte subsets of Peyer's patches (PP) and spleen in endotoxemic mice.

METHODS

Female Balb/c mice were fed over a period of 10 days either with an isocaloric and isonitrogenous control diet (Control), a glutamine enriched diet (Diet I) or a diet containing glutamine, arginine, glycine, and n-3 fatty acids (Diet II). On day 7 the mice were challenged intraperitoneally with 25 microg LPS. The lymphocyte subpopulations (B cells, T cells, CD4+ and CD8+) of PP and spleen were analysed by flow cytometry. Glutathione content of small intestinal mucosa and spleen was determined by HPLC and luminal small intestinal IgA by ELISA.

RESULTS

Both experimental diets increased the number of B and T cells in the PP and that of T cells in the spleen (P<0.01). Glutathione content in PP and spleen was higher under administration of key nutrients (P<0.05). Diet II reduced luminal small intestinal IgA content in comparison to the two other groups.

CONCLUSION

The addition of arginine, glycine and n-3 fatty acids to a glutamine supplemented diet does not enhance lymphocyte numbers in PP and spleen, but reduces intestinal IgA content.