Participation of the adrenal gland in the anti‐inflammatory effect of polyunsaturated diets

Abstract

The effect of an n-3 (fish) and n-6 (soybean) fatty acid-rich diet on carrageenin paw oedema in rats, and the participation of adrenal gland, corticosterone and α2-macroglobulin (α2-M) in this process were studied. A significant inhibition of carrageenin oedema was observed not only in rats fed a diet rich in fish oil but also in the soybean group. α2-M was not detectable before carrageenin injection, suggesting that this putative antiinflammatory factor does not participate in the observed anti-inflammatory effect. Corticosterone levels were higher in fat-fed than in control rats, before carrageenin stimulus and adrenalectomy abolished the anti-inflammatory response in fat-fed animals, showing the important role of the adrenocortical hormones in this process.

Effect of Fish or Soybean Oil-Rich Diets on Bradykinin, Kallikrein, Nitric Oxide, Leptin, Corticosterone and Macrophages in Carrageenan Stimulated Rats

“…These results are similar to other [33] in neutrophils from rats fed a soybean-rich diet. H 2 O 2 is an important citotoxic agent [34] and its lower release could contribute to the anti-inflammatory effect of the hyperlipidic diets, as observed previously [12,27] and reproduced in the present study. Some reports have shown decreased activity of superoxide-dismutase (SOD), the enzyme catalyzing H 2 O 2 formation, in plasma and in different tissues of animals treated with nY3 or nY6 PUFA-rich diets [35,36].…”

“…Our previous [12] and present results showed that nY6 and nY3 PUFA-rich diets had a similar antiinflammatory effect and we were presently able to correlate this effect with similar changes of inflammatory mediators. The doubt remains as on the real beneficial effects of reducing the acute inflammation, since the inflammatory process is a physiological response to tissue injury, aimed at reestablishing homeostasis.…”

“…These different observations could be attributed to different cell types and quantities of different fatty acids on the high-lipid diets used. Additionally, the reduction of H 2 O 2 production, observed in the present study, could also be attributed to the high basal levels of corticosterone, found in the lipid groups [12], since this hormone can reduce H 2 O 2 production and activity of antioxidant enzymes, such as SOD, in macrophages in culture [39].…”

“…However, we previously observed that both fish and soybean oil-rich diets were able to attenuate the acute inflammatory process, which could be partially attributed to increased corticosterone levels [12].…”

Soybean and fish oil mixture increases IL-10, protects against DNA damage and decreases colonic inflammation in rats with dextran sulfate sodium (DSS) colitis

“…This effect was partially attributed to the elevated basal corticosterone levels induced by these diets [38,39]. Here, we show that plasma corticosterone levels did not differ in the three experimental groups.…”