Fish oil diet may reduce inflammatory levels in the liver of middle-aged rats

Abstract

The impact of dietary soybean oil, lard and fish oil on physiological responses in middle age is little studied. In this study, we investigated the changes of oxidative stress, inflammatory cytokines, telomere length, and age-related gene expression in the liver of middle-aged rats in response to the above three fat diets. Male Sprague Dawley rats (12 months old) were fed AIN-93M diets for 3 months, in which soybean oil was equivalently replaced by lard or fish oil. As compared to the lard diet, intake of fish oil diet significantly decreased body weight gain, white blood cell count, and levels of hepatic triacylglycerol, total cholesterol, fat accumulation, low-density lipoprotein, oxidative stress and inflammatory cytokines (P < 0.05), but increased telomere length (P < 0.05). On the other hand, lard diet and soybean oil diet showed great similarity in the above variables. PCR array analysis further indicated that fish oil diet significantly down-regulated gene expression related to inflammatory response, apoptosis, DNA binding, proteostasis and telomere attrition. Differentially expressed genes were enriched in the complement and coagulation cascades pathways. Such physiological and molecular responses could be due to different fatty acid composition in fish oil, lard and soybean oil.

Intake of Fish Oil Specifically Modulates Colonic Muc2 Expression in Middle‐Aged Rats by Suppressing the Glycosylation Process

“…Our previous study showed that intake of fish oil for 3 months induced a higher level of inflammation in the colon . However, the present study did not show significant differences in IL‐1β, IL‐6, IL‐10, IL‐12, NF‐κB, TNF‐α, and TGF‐β mRNA levels ( p > 0.05, Figure A–G).…”

“…However, recent studies have mainly concerned the association between high‐fat diet and gut microbiota and metabolic disorders, but few studies focused on the normal intake of dietary fats. A previous study indicated that, at a normal dose (4%), the fish oil diet group induced higher abundances of Desulfovibrionaceae and Bilophila in the colon, which could impair intestinal barrier function and finally increase the risk of inflammation . This study further confirmed the potential negative effect of fish oil on gut barrier.…”

“…Animal diets were formulated by Trophic Animal Feed High‐Tech Co., Ltd (Nantong, China), according to the recommendation of the American Institute of Nutrition for middle‐aged rats (AIN‐93M) . Briefly, the formulations comprised of 4% soybean oil, pork lard, or fish oil, 14.0% protein, 46.6% cornstarch, 15.5% dextrinized cornstarch, 10.0% sucrose, 5.0% fiber, 3.5% mineral mix (AIN‐93‐M), 1.0% vitamin mix (AIN‐93‐VX), 0.2% L‐cystine, 0.3% choline bitartrate, and 0.0008% tert‐butylhydroquinone . Soybean oil was bought from Shanghai Jiali Oil Industry Co. Ltd (Shanghai, China).…”

“…Recent studies indicated that the impacts of fish oil diet could be tissue‐specific. At a normal dose (4%), the intake of fish oil significantly decreased the level of fat accumulation, oxidative stress, and inflammatory cytokines in the liver but increased the abundance of phylum Proteobacteria and genus Desulfovibrio as well as the inflammatory cytokines in the colon …”

“…On one hand, high‐fat diet may induce metabolic disorders, including obesity, diabetes, and inflammation . On the other hand, different dietary fats have distinct effects on gut bacteria composition, liver metabolism, and phenotypes . Such a difference could be mainly attributed to the difference in fatty acid composition in diets .…”