Effects of Long-Term Oral Administration of Arachidonic Acid and Docosahexaenoic Acid on the Immune Functions of Young Rats

Abstract

Natural killer (NK) cells have many functional activities, including cytotoxicity and the capacity to produce cytokines and chemokines. NK cell activity is regulated partly by eicosanoids, which are produced from arachidonic acid (ARA) and eicosapentaenoic (EPA) acid. In this study, we investigated the effects of long-term therapy with ARA or docosahexaenoic acid (DHA) on the cytotoxic effects of the NK cells of young rats, which were fed on a nonfish oil diet for two generations. Control oil, ARA (240 mg/kg BW/day) or DHA (240 mg/kg BW/day) were orally administrated to the rats for 13 weeks before determining the cytotoxic activity of NK cells from the spleen against YAC-1 mouse lymphoma cell line, as well as the plasma levels of docosanoids or eicosanoids and inflammatory cytokines. Long-term ARA administration significantly suppressed the cytotoxic activity of NK cells. Moreover, ARA administration significantly increased the plasma levels of ARA, prostaglandin (PG) E2, and PGD2. However, DHA administration did not produce any different effects compared with those in the control rats. Furthermore, the inflammatory cytokine levels were not affected by the administration of ARA or DHA. These results suggest that long-term ARA administration has an inhibitory effect on the tumor cytotoxicity of NK cells in rat spleen lymphocytes owing to the enhanced synthesis of PGE2 and PGD2 from ARA because of the elevated plasma ARA levels in young rats.

Chronic Arachidonic Acid Administration Decreases Docosahexaenoic Acid- and Eicosapentaenoic Acid-Derived Metabolites in Kidneys of Aged Rats

“…Next we assessed the levels of LPO and ROS as well as inflammatory cytokine levels in plasma; these were not affected by the ARA treatment, suggesting that ARA-administration itself did not cause inflammation and oxidative stress. These results agree with those of our previous study [ 16 ]. Yoshizawa et al reported that an ARA-rich diet for dams during gestation and lactation does not modify N -methyl- N -nitrosourea-induced renal preneoplastic lesions in their offspring [ 25 ], indicating that exogenous free-form ARA does not induce inflammation or oxidative stress in the kidney.…”

“…Fatty acid composition in the F-1 diet was described previously [ 15 ]. ARA oil was obtained from Cargill Alking Bioengineering (Wuhan and Hubei, China) [ 16 , 17 ]. The fatty acid compositions of the ARA and control oils are shown in Table 1 .…”

Effects of n-3 PUFAs on Intestinal Mucosa Innate Immunity and Intestinal Microbiota in Mice after Hemorrhagic Shock Resuscitation

“…This is consistent with a previous study, which showed that n -3 PUFAs increased the levels of IL-10 in mice subjected to Citrobacter rodentium infection [27]. Increased levels of anti-inflammatory cytokines confirmed that n -3 PUFAs could alleviate the systemic inflammatory response induced by injury [28,29,30]. Furthermore, based on previous studies, n -3 PUFAs may also reverse the downregulation of lysozyme and mucin 2 after HSR [21,31,32].…”

Differential effects of docoosahexaenoic and arachidonic acid on fatty acid composition and myosin heavy chain-related genes of slow- and fast-twitch skeletal muscle tissues

“…Table 1 shows the fatty acid composition of each dietary oil. The oil administrations were determined as described previously [22]. The G2 young rats (5 weeks old) were randomly divided into three groups: control group, DHA group (the triglyceride form of DHA rich oil: 240 mg/kg BW/day), and ARA group (the triglyceride form of ARA rich oil: 240 mg/kg BW/day).…”