Gene Expression Profile of Porcine Tissues in Response to Short-Term Feeding of Dietary Fiber Followed By a High-Fat Diet

Sixty-three mixed-sex Ossabaw pigs (28 d of age, 5.62 ± 0.20 kg BW) were used to investigate the effects of early feeding of dietary fiber on later gene expression of markers of lipid metabolism, inflammation, and tight junction proteins. Pigs were blocked by BW and allotted by sex and litter to 1 of 4 treatments (8 pens/treatment; 2 pigs/pen). Treatments were arranged in 2x2 factorial design, with 2 fiber types (inulin or cellulose) and 2 fat levels (5 or 15%, as-fed basis; LF and HF, low- and high-fat diets, respectively). Pigs received diets containing either inulin or cellulose for the first 56 d and thereafter were fed LF and HF containing no added fiber type from d 56 to 140. On d 140, samples of omental and mesenteric fat, liver, LM, jejunum, and ileum were collected to measure mRNA abundance of ACO (acyl-CoA oxidase), CPT1a (carnitine palmitoyltransferase 1a), FAS (fatty acid synthase), SREBP-1c (sterol regulatory element-binding protein-1c), PGC1a (PPAR-γ coactivator 1a), PPARa, IL-6 (interleukin-6), and TNFa (tumor necrosis factor a) by quantitative real-time PCR. Claudin (CL)-3 and CL-4 mRNA abundances were also quantified in the jejunum and ileum samples. Relative gene expression was calculated by the ∆∆Ct method after normalization to 18S rRNA or GAPDH. Data were log-transformed and analyzed using the MIXED procedure of SAS. No fiber x fat interactions were observed for the mRNA abundance of any of the genes studied in the omental fat, liver, LM, and jejunum. There was a fiber x fat interaction for PGC1ɑ expression (P = 0.03) in the ileum and for TNFɑ expression (P < 0.01) in the mesenteric fat, as PGC1ɑ mRNA abundance was decreased (P = 0.03) and TNFɑ mRNA abundance was increased (P < 0.01) when the HF was fed only for pigs that received dietary inulin during early life. Regardless of fat level, adding dietary inulin increased (P ≤ 0.02) jejunal expression of SREBP-1c and CL-4, but reduced (P = 0.02) TNFɑ expression in the ileum. Pigs fed HF had greater (P = 0.03) TNFɑ expression in the LM than pigs fed LF, regardless of fiber type. Feeding either cellulose or HF to pigs led to greater (P ≤ 0.02) ileal IL-6 expression than inulin and LF, respectively. In summary, HF following dietary inulin inclusion during early life of pigs may contribute to future obesity and gastrointestinal inflammation.