EFFECTS OF HIGH-FAT AND HIGH-SALT DIETS ON MESENTERIC ADIPOSE TISSUE: ROLE OF THE NATRIURETIC PEPTIDE SYSTEM

Objective: The role of the natriuretic peptide system and its receptors in mesenteric adipose tissue in the context of high-fat and high-salt diets (HFHS) is currently unknown. We studied the effects of diets on plasma levels of atrial natriuretic peptide (ANP); expression of NPR-A and NPR-C receptors; inflammation and fibrosis markers in mesenteric adipose tissue as well as its relationship with systolic blood pressure (SBP) and visceral adiposity in male Wistar rats. Design and method: Four groups were studied for 6 weeks: Control (C): balanced diet (0.4% NaCl); HF: 60% of calories from fat; HS: 8% NaCl in food; and HFHS. We determined: SBP; mesenteric adiposity index (AI); diuresis, creatinine clearance (CrCl), fractional (FENa) and urinary sodium excretion (UENa); plasma levels of ANP by ELISA; expression of NPR-A, NPR-C, interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), nuclear factor kappa B (NF-kB) and transforming growth factor-beta (TGF-beta) by Western Blot. Results: SBP increased in all three groups (mmHg, HF: 157±1; HS: 171±4; HFHS: 175±3 vs C: 123±1, p<0.01). In the HS and HFHS groups diuresis, FENa and UENa were higher than in C and HF groups (p<0.05) with no changes in CrCl. Mesenteric AI (%) increased in HF: 0.76±0.01 vs C: 0.61±0.01, (p<0.01) while it decreased in HS: 0.52±0.03 and HFHS: 0.58±0.01 vs. HF groups (p<0.01). Plasma levels of ANP (ng/mL) decreased in HF: 0.25±0.02 and HFHS: 0.51±0.05 groups vs. C: 0.77±0.05, (p<0.01). NPR-A expression in mesenteric adipose tissue was higher in HS, lower in HF vs. C (p<0.01), while HFHS presented a lower expression than C but higher than HF. On the other hand, NPR-C expression was higher in HF, lower in HS vs. C (p<0.01) and in HFHS it was higher than HS (p<0.05) and slightly higher than C. Furthermore, IL-6, NF-kB, TNF-alpha and TGF-beta expressions were increased in HF, HS, HFHS compared to C (p<0.05). Conclusions: HF is associated with an increase in mesenteric adiposity, while HS decreases it. These effects could be due to a differential expression of NPR-A and NPR-C receptors at the level of adipose tissue.