(n-3) Fatty Acids Reduce the Release of Prostaglandin E2 from Bone but Do Not Affect Bone Mass in Obese (fa/fa) and Lean Zucker Rats,

Abstract

Childhood obesity is prevalent and linked to the development of Type 2 diabetes mellitus (DM) and poor bone health. Some PUFA enhance bone mass and thus may improve bone health in obese children. The study objective was to determine the effects of dietary (n-6) compared with (n-3) essential PUFA and long-chain PUFA (LCPUFA) on bone in an obese and insulin-resistant state. Male fa/fa (n = 48) and lean Zucker rats (n = 48) were fed diets containing safflower oil [SO, high (n-6) PUFA], flaxseed oil [FXO, high (n-3) PUFA], or menhaden oil [MO, high (n-3) LCPUFA] for 9 wk. Measurements included the following: femur bone area (BA), mineral content (BMC), density (BMD), morphometry and ex vivo release of prostaglandin E(2) (PGE(2)); plasma osteocalcin and C-terminal telopeptides of type I collagen. Differences among groups were detected using 2-way ANOVA. Genotype effects in the fa/fa rats included lower femoral weight, length, BA, and BMC, as well as femoral head and proximal epiphysis widths compared with the lean rats, but BMD was not affected. Femur BA, BMC, and BMD did not differ among the dietary groups, but diaphysis width was elevated in the MO group and PGE(2) release was reduced by the FXO and MO diets. No genotype x diet interactions were observed. These data indicate that the fa/fa Zucker rat is at risk for low bone mass and that dietary (n-3) FA effectively reduce PGE(2) release. Whether reduced PGE(2) will support optimal peak bone mass during childhood and conserve bone mass with aging warrants investigation.

Long-term supplementation of dietary omega-6/omega-3 ratios alters bone marrow fatty acid and biomarkers of bone metabolism in growing rabbits

“…Enzyme activity was expressed as U/L. Bone organ culture was performed as previously described (Blanaru, Kohut, Fitzpatrick-Wong, & Weiler, 2004;Mollard et al, 2005b;Watkins et al, 2000a;Watkins et al, 2001e). Briefly, tibia samples (1 g) were incubated in 10 ml of Hank's balanced salt solution (Mediatech, Inc., Manassas, VA, USA) for 2 h at 37°C in a shaking water bath, followed by the removal of bone and rapid freezing of solution at À20°C for 1 week until duplicate analysis of PGE 2 by a competitive enzyme-linked immunosorbent assay (ELISA) technique using a rabbit polyclonal antibody PGE 2 kit (Oxford Biomedical Research, Inc., Oxford, MI, USA).…”

“…In addition to the alteration in PGs production, some researchers have indicated that the biological mechanisms involving the role of x3 and x6 polyunsaturated fatty acids in bone metabolism (formation and resorption) include osteoblasts differentiation and proliferation, calcium absorption and excretion, inflammation, and lipid oxidation (Claassen, Coetzer, Steinmann, & Kruger, 1995a;Corwin, 2003;Haag, Magada, Claassen, Bohmer, & Kruger, 2003;Mollard, Gillam, Wood, Taylor, & Weiler, 2005b;Parhami, 2003;Sun et al, 2004;Watkins et al, 2000a;Watkins et al, 2001b;Watkins et al, 2003). Therefore, by including x6 (ARA) and x3 (EPA & DHA) LC PUFA and altering their ratio in the diet, it is possible to influence the amount of PGE 2 in bone thus reach an amount that would favor bone formation versus resorption.…”

Functional Foods and Bone Health: Where are we at?

“…Other developmental models (Weiler et al 2002Mollard et al 2005) that are representative of disease states (polycystic kidney disease, inflammatory bowel disease, hyperinsulinemia) are discussed in Section 21.7.1.4 (Table 21.9).…”

“…The effects of FS oil or FS oil in combination with SDG have been investigated using animal models of kidney disease (Weiler et al 2002, obesity (Mollard et al 2005) and inflammatory bowel disease (Table 21.9). Compromised bone health is a secondary characteristic of these diseases.…”

“…Using male 6-week-old lean and fa/fa Zucker rats, Mollard et al (2005) determined the effects of high LA (sunflower oil mixture), ALA (FS oil mixture) and EPA/DHA (menhaden oil mixture) diets on BMD, BMC and markers of bone formation (osteocalcin) and bone resorption (C-terminal telopeptides of type I collagen) in the early stages of disease, which is also a representation of juvenile obesity (Table 21.9) (Mollard et al 2005). After 9 weeks of treatment on their respective diets, significantly lower BMD and BMC were observed in the diseased rats compared to their healthy counterparts.…”