Effect of dietary polyunsaturated fatty acids on prostaglandin E(2) and insulin-like growth factor-I in bone modeling
Abstract
Three experiments were conducted to evaluate the effects of dietary polyunsaturates on prostaglandin (PG) E$\sb2$ and insulin-like growth factor-I (IGF-I) in bone modeling. Results from experiment one showed that the fatty acid composition of bone polar and neutral lipids reflected the type of dietary lipids fed to chicks. Generally, (n-3) PUFA increased the concentration of 20:5(n-3) in bone of chicks given menhaden oil compared to those given soybean oil. Feeding butter to chicks increased periosteal bone formation rates, total new bone formation rates, and intracortical porosity in the tibiotarsi of chicks at 21 d compared to those given soybean oil, menhaden oil, or margarine. Consumption of (n-3) PUFA to chicks elevated the concentrations of IGF-I in plasma at 14 d, and in liver, bone, and cartilage at 21 d compared to those given the (n-6) PUFA. Results from experiment two confirmed that dietary (n-3) PUFA enriched the 20:5(n-3) and 22:6(n-3) concentrations and elevated the IGF-I levels in bone of chicks at 14 d. The data also demonstrated that dietary (n-3) PUFA depressed ex vivo PGE$\sb2$ production in bone organ cultures at 16 and 32 d. Moreover, results from experiment three revealed that acetylsalicylic acid (ASA), an inhibitor of cyclooxygenase, depressed ex vivo PGE$\sb2$ production in bone organ cultures and modulated the concentrations of IGF-I in bone of chicks at 17 d. Chicks fed soybean oil had a higher production of ex vivo PGE$\sb2$ in bone organ cultures and a lower bone formation rate compared to those given menhaden oil at 17 d. This research demonstrated that dietary PUFA modulated the fatty acid composition of bone and altered ex vivo PGE$\sb2$ biosynthesis in bone organ cultures. Further, saturated fatty acids enhanced bone formation compared to unsaturated fatty acids in our animal model. The enrichment of bone with dietary sources of (n-3) PUFA depressed PGE$\sb2$ production in bone yet normal bone modeling was sustained. Future studies should be conducted to examine the effects of eicosanoids biosynthesized from (n-3) PUFA on bone formation and on IGF-I production in bone.
Degree
Ph.D.
Advisors
Watkins, Purdue University.
Subject Area
Food science|Nutrition
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