linoleic-acid and methyl-oleate

Islet adaptation to pregnancy is largely influenced by prolactin and placental lactogens. In addition serum lipids are significantly increased. Here, we report the novel observation that prolactin and oleic acid synergistically stimulate islet cell proliferation and islet growth. In neonatal rat islets, prolactin increased proliferation 6-fold, oleic acid 3.5-fold, and their combination 15-fold. The expression of insulin in these dividing cells establishes them as β-cells. Similar changes were seen in islet growth. This synergy is restricted to monounsaturated fatty acids and does not occur with other islet growth factors. Oleic acid increases prolactin-induced STAT5 phosphorylation, even though by itself it is unable to induce STAT5 phosphorylation. Their effects on Erk1/2 phosphorylation are additive. Some of the synergy requires the formation of oleoyl CoA and/or its metabolites. Unexpectedly, methyl oleic acid, a non-metabolizable analog of oleic acid, also shows synergy with prolactin. In summary, prolactin and oleic acid synergistically stimulate islet cell proliferation and islet growth in rat islets, oleic acid increases prolactin-induced STAT5 activation, and requires both the metabolism of oleic acid and non-metabolized oleic acid. Since oleic acid is the most abundant monounsaturated fatty acid in serum that is elevated during pregnancy, it may contribute to increased β-cell proliferation seen during pregnancy.

Topics: Animals; Animals, Newborn; Biomarkers; Cell Proliferation; Fatty Acids, Monounsaturated; Growth Hormone; Insulin; Insulin-Secreting Cells; Islets of Langerhans; Linoleic Acid; MAP Kinase Signaling System; Oleic Acid; Oleic Acids; Palmitic Acid; Phosphorylation; Prolactin; Protein Processing, Post-Translational; Rats, Sprague-Dawley; STAT5 Transcription Factor; Tissue Culture Techniques; Up-Regulation

The rates of reaction with ozone of some biological antioxidants and simple polyunsaturated fatty acids (PUFA) have been measured in water or in aqueous micellar solutions. At pH 7.0 the rate constants are ca. 10(6) M-1 sec-1 for urate, alpha-tocopherol, and PUFA, and 6 X 10(7) M-1 sec-1 for ascorbate. When ozone-containing air is breathed, ascorbate in the lung may undergo direct ozonation. However, alpha-tocopherol is probably spared direct reaction with ozone because it doesn't effectively compete with PUFA in pulmonary membranes; rather, tocopherol is used to scavenge radicals produced from the ozone-PUFA reaction.

Topics: Antioxidants; Ascorbic Acid; Chemical Phenomena; Chemistry; Fatty Acids, Unsaturated; Linoleic Acid; Linoleic Acids; Oleic Acid; Oleic Acids; Ozone; Uric Acid; Vitamin E

Topics: alpha-Linolenic Acid; Fatty Acids; Humans; Linoleic Acid; Linoleic Acids; Oleic Acids; Oxygen