Adiponectin is associated with serum and adipose tissue fatty acid composition in rats

The objective of the present work is to analyse the relationships between changes in adiponectin and fatty acid composition in serum and adipose tissue in rats. Samples from serum and different adipose depots (periovarian, mesenteric and subcutaneous) were obtained from ageing rats (14- and 20-month-old) to determine fatty acid composition (gasliquid chromatography). In serum, insulin (radioimmunoassay) and adiponectin levels (enzyme-linked immunosorbent assay) were also measured, while adiponectin gene expression was analysed (real time-qPCR) in all fat depots. There were significant age-related reductions in adipose tissue saturated (SFA) and trans fatty acids and increases in monounsaturated fatty acids in parallel with diminished adiponectin expression in periovarian and mesenteric adipose tissue (p<0.05). Age-independent negative correlations were found between adiponectin gene expression in mesenteric adipose tissue and C12:0, C14:0 and C18:2 trans fatty acids (p<0.05). There was a positive association between serum adiponectin and adipose tissue oleic acid, while palmitoleic acid was negatively associated with adiponectin expression and positively correlated with insulin concentration. For the first time, positive relationships are reported between the proportion of n-6 polyunsaturated fatty acids (PUFA) in adipose tissue and adiponectin concentration and expression. In summary, adiponectin expression and serum levels are associated with fatty acid composition, with SFA, trans and palmitoleic fatty acids appearing as negative markers for adiponectin, and oleic acid and n-6 PUFA as positive ones. In addition, most associations were found in the visceral depots, highlighting the importance of visceral fat in the metabolic status.