Dietary conjugated linoleic acid preserves pancreatic function and reduces inflammatory markers in obese,...

Pancreatic preservation is an important part of diabetes management that may occur with improved peripheral insulin sensitivity and attenuated low-grade adipose tissue inflammation. The objective of the current study was to determine the response of obese, insulin-resistant fa/fa Zucker rats vs lean controls to dietary conjugated linoleic acid (CLA) supplementation with respect to pancreatic islet size, insulin resistance, and markers of inflammation and adipose glucose uptake. Six-week-old fa/fa and lean Zucker rats (n = 20 per genotype) were fed either a 1.5% CLA mixture or control diet for 8 weeks. Oral glucose tolerance testing was conducted at 7.5 weeks. Fasting serum haptoglobin, insulin, and C-peptide were assayed, and select messenger RNA (mRNA) and protein markers of inflammation and glucose metabolism were measured in adipose and liver tissues. CLA-fed fa/fa Zucker rats had smaller islet cell size, improved oral glucose tolerance and insulinemia, and attenuated serum haptoglobin levels compared with control-fed fa/fa Zucker rats, despite no differences in body weight and a slightly higher visceral adipose mass. CLA did not alter insulin sensitivity or islet size in lean Zucker rats. The CLA-fed fa/fa rats also had greater adipose glucose transporter-4 mRNA and less adipose tumor necrosis factor alpha mRNA and protein compared with control-fed fa/fa rats. In contrast, other markers of inflammation and glucose metabolism including adipose macrophage inflammatory factor, macrophage inflammatory protein-2, and liver pyruvate carboxylase and pyruvate dehydrogenase kinase 4 were not significantly changed. These results suggest that CLA supplementation preserved pancreatic function in conjunction with improved peripheral glucose use and reduced inflammation in fa/fa Zucker rats.