Dietary conjugated linoleic acid preserves pancreatic function and reduces inflammatory markers in obese, insulin-resistant rats.

Abstract

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.

• Authors: Amy Noto, Peter Zahradka, Natasha R Ryz, Natalia Yurkova, Xueping Xie, Carla G Taylor
• Journal: Metabolism: clinical and experimental (Metabolism) Vol. 56 Issue 1 Pg. 142-51 (Jan 2007) ISSN: 0026-0495 [Print] United States
• PMID: 17161237 (Publication Type: Journal Article, Randomized Controlled Trial, Research Support, Non-U.S. Gov't)

Chemical References

• Dietary Fats, Unsaturated
• Haptoglobins
• Insulin
• Linoleic Acids, Conjugated
• Pyruvate Dehydrogenase Acetyl-Transferring Kinase
• C-Reactive Protein
• Protein Kinases
• Protein Serine-Threonine Kinases
• Pyruvate Carboxylase

Topics

• Adipose Tissue (metabolism)
• Animals
• Blotting, Western
• C-Reactive Protein (metabolism)
• Dietary Fats, Unsaturated (administration & dosage)
• Glucose Tolerance Test
• Haptoglobins (metabolism)
• Insulin (blood)
• Insulin Resistance (physiology)
• Insulin-Secreting Cells (cytology, metabolism)
• Linoleic Acids, Conjugated (administration & dosage)
• Liver (enzymology, metabolism)
• Organ Size (drug effects, physiology)
• Pancreas (anatomy & histology, metabolism)
• Protein Kinases (genetics, metabolism)
• Protein Serine-Threonine Kinases
• Pyruvate Carboxylase (genetics, metabolism)
• Pyruvate Dehydrogenase Acetyl-Transferring Kinase
• Rats
• Rats, Zucker
• Reverse Transcriptase Polymerase Chain Reaction