Research

Oleic acid and peanut oil high in oleic acid reverse the inhibitory effect of insulin production of the inflammatory cytokine TNF-α both in vitro and in vivo systems

Evros K Vassiliou¹ , Andres Gonzalez¹ , Carlos Garcia¹ , James H Tadros² , Goutam Chakraborty³ and Jeffrey H Toney⁴

¹  Department of Biological Sciences, Kean University, 1000 Morris Avenue, Union, New Jersey 07083, USA

²  Department of Medicine, St. Joseph's Hospital, 703 Main Street, Paterson, New Jersey 07503, USA

³  Department of Neurochemistry, Nathan Kline Institute, 140 Old Orangeburg Road, Orangeburg, New York 104624, USA

⁴  College of Natural, Applied and Health Sciences, Kean University, 1000 Morris Avenue, Union, New Jersey 07083, USA

author email corresponding author email

Lipids in Health and Disease 2009, 8:25doi:10.1186/1476-511X-8-25

Published:	26 June 2009

Abstract

Background

Chronic inflammation is a key player in pathogenesis. The inflammatory cytokine, tumor necrosis factor-alpha is a well known inflammatory protein, and has been a therapeutic target for the treatment of diseases such as Rheumatoid Arthritis and Crohn's Disease. Obesity is a well known risk factor for developing non-insulin dependent diabetes melitus. Adipose tissue has been shown to produce tumor necrosis factor-alpha, which has the ability to reduce insulin secretion and induce insulin resistance. Based on these observations, we sought to investigate the impact of unsaturated fatty acids such as oleic acid in the presence of TNF-α in terms of insulin production, the molecular mechanisms involved and the in vivo effect of a diet high in oleic acid on a mouse model of type II diabetes, KKA^y.

Methods

The rat pancreatic beta cell line INS-1 was used as a cell biological model since it exhibits glucose dependent insulin secretion. Insulin production assessment was carried out using enzyme linked immunosorbent assay and cAMP quantification with competitive ELISA. Viability of TNF-α and oleic acid treated cells was evaluated using flow cytometry. PPAR-γ translocation was assessed using a PPRE based ELISA system. In vivo studies were carried out on adult male KKA^y mice and glucose levels were measured with a glucometer.

Results

Oleic acid and peanut oil high in oleic acid were able to enhance insulin production in INS-1. TNF-α inhibited insulin production but pre-treatment with oleic acid reversed this inhibitory effect. The viability status of INS-1 cells treated with TNF-α and oleic acid was not affected. Translocation of the peroxisome proliferator- activated receptor transcription factor to the nucleus was elevated in oleic acid treated cells. Finally, type II diabetic mice that were administered a high oleic acid diet derived from peanut oil, had decreased glucose levels compared to animals administered a high fat diet with no oleic acid.

Conclusion

Oleic acid was found to be effective in reversing the inhibitory effect in insulin production of the inflammatory cytokine TNF-α. This finding is consistent with the reported therapeutic characteristics of other monounsaturated and polyunsaturated fatty acids. Furthermore, a diet high in oleic acid, which can be easily achieved through consumption of peanuts and olive oil, can have a beneficial effect in type II diabetes and ultimately reverse the negative effects of inflammatory cytokines observed in obesity and non insulin dependent diabetes mellitus.