The Effects of Dexamethasone Treatment and Dietary Fat Composition on Liver Lipid Metabolism in Mice Consuming High Fat Diets

Abstract

Omega‐3 fatty acids are essential fats that the body cannot produce on its own and play a very integral role in the body in regard to inflammation and hormone production. Glucocorticoids are hormones that are also effective in inflammation reduction and suppressing the immune system; however, often have many detrimental side effects such as adipose accumulation, muscle atrophy and metabolic dysfunction. The purpose of this research experiment was to examine the effects dexamethasone treatment in combination with diets high in either omega‐3 fatty acids or omega‐6 fatty acids on markers of lipid metabolism in the liver. For a span of 4 weeks, two groups of mice were placed on a diet consisting of 45% fat containing either high omega‐3 or omega‐6 fatty acids. On the fifth week mice were randomized to two groups per diet and received either PBS placebo or Dexamethasone (Dex) injections daily. We hypothesized that Dex treatment would induce liver lipid accumulation and an omega‐3 rich diet would prevent this. At the completion of the 5 weeks, tissue was harvested and liver triglycerides were measured. There was a main effect of omega‐3 diet to have lower liver triglyceride levels (p=0.01). Fasn, Crat, Hsl, Cd36, and Fabp mRNA levels were measured in liver tissue. The resulted show that CratmRNA (p=.0153) and HslmRNA (p=.0417) was increased with omega‐3 rich diet, but there was no effect of Dex treatment. The Cd36 (p=.0495) and Fabp(p=.0229) mRNA increased in omega‐6 rich diets treated with Dex and omega‐3 high fat diet attenuated this increase. It can be concluded that one week of Dexamethasone treatment altered liver lipid signaling primarily by increasing lipid import and transport regulators, and omega‐3 high fat diet was able to prevent this increase. Additionally, omega‐3 high fat diet increase markers of lipid metabolism that were unaltered with one week of dex. These data suggest that omega‐3 fatty acids may help prevent the detrimental side effects of glucocorticoid treatment.