The Combination of a High-fat Diet and Chronic Stress Aggravates Insulin Resistance in Wistar Male Rats

Abstract

We observed the effects of the combination of a high-fat diet and chronic stress on insulin resistance. Male Wistar rats were fed on either a control or a high-fat diet and given chronic stress with the electric foot shock or not for 10 weeks. After checking the glucose infusion rate (GIR) and the HOMA-IR index, the results showed that the three groups all revealed insulin resistance with increased free fatty acid (FFA), adrenocorticotropic hormone (ACTH) and corticosterone in the serum, in addition to increased tumour necrosis factor alpha (TNF-alpha) in the serum and adipose tissue, and decreased density of high affinity receptors (R1) and expression of peroxisome proliferator-activated receptor-alpha (PPARalpha) mRNA in the hepatocytes as compared with the control, but the highest alteration on aforementioned parameters revealed in the chronic stress fed with a high-fat diet. Significant interactions between high-fat diet and chronic stress were revealed on GIR, HOMA-IR index, FFA, ACTH, corticosterone, TNF-alpha (in adipose tissue) and R1. These observations strongly suggest that a combination of a high-fat diet and chronic stress can produce a synergic effect on aggravating insulin resistance associated with the abnormal hypothalamic-pituitary-adrenocortical axis, endocrine abnormality of the adipose tissue, and pathological changes of the liver.

Comparison of the effects of acute and chronic psychological stress on metabolic features in rats

“…In agreement with our results, it was shown that inducing a moderate hypercortisolism by hydrocortisone infusion (for 3 h) in human subjects, which is equivalent to that observed in response to a mild stress, did not change HOMA-IR index (Darmon et al, 2006). On the other hand, chronic exposure of normal chow fed male Wistar rats to electric footshock assisted with noise for 10 weeks (Fu et al, 2009) increased HOMA-IR index. The differences between results may be due to the variation in the type, duration, and intensity of the applied stressor.…”

Simultaneous changes in high-fat and high-cholesterol diet-induced steatohepatitis and severe fibrosis and those underlying molecular mechanisms in novel SHRSP5/Dmcr rat

“…Increased TNF-a gene expression and oxidative stress in the liver has been observed in NASH patients [1,28,29] and other rodent models [6,[30][31][32], with more advanced liver fibrosis accompanied by extensive hepatic TNF-a expression present in advanced NASH patients [1,28]. We found that the HFC-diet treatment appeared to facilitate TNF-ainduced inflammatory reactions throughout the experimental period, with a pronounced peak at 8 weeks.…”

The Effects of a Fat- and Sugar-Enriched Diet and Chronic Stress on Nonalcoholic Fatty Liver Disease in Male Wistar Rats

“…The stress-induction method employed a random electric foot shock associated with noise, the same method as in our previous study [18]. The rats were housed in testing boxes (320 9 215 9 170 mm, length 9 width 9 height).…”

“…So far, there has been no report about the co-effects of several factors like chronic stress with a fat-enriched diet in generating NAFLD. Our previous research has demonstrated that a combination of a high-fat, high-sugar diet and chronic stress can produce a synergic effect on aggravating IR associated with the elevation of serum-free fatty acid (FFA) and the activation of the hypothalamic-pituitary-adrenocortical (HPA) axis, in addition to increased TNF-a in the serum and adipose tissue, and decreased density of high-affinity receptors and expression of peroxisome proliferator-activated receptor-a (PPARa) mRNA in the hepatocytes [18]. The current work was designed to extend our understanding of whether stress and diet produce synergistic effects on NAFLD as they do on IR.…”