Abstract

Neuregulins (NRGs) are a family of signaling proteins that bind to receptor tyrosine kinases of the ErbB family (ErbB2 to ErbB4), which can homo- or he- terodimerize depending on their structural features and cell type. Many studies have proposed that decreased NRG levels are a common characteristic of obesity. In liver and adipose tissue, the increase in NRG expression has protective effects against obesity. However, it is still unknown whether ErbBs expression is altered in this pathology. We hypothesized that high fat diet -induced obesity downregulates ErbB receptors expression in obese mice compared to normal weight mice. Males C57BL/6 mice (n=6-7 for each group) were fed for 12 weeks and divided into: (i) control diet (CD; 10% -kcal fat, 20% -kcal protein, 70% -kcal carbohydrates), and (ii) high fat diet (HFD; 60% -kcal fat, 20% -kcal protein, 20% -kcal carbohydrates). General parameters and ErbBs expression (qPCR, immunohistochemistry and Western blot) were evaluated. We observed a significant increase in final body weight (47%), adipose tissue to body weight ratio (244%) and HOMA-IR (69%), among other parameters, in obese mice. In HFD group significantly decreased ErbB2 (48%) and ErbB3 (66%) mRNA levels in liver (no change in ErbB4), and ErbB2 (43%), ErbB3 (76%) and ErbB4 (35%) in adipose tissue, compared to CD. Furthermore, ErbB2 and ErbB3 protein levels decreased significantly in HFD group compared to the CD in liver. Therefore, our results suggest that HFD-induced obesity significantly decreases ErbBs expression in liver and adipose tissue in this murine model, that may be associated with alterations in the NRG pathway in obese mice.