The insulin receptor (IR) regulates nutrient uptake and utilization in multiple organs, but its role in the intestinal epithelium is not defined. This study developed a mouse model with villin-Cre (VC) recombinase-mediated intestinal epithelial cell (IEC)-specific IR deletion (VC-IRΔ/Δ) and littermate controls with floxed, but intact, IR (IRfl/fl) to define in vivo roles of IEC-IR in mice fed chow or high-fat diet (HFD). We hypothesized that loss of IEC-IR would alter intestinal growth, biomarkers of intestinal epithelial stem cells (IESC) or other lineages, body weight, adiposity, and glucose or lipid handling. In lean, chow-fed mice, IEC-IR deletion did not affect body or fat mass, plasma glucose, or IEC proliferation. In chow-fed VC-IRΔ/Δ mice, mRNA levels of the Paneth cell marker lysozyme (Lyz) were decreased, but markers of other differentiated lineages were unchanged. During HFD-induced obesity, IRfl/fl and VC-IRΔ/Δmice exhibited similar increases in body and fat mass, plasma insulin, mRNAs encoding several lipid-handling proteins, a decrease in Paneth cell number, and impaired glucose tolerance. In IRfl/fl mice, HFD-induced obesity increased circulating cholesterol; numbers of chromogranin A (CHGA)-positive enteroendocrine cells (EEC); and mRNAs encoding Chga, glucose-dependent insulinotrophic peptide (Gip), glucagon (Gcg), Lyz, IESC biomarkers, and the enterocyte cholesterol transporter Scarb1. All these effects were attenuated or lost in VC-IRΔ/Δ mice. These results demonstrate that IEC-IR is not required for normal growth of the intestinal epithelium in lean adult mice. However, our findings provide novel evidence that, during HFD-induced obesity, IEC-IR contributes to increases in EEC, plasma cholesterol, and increased expression of Scarb1 or IESC-, EEC-, and Paneth cell-derived mRNAs.
|Original language||English (US)|
|Journal||American Journal of Physiology - Gastrointestinal and Liver Physiology|
|State||Published - Jan 15 2015|
- Glucose-dependent insulinotrophic peptide
- Small intestine
ASJC Scopus subject areas
- Physiology (medical)