High fat diet increases adipose tissue mass, but not lean tissue mass in age‐relevant postmenopausal mice in association with induction of VEGF expression and angiogenesis in adipose tissue

Abstract

The role of angiogenesis in obesity has not been clearly characterized. In the present study, ovariectomy (OVX) was performed in 8 eighty week‐old C57BL/6 mice, then followed by a low‐fat (4%, LF, n=4) or a high‐fat (60%, HF, n=4) diet for 4 wks. The lean mass (LM) or fat mass (FM) composition was monitored by EchoMRI weekly. At the end of the experiment, blood samples, visceral fat, and the heart and limb muscles were collected for measuring VEGF expression using ELISA and vascular density (VD) using CD31 immunochemistry. Increased body weight (47.6±3.5 vs. 34.6±2.8 g; P<0.01) was due to increased FM (23.3±2.7 vs. 11.6±2.1 g; P<0.01) in OVX/HF vs. OVX/LF mice. But, a high fat diet didn't change LM (22.8±2.1 vs. 21.5±1.9 g) in OVX/HF mice, compared to OVX/LF mice. There was a two‐fold increase in the ratio of visceral fat/BW in OVX/HF mice, compared to those in OVX/LF group (0.084±0.005 vs. 0.043±0.003; P<0.01). Plasma VEGF levels (70±7 vs. 49±3 pg/ml) and visceral fat VEGF levels (431±39 vs. 210±22 pg/mg protein) were significantly increased in OVX/HF mice, compared to OVX/LF group, respectively (4=6; P<0.01). There was an increased VD in visceral fat but not in the heart and limb muscles in OVX/HF mice, compared to OVX/LF group. The results support the hypothesis that adipose tissue responds more sensitively to a high fat diet due to increased VEGF expression and angiogenesis.