Elisa D’Alessandro¹, Philippe Vangrieken², Ward van Deurse², Marion Kuiper¹, Geertje Swennen¹, Nicole Bitsch³, Etto C. Eringa^1,4

¹Department of Physiology, Cardiovascular Research Institute Maastricht, Maastricht University, ²Department of Internal Medicine, Cardiovascular Research Institute Maastricht, Maastricht University, ³Central Animal Facility (CPV), Maastricht University, Maastricht, The Netherland, ⁴Department of Physiology, Amsterdam UMC, Amsterdam Cardiovascular Sciences, the Netherlands

Corresponding author: Elisa D’Alessandro, e.dalessandro@maastrichtuniversity.nl

Background

Healthy perivascular adipose tissue (PVAT) controls insulin-stimulated glucose uptake and microvascular function. In obesity and type 2 diabetes, PVAT adopts a pro-inflammatory and vasoconstrictor phenotype possibly contributing to microvascular dysfunction and insulin resistance.

Aim

To investigate the role of PVAT in vascular inflammation, insulin-mediated skeletal muscle perfusion, and muscle signaling in a mouse model of prediabetes.

Methods

Five-week-old C57BL/6J mice (20 females and 20 males) were fed ad libitum with either chow (CD) or Western diet (WD) for 8 weeks. Groups were matched for sex and age. At week 6, the PVAT around the gracilis artery and vein of the left hindlimb was either removed (WD-removal, n=10) or disconnected from the adjacent muscle (WD-disconnect, n=10). Sham surgery was performed on the contralateral limb of the surgery groups and in left hindlimb of the control groups (CD-sham, n=10 and WD-sham, n=10). At week 8, the perfusion of the microcirculation of the gracilis muscle was assessed via contrast-enhanced ultrasonography (CEUS) before (baseline) and during hyperinsulinemic-euglycemic clamp.

Results

Eight weeks of WD significantly increased body weight (WD: 29±2.1 vs.

CD: 27±1.6 grams, p=0.01) and fasting glucose levels (WD: 12.1±3.3 vs. CD: 8.9±3.2 mmol/l, p=0.04) in male but not in female mice (WD: 21.8±1.2 vs. CD: 20.8±0.5 grams, p=0.3; WD: 11.3±1.5 vs. CD: 9.8±3.2 mmo/l, p=0.4).

In males, the glucose infusion rate (GIR) during the clamp was significantly decreased in WD as compared to CD mice (WD: 40±9.4 vs. CD: 58.2±14.5 mg/kg/min p<0.01). In females, a trend towards the decrease in GIR was observed in WD mice (WD: 50.8±5.6 vs. CD: 61.8±4 mg/kg/min, p=0.1).

Insulin-mediated microvascular recruitment did not differ between experimental groups. However, total microvascular blood flow was significantly decreased in all WD groups after clamp (WD-sham: baseline: 1478±657.4 vs. clamp: 938.4±552.8 a.u., p=0.01; WD-removal: baseline: 3946±466.5 vs. clamp: 1662±274.6 a.u., p=0.002; WD-disconnection: baseline: 1284±1249 vs. clamp: 580±399.7 a.u., p=0.04), while microvacular blood flow velocity was only decreased in the WD-disconnect group (baseline: 0.4±0.2 vs. clamp: 0.2±0.1 sec^-1, p=0.05).

Conclusions

Eight weeks of WD increased body weight and systemic insulin resistance in male, but not female C57BL/6J mice. Moreover, WD significantly decreased muscle blood flow in response to insulin, which was not improved by surgical manipulation of the PVAT surrounding the microvasculature. Gene and protein expression analyses of mice skeletal muscle will be conducted to assess the effect of PVAT on insulin signaling and muscle inflammation.