Evaluation of adipose tissue distribution in obese fa/fa Zucker rats by in vivo MR imaging: effects of peroxisome proliferator-activated receptor agonists

Abstract

High-resolution MRI of obese (fa/fa) Zucker rats was investigated to characterize and assess in vivo adipose tissue distribution. Thirty animals were gavaged with a placebo, a PPARgamma activator (pioglitazone), or a dual PPARalphagamma activator (LM 4156). At day 15, T1-weighted images were acquired in vivo using a 2TMRI system with a high in-plane spatial resolution (254 microm). Fat volumes of selected territories were measured by image segmentation, and the retroperitoneal fat was weighed post-mortem. Body-weight gain was significant with pioglitazone (101.8+/-5.9 g, p<0.01 vs. placebo). The good quality of MR images allowed the delimitation and quantification of different fat territories. In response to pioglitazone, the retroperitoneal fat was more important compared to placebo (+23%, p<0.01) while subcutaneous fat was not different. No significant effects were observed with LM 4156. In vivo measurements of fat volumes were strongly correlated with ex vivo tissue weights (r=0.91). High-resolution MRI provides an in vivo measurement of adipose tissue distribution in obese Zucker rats. Specific fat depots of regions that were particularly involved in drug response were determined in vivo. Fat remodeling was observed with pioglitazone but not with a dual PPARalphagamma activator (LM 4156).

Pioglitazone reduces central obesity in polycystic ovary syndrome women

“…Thiazolidinediones can stimulate adipocyte differentiation and apoptosis of large adipocytes and result in an increased population of small, more insulin-sensitive adipocytes. Pioglitazone increases subcutaneous adipocyte and insulin secretion in PCOS patients and improves insulin sensitivity and hepatic clearance of insulin [8,15,16]. In addition, they can reduce inflammation and promote lipid storage [17].…”

In vivo imaging of lipid storage and regression in diet-induced obesity during nutrition manipulation

“…Magnetic resonance imaging (MRI) and proton magnetic resonance spectroscopy ( 1 H-MRS) have recently been shown to provide information on the distribution and constitution of specific adipose tissue compartments in rodents (3,15,16,27,33,48). In addition, the noninvasive nature of MRI makes it the method of choice for translational studies into the clinical setting (5).…”

Dietary conjugated linoleic acid preserves pancreatic function and reduces inflammatory markers in obese, insulin-resistant rats

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