Abstract
Peroxisome proliferator-activated receptor γ (PPARγ) modulators are expected to exert anti-diabetic effects without PPARγ-related adverse effects, such as fluid retention, weight gain, and bone loss. The present study showed that the novel tetrazole derivative KY-903 exerted similar selective PPARγ partial agonist properties to INT-131, a known PPARγ modulator, in transactivation assays, and decreased plasma glucose and triglyceride levels with increases in adiponectin levels in diabetic KK-Ay mice. These effects were similar to those of pioglitazone. Pioglitazone, but not KY-903, increased adipose tissue and heart weights. In pre-adipocytes (3T3-L1), KY-903, in contrast to pioglitazone, increased adiponectin mRNA levels without adipocyte differentiation, indicating anti-diabetic effects via adiponectin without adipogenesis. In ovariectomized rats fed a high-fat diet (OVX/HFD), KY-903 and pioglitazone decreased plasma triglyceride and non-esterified fatty acid levels and increased adiponectin levels, indicating insulin sensitization via adiponectin. KY-903 reduced body weight gain and adipose tissue weight, while pioglitazone increased heart weight and markedly reduced bone mineral density. In mesenchymal stem cell-like ST2 cells, KY-903 slightly reduced osteoblast differentiation without adipocyte differentiation, while pioglitazone markedly reduced it with adipocyte differentiation. In conclusion, KY-903 is a novel PPARγ modulator that exerts anti-diabetic effects without body weight gain or cardiac hypertrophy in diabetic mice and anti-obesity effects with minor bone loss in OVX/HFD, possibly due to increases in adiponectin levels without adipogenesis.