Abstract

Amylin treatment improves body weight and glucose control, although it is limited by a short action and need for high doses. Dual amylin and calcitonin receptor agonists (DACRAs) are dual amylin and calcitonin receptor agonists with beneficial effects beyond those of amylin. However, to what extent the additional benefits reside in their higher potency or their targeting of the calcitonin receptor remains unclear. Here we deconstruct the receptors involved in the effects of a DACRA, KBP-088, by comparing it to rat amylin (rAMY), rat calcitonin (rCT), and their combination in obese high-fat diet (HFD) and diabetic Zucker diabetic fatty (ZDF) rats. HFD-fed Sprague-Dawley rats and ZDF rats were treated for 4 weeks with KBP-088 (5 µg/kg per day), rAMY (300 µg/kg per day), rCT (300 µg/kg per day), and the combination of rAMY and rCT (300+300 µg/kg per day) using infusion pumps. Body weight, food intake, fasting glycemia, glycated hemoglobin type A1c levels, and glucose tolerance were assessed. In obese HFD-fed rats, KBP-088, rAMY, and the combination of rAMY and rCT significantly reduced body weight and improved glucose tolerance, whereas rCT alone had no effect. In diabetic ZDF rats, rCT was efficient in lowering fasting glycemia similar to rAMY, whereas dual activation by KBP-088 and the combination of rAMY and rCT were superior to activating either receptor alone. In conclusion, calcitonin therapy regulates fasting blood glucose in a diabetic rat model, thereby underscoring the importance of calcitonin receptor activation as well as the known role of amylin receptor agonism in the potent metabolic benefits of this group of peptides.