Weight loss and hypophagia after high-dose AT ₁-blockade is only observed after high dosing and depends on regular leptin signalling but not blood pressure

AT ₁-blockade has been shown to induce weight loss in animals or patients. The aim of this study was to investigate whether weight reduction after AT ₁-blockade is dependent on dose, blood pressure reduction and leptin signalling. Spontaneously hypertensive rats (SHR) and lean and obese Zucker rats were treated for 4 weeks with candesartan (0, 2, 6 or 16 mg/kg/day). Body weight, food intake and hypothalamic mRNA levels of (an)orexigenic peptides were determined. Obese Zucker rats served as a model of primary leptin resistance. In SHR, body mass index and food intake were decreased selectively by 16 mg/kg/day candesartan but not after using normal (2 mg/kg/day) or supranormal (6 mg/kg/day) doses. Correlation analysis between blood pressure and body weight indicated no relationship of hypotensive potency on weight loss. The hypothalamic mRNA levels of the orexigenic peptide MCH (melanin- concentrating hormone) were diminished in parallel. Consistent to the results in SHRs, 16 mg/kg/day candesartan revealed a decrease of body weight, food intake and hypothalamic MCH mRNA levels in lean Zucker rats. In obese Zucker rats, none of these parameters were reduced by candesartan. Loss of body weight and hypophagia are not general features of AT ₁-blockers, since neither was seen after normal or moderately supranormal doses, but they were, after the highest doses. These actions of AT ₁-blockers occur independently of their ability to lower blood pressure. They do depend on an intact leptin signalling, since they were absent in obese Zucker rats that feature a genetic mutation of the leptin receptor.