Nasal Apelin-13 Administration with Nrf2 and HO-1 Inhibitors

For nasal administration, the Apelin-13 (0.2 mg/kg, 1 mg/kg) solution (10 μL) was pipetted bilaterally on the rhinarium, i.e., the glabrous skin around the nostrils, and allowed to diffuse in the squamous epithelium. After the drip, the mouse was fixed for 5–10 s to ensure the liquid was fully inhaled. Donepezil (Sigma-Aldrich, St. Louis, MO, USA) were dissolved in 0.9% saline. A freshly prepared solution of Donepezil was administered orally daily at a dose of 5 mg/kg [16 (link)]. ML385 (Medchem Express, South Brunswick, NJ, USA) is a specific inhibitor of Nrf2. Before each administration of Apelin-13, the mice received an intraperitoneal injection of 30 mg/kg ML385 [17 (link)], dissolved in saline containing 50% PEG300, with a 30 min interval. Zn(II)-protoporphyrin IX (ZnPP, Medchem Express, South Brunswick, NJ, USA) is an inhibitor of HO-1. Mice were injected intraperitoneally with 25 mg/kg ZnPP [18 (link)] (dissolved in saline) 30 min before each administration of Apelin-13.