Chemical structure of morin and experimental protocol for the chronic asthma model. (a) Chemical structure of morin. (b) BALB/c mice were sensitized with OVA and aluminum hydroxide gel by intraperitoneal injection on days 0, 7, and 14 and then challenged with aerosolized 5% OVA for 30 min per day, three days per week for eight weeks, beginning on the 16th day of the experiment. The control mice were sensitized and challenged only with saline. Morin, DEX, or a vehicle (DMSO) was given by intraperitoneal injection at 30 min before each OVA challenge. i.p.: intraperitoneal injection; i.n.: inhalation.