MMP9 and Alzheimer disease: Moreover, both short and chronic (once a day for 10 days) 5-HT4 stimulation with high RS 67333 dose (3 mg/kg, i.p.)can reduce amyloidogenesis in 10- to 12-month-old Tg2576 mice (another mouse model of AD) possibly through matrix metalloproteinase-9 (MMP-9) up-regulation (Hashimoto et al., 2012).