AQP4 and Alzheimer disease: Since matrix metalloprotein 9 (MMP-9) mediated β-DG cleavage has been reported as a potential cause of AQP4 depolarization 30, we reasoned that improvement of aberrant AQP4 polarity by OT administration could be attributed to MMP-9 upregulation, validated by significantly declined levels after OT administration in AD mice (Figure 2M).