Estradiol depends on MMP-9 activity to enhance hippocampal memory consolidation but does not influence MMP-9 expression. OVX female mice (n = 8–11/group) received ICV infusion of vehicle or E2 (10 μg) and DH infusion of vehicle or MMPI (0.5 μg/hemisphere) immediately following object training (A). In an object placement test 24 hr later (B) or an object recognition test 48 h later (C), mice infused with E2 +vehicle (OP: n = 11; OR: n = 8), but not E2 +MMPI (OP: n = 8; OR: n = 8), spent significantly more time than chance with the moved or novel objects (dotted line at 15 s, #p < 0.05). Mice treated with E2 +vehiele also spent significantly more time with the moved or novel objects compared to vehiele+vehiele (OP: n = 9; OR: n = 9) or E2 +MMPI groups (OP: n = 8; OR: n = 10; * p < 0.05). DH tissue collected 1 hr after infusion showed no change to MMP-9 protein expression following E2 and MMPI treatment (D, E). Error bars indicate mean ± SEM.