Hm650v

The AD model mice used were APP/PS1 double-transgenic (B6C3-Tg [APPswe, PS1dE9]85Dbo/J) mice obtained from Jackson Laboratory. They were maintained and bred in the Animal and Plant Care Facility of The Hong Kong University of Science and Technology (HKUST). The experimental protocols were approved by the Animal Ethics Committee of HKUST and conducted in accordance with the Code of Practice Care and Use of Animals for Experimental Purposes of Hong Kong. trans-OCMA in 85 μmol/kg body weight (injection volume 10 mL/kg) was injected intraperitoneally into 6–7 month old APP/PS1 mice daily for 4 weeks. Mice injected with vehicle (3% dimethyl sulfoxide/10% Tween-80 in water (3:10:87 by volume) served as controls. LTP was measured in the hippocampal Schaffer-collateral (SC) pathway after high-frequency stimulation (HFS). To measure LTP after the 4 week treatment, we sacrificed the mice by decapitation. Whole brains were immediately resected and soaked in ice-cold artificial cerebrospinal fluid (aCSF) supplemented in 95% O₂/5% CO₂. Brain slices (300 μm) were then prepared using a vibratome (HM650V; Thermo Fisher Scientific) and soaked in oxygenated aCSF for 2 h at 32 °C for recovery. LTP formations were recorded using a multielectrode array system (MED-64, Panasonic International, Inc.) and paradigms were conducted as previously described.^{24 (link),25 (link)}

Mice were transcardially perfused with cold phosphate-buffered saline (PBS, pH 7.4), followed by 4% paraformaldehyde (PFA) in PBS. Brains were removed from the skull and post-fixed in 4% PFA for 1–2 days at 4°C. Free-floating coronal sections (40 μm) were collected using a vibrating microtome (Thermo Scientific HM 650V) and washed twice for 10 minutes each in PBS containing 0.3% triton X-100. Sections were then incubated in blocking buffer (20% donkey serum in PBS) for 1 hour at room temperature, with gentle agitation. Incubation in primary antibody (anti-β-galactosidase, Invitrogen A-11132; 1∶200) was carried out in the same media at 4°C with gentle agitation, for 48 hours. After removal of primary antibody, sections were washed four times for 15 minutes each in PBS at room temperature. Sections were then incubated overnight at 4°C with a fluorescently tagged secondary antibody (AlexaFluor-488, 1:1000), diluted in PBS. Sections were washed briefly in PBS and mounted using DAPI Fluoromount-G (Southern Biotech, Birmingham, AL). Image acquisition and processing were performed at The Light Microscopy Facility at the Max Planck Florida Institute with a LSM 880 Zeiss confocal microscope controlled with ZEN 2011 software (Carl Zeiss, Oberkochen, Germany).