Alzheimer's Disease Rat Model via Amyloid-Beta Injection

We dissolved 1mg Aβ_25–35 (A4559, Sigma) dry powder in 500 ul of 0.9% normal saline to prepare a 2 ug/ul solution and incubated for 7 days in a 37°C incubator after sonication, and the incubated Aβ_25–35 oligomers were flocculent and stored in a refrigerator at 4°C for later use. Sodium pentobarbital was selected as an anaesthetic for rats, and we used a brain stereotaxic apparatus to fix and mark the coordinates of rats' heads. We prepared the head skin of the rats and drilled two holes (coordinates: 3 mm below the bregma and 2 mm on both sides of the midline) in the skull with a dental drill. We absorbed 5 ul of Aβ_25–35 solution with a microsyringe and fixed it on the injection frame of the brain stereotaxic apparatus. We manipulated the instrument to lower the injection needle and probe into the hole, pierced the subdural by 2.6 mm, slowly injected the solution within 5 minutes, stopped for 15 minutes after the injection, and slowly withdrew the needle within 5 minutes. The skull hole was closed with paraffin, and the injection procedure was the same on the other side. After 7 days of injection, surviving rats can become AD models [19 (link), 20 (link)].