This article describes a method for establishing a zebrafish model of Alzheimer's disease by injecting synthetic amyloid peptides into the forebrain. The accumulation of these peptides leads to the formation of toxic amyloid plaques that damage neurons.
Fill a glass injection capillary with a solution of synthetic monomeric amyloid peptides, which are abnormal peptides with aggregation-prone properties.
Insert the capillary into a microinjection holder.
Simultaneously place a zebrafish in a petri dish containing an anesthetic solution.
Once the fish is anesthetized, hold it laterally with forceps to secure the head.
Make a small incision in the fish skull at the junction of the two lateral plates to access the neuron-rich forebrain.
Now, insert the capillary needle through the incision, and inject the amyloid peptide solution into the forebrain.
Transfer the zebrafish to a recovery container with circulating water.
Inside the forebrain, the amyloid peptides accumulate near the neurons.
These peptides spontaneously misfold to form beta-sheets and aggregate around the neurons to form toxic amyloid plaques.
These plaques damage the neurons and impair their signal transmission.
This establishes a zebrafish model of Alzheimer's disease, a brain disorder characterized by amyloid plaques.
Use a needle puller with parameters outlined in the text protocol, to prepare glass injection capillaries. Adjust the pressure setting on the pressure source to 25 PSI. Then, on the micro injector set the hold pressure to 20 PSI, the eject pressure to 10 PSI, the period value to 2.5, and the gating value to 100 milliseconds. Next, load the glass capillary with the injection solution.
Then, insert the glass capillary into the micro injection holder, and adjust the injection angle to 45 degrees. Place one fish into a new Petri dish filled with anesthetization solution. Once it is anesthetized, hold the fish with forceps and orient it for injection. Using the tip of a 30 gauge needle, generate a slit in the skull over the optic tectum where the two lateral plates meet. Use only the tip of the needle, and do not penetrate more than 1 millimeter through the skull.
Then, while continuing to hold the fish, insert the tip of the glass capillary through the incision site. Orient the tip of the glass capillary towards the telencephalon at a 45 degree angle, then inject 1 microliter of the solution. Place the fish back into a transport container until it recovers. Then, connect to the container to the regularly circulating fish water to ensure optimum water quality.
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