Drug Microinjection with Electrophysiological Recording in a Rat Brain

Start with an injectrode, an electrode-containing injection system. This features a microneedle and a silver wire electrode inserted within a glass micropipette.

Fill the injectrode with a test drug solution containing a dye to facilitate tracking of the drug's spread within the brain.

Attach a syringe filled with mineral oil to the injectrode. Wipe away any excess liquid.

Secure this injectrode onto a stereotaxic unit and connect it to a micropump system.

Position the injectrode on the target brain region of an anesthetized rat with a surgical hole in the skull.

Gradually lower the injectrode to penetrate the target region.

Halt the insertion upon receiving specific electrical signals that confirm the optimal injectrode placement.

Cover the exposed skull with warm agar to prevent tissue drying.

Allow the brain tissue to stabilize.

Inject the desired dosage of the drug.

Record electrical signals to monitor neuronal activity in response to the administered drug.

Prepare the injectrode by first filling a 5 to 10-microliter syringe with mineral oil. Next, prepare the drug of interest with a dye in physiological saline. Here, 0.5% Chicago Sky blue is mixed with 300 micromolar GABA. Now