Electroconvulsive stimulation (ECS) procedure

Electroconvulsive Stimulation (ECS) Procedure

Eri Segi-Nishida¹, Katsunori Kobayashi²

¹Department of Biological Science and Technology, Faculty of Advanced Engineering, Tokyo University of Science, Tokyo, Japan.

²Department of System Neurophysiology, Wakayama Medical University, Wakayama, Japan.

Abstract

Electroconvulsive therapy (ECT) is an effective treatment for medication-resistant depression. Although ECT has been used for many decades, its cellular mechanism of action is not fully understood. Here, we describe a protocol of electroconvulsive stimulation, an animal model of ECT, in anesthetized mice. 

Materials

• Electroconvulsive stimulation (ECS) device (ECT Unit; Ugo Basile, Gemonio, Italy)
• Ear-clip electrodes (two electrodes) (ECT Unit; Ugo Basile, Gemonio, Italy)
• Anesthesia system (TK-36, Biomachinery)
• Plastic induction chamber with lid
• Isoflurane
• Sterile saline

Preparation

1. Connect the cables to the ECS device and turn on the power.
2. Set up and calibrate the anesthesia system.
3. Connect the ear-clip electrodes to the ECS device.
4. Soak the ear-pad portions of the electrodes in sterile saline to ensure proper electrical conductivity.
5. Connect the two electrodes together at the ear-pad portions and perform a test discharge (without an animal) to confirm proper function.

Stimulation parameters for test pulse:

• Frequency: 100 pulses/s
• Pulse width: 0.5 ms
• Shock duration: 1.0 s

ECS Procedure

Note: Before starting, adjust the current intensity to the intended experimental value (25–30 mA).

1. Place the mouse into the plastic induction chamber and initiate anesthesia with 1.5-2% isoflurane.
2. During induction, perform a loop check to ensure appropriate current flow.
   • Before treating each animal, soak the ear electrodes in saline to maintain conductivity.
3. For C57BL/6 (BL6) mice, maintain anesthesia for approximately 1–1.5 minutes.
4. Confirm the absence of righting reflexes.
5. Remove the mouse from the chamber and quickly attach the electrodes to both ears.
   • Ensure that no fur is caught between the electrode and skin.
   • Prevent direct contact between the two electrodes.
6. Gently lift the mouse by grasping the skin at the back of the neck.
7. As the mouse begins to emerge from anesthesia, press and hold the “Shock” button to deliver ECS.

Successful seizure induction is confirmed by observation of a typical tonic–clonic response:

• Tonic phase (body contraction): approximately 2–4 seconds
• Clonic/extension phase (body extension): approximately 5–10 seconds

Mice anesthetized in the same way without electrical shock are used as control.