A Marked Effect of Electroconvulsive Stimulation on Behavioral Aberration of Mice with Neuron-Specific Mitochondrial DNA Defects

We developed transgenic (Tg) mice modeling an autosomally inherited mitochondrial disease, chronic progressive external ophthalmoplegia, patients with which sometimes have comorbid mood disorders. The mutant animals exhibited bipolar disorder-like phenotypes, such as a distorted day-night rhythm and a robust activity change with a period of 4-5 days, and the behavioral abnormalities were improved by lithium. In this study, we tested the effect of electroconvulsive stimulation (ECS) on the behavioral abnormalities of the model. Electroconvulsive therapy, which has long been used in clinical practice, provides fast-acting relief to depressive patients and drug-resistant patients. We performed long-term recordings of wheel-running activity of Tg and non-Tg mice. While recording, we administrated a train of ECS to mice, six times over two weeks or three times over a week. The treatment ameliorated the distorted day-night rhythm within three times of ECS, but it had no effect on the activity change with a period of 4-5 days in the female mice. To study the mechanism of the action, we investigated whether ECS could alter the circadian phase but found no influence on the circadian clock system. The potent and fast-acting efficacy of ECS in the mutant mice supports the predictive validity of the mice as a model of bipolar disorder. This model will be useful in developing a safe and effective alternative to lithium or electroconvulsive therapy.