Yawning induced by apomorphine, physostigmine or pilocarpine is inhibited by electroconvulsive shock (ECS)

Single and repeated ECS decrease sensitivity of dopamine D2 and acetylcholine receptors as measured by yawning behavior. This reduced sensitivity is dependent from the number of applied shocks, since effects of repeated ECS disappear 5 days after the last shock but effect of single ECS disappear 24 h after the shock.