Effect of intermittent hypokinesia of varied duration on conditioned reflexes, the EEG, and blood neurotransmitter levels in rats.

Abstract

1. Intermittent hypokinetic states (from 1 to 6 weeks in duration) bring about a combination of behavioral, autonomic, conditioned-reflex, bioelectrical, and neurotransmitter disturbances which depend on the duration of immobilization. 2. Immobilization of animals for 1 week leads to the development of an acute state of emotional stress expressed as abnormal motor excitation, a disturbance of defensive conditioning, an unstable pattern of sleep and waking, and liberation of catecholamines into the blood stream with a predominantly relative increase in the adrenalin concentration. 3. Immobilization for 3 weeks is accompanied by the development of a compensatory systemic reaction with improvement of conditioned-reflex activity, stabilization of the sleep-waking sycle, and a sharp increase in the relative blood noradrenalin level accompanied by a further rise in blood catecholamine levels. 4. Immobilization for 6 weeks causes the appearance of the initial signs of exhaustion of the adaptive systems of the body: intensification of protective grooming reactions, worsening of defensive conditioned reflex formation, changes in the quantitative and qualitative characteristics of sleep, and a fall in the blood catecholamine and acetylcholine levels.