Dose-Dependent Mechanisms of Melatonin on the Functioning of the Cardiovascular System and on the Behavior of Normotensive Rats of Different Ages

The purpose of the work on normotensive rats of different age groups (3, 15, and 22 months) is to study the synchronism between the functioning of the cardiovascular system and the locomotor activity of animals in open field tests by a single injection of exogenous melatonin in different doses (1 and 10 mg/kg). The studies show a unidirectional dose-dependent effect of exogenous melatonin on the locomotor activity of rats of different ages and an age-dependent effect of melatonin on the parameters of the cardiovascular system. The results show the possible desynchronization between the circadian rhythms of locomotor activity and the functioning of the cardiovascular system with aging, which can lead to a discrepancy between hemodynamic parameters and the level of locomotor activity.