[The comparative evaluation of the effect of the season on the formation of a nighttime melatonin peak in young sexually mature and old rats]

Abstract

Night melatonin concentration in blood serum has been studied in intact Wistar young pubertal and old male rats in different seasons--in winter (light regime: 9 hours light, 15 hours dark) and in summer (light regime: 15 hours light, 9 hours dark). It is shown that night peak of this index depends both on the age and season. Serum melatonin level decreases at midnight in old male rats as against the young ones. This decrease is redoubled under conditions of increase in light day duration. The importance of seasonal peculiarities of night peak melatonin formation in the mechanism metabolopathy in aging is under discussion.