Melatonin prevents the development of the metabolic syndrome in male rats exposed to different light/dark regimens.

Effect of light regimens (standard 12:12 light/dark, constant light, natural lightning of the north-west of Russia) and that of melatonin on the development of metabolic syndrome during aging of rats was studied. It was found out that during the process of aging of rats kept in the conditions of the broken rhythm of day and night, different disturbances of metabolism in the form of abdominal obesity, hyperinsulinemia, hypercholesterolemia, hyperglycemia, hyperbetalipoproteinemia and glycosuria occurred. These disturbances can be considered to be metabolic syndrome or the syndrome of insulin resistance. The use of melatonin at night time starting in the rats of 4 month old allowed to decrease the age metabolism disorders in the rats. This fact indirectly proves the insufficiency of this hormone in human in the conditions of natural lighting of the north-west of Russia.