Absence of Photoperiodism and Digestive Enzymes in Rats: The Role of Age and the Endogenous Melatonin Level

Abstract

The effect of the prolonged absence of a photoperiodic signal (constant lighting and constant darkness) on changes in the activity of digestive enzymes in the late postnatal ontogenesis of rats is studied. Age-related alterations were characterized by a change in enzyme activity, as well as a redistribution of the functional activity between the amylo- and lipolytic links and the upper (pancreas) and lower (small intestine) divisions of the gastrointestinal tract. It was shown that, with age, the enzyme activity was affected both by an absence of photoperiodism and by a melatonin level associated with the light regime. Age-related changes characterizing “aging” of the digestive system were observed later under light deprivation conditions than with standard illumination and especially constant illumination.