THE INFLUENCE OF FUNCTIONAL ALTERATION ON MONOAMINE OXIDASE AND CATECHOL‐<i>O</i>‐METHYL TRANSFERASE IN THE VISUAL PATHWAY OF RATS¹

Abstract

Abstract —Rats were reared in complete darkness or under chronic stimulation with flashing light from birth to the age of 7 weeks. Light deprivation caused a significant increase in monoamine oxidase activity (measured with [ 14 C]serotonin) of about 30 per cent in the structures of the visual pathway. Chronic stimulation with flashing light had no influence on the activity of monoamine oxidase in either visual or non‐visual structures. The activity of catechol‐ O ‐methyl transferase in the brain areas of light‐deprived rats was reduced, in light‐stimulated rats it was slightly increased. In mother rats kept together with their litters in either complete darkness or flashing light for 5 weeks no change in monoamine oxidase activity was observed. The activity of catechol‐ O ‐methyl transferase in mother rats kept in darkness was significantly decreased in all brain regions studied; in light‐stimulated animals the enzyme activity was not affected.