Activity of some enzymes which synthesize and metabolize catecholamines in the brain and peripheral organs in developing rats.

Activities of monoamine oxidase (MAO), DOPA-decarboxylase (DD), phenoletha-nolamine-N-methyltransferase (PNMT) and phosphodiesterase (PDE) were studied in the brain and its parts, heart, kidneys, adrenals and liver in developing rats. In vitro, the action of nialamid on MAO activity in the liver, RO-4-4602 on DD activity in the liver, and D(-) INPEA on PNMT activity in the adrenals was investigated. The influence of 6-hydroxydopamine (6-OHDA), 200 mg/kg i. p., on MAO activity in the liver of developing rats was also studied. Irregular changes in activities of examined enzymes during development were observed. 6-OHDA, nialamid and RO-4-4602 inhibited enzyme activities in young rats more strongly than in adult animals.