The effect of prolonged vasopressin administration on the level and metabolism of catecholamines in the rat brain and kidneys.

Dopamine (DA) and noradrenaline (NA) levels and activities of the enzymes metabolizing catecholamines were determined in the rat brain and kidneys during prolonged (4 weeks) administration of lysine vasopressin (LVP) and 2 weeks after its withdrawal. DA level was elevated during the whole period of experiment. NA level increased mainly after LVP withdrawal. Dopa-decarboxylase activity was elevated in all the experimental animals. Tyrosine and dopamine-beta-hydroxylase activities increased at the final period of LVP administration and after its withdrawal. Activities of MAO and COMT were markedly increased only after 3 weeks of LVP administration.