The effect of pregnancy on the metabolism of noradrenaline in reproductive organs of the rabbit.

The metabolites of (-)-3H-noradrenaline (1.2 mumol l-1) formed by uteri from non-pregnant mature rabbits were, in descending order of importance, 3H-DOPEG greater than 3H-MOPEG greater than 3H-NMN greater than 3H-VMA (3H-DOMA not measured). The pattern of metabolite formation per unit mass of tissue was markedly different in uteri from 28 day pregnant rabbits due to a fourfold increase in 3H-NMN formation and a fourfold decrease in 3H-DOPEG formation. The effects of cocaine indicated that 3H-NMN was largely extraneuronal in origin and 3H-DOPEG was both neuronal and extraneuronal in origin. The pattern of metabolite formation in pregnant rabbit uteri closely resembled the reported pattern in uteri from ovariectomized rabbits treated with 17 beta-oestradiol and progesterone. In the rabbit oviduct and ovary, the patterns of metabolite formation, and their modification by cocaine, indicated that (-)-3H-noradrenaline was metabolised mainly by intraneuronal deamination in the oviduct and mainly by extraneuronal O-methylation in the ovary. Pregnancy did not affect (-)-3H-noradrenaline metabolism in the oviduct, but decreased the metabolism in the ovary.