Metabolism of histamine during pregnancy in the rat.

In order to clarify histamine metabolism during the period of pregnancy in which this amine attains the highest levels, pregnant and non-pregnant rats were submitted to four different treatments: 14C-histamine; 14C-histamine + histamine dihydrochloride; 14C-histamine + aminoguanidine; 14C-histidine. Paper chromatography and autoradiographic techniques were used to separate and to detect 14C-histamine metabolites. Total radioactivity excreted and percentages of histamine metabolites were calculated by liquid scintillation. Our results support two principal hypotheses: 1) Oxidation is the main catabolic pathway for histamine degradation in pregnant and non-pregnant rats. 2) Pregnant rats, in opposition to non-pregnant, show an increased capacity to metabolize histamine by oxidative deamination.