Synthesis and metabolism of a histamine metabolite, 1-methyl-4-(β-aminoethyl)-imidazole

Formation and catabolism of histamine in brain tissue in vitro

“…Benzene is reported to enhance the activity of histidine decarboxylase from rabbit kidney and to inhibit strongly the enzymic action of histidine decarboxylase obtained from rat stomach and from mast cells (Waton, 1956a, b;Schayer, 1957;Rothschild & Schayer, 1958). In the present experiments the addition of one drop (approx.…”

“…Pyridoxal-5-phosphate is a co-enzyme of several amino acid decarboxylases, including histidine decarboxylase (Blaschko, 1957;Rothschild & Schayer, 1958). No difference was observed in the formation of 14C-histamine between samples of cortex and of hypothalamus incubated with and without pyridoxal-5-phosphate.…”

“…The extraction of methylhistamine is described by Rothschild & Schayer (1958). The principle of this method is based upon the finding that chloroform is an excellent solvent for the separation of methylhistamine from histamine.…”

Effects of Chlorpromazine and Bromolysergic Acid Diethylamide on Gastric Secretion of Acid Induced by Histamine in Rats

“…Indirect evidence of the mode of action of chlorpromazine is given by the observations that chlorpromazine further enhances responses to histamine in animals previously treated with iproniazid, whereas additional potentiation of responses to histamine does not occur when iproniazid is given to animals previously treated with chlorpromazine. In animals treated with iproniazid alone, in which oxidative deamination of methylhistamine by monamine oxidase is inhibited (Rothschild & Schayer, 1958), exogenous histamine and its ringmethylated derivative will persist at higher concentrations than in untreated animals; if chlorpromazine inhibits formation of methylhistamine, even greater potentiation of the effect of histamine would be expected to occur in animals previously treated with iproniazid. However, when chlorpromazine is given alone, the effect of histamine is potentiated but the subsequent administration of iproniazid does not affect responses to histamine, probably because there is less substrate for monamine oxidase.…”

“…Known pathways for histamine catabolism are oxidative deamination by diamine oxidase and methylation in the imidazole ring (Rothschild & Schayer, 1958). In man, imidazole ring methylation is the most important pathway, and 50 to 70% of the radioactivity of injected ['4C]-histamine appears in the urine as methylated derivatives (Schayer & Cooper, 1956; Nilsson, Lindell, Schayer & Westling, 1959;Lindell, Nilsson, Roos & Westling, 1960).…”