SEX DIFFERENCES IN HISTIDINE DECARBOXYLASES IN RAT STOMACH

The stomach of the male rat contains both a soluble and an insoluble histidine decarboxylase. The soluble enzyme in the glandular stomach is the one which is generally assumed to be associated with gastric secretion. The insoluble enzyme is located in the debris fraction of the forestomach and the activity varies widely in different animals. In female rats the activity of the insoluble enzyme is very low, whereas the activity of the soluble enzyme in the glandular stomach is similar to that found in male rats. In male rats starvation causes a more rapid depletion of the insoluble enzyme than of the soluble histidine decarboxylase. Refeeding or an injection of insulin causes a sharp rise in histidine decarboxylase activity in the glandular stomach, but does not affect the insoluble enzyme in the forestomach. At the present time there is little evidence to suggest that the insoluble enzyme is of major importance in studying the role of histamine in gastric secretion. © 1969.