Development of Gastric Histidine Decarboxylase in the Rat

Abstract

Gastric mucosal histidine decarboxylase (HDase) was measured in fetal rats between days 16 and 21 of gestation, and in newborn rats up to weaning. HDase was not detected in fetal stomach. Its activity developed from day 1 after birth (29 ± 2 pmol CO2/mg protein/h) and increased up to day 18 when it reached the fed adult level (894 ± 170 pmol C O2/mg protein/h). Weaning increased HDase activity significantly (weaned versus un‐weanedrats: 1,664 ± 150 and 1,036 ± 170 pmol C O2/mg protein/h; p < 0.005). Up to day 18, HDase activity was not altered by 16 h to 24 h of fasting. From that day on, HDase became sensitive to both pentagastrin and carbachol. These results indicate that complete functional maturation of histamine‐producing cells is only reached at day 18, just before weaning. This developmental pattern may explain the differences observed between fetal and adult regulation of gastric acid secretion.