Histidine decarboxylase and growth

2-3 days after birth its activity falls precipitously to the low level observed in adult rats . The histidine decarboxylase of the foetal rat liver has been fully characterized Table 4.4), and its properties clearly indicate that it is the specific enzyme. The feeding of a pyridoxine-deficient diet and the 

Adult rats in which the liver is regenerating after partial hepatectomy excrete increased amounts of histamine in the urine, and this has been attributed to the growth of the regenerating liver . However, the histamine does not originate in the liver, as no increased histidine decarboxylase activity is demonstrable in the regenerating tissue in 

The peak of histidine decarboxylase activity in foetal rat liver coincides. approximately with that of haemopoietic activity . Subsequently, the bone marrow of the adult rat was found to contain a specific histidine decarboxylase Table 4.4), thus supporting the possibility of a connection between haemopoiesis and the formation of histamine . Histidine decarboxylase also occurs in the bone marrow of the guinea-pig this enzyme activity, which was shown to be related to the number of basophils, does not, however, support a relationship between histidine decarboxylase activity and growth, since the basophils in the buffy layer of guinea-pig blood have also a considerable histamine-forming capacity, but contain no cells in mitosis .  

The formation of collagen also provides an index of reparative growth. In agreement with the view that there is a relationship between histidine 

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We have seen that the first indication of a relationship between histidine decarboxylase and growth arose from studies in pregnant rats. Increased specific histidine decarboxylase activity was found in the foetal liver and the... 

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