Histamine in mammary gland: Pregnancy and lactation

1. Histamine concentration, kistidine decarboxylase (HDC), histamine N-methyltransferase (HMT) and transglutaminase (TG ase) activities have been followed in mouse and guinea pig mammary gland during pregnancy and lactation. 2. The most significant changes concerned histidine decarboxylase (HDC) activity and their pattern was similar for the two species. In either species 2nd trimester of pregnancy was associated with stimulation whereas early lactation was associated with reduction of the tissue HDC activity. 3. Hormonal control of HDC is suggested on the basis of Variations in the enzyme activity and histamine concentration in mammary gland during estrous cycle. 4. The circumstantial evidence is provided indicating that histamine might be involved in pregnancy associated growth of mammary gland and in excretory activity of lactating gland. Copyright (C) 1996 Elsevier Science Inc.