Histamine formation by mouse preimplantation embryos

Abstract

Mouse embryos recovered on the 4th day of pregnancy produced histamine, as evidenced by the 14CO2 produced from carboxy labeled L-histidine, at the rate of 1.5 .+-. 0.3 (SEM [standard error of the mean]) pmol/embryo per h. Most (83.2 .+-. 4.6%) of the embryos flushed from the oviducts on day 3 of pregnancy (4-8 cell stage) developed into blastocysts within 48 h after being placed in culture. Inclusion of L-histidine hydrochloride (4.7 .times. 10-4 M) in the culture medium did not alter this development but DL-.alpha.-methylhistidine (3.8 .times. 10-4 M), a histidine decarboxylase inhibitor, reduced the number of embryos developing into blastocysts to only 10.8 .+-. 6.8%. A combination of L-histidine and DL-.alpha.-methylhistidine in the medium prevented the growth-retarding effect of the latter compound. Apparently mouse embryos can produce histamine and this is necessary for normal development.