Effects of coumestrol administration to maternal mice during pregnancy and lactation on immunoblogulin A‐secreting cells in mammary glands

Mortality and morbidity of neonates continue to be major problems in humans and animals, and immunoblogulin A (IgA) provides protection against microbial antigens at mucosal surfaces. The present study was conducted to clarify the effects of coumestrol administration to maternal mice during pregnancy and lactation on IgA antibody‐secreting cells (ASC) in mammary glands in lactating mice. From 6.5 to 16.5 days post coitus and 1 to 13 days post partum (dpp), maternal mice were administered coumestrol at 200 μg/kg body weight/day. Coumestrol administration increased the number of IgA ASC and the messenger RNA expression of IgA C‐region and vascular cell adhesion molecule‐1 in mammary glands of maternal mice at 14 dpp, but coumestrol administration had no effect on the number of IgA ASC in the ileum. Coumestrol administration increased serum IgA concentration in maternal mice at 14 dpp, but IgA concentrations in serum, stomach contents, intestine and feces of neonatal mice were not affected by treatment. These results imply that coumestrol administration to maternal mice during pregnancy and lactation is effective in increasing the numbers of IgA ASC in mammary glands during lactation owing to the activated messenger RNA expressions of IgA C‐region and vascular cell adhesion molecule‐1 in mammary gland.