Cyclosporine and pregnancy in the rat

Female Wistar rats mated with male Wistar rats were given 15 mg/kg cyclosporine (CsA) per day during pregnancy (to 21 days after coitus). Other rats were mated and were used as controls. The pups born from treated mothers were fed by control mothers and those born from control mothers were fed by treated mothers. The newborn rats showed temporary defects in the development of some hemopoietic organs (the thymus, spleen, liver, and bone marrow). There was no difference in the structure of the organs studied between the litters fed by control mothers and those fed by treated mothers. The structure of the hemopoietic organs resembled those of the controls 30 days after birth. Our findings show that the delay in the development of the organs studied is due to the transplacental passage of CsA and suggest that it could be due to CsA interference in the maternal immune response to specific embryonic antigens.