The effects of periconceptional folic acid and vitamin supplementation on maternal folate levels and on neurulating hamster embryos in vivo.

We studied the effects of periconceptional oral supplementation of folic acid and vitamins on the maternal red blood cell (RBC) folate level of golden hamsters (Mesocricetus auratus, Waterhouse). The effects of folate deficiency and supplementation on the process of neurulation and the incidence of resorptions were evaluated. Groups of at least eleven mature virgin female hamsters were placed on one of six specific regimens which started two weeks prior to mating and continued until sacrifice on day nine of pregnancy. Just prior to sacrifice, blood samples were drawn by cardiac puncture to measure maternal folic acid levels in red blood cells. The staging of the embryos was based on O'Rahill's modification of Streeter's developmental horizons in human embryos. Considerable variation was observed in the stage of embryonic development of 9-day-old hamster embryos, both between littermates and between litters of the same gestational age. A high overall incidence of open neural tubes was observed, which did not reflect neural tube closure failures. A folate-free diet caused retardation of the embryonic development, although maternal folate levels were unaffected (p < 0.01). The RBC folate levels in the animals which received oral supplementation with folic acid was significantly higher than that in the unsupplemented controls (p < 0.001). Folic acid supplementation alone increased the RBC folate level significantly more than combined supplementation with multivitamins (p < 0.001). The data indicate that oral supplementation with folic acid and/or multivitamins produce adequate maternal RBC folate levels. An inadequate maternal folate intake can affect the growth of neurulating embryos even if the maternal RBC folate levels are still sufficient.(ABSTRACT TRUNCATED AT 250 WORDS)