Fetoplacental growth and placental protein synthesis in rats after chronic maternal cocaine administration.

This study evaluated the effects of chronic exposure to cocaine during pregnancy on the morphology and function of the placenta. Pregnant rats received either 45 or 60 mg/kg of cocaine hydrochloride by i.p. injection as a divided daily dose on days 8 to 18 of gestation. The maternal weight gain decreased by 20% to 24% (P < .05) in the two cocaine treatment groups, whereas the placental weight was not significantly altered. Fetal growth showed a dose-related decrease in the 45- and 60-mg/kg cocaine treatment groups; fetal body weights and length were significantly decreased by 5% to 10%. The plasma levels of cocaine were 0.79 and 1.09 micrograms/ml in the 45- and 60-mg treatment dose groups, respectively; the level in the fetal plasma was 3-fold higher in the latter group. Placental tissue explants were cultured in the presence of [35S]-methionine to investigate whether cocaine exposure altered placental protein synthesis. Secreted proteins were analyzed by polyacrylamide gel electrophoresis followed by fluorography or by western blotting and immunostaining with antibodies to placental prolactin-like proteins-B and -C and growth hormone-related protein-1. The data showed that there were no quantitative or qualitative changes in placental peptide hormone secretion as a result of the cocaine treatment. These data indicate that chronic cocaine exposure in the pregnant rat is associated with fetal growth retardation in the absence of alterations in placental morphology or secretory protein synthesis.