Exposure to Halothane and Enflurane Affects Learning Function of Murine Progeny

This study was conducted to assess the learning function of murine progeny born of mothers that had received either 1% or 2% halothane or 2% or 4% enflurane, on days 6 and 10 or days 14 and 17 or gestation. Their timed performance at the age of 6 to 7 weeks was compared in a maze with that of control mice of similar ages that had not been exposed to anesthetics prenatally. All mice exposed to halothane in utero performed poorly at first, especially the group with mothers exposed to 2% halothane on days 14 and 17 of pregnancy. By the 10th training period, the performance of all mice improved but remained significantly slower than control mice. The offsprings of mice exposed to enflurane also performed poorly on the first training period, but between the fifth and seventh training periods, made statistically significant progress. However, they too remained slower in maze performance than control mice. Although blood pressure and arterial blood gas studies were only performed on two pregnant mice, data obtained suggest that the anesthetics did not have sufficient effect on respiration to affect our results. Second generation offspring, born to dams exposed to 2% halothane in utero late in pregnancy and sired by normal unexposed males, were also consistently slower than control mice, indicating a possible genetic effect induced by the anesthetic.