Effects of exposure to halothane, isoflurane, and sevoflurane on embryo viability and gestation in female mice

Resumo

Although the negative effects of inhalation anaesthetics on fertility have been known for a while, the stages during the reproductive cycle at which these effects occur and the mechanisms of action are largely unknown. This study aimed to evaluate the effects of acute exposure of female mice to halothane, isoflurane, and sevoflurane prior to mating. BALB/c female mice (n=160) were allocated in groups of 20 to halothane (HG), isoflurane (IG), sevoflurane (SG), and oxygen/sham (SH) treatment groups and their respective control groups (CGs). The mice were exposed to 1 minimum alveolar concentration (MAC) of the corresponding anaesthetic or oxygen for 4 h/day over 5 consecutive days. Two days after exposure, females were mated with males (ratio 2:1 female/male) for five consecutive days. Every morning, females were checked for the presence of vaginal plugs. Half of the females that exhibited plugs were euthanised 72 h later for embryo evaluation. The remaining females were euthanised on the 14th day of pregnancy for foetal evaluation. A low number of morulae and total embryos (morulae + blastocysts) were observed in the HG (P<0.05). The number of implantations was lower in the HG (6.0) compared with the IG (11.8) and SG (12.4) (P<0.05). Exposure to halothane is not recommended for use in female mice prior to mating procedures because it leads to decreased embryo production and pregnancy failure. Sevoflurane induces a delay in embryo development, thereby influencing the morulae to blastocyst ratio. Isoflurane is the safest of the tested anaesthetics for use in female mice prior to mating.