Objective:To investigate the effects and possible mechanisms of γ-aminobutyric acid(GABA)on preimplantation embryo development in mice. Methods:(1)The embryos at different development stages were collected and the localization of GABA

B-type receptor protein(GB1)

the π subunit of A-type receptor(GABRP)

and L-glutamic acid decarboxylase 67(GAD67)was detected by immunofluorescence staining.(2)The embryos at different development stages were cultured in vitro in KSOM medium containing 10

20

30

40

or 50 μg/μL GABA and 40 μmol/L 2-hydroxysaclofen(GABA B-type receptor antagonist)for 48-72 h

respectively

and blastocyst formation rate was counted. Results:(1)GABA and GB1 are mainly expressed in the membranes of 2-cell and 4-cell embryos

while in the 8-cell to blastocyst stages

they are localized in the nucleus. However

GABRP was not detected in preimplantation embryos at any stage. In addition

GAD67

a key GABA synthetase

was mainly localized in the cytoplasm in preimplantation embryos.(2)The blastocyst formation rate of each development stage was significantly declined in a dose-dependent manner. In addition

the blastocyst formation rate of 2-cell embryos stage was remarkably inhibited by 10 μg/μL GABA(92% vs. 99%

χ~2=5.70

P=0.035).(3)40 μmol/L 2-hydroxysaclofen could effectively reverse the inhibitory effect of 30 μg/μL and 40 μg/μL GABA on blastocyst formation(99% vs. 45%

χ~2=72.32

P=0.000;99% vs. 4%

χ~2=180.66

P=0.000). Conclusion:GABA could affect the development of preimplantation embryos through its B-type receptor in mice.