Objective       To evaluate level changes of protein kinase C epsilon (PKC-ε)/phosphorylated PKC-ε (pPKC-ε) and h1 calponin (h1 CaP)/phosphorylated h1 CaP (ph1 CaP) in myometrium of pregnant mice during pregnancy

and to investigate their relationship with labor at term and preterm and the involved mechanisms.       Methods       Pregnant mice were given 6 mg/g ethanol by gavage to construct mouse model of preterm labor. According to different periods of pregnancy

mice were divided into a non-pregnancy(NP) group

an early pregnancy (EP

gestational day 7) group

a middle pregnancy (MP

gestational day 12) group

a late pregnancy (LP

gestational day 18) group

a term labor (TL) group and a preterm labor (PL) group. Each group included 10 mice. Protein levels of PKC-ε/pPKC-ε and h1 CaP/ph1 CaP in mice myometrium were detected by Western blotting.       Results       Protein levels of PKC-ε and h1 Cap in the TL and PL groups were significantly higher than those in the NP

EP and MP groups (P0.01)

while the differences among the LP

TL and PL groups were not significant (P0.05). The ratios of pPKC-ε/PKC-ε and ph1 CaP/h1 CaP in the TL and PL groups were significantly higher than those in the NP

EP

MP and LP groups (P0.01)

while the difference between the TL and PL groups was not significant (P0.05). The change of pPKC-ε/PKC-ε was positively correlated with the change of ph1 CaP/h1 CaP (r=0.73

P0.05).       Conclusion       Protein levels of PKC-ε and h1 CaP in mice myometrium both reach the peak at pre-labor. Levels of pPKC-ε and ph1CaP both reach the peak at parturition. PKC-ε is suggested to contribute to the initiation of term and preterm labor through h1 CaP phosphorylation.