[Expression of NMBR in myometrium in pregnant mice at different gestational ages and its relation with parturition].

OBJECTIVE

To investigate the spatiotemporal expression of neuromedin B receptor (NMBR) in mice myometrium at different pregnant stages, as well as its mechanism and relation with parturition.

METHODS

The pregnant mice were divided into no-pregnancy (NP), early pregnancy (EP), mid-pregnancy (MP), late-pregnancy (LP), parturition (PT) and postpartum (PP) groups (12 mice in each group), according to pregnant stage. The mRNA and protein expression of NMBR, HSP70 and IL-6 were detected in myometrium in pregnant mice by semi-quantitative RT-PCR and Western blot, while NF-kappaB-P65 DNA binding activity was determined by NoShift transcription factor assay kits, respectively. Their relation with parturition was analyzed.

RESULTS

The mRNA expression level of NMBR in the PT group was significantly higher than that in the NP, EP, LP and PP groups (P<0.05), but this difference was not observed in the MP group (P>0.05). The NMBR protein in PT group was significantly higher than that in the other 5 groups (P<0.01). NF-kappaB-P65 DNA binding activity at PT group was remarkably higher than that in the NP, LP and PP groups (P<0.05). The expression of IL-6 mRNA was significantly higher than that in the NP, LP and PP groups (P<0.05), its protein expression in PT and LP groups was significantly higher than that in the NP and PP groups (P<0.05). The expression of HSP70 mRNA in the PT group was significantly higher than that in the NP and PP groups (P<0.05), and the protein of HSP70 was significantly up-regulated in PT and PP groups compared with in NP and LP groups (P<0.05). The DNA-binding activity of P65 was positively correlated to the mRNA expression of NMBR and IL-6 (r=0.40, P<0.01; r=0.30, P<0.05), so were positively correlated to DNA-binding activity of P65, mRNA expression of HSP70 and NMBR ( r=0.40, P<0.01; r=0.49, P<0.01). DNA-binding activity of P65 did not correlate with the mRNA expression of HSP70.

CONCLUSION

The mRNA and protein expressions of NMBR reach a peak at the onset of labor. NMBR may play an important role in the parturition via NF-kappaB P65-IL-6 signal transduction pathway. It may also influence the onset of labor by regulating HSP70, but this role does not rely on P65 pathway.