OBJECTIVETo investigate the effects of estrogen on the expression of phosphofructokinase muscle-specific isoform (PFK-M) in genioglossus of chronic intermittent hypoxia (CIH) rats.

METHODSFifty male SD rats were randomly divided into five groups: the normal control group (NC), the chronic intermittent hypoxia group (CIH), and three doses of estrogen plus hypoxia groups (LE, ME, HE). Rats in the latter four groups were used to build CIH models (8 h/d, 5 weeks). In the mean time, rats in the latter three groups were injected with three dose levels of estrogen (0.1, 0.2, 0.3 mg/kg), and rats in NC and CIH groups were injected with sterile olive oil as control. At the end of the treatment, the genioglossus was isolated and quickly removed. The mRNA levels of PFK-M were determined by real-time RT-PCR and the protein content of PFK-M was detected by Western blotting analysis.

RESULTSPFK-M mRNA and protein in CIH group (2.144 ± 0.260, 0.875 ± 0.025) were both higher than those (1.000 ± 0.259, 0.413 ± 0.013) in NC group (P < 0.05). The expression of PFK-M mRNA in LE, ME and HE groups were 1.424 ± 0.193, 1.395 ± 0.251 and 1.310 ± 0.094, respectively. The expression of protein in LE, ME and HE groups were 0.638 ± 0.015, 0.576 ± 0.017 and 0.505 ± 0.021, respectively. Compared with CIH group, the expression of PFK-M mRNA and protein in LE, ME and HE groups were all inhibited significantly (P < 0.05). Among the three treatment groups, decreased protein content of PFK-M was observed only in HE group when compared with LE group (P < 0.05), but no significant difference was detected in the expression of PFK-M mRNA.

CONCLUSIONSCIH exposure could increase the expression of PFK-M mRNA and protein in rat genioglossus, while estrogen administration could dose dependently inhibit the overexpression.