Objective: To investigate the expression of hypoxia-inducible factor-1α (HIF-1α) and regulation of estrogen on genioglossus of chronic intermittent hypoxia (CIH) rats.
Methods: Fifty male SD rats were randomly divided into five groups: normal group (N), CIH group (C), and three doses of estrogen plus CIH groups (L, M, H). Rats in the latter four groups were used to built CIH models. In the mean time, rats in the latter three groups were injected with three dose levels of estrogen. Five weeks later, in vivo isometric contractile properties were investigated, and the other side of rat genioglossus was isolated and removed. The mRNA levels of HIF-1α were determined by real-time PCR and the protein content of HIF-1α was detected by Western blot analysis.
Results: (1) In fatigue test, compared with N group, there was a significant decrease in fatigue resistance in C group (P<0.01). While a significant increase in fatigue resistance was observed in M and H groups when compared with C group (P<0.05);(2) Compared with N group, HIF-1α mRNA and protein were both higher than those in N group (P<0.05); (3) Compared with C group, the mRNA levels of HIF-1α in M and H groups decreased significantly, while decreased protein content of HIF-1α was observed only in H group (P<0.05).
Conclusions: CIH exposure could attenuate the fatigue resistence of genioglossus and induce the expression of HIF-1α mRNA and protein, while high dose of estrogen administration could inhibit the overexpression of HIF-1α thus improve muscle endurance under hypoxia conditions.