[Effect of estrogen on genioglossus and hypoglossal nucleus of female rats].

PUEPOSE: To study the hypoglossal nucleus spontaneous discharge and genioglossus function of SD rats with different estrogen levels, and explore the possible central pathways of estrogen protecting upper airway stability.

METHODS

Thirty SD rats were randomly divided into 3 groups: sham operation group (Sham), ovariectomized group (OVX) and ovariectomized + estrogen covering group (OVX+E2). The hypoglossal nucleus spontaneous discharge frequency and maximum amplitude of spontaneous discharge were measured with extracellular recording technique；BL-420 biological was used to detect the genioglossus EMG and contraction. The measurements included the average frequency, the maximum frequency, the integral amplitude, the maximum amplitude of the genioglossus, the amplitude of the evoked EMG, the critical fusion frequency, the 50% tonic contraction, and the intensity of the stimulus. SPSS 13.0 software package was used to analyze the data with One-way ANOVA.

RESULTS

The hypoglossal nucleus spontaneous discharge frequency and maximum amplitude of spontaneous discharge in OVX group were significantly lower than the Sham group and OVX+E2 group (P<0.05). The genioglossus EMG maximum frequency, average frequency, amplitude and integral maximum discharge magnitude, 50% tonic contraction drive of genioglossus in OVX group were significantly lower than the Sham and OVX+E2 group (P<0.05); the threshold stimulation strength and critical fusion frequency in OVX group were significantly higher than the Sham and OVX + E2 group (P<0.05); there was no significant difference between OVX+ E2 group and the Sham group (P>0.05); there was no significant difference among the three groups (P>0.05).

CONCLUSIONS

Estrogen changes excitability of hypoglossal nucleus and affect contraction of genioglossus. Estrogen levels can affect genioglossus contraction function and the ability of resistance to fatigue.