OBJECTIVETo explore gene expression of estrogen receptor (ERalpha, ERbeta) and androgen receptor (AR) in genioglossal muscle (GG) of adult male rats, and to investigate the effects of sex hormones on GG activities, ERalpha, ERbeta and AR expression.

METHODSGG samples were collected from 10 healthy adult male rats. Total RNA were extracted and subjected to fluorescent quantitative reverse transcription-polymerase chain reaction (FQ RT-PCR) for quantitative measurement of ERalpha, ERbeta and AR mRNAs. The other 24 male rats were randomly divided into 3 groups: control group, estrogen group (intramuscular injection of estrogen 0.1 mg/kg, twice a week) and androgen group (intramuscular injection of androgen 2.5 mg/kg, twice a week). The electromyographic activities (EMG) and contract tension of GG were investigated after 4-week treatment. The expression of ERalpha, ERbeta and AR was assessed by Western blot.

RESULTSThe mRNA expression ratios of AR/GAPDH, ERalpha/GAPDH, ERbeta/GAPDH and ERalpha/ERbeta were (295.80 +/- 127.20), (2042.00 +/- 921.57), (65.96 +/- 29.57) and (36.83 +/- 19.66), respectively. The mRNA level of ERalpha was significantly higher than that of ERbeta (P < 0.01). Compared with the control group, the EMG of GG was intensified in the estrogen group (P < 0.01). GG contractility did not change significantly (P > 0.05), and ERalpha expression in GG was up-regulated by estrogen (P < 0.05); while in the androgen group, the EMG of GG was weakened (P < 0.05). P(t) and P(0) were slightly increased (P > 0.05) and the decline rate of P(0) was markedly quickened (P < 0.05). AR and ERbeta expressions were down-regulated by androgen (P < 0.05).

CONCLUSIONSBoth AR and ER were expressed in GG of adult male rats, and ERalpha was expressed more abundantly than ERbeta. Estrogen could greatly improve activities of GG and stimulate the expression of ERalpha. Whereas, androgen could restrain activities of GG, impair its fatigue resistance capacity and inhibit the expression of AR and ERbeta.