Effects of phytoestrogen genistein on genioglossus function and oestrogen receptors expression in ovariectomized rats.
OBJECTIVE
This study was designed to investigate the effects of genistein on genioglossal muscle function and the expression of oestrogen receptors (ERs) in the ovariectomized rats.


METHODS
Fifty female Sprague-Dawley rats were randomly divided into 5 groups: the control group (SHAM), the ovariectomized group (OVX), the ovariectomized rats receiving low genistein dosage (OVX+L), the moderate genistein dosage group (OVX+M) and the high genistein dosage group (OVX+H). Oestradiol level was detected by radioimmunity. The isometric twitch tension (P(t)) and tetanic tension (P(0)) of the GG muscle were measured in response to electrical field stimulation. The expression of ERs on the mRNA and protein levels was measured by real-time PCR and western blot respectively.


RESULTS
Ovariectomy decreased muscle fatigue resistance and the expression of different ERs significantly. Genistein treatment resulted in a dose-dependent protective effect on muscle fatigability and a parallel dose-responsive increase in the expression of oestrogen receptors mRNA and protein levels in genioglossus, with larger effects on oestrogen receptor beta vs. alpha. In contrast to the improvements in fatigability, there was no treatment effect on isometric twitch or tetanic tensions.


CONCLUSIONS
The results indicated that genistein increased muscle fatigue resistance in addition to effects on receptors, and the up-regulation of receptors expression may be a possible mechanism by which genistein improved fatigue.
Department of Orthodontics, School of Stomatology, Tongji University, 399 YanChangZhong Road, Shanghai 200072, China.
Wen
W
Li
Yue-hua
YH
Liu
D000818:Animals; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000097:blood; D005260:Female; D015870:Gene Expression; D019833:Genistein / Q000008:administration & dosage*; D009119:Muscle Contraction / Q000187:drug effects; D018763:Muscle Fatigue / Q000187:drug effects*; D010052:Ovariectomy; D010053:Ovary / Q000502:physiology; D010609:Pharyngeal Muscles / Q000187:drug effects* / Q000502:physiology*; D048789:Phytoestrogens / Q000008:administration & dosage*; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D011960:Receptors, Estrogen / Q000096:biosynthesis* / Q000235:genetics; D015854:Up-Regulation
D048789:Phytoestrogens; D011960:Receptors, Estrogen; D004958:Estradiol; D019833:Genistein