[Effects of long-term estrogen replacement treatment on the blood pressure and expression of IR and IRS-1 in myocardium].
OBJECTIVE
To determine the effects of long-term estrogen replacement treatment on blood pressure and expressions of insulin receptor (IR) and insulin receptor substrate-1 ( IRS-1) in myocardium.


METHODS
Fifty female SD rats were randomly divided into 3 groups. And then sham ( n = 16), ovariectomy (OVX, n = 17), and estrogen replacement treatment group (OVX + E2, n = 17) were established. Systolic blood pressure of tail artery was determined by tail-cuff technique before the operation and on week 12 after the operation. The expressions of IR and IRS-1 were measured by RT-PCR in myocardium of SD rats.


RESULTS
Blood pressure [ (118.75+/-2.77) mmHg] in OVX was significantly higher than that in the sham [ ( 103.86+/-1.84) mmHg, P < 0.05 ] and OVX + E2 [( 107.83+/-3.24) mmHg, P < 0.05 ] rats. Expression of IRS-1 in OVX group was significantly lower ( 1.2588+/-0.1045)than that in the sham(2.2089+/-0.0988, P <0.05) and OVX + E2 groups ( 1.9100+/-0.1230, P <0.05 ). However, there was no difference on blood pressure and expression of IRS-1 between sham and OVX + E2 groups (P > 0.05 ). The difference of IR expression has no statistical significance among the 3 groups.


CONCLUSIONS
Long-term estrogen replacement treatment might protect cardiovascular system through decreasing the blood pressure and inducing the expression of IRS-1 in myocardium. However, plasma estrogen level doesn't significantly influence the IR expression.
Liu
Mei-lian
ML
Department of Biochemistry, Institute of Biological Science and Technology, Central South University, Changsha 410078, China.
Xu
Xia
X
Xie
Ping
P
Lu
Jin
J
Chen
Shu-hua
SH
Zeng
Wei-min
WM
Song
Hui-ping
HP
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D004958:Estradiol / Q000494:pharmacology; D015914:Estrogen Replacement Therapy; D005260:Female; D055504:Insulin Receptor Substrate Proteins; D009206:Myocardium / Q000378:metabolism*; D010052:Ovariectomy; D010750:Phosphoproteins / Q000096:biosynthesis* / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D011972:Receptor, Insulin / Q000096:biosynthesis* / Q000235:genetics; D013997:Time Factors
D055504:Insulin Receptor Substrate Proteins; C526296:Irs1 protein, rat; D010750:Phosphoproteins; D004958:Estradiol; D011972:Receptor, Insulin