| Objective: With the ovary function and the level of estrogen declining,perimenopausal and postmenopausal women appear sorts of symptoms and signs of physiological and psychological aspects, affecting the quality of their life in different extent. Researches have confirmed that hormone replacement therapy in the "window period" can effectively relieve symptoms of menopause, prevent osteoporosis, reduce the disease of heart head blood-vessel, and the occurrence of senile diseases such as metabolic syndrome risk. In recent years, studies have shown that there is a close relationship among estrogen, telomere, telomerase and the aging. Telomere is located at the end of eukaryotic chromosome tandem repetitive DNA sequences, and its main function is to avoid the chromosome degraded by the nuclease, prevent chromosome mutual integration and restructuring, so as to maintain the integrity and stability of the chromosome. Once telomeres deletion, cells will lose the proliferation gradually,resulting in cell aging and death. Telomerase is a ribosome constituted by protein and RNA,which can add the telomere fragment to the end of telomeres. Studies found that the activity of telomerase is associated with the length of the telomere. The higher the activity of telomerase is,the longer the telomeres and the more cell division will be, and then the life expectancy of the chromosome extended.Telomerase reverse transcriptase is mainly subunit of the regulation of human telomerase activity. Along with the increasing of telomerase activity, the level of TERT m RNA expression also increases accordingly. The aim of this study was to investigate the anti-aging effects of oral estrogen on the telomerase activity and TERT m RNA level in ovariectomized female Sprague-Dawley(SD) rats in order toprovide experimental and theoretical basis for estrogen replacement therapy in perimenopausal and postmenopausal women.Methods : Thirty-three three-month-old female rats were randomly divided into ovariectomized experimental group(Treated, n=11), ovariectomized control group(OVX, n=11) and sham-operated group(Sham, n=11). The rats in the Tested group were given 0.21 mg/kg estradiol valerate intragastric administration while other two groups were given the equal physiological saline intragastric administration. All of the animals were euthanized 12 weeks after treatment, and abdominal aortic blood samples were taken to assess the level of estradiol(E2), follicle stimulating hormone(FSH) by ELISA. Telomerase activity and telomerase reverse transcriptase(TERT)m RNA expression in the heart, liver, brain tissues of all rats were measured by TRAP-ELISA and RT-q PCR, respectively.Results:The serum E2 level in the Treated and Sham group were significantly higher than that in the OVX group(P<0.05), The serum FSH levels were significantly lower than that in the OVX group(P<0.05). Compared to the OVX and the Sham group,the value of ΔA on telomerase activity in the Treated group was significantly increased(P<0.05). The telomerase activity was negative and ?A value was low in the OVX and Sham group, no statistical difference between them(P>0.05). The TERT m RNA ΔCt of the heart in the Treated group was significantly lower than that in the liver and brain tissues(P<0.05).The value of TERT m RNA ΔCt in the heart,liver and brain tissues in the Tested group was significantly lower than those in the OVX and Sham group(P<0.05). But there was no significant difference between the OVX and Sham group(P>0.05).Conclusions:Estrogen can significantly up-regulate telomerase activity and TERT m RNA expression in the ovariectomized female SD rats to delay senescence. |
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