Modification of Sex Hormones with RGD-Peptide: A Strategy of Improving HRT and Other Secondary Osteoporosis Therapy

In the time of transition from premenopausal state to postmenopausal state the capacity of ovary producing sex hormones including estrogens, progesterone and testosterone cuts down [1]. Due to the menopause the level of serum oestrogen dramatically decreases, which increases the production of bone-resorbing cytokines and osteoblasts and then increases the number and activity of osteoclast, thereby increasing the bone loss [2]. Hormonal replacement therapy (HRT) is able to prevent bone loss for sex hormones-deficient menopausal women and consequently is of clinical importance for the treatment of osteoporosis. [1-3] In Europe and USA the osteoporosis prevention of 25-50% of the post-menopausal women rely on HRT [2,5, 6]. In past years, however, the large international studies, such as the randomized Woman Health Initiative, the observational Million Women Study and the Women’s International Study of long Duration, discussed both of the adverse and beneficial effects of post-menpausal HRT [7]. In respect of the adverse effects, the discussion was focused on HRT induced risk of breast cancer [8-11], venous thromboembolism [12], stroke and myocardial infarction [13], as well as coronary heart diseases [14]. To limit these adverse effects a series of regimens of HRT, such as continuous combination of oestrogen and progestogen or continuous oestrogen and interruptted progestogen [15], and with dehydroepiandrosterone as a new strategic tool [16], were developed. In general these regimens confer no positive result, and thus new strategies are still needed.