Sex steroid hormones are key molecules to prepare the decidual response and their levels are important in this process. Imbalances of the levels of steroid hormones are cause of implantation failure and other diseases including physical weakness. Androgen replacement therapy or selective androgen receptor modulator are used to overcome various diseases but long-term use may cause of side effects. In previous report, it is suggested that the steroid hormonal complexes derived from pig enhance the proliferation of satellite cell. Therefore, to evaluate the possible usage of steroid hormonal complex derived from pig testis (tS-C), the effects of tS-C on uterine response were studied using the model of artificial decidua. tS-C did not disturb the rhythmical estrus cycle. Artificial-induced decidual response was normally induced in tS-C administered mice. The histological characters of the decidua of tS-C administered mice were not different from the vehicle. The expression patterns of molecular markers of decidua were not different between vehicle and tS-C group. Collectively these results suggested that tS-C does not disturb the uterine responsibility to the embryo. In addition, our results suggested that tS-C can be applied to overcome the various problems such as loss of muscle mass and anemia.

Pivotal roles of steroid hormones in uterine endometrial function are well established from the mouse models carrying the null mutation of their receptors. Literally androgen belongs to male but interestingly it also detected in female. The fluctuations of androgen levels are observed during reproductive cycle and pregnancy, and the functional androgen receptor is expressed in reproductive organs including uterus. Using high throughput methodology, the downstream genes of androgen have been isolated and revealed correlations between other steroid hormones. In androgen-deficient mice, uterine responses to exogenous gonadotropins are impaired and the number of pups per litter is reduced dramatically. As expected androgen has important role in decidual differentiation through AR. It regulates specific gene network during those cellular responses. Recently we examined the effects of steroid hormonal complex containing high level of androgen. Interestingly, on the contrary to the androgen-alone administration, the hormonal complex did not disturb the decidual reaction and the pubs did not show any morphological abnormality. It is suspected that the complexity of communication between other steroid hormone and their receptors are the reasons. In summary, androgen exists in female blood and it suggests the importance of androgen in female reproduction. However, the complex interactions with other hormones are not fully understood compared with estrogen and progesterone. The further studies to evaluate the possible role of androgen are needed and important to provide the in vivo rational for the prevention of associated pregnancy complications and help human's health.