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  • Rajagopala Sridaran, Ph.D.

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  • Rajagopala Sridaran, Ph.D.
      Professor, Department of Physiology


    Contact Information
    Phone: (404) 752-1684
    Fax: (404) 752-1045
    Email: rsridaran@msm.edu
    Education
    B.Sc., University of Madras, Government Arts college, Salem, India (Zoology)
    M.Sc., University of Madras, Madras Christian College, Tambaram, Chennai, India (Zoology)
    Ph.D., University of Health Sciences/Chicago Medical School (Physiology/Endocrinology)

    Research Interests
    Reproductive endocrinology, gravity during pregnancy, molecular and cellular antifertility actions of gonadotropin-releasing hormone (GnRH); role of luteal GnRH in corpus luteum demise and parturition; Role and regulation of ovarian GnRH and its receptors in chemoresistant ovarian cancer.

    The primary research interest of my laboratory has been to establish the presence of gonadotorpin releasing hormone (GnRH) and its receptors in the female reproductive tract. We and our collaborators have established the presence of GnRH and its receptors in the female reproductive tract of lower vertebrates, bat, and rat. We recently established their presence in the monkey and plan to extend these observations in women. Although we believe a strong possibility of their role in the steroidogenesis by the corpus luteum/ovary, we do not rule out any other roles in the reproductive tract functions during normal cycles or during pregnancy.

    Rat Studies: Progesterone is responsible for maintaining pregnancy in the rat. We have demonstrated that the administration of a GnRH agonist suppresses luteal steroidogenesis resulting in the termination of pregnancy in the rat and the induction of apoptosis of the corpus luteum (CL). We further demonstrated that suppression of luteal steroidogenesis by GnRH or bradykinin involves intracellular calcium signaling. We also demonstrated the presence of GnRH and its receptor mRNA in the ovary indicating the local synthesis of both ligand and its receptor in the rat ovary. Based on these findings, we hypothesize that the ovary is a “mini-brain” or perhaps the brain is a “mini-ovary.” Collectively these data support an autocrine/paracrine action of GnRH in the reproductive tract.

    Non-human Primate Studies: Our recent observations (immunoblot data) demonstrate, for the first time, that GnRH receptors and bradykinin receptors are present in a primate (monkey) ovary in significant quantities. We further demonstrated by using radioimmunoassay that GnRH I and GnRH II are present in significant quantities in the CL at various stages of the luteal phase of the menstrual cycle. Human Studies: Our preliminary data support the presence of high levels of GnRH I and GnRH II in the ovaries of women with polycystic ovarian syndrome (PCOS).

    Our preliminary data generated in the laboratories of Sridaran and Tsang suggest that Cisplatin resistance in the ovarian cancer cells is inversely related to the GnRHR II content in response to Cisplatin treatment and this resistance may be associated in part with dysregulation of calcium signaling.

    Significance: Therefore, we believe that the knowledge we gain from these ongoing studies in my laboratory will delineate a role for the GnRH of the ovary/CL/oviduct in the regulation of ovarian function and also in the development of resistance to ovarian cancer and thus the treatment. Further, it will help us understand the underlying cause of other disorders relating to the ovary.

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