In female mammals, sexual maturation is initiated by a change in the release pattern of pituitary gonadotropins, luteinizing hormone (LH) and follicle-stimulating hormone (FSH), and a consequential increase in the secretion of ovarian sex-steroids, estradiol and progesterone. Orchestrating these endocrine changes is a diffuse population of hypothalamic neurons that produce the neuropeptide, gonadotropin-releasing hormone (GnRH). Although the development and functional integration of GnRH neurons with the rest of the central nervous system is still poorly understood, recent progress has been made on several fronts. For example, there is now evidence that some mammalian species express more than one molecular form of GnRH (GnRH-I and GnRH-II), and that the two corresponding GnRH neuronal sub-populations may play different roles in the regulation of reproductive function and behavior. Moreover, through the use of transgenic animal models, neuronal fiber tracing, gene expression profiling, and electrophysiologcal recordings, new insights have been gained into the mechanisms that regulate GnRH release. The focus of this Research Topic is on the positive and negative actions that estrogens exert within the mammalian hypothalamus, especially on the reproductive neuroendocrine axis around the time of the preovulatory LH surge. Our hope is that a deeper understanding of the endocrine interactions between the hypothalamus, pituitary gland, and gonads will provide a solid foundation upon which to develop more effective therapies for pubertal disorders, infertility, and menopause.
In female mammals, sexual maturation is initiated by a change in the release pattern of pituitary gonadotropins, luteinizing hormone (LH) and follicle-stimulating hormone (FSH), and a consequential increase in the secretion of ovarian sex-steroids, estradiol and progesterone. Orchestrating these endocrine changes is a diffuse population of hypothalamic neurons that produce the neuropeptide, gonadotropin-releasing hormone (GnRH). Although the development and functional integration of GnRH neurons with the rest of the central nervous system is still poorly understood, recent progress has been made on several fronts. For example, there is now evidence that some mammalian species express more than one molecular form of GnRH (GnRH-I and GnRH-II), and that the two corresponding GnRH neuronal sub-populations may play different roles in the regulation of reproductive function and behavior. Moreover, through the use of transgenic animal models, neuronal fiber tracing, gene expression profiling, and electrophysiologcal recordings, new insights have been gained into the mechanisms that regulate GnRH release. The focus of this Research Topic is on the positive and negative actions that estrogens exert within the mammalian hypothalamus, especially on the reproductive neuroendocrine axis around the time of the preovulatory LH surge. Our hope is that a deeper understanding of the endocrine interactions between the hypothalamus, pituitary gland, and gonads will provide a solid foundation upon which to develop more effective therapies for pubertal disorders, infertility, and menopause.