Chapters authored
Studies on the Character of Hypothalamic GnRH Neurons and Kisspeptin Neurons Using Hypothalamic Cell Models
The hypothalamic-pituitary-gonadal (HPG) axis controls the hormonal network responsible for reproductive functions. In the past, hypothalamic gonadotropin-releasing hormone (GnRH) neurons have been positioned at the highest level in the HPG axis. After the discovery of the indispensable roles of hypothalamic kisspeptin in GnRH neurons, our understanding of the neuroendocrine regulation of the HPG axis was reconfirmed, and it is now recognized that hypothalamic kisspeptin neurons are positioned at the summit of the HPG axis. Accumulating evidence shows that kisspeptin neurons are responsible for the onset of puberty and sex steroid feedback mechanisms by modulating the activity of GnRH neurons. Furthermore, the identification of kisspeptin in the hypophyseal portal circulation suggests that this peptide has some direct roles in the pituitary gland. The detailed mechanisms underlying the regulation of GnRH by kisspeptin and the regulatory control of kisspeptin neurons are still largely unknown because of the limitations of the experimental models. The establishment of GnRH-expressing and kisspeptin-expressing cell models has enabled us to examine the character of these neuronal cells. In this chapter, we describe our in vivo studies examining the character of GnRH neurons and kisspeptin neurons in the hypothalamus using hypothalamic GnRH- and/or kisspeptin-expressing cell models.
Part of the book: Hypothalamus in Health and Diseases