Role of the Kiss1/Kiss1r system in the regulation of pituitary cell function

- The Kiss/Kiss1r system plays a key role in the control of pituitary gland function.
- Kisspeptin can modulate pituitary function acting at the hypothalamic level.
- Kisspeptin can also regulate pituitary function acting directly on pituitary cells.
- The Kiss1/Kiss1r system is locally expressed at the pituitary gland.
- Kisspeptin can establish an autocrine/paracrine regulatory loop at the pituitary.

Kisspeptin (Kiss1) is an amidated neurohormone that belongs to the RF-amide peptide family, which has a key role in the control of reproduction. Specifically, kisspeptin regulates reproductive events, including puberty and ovulation, primarily by activating the surface receptor Kiss1r (aka GPR54), at hypothalamic gonadotropin-releasing hormone (GnRH) neurons. More recently, it has been found that kisspeptin peptide is present in the hypophyseal portal circulation and that the Kiss1/Kiss1r system is expressed in pituitary cells, which suggest that kisspeptin could exert an endocrine, paracrine or even autocrine role at the pituitary gland level. Indeed, mounting evidence is pointing towards a direct role of kisspeptin in the control of not only gonadotropins but also other pituitary secretions such as growth hormone or prolactin. In this review, we summarize the most recent advances in the study of the role that the Kiss/Kiss1r system plays in the control of pituitary gland function, paying special attention to the direct role of this neuropeptide on pituitary cells and its interactions with other relevant regulators.