Neurobiological mechanisms underlying GnRH pulse generation by the hypothalamus.
Gonadotropin-releasing hormone (GnRH) secretion has two modes of release in mammalian species; the surge mode and the pulse mode. The surge mode, which is required for the induction of the preovulatory gonadotropin discharge in most species, is induced by the positive feedback of estrogen secreted by the mature ovarian follicle. The pulse mode of GnRH secretion stimulates tonic luteinizing hormone (LH) and follicle-stimulating hormone (FSH) secretion which drives folliculogenesis, spermatogenesis and steroidogenesis and is negatively fine-tuned by estrogen or androgen. The GnRH pulse-generating mechanism is sensitive to environmental cues, such as photoperiod, nutrition and stress surge-generating mechanism is relatively emancipated from these environmental cues. The present article first provides a brief historical background to the work that led to the concept of the GnRH pulse generator: a hypothalamic network that is central to our understanding of the regulation of reproduction. We then discuss possible neurobiological mechanisms underlying GnRH pulse generation, and conclude by proposing that kisspeptin neurons in the arcuate nucleus are key players in this regard.
Maeda
Kei-Ichiro
K
Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan. kei_maeda@nagoya-u.jp
Ohkura
Satoshi
S
Uenoyama
Yoshihisa
Y
Wakabayashi
Yoshihiro
Y
Oka
Yoshitaka
Y
Tsukamura
Hiroko
H
Okamura
Hiroaki
H
D000818:Animals; D004399:Dynorphins / Q000502:physiology; D004777:Environment; D005640:Follicle Stimulating Hormone / Q000502:physiology; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism*; D006801:Humans; D007031:Hypothalamus / Q000502:physiology*; D059648:Kisspeptins; D007986:Luteinizing Hormone / Q000378:metabolism; D009446:Neurobiology; D015287:Neurokinin B / Q000502:physiology; D009474:Neurons / Q000502:physiology; D013256:Steroids / Q000502:physiology; D025521:Tumor Suppressor Proteins / Q000502:physiology
C106628:KISS1 protein, human; D059648:Kisspeptins; D013256:Steroids; D025521:Tumor Suppressor Proteins; D007987:Gonadotropin-Releasing Hormone; D004399:Dynorphins; D015287:Neurokinin B; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone