Kisspeptin and GnRH Pulse Generation - Kisspeptin Signaling in Reproductive Biology - page 289

Chapter 14
Kisspeptin and GnRH Pulse Generation
Hiroaki Okamura , Hiroko Tsukamura , Satoshi Ohkura ,
Yoshihisa Uenoyama , Yoshihiro Wakabayashi , and Kei-ichiro Maeda
Abstract The reproductive neuropeptide gonadotropin-releasing hormone (GnRH)
has two modes of secretion. Besides the surge mode, which induces ovulation in
females, the pulse mode of GnRH release is essential to cause various reproductive
events in both sexes, such as spermatogenesis, follicular development, and sex ste-
roid synthesis. Some environmental cues control gonadal activities through modu-
lating GnRH pulse frequency. Researchers have looked for the anatomical location
of the mechanism generating GnRH pulses, the GnRH pulse generator, in the brain,
because an artifi cial manipulation of GnRH pulse frequency is of therapeutic impor-
tance to stimulate or suppress gonadal activity. Discoveries of kisspeptin and, con-
sequently, KNDy (kisspeptin/neurokinin B/dynorphin) neurons in the hypothalamus
have provided a clue to the possible location of the GnRH pulse generator. Our
analyses of hypothalamic multiple-unit activity revealed that KNDy neurons located
in the hypothalamic arcuate nucleus might play a central role in the generation of
GnRH pulses in goats, and perhaps other mammalian species. This chapter further
discusses the possible mechanisms for GnRH pulse generation.
H. Okamura • Y. Wakabayashi
Animal Physiology Research Unit, Division of Animal Sciences, National Institute
of Agrobiological Sciences, Tsukuba , Ibaraki , Japan
e-mail: [e-mail]
H. Tsukamura • Y. Uenoyama
Graduate School of Bioagricultural Sciences, Laboratory of Reproductive Science,
Nagoya University , Nagoya , Japan
K.-i. Maeda ( * )
Animal Breeding, Veterinary Medical Sciences , The University of Tokyo , Tokyo , Japan
e-mail: [e-mail]
S. Ohkura
Graduate School of Bioagricultural Sciences, Laboratory of Animal Production,
Nagoya University , Nagoya , Japan