PACAP was discovered 30 years ago in Dr. Akira Arimura's laboratory. In the past three
decades since then, it has become evident that this peptide plays numerous crucial
roles in mammalian organisms. The most important functions of PACAP are the following:
1. neurotransmitter, 2. neuromodulator, 3. hypophysiotropic hormone, 4. neuroprotector.
This paper reviews the accumulated data regarding the distribution of PACAP and its
receptors in the mammalian hypothalamus and pituitary gland, the role of PACAP in
the gonadotropin hormone secretion of females and males. The review also summarizes
the interaction between PACAP, GnRH, and sex steroids as well as hypothalamic peptides
including kisspeptin. The possible role of PACAP in reproductive functions through
the biological clock is also discussed. Finally, the significance of PACAP in the
hypothalamo-hypophysial system is considered and the facts missing, that would help
better understand the function of PACAP in this system, are also highlighted.
