What is the role of PACAP in gonadotrope function?
Strong evidence in favor of a direct action of hypothalamic PACAP at the pituitary to modulate gonadotrope function has been acquired mainly by in vitro studies using cultured pituitary cells or gonadotrope cell lines. In particular, PACAP has been shown to cooperate with GnRH, the primary regulator of gonadotropes, to regulate/modulate gonadotropin subunit gene expression, gonadotropin release as well as gonadotrope responsiveness. These effects of PACAP appear to be due essentially to its high potent stimulatory action on the cAMP/protein kinase pathway. Ensuing mechanisms include signaling cross-talk and/or enhanced gene expression within gonadotropes. PACAP may also indirectly operate on these cells through paracrine mechanisms. While PACAP has long been viewed as a hypophysiotropic factor, a locally produced PACAP has also been described. Interestingly, both appear similarly up-regulated at proestrus of the reproductive cycle in female rats. Further in vivo investigation is now necessary to ascertain the physiological relevance of the observed pituitary PACAP effects and especially to evaluate the respective contribution of hypothalamic and pituitary PACAP in the dynamic control of gonadotrope function.
Counis
Raymond
R
Physiologie de l'axe gonadotrope, UMR CNRS 7079, Physiologie et Physiopathologie, Université Pierre & Marie Curie-Paris 6, 75252 Paris, France. Faymond.counis@suv.jussieu.fr
Laverrière
Jean-Noël
JN
Garrel-Lazayres
Ghislaine
G
Cohen-Tannoudji
Joëlle
J
Larivière
Sigolène
S
Bleux
Christian
C
Magre
Solange
S
D000818:Animals; D000242:Cyclic AMP / Q000378:metabolism; D005260:Female; D052681:Gonadotrophs / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism; D008954:Models, Biological; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide / Q000494:pharmacology*; D010902:Pituitary Gland / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects
D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D007987:Gonadotropin-Releasing Hormone; D000242:Cyclic AMP