Localization, Characterization, and Second Messenger Coupling of Pituitary Adenylate Cyclase-Activating Polypeptide Receptors in the Fetal Human Adrenal Gland during the Second Trimester of Gestation*

Laurent Yon (1, 2) , Lyne Breault (3) , Vincent Contesse (2, 1) , Grégory Bellancourt (1, 2) , Catherine Delarue (1, 2) , Alain Fournier (4) , Jean-Guy Lehoux (3) , Hubert Vaudry (1, 2) , Nicole Gallo-Payet (3)

1 Neuroendocrinologie cellulaire et moléculaire
2 IFRMP 23 - Institut Fédératif de Recherches Multidisciplinaires sur les Peptides
3 UdeS - Faculté de médecine et des sciences de la santé [Sherbrooke]
4 INRS-IAF - Institut Armand Frappier

The distribution and pharmacological properties of pituitary ad-enylate cyclase-activating polypeptide (PACAP) receptors were studied in the fetal human adrenal gland during the second trimester of gestation. Autoradiographic studies, using [ 125 I]PACAP27 as a ra-dioligand, revealed that PACAP-binding sites are exclusively located on chromaffin cells of adrenals from fetuses 14-20 weeks old. Biochemical characterization of binding revealed the occurrence of a single class of PACAP-binding sites with a dissociation constant value of 0.32-0.74 nmol/L and a binding capacity of 0.30-0.81 pmol/mg wet tissue. PACAP27 and PACAP38 were equipotent in competing for [ 125 I]PACAP27 binding (IC 50 ϭ 0.28-0.64 nmol/L and 0.15-0.81 nmol/L, respectively), and the Hill coefficients were close to 1. In contrast, vasoactive intestinal polypeptide was much less efficient in displacing the tracer (IC 50 ϭ 4-362 nmol/L), and the Hill coefficients were less than 0.6. PACAP38 induced a dose-dependent increase in cAMP production in fetal human adrenal cell suspension (ED 50 ϭ 0.07 Ϯ 0.02 nmol/L), as well as in cells maintained in culture for 5 days (5.4 Ϯ 1.8 nmol/L). In constrast, PACAP38 induced a modest increase in inositol phosphate formation. These data indicate that type I PACAP receptors are present in the early stages of the human me-dulla organization during the process of migration of chromaffin cells from the periphery to the central part of the gland. The present results suggest that PACAP could be involved in the regulation of the human adrenochromaffin cells during ontogenesis.

Domains: Life Sciences [q-bio]

Laurent Yon, Lyne Breault, Vincent Contesse, Grégory Bellancourt, Catherine Delarue, et al.. Localization, Characterization, and Second Messenger Coupling of Pituitary Adenylate Cyclase-Activating Polypeptide Receptors in the Fetal Human Adrenal Gland during the Second Trimester of Gestation*. Journal of Clinical Endocrinology and Metabolism, 1998, 83 (4), pp.1299-1305. ⟨10.1210/jcem.83.4.4690⟩. ⟨hal-02334689⟩