Molecular, cellular, and functional characterizations of pituitary adenylate cyclase-activating polypeptide and its receptors in the cerebellum of New and Old World monkeys.
The neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP) exerts trophic activities during cerebellar development, and a neuroprotective effect of PACAP has been demonstrated in pathological conditions such as stroke. However, all these data have been obtained in rodents, and neuroprotective effects of PACAP in primates remain unknown. Because of their evolutionary relationships with humans, monkeys represent powerful models for validating the therapeutic interest in PACAP. The objective of the present study was to characterize PACAP and its receptors in the cerebellum of two nonhuman primates. RT-PCR and in situ hybridization experiments revealed that PACAP is expressed in the cerebellum by Purkinje cells. Via immunohistochemistry, PACAP was detected in Purkinje cells and radial glial fibers. With regard to PACAP receptors, PAC1-R and VPAC1-R were detected by RT-PCR. In situ hybridization revealed a strong expression of PAC1-R and VPAC1-R in the granule cell layer (GCL), and VPAC1-R was also expressed in the Purkinje cell layer. A high density of PACAP binding sites was visualized in the GCL and the Purkinje cell layer. Competition studies indicated that, in the GCL, PACAP induced complete displacement of [(125)I]PACAP27 binding, whereas vasoactive intestinal polypeptide (VIP) was a weak competitor. In contrast, in the Purkinje cell layer, both PACAP and VIP displaced [(125)I]PACAP27 binding. Measurement of cAMP levels showed that PACAP is a powerful activator of adenylyl cyclase, whereas VIP is about 100-fold less potent. Altogether, these observations constitute the first demonstration of a functional PACAPergic system in monkey cerebellum. They strongly suggest that neuroprotective effects of PACAP can be transposed to primates, including human.
Institut National de la Santé et de la Recherche Médicale (INSERM) U413, Laboratory of Cellular and Molecular Neuroendocrinology, European Institute for Peptide Research (IFRMP 23), University of Rouen, 76821 Mont-Saint-Aignan, France.
Nicolas
N
Aubert
Magali
M
Basille
Anthony
A
Falluel-Morel
David
D
Vaudry
Christine
C
Bucharles
Valerie
V
Jolivel
Cecile
C
Fisch
Stephane
S
De Jouffrey
Jean-Francois
JF
Le Bigot
Alain
A
Fournier
Hubert
H
Vaudry
Bruno J
BJ
Gonzalez
D000818:Animals; D002144:Callithrix; D002531:Cerebellum / Q000166:cytology / Q000378:metabolism*; D005260:Female; D007150:Immunohistochemistry; D008252:Macaca fascicularis; D008297:Male; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide / Q000378:metabolism*; D051236:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide / Q000145:classification / Q000378:metabolism*
D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D051236:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide