The Journal of Neuroscience, June 1, 2001, 21(11):3849-3859
Pituitary Adenylyl Cyclase-Activating Polypeptide Stimulates DNA
Synthesis But Delays Maturation of Oligodendrocyte Progenitors
Matthew
Lee1,
Vincent
Lelièvre1,
Paul
Zhao1,
Mike
Torres2,
Williams
Rodriguez1,
Ji-Yun
Byun1,
Sameer
Doshi1,
Yevgenyia
Ioffe1,
Gauree
Gupta1,
Araceli Espinosa
de los
Monteros1,
Jean
de
Vellis1, and
James
Waschek1
1 Departments of Neurobiology and Psychiatry and Mental
Retardation Research Center and 2 Department of Biological
Chemistry, University of California, Los Angeles, Los Angeles,
California 90024-1759
The neuropeptide pituitary adenylyl cyclase-activating peptide
(PACAP) and one of its receptors (PAC1) are
expressed in embryonic neural tube, where they appear to regulate
neurogenesis and patterning. We now show that PAC1 gene
expression is also present in neonatal rats in the ventricular and
subventricular zones and in the optic chiasm, areas that are rich in
oligodendrocyte (OL) progenitors (OLP). Because actions of PACAP on OLP
have not been reported, we examined the effects of PACAP on the
proliferation of purified OLP in culture and on myelinogenesis in
cerebellar slices. Northern analyses on total RNA from purified glial
cell subtypes revealed an abundant 7 kb hybridizing transcript in OLP,
which was confirmed to correspond to the PAC1 receptor by
reverse transcription-PCR. The presence of this receptor was also
corroborated by radioligand binding and cAMP assay. In cultured OL,
receptor density decreased during maturation but was partially
counterbalanced by the appearance of sites that bound both PACAP and
the related peptide vasoactive intestinal peptide. PACAP increased DNA
synthesis in OLP cultures almost twofold and increased the
bromodeoxyuridine-labeling index in O4-positive OLP. PACAP
treatment also resulted in decreased sulfate incorporation into
sulfatide in cultures of differentiating OL. The PACAP effect on
sulfatide synthesis was fully reproduced in a cerebellar explant model.
These findings indicate that PACAP may act at two stages during OL
development to (1) stimulate proliferation and (2) delay
maturation and/or myelinogenesis.
Key words:
PACAP receptors (PAC1); PACAP; oligodendrocytes; proliferation; cAMP; myelination
Copyright © 2001 Society for Neuroscience 0270-6474/01/21113849-11$05.00/0