VIP receptor subtypes in mouse cerebral cortex: evidence for a differential localization in astrocytes, microvessels and synaptosomal membranes

Details

Serval ID
serval:BIB_B02A61008C12
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
VIP receptor subtypes in mouse cerebral cortex: evidence for a differential localization in astrocytes, microvessels and synaptosomal membranes
Journal
Brain Research
Author(s)
Martin  J. L., Feinstein  D. L., Yu  N., Sorg  O., Rossier  C., Magistretti  P. J.
ISSN
0006-8993
Publication state
Published
Issued date
07/1992
Peer-reviewed
Oui
Volume
587
Number
1
Pages
1-12
Notes
Journal Article
Research Support, Non-U.S. Gov't --- Old month value: Jul 31
Abstract
The binding characteristics of a monoiodinated form of vasoactive intestinal peptide (M-[125I]VIP) to the membranes of astrocytes, intraparenchymal microvessels and synaptosomes were analyzed in mouse cerebral cortex. Binding to astrocytes, studied in primary cultures, indicates the presence of a single class of high affinity binding sites with a Kd of 3.3 nM and a Bmax of 565 fmol/mg protein. The structurally related peptide secretin does not compete for sites labeled by M-[125I]VIP. In cultured astrocytes, VIP has been previously shown to promote glycogenolysis. Secretin, despite its lack of interaction with sites labeled by M-[125I]VIP, stimulates glycogenolysis with an EC50 of 0.5 nM, thus demonstrating the presence in astrocytes of functional secretin receptors independent from those for VIP. Trypsinization of the primary astrocyte cultures followed by replating as secondary cultures, reveals a second class of low affinity binding sites, with a Kd of 41.3 nM and a Bmax of 881 fmol/mg protein. Secretin does not compete for this class of low affinity binding sites either. Binding of M-[125I]VIP to intraparenchymal microvessels reveals the presence of two classes of binding sites with Kd of 1.4 and 30.3 nM, and Bmax of 7.1 and 73.8 pmol/mg protein, respectively. Similar to what is observed in primary or secondary astrocyte cultures, secretin does not interact with these sites. In this cell type VIP stimulates cAMP formation with an EC50 of 18 nM, while secretin is ineffective. Finally, in agreement with previous reports in rat and guinea pig cerebral cortex, two classes of binding sites are observed in synaptosomal membranes: a high affinity class with a Kd of 4.9 nM and a Bmax of 316 fmol/mg protein, and a low affinity class with a Kd of 42.8 nM and a Bmax of 1578 fmol/mg protein. In contrast to what is observed in non-neuronal membranes, in synaptosomal membranes, secretin effectively competes for sites labeled by M-[125I]VIP with an EC50 of approximately 150 nM. These results indicate that secretin may represent a useful tool to discriminate between neuronal and non-neuronal VIP binding sites, since it competes with M-[125I]VIP exclusively for the neuronal class of binding sites.
Keywords
Animals Animals, Newborn Astrocytes/*metabolism Bucladesine/pharmacology Capillaries/metabolism Cells, Cultured Cerebral Cortex/*metabolism Glycogen/metabolism Male Mice Neurons/metabolism Peptide PHI/pharmacology Receptors, Gastrointestinal Hormone/*metabolism Receptors, Vasoactive Intestinal Peptide Synaptic Membranes/*metabolism Vasoactive Intestinal Peptide/metabolism
Pubmed
Web of science
Create date
20/01/2008 18:22
Last modification date
20/08/2019 15:19
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