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Coexpression of Several Types of Metabotropic Nucleotide Receptors in Single Cerebellar Astrocytes
Author(s) -
Jiménez Ana I.,
Castro Enrique,
Communi Didier,
Boeynaems JeanMarie,
Delicado Esmerilda G.,
MirasPortugal M. Teresa
Publication year - 2000
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.2000.0752071.x
Subject(s) - metabotropic receptor , neuroscience , cerebellum , biology , metabotropic glutamate receptor , receptor , genetics , glutamate receptor
We have examined the expression of mRNA for several P2Y nucleotide receptors by northern blot analysis in purified type 1 cerebellar astrocyte cultures. These results suggest that different P2Y subtypes could be responsible for ATP metabotropic calcium responses in single type 1 astrocytes. To identify these subtypes we have studied the pharmacological profile of ATP calcium responses using fura‐2 microfluorimetry. All tested astrocytes responded to ATP and UTP stimulations evoking similar calcium transients. Most astrocytes also responded to 2‐methylthioATP and ADP challenges. The agonist potency order was 2‐methylthioATP > ADP > ATP = UTP. Cross‐desensitization experiments carried out with ATP, UTP, and 2‐methylthioATP showed that 2‐methylthioATP and UTP interact with different receptors, P2Y 1 and P2Y 2 or P2Y 4 . In a subpopulation of type 1 astrocytes, ATP prestimulation did not block UTP responses, and UDP elicited clear intracellular Ca 2+ concentration responses at very low concentrations. 2‐MethylthioATP and UTP calcium responses exhibited different sensitivity to pertussis toxin and different inhibition patterns in response to P2 antagonists. The P2Y 1 ‐specific antagonist N 6 ‐methyl‐2′‐deoxyadenosine 3′,5′‐bisphosphate (MRS 2179) specifically blocked the 2‐methylthio‐ATP responses. We can conclude that all single astrocytes coexpressed at least two types of P2Y metabotropic receptors: P2Y 1 and either P2Y 2 or P2Y 4 receptors. Moreover, 30‐40% of astrocytes also coexpressed specific pyrimidine receptors of the P2Y 6 subtype, highly selective for UDP coupled to pertussis‐toxin insensitive G protein.