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Absence of P 2 ‐purinoceptors in hippocampal pathways
Author(s) -
Stone T.W.,
Cusack N.J.
Publication year - 1989
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1989.tb11996.x
Subject(s) - adenosine , nucleotide , chemistry , purinergic receptor , carbachol , adenine nucleotide , hippocampal formation , p2y receptor , adenosine triphosphate , adenosine receptor , adenosine a1 receptor , inhibitory postsynaptic potential , purinergic signalling , receptor , biochemistry , biophysics , neuroscience , biology , agonist , gene
1 Many apparent actions of adenosine 5″‐triphosphate (ATP) are mediated by adenosine produced by enzymatic hydrolysis of the nucleotide. Previously described actions of ATP in the CNS have been partly due to this phenomenon. In the present study analogues of ATP, which are not hydrolysed to adenosine, were used to seek responses to activating nucleotide (P 2 ) receptors in the hippocampus. The analogues used were l ‐adenosine‐5″‐(β,γ‐methylene)‐triphosphonate and 2‐methylthio‐adenosine‐5″‐(β,γ‐difluoromethylene)‐triphosphonate. 2 Neither of the stable nucleotides had any effect on orthodromically evoked synaptic potentials in the CAl region of rat hippocampal slices. Adenosine and ATP had inhibitory actions that could be prevented by the P 1 ‐receptor blocker 8‐phenyltheophylline. 3 The stable nucleotides had no consistent effects on the firing rate of single neurones in stratum pyramidale of the CA1 region, although adenosine and ATP produced a xanthine‐sensitive inhibition. 4 Adenosine selectively reduced the sensitivity of CA1 neurones to microiontophoretically applied carbachol whereas stable nucleotides did not. 5 It is concluded that there are neither P 2X ‐ nor P 2Y ‐receptors for adenine nucleotides on rat hippocampal CA1 pyramidal cells at the Schaffer collateral and commissural terminals in stratum radiatum.