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Characterization of CB1 Receptors on Rat Neuronal Cell Cultures: Binding and Functional Studies Using the Selective Receptor Antagonist SR 141716A
Author(s) -
Jung M.,
Calassi R.,
RinaldiCarmona M.,
Chardenot P.,
Le Fur G.,
Soubrié P.,
OuryDonat F.
Publication year - 1997
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.1471-4159.1997.68010402.x
Subject(s) - cannabinoid receptor , forskolin , adenylyl cyclase , receptor , cannabinoid receptor agonists , cannabinoid , protein kinase a , biology , microbiology and biotechnology , chemistry , medicine , endocrinology , agonist , kinase , biochemistry
This study was undertaken to characterize further the central cannabinoid receptors in rat primary neuronal cell cultures from selected brain structures. By using [ 3 H]SR 141716A, the specific CB1 receptor antagonist, we demonstrate in cortical neurons the presence of a high density of specific binding sites ( B max = 139 ± 9 fmol/mg of protein) displaying a high affinity ( K D = 0.76 ± 0.09 n M ). The two cannabinoid receptor agonists, CP 55940 and WIN 55212‐2, inhibited in a concentration‐dependent manner cyclic AMP production induced by either 1 µ M forskolin or isoproterenol with EC 50 values in the nanomolar range (4.6 and 65 n M with forskolin and 1.0 and 5.1 n M with isoproterenol for CP 55940 and WIN 55212‐2, respectively). Moreover, in striatal neurons and cerebellar granule cells, CP 55940 was also able to reduce the cyclic AMP accumulation induced by 1 µ M forskolin with a potency similar to that observed in cortical neurons (EC 50 values of 3.5 and 1.9 n M in striatum and cerebellum, respectively). SR 141716A antagonized the CP 55940‐ and WIN 55212‐2‐induced inhibition of cyclic AMP accumulation, suggesting CB1 receptor‐specific mediation of these effects on all primary cultures tested. Furthermore, CP 55940 was unable to induce mitogen‐activated protein kinase activation in either cortical or striatal neurons. In conclusion, our results show nanomolar efficiencies for CP 55940 and WIN 55212‐2 on adenylyl cyclase activity and no effect on any other signal transduction pathway investigated in primary neuronal cultures.