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The δ‐Opioid Receptor in SK‐N‐BE Human Neuroblastoma Cell Line Undergoes Heterologous Desensitization
Author(s) -
Namir Noureddine,
Polastron Jocelyne,
Allouche Stéphane,
Hasbi Ahmed,
Jauzac Philippe
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.1471-4159.1997.68041764.x
Subject(s) - adenylyl cyclase , etorphine , chemistry , medicine , endocrinology , homologous desensitization , dopaminergic , adcy9 , desensitization (medicine) , receptor , opioid receptor , enkephalin , opioid , pharmacology , biology , (+) naloxone , dopamine , biochemistry
The human neuroblastoma cell line SK‐N‐BE expresses δ‐opioid receptors negatively coupled to adenylyl cyclase. Prolonged treatment (2 h) of the cells with 100 n M etorphine leads to an almost complete desensitization (8.2 ± 5.9 vs. 45.8 ± 8.7% for the control). Other receptors negatively coupled to adenylyl cyclase, namely, D2‐dopaminergic, α 2 ‐adrenergic, and m2/m4‐muscarinic, were identified by screening of these cells, and it was shown that prolonged treatment (2 h) with 1 µ M 2‐bromo‐α‐ergocryptine or 1 µ M arterenol resulted in a marked desensitization of D2‐dopaminergic and α 2 ‐adrenergic receptors, respectively. Cross‐desensitization experiments revealed that pretreatment with etorphine desensitized with the same efficiency the δ‐opioid receptor and the D2‐dopaminergic receptor, and pretreatment with 2‐bromo‐α‐ergocryptine also desensitized both receptors. In contrast, pretreatment with etorphine desensitized only partly the α 2 ‐adrenergic receptor response, whereas pretreatment with 1 µ M arterenol partly desensitized the δ‐opioid receptor response. It is concluded that the δ‐opioid receptor‐mediated inhibitory response of adenylyl cyclase undergoes heterologous desensitization, and it is suggested that δ‐opioid and D2‐dopaminergic receptors are coupled to adenylyl cyclase via a G i2 protein, whereas α 2 ‐adrenergic receptor could be coupled to the enzyme via two G proteins, G i2 and another member of the G i /G o family.