Premium
Morphine‐induced activation of the map kinase ERK in neostriatal neurons expressing the endogenous mu opioid receptor is rescued by dominant positive arrestin3
Author(s) -
Macey Tara A,
Lowe Janet,
Bruchas Michael R,
Chavkin Charles
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.5.a1122-a
Subject(s) - agonist , mapk/erk pathway , chemistry , kinase , enkephalin , opioid receptor , phosphorylation , receptor , beta adrenergic receptor kinase , microbiology and biotechnology , endocrinology , medicine , opioid , biology , g protein coupled receptor , biochemistry
Mu opioid receptor (MOR) activation of the MAP kinase ERK (pERK) has been previously characterized using heterologously expressed receptors and arrestins. In this study we investigated whether activation of endogenous MOR could stimulate ERK phosphorylation and attempted to define the role of endogenous arrestin3. The MOR agonist fentanyl (100 nM) caused significant activation (62% above basal levels) of pERK in primary cultured neurons harvested from wildtype mice as assessed using immunoblot analysis and confocal microscopy. However, pERK activation by fentanyl was not evident in neurons harvested from MOR‐knockout (KO) or G‐protein receptor kinase 3 (GRK3) KO mice. Morphine (10 μM) treatment of wildtype, MOR KO or GRK3 KO mice did not elicit pERK activation. However, when dominant positive arrestin3 (R170E) was transfected, morphine greatly enhanced activation (70% above basal levels) of pERK (p<0.01). Treatment of R170E‐transfected neostriatal neurons with fentanyl did not potentiate its activation of pERK. In addition, treatment with fentanyl and morphine, to a lesser extent, increased the colocalization of endogenous MOR and endogenous arrestin3 as assessed using confocal microscopy. The activation of the MAP kinase p38 was not increased by either fentanyl or morphine treatment in neurons cultured from wildtype, MOR KO, or GRK3 KO mice. These results support the concept that MOR activation of ERK requires receptor phosphorylation by GRK and the association of arrestin in order to initiate the cascade resulting in ERK phosphorylation (DA11672, T32NS07332)