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Characterization of the kappa opioid receptor‐mediated G protein signaling in mouse striatum using a [ 35 S]GTPγS binding assay (659.6)
Author(s) -
Zhou Lei,
Stahl Edward,
Lovell Kimberly,
Slauson Stephen,
Frankowski Kevin,
Aube Jeffrey,
Bohn Laura
Publication year - 2014
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.28.1_supplement.659.6
Subject(s) - dynorphin , κ opioid receptor , dynorphin a , striatum , chemistry , pharmacology , antagonist , opioid peptide , receptor , opioid , medicine , endocrinology , biochemistry , biology , dopamine
The kappa opioid receptor/dynorphin system is an endogenous system involve in modulating stress responses. Disruption of the ability to respond appropriately to stress can lead to elevated risks of developing mood disorders including depression, anxiety, and drug addiction. The dynorphin peptides are products cleaved from prodynorphin of varying amino acid length and are considered the cognate high affinity ligands for the KORs. However, they also promiscuously bind to and activate other opioid receptors in the brain. Here we seek to determine what component of dynorphin signaling can be attributed specifically to KOR by investigating the pharmacological profiles of dynorphin peptides in wild‐type (WT), KOR knockout (KOR‐KO), and mu opioid receptor knockout (MOR‐KO) mice using [ 35 S]GTPγS binding assay in striatal membrane preparations. We find that dynorphin peptides are efficacious in stimulating [ 35 S]GTPγS binding in WT striatum in a manner that resists concentration‐induced plateau. While KOR activation contributes significantly to dynorphin‐induced [ 35 S]GTPγS binding in striatum, our studies identify a significant contribution of MOR‐induced coupling as well. Moreover, we find that KOR displays a constitutive activity in striatum that can be inhibited by antagonist pretreatment; the constitutive activity is not present in KOR‐KO striatum. Recently developed, functionally selective small molecule KOR agonists as well as new selective KOR antagonists were also tested in striata. Our studies in characterization of dynorphin’s effects at the KOR in brain will be essential for developing ex vivo assays that assess the selective contributions of biased KOR ligands that have been recently developed. Grant Funding Source : Supported by NIDA grant R01 DA031927(LMB, JA)