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Novel systemically active galanin receptor 2 ligands in depression‐like behavior
Author(s) -
Saar Indrek,
Lahe Jaanus,
Langel Kent,
Runesson Johan,
Webling Kristin,
Järv Jaak,
Rytkönen Jussi,
Närvänen Ale,
Bartfai Tamas,
Kurrikoff Kaido,
Langel Ülo
Publication year - 2013
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 - 10.1111/jnc.12274
Subject(s) - galanin , galanin receptor , tail suspension test , neuropeptide , pharmacology , receptor , in vivo , behavioural despair test , endocrinology , medicine , chemistry , antidepressant , biology , hippocampus , microbiology and biotechnology
Neuropeptide galanin and its three G‐protein coupled receptors, galanin receptor type 1–galanin receptor type 3 (GalR1–GalR3), are involved in the regulation of numerous physiological and disease processes, and thus represent tremendous potential in neuroscience research and novel drug lead development. One of the areas where galanin is involved is depression. Previous studies have suggested that activation of GalR2 leads to attenuation of depression‐like behavior. Unfortunately, lack of in vivo usable subtype specific ligands hinders testing the role of galanin in depression mechanisms. In this article, we utilize an approach of increasing in vivo usability of peptide‐based ligands, acting upon CNS . Thus, we have synthesized a series of novel systemically active galanin analogs, with modest preferential binding toward GalR2. We have shown that specific chemical modifications to the galanin backbone increase brain levels upon i.v. injection of the peptides. Several of the new peptides, similar to a common clinically used antidepressant medication imipramine, exerted antidepressant‐like effect in forced swim test, a mouse model of depression, at a surprisingly low dose range (< 0.5 mg/kg). We chose one of the peptides, J18, for more thorough study, and showed its efficacy also in another mouse depression model (tail suspension test), and demonstrated that its antidepressant‐like effect upon i.v. administration can be blocked by i.c.v. galanin receptor antagonist M35. The effect of the J18 was also abolished in GalR2 KO animals. All this suggests that systemically administered peptide analog J18 exerts its biological effect through activation of GalR2 in the brain. The novel galanin analogs represent potential drug leads and a novel pharmaceutical intervention for depression.We utilize several chemical modifications to increase in vivo usability of peptide‐based ligands, acting upon CNS. Accordingly, we introduce a series of novel systemically active galanin analogues, with modest preferential binding towards GalR2, and demonstrate their ability to attenuate depression‐like behavior via brain GalR2 in different mouse models of depression.