Galanin(2-11)

Galanin signals through three receptor subtypes with overlapping but distinct roles, and progress long depended on ligands that could tell the subtypes apart. Galanin(2-11), the decapeptide spanning galanin residues two through eleven and also designated AR-M1896, filled that need as a GalR2-preferring agonist. It was deployed to test the hypothesis that different galanin receptors mediate opposing actions in pain processing, and in a rat neuropathic pain model it revealed that low-dose galanin is pronociceptive through GalR2 whereas the anti-allodynic effect of high-dose galanin is mediated by GalR1; the GalR2-selective galanin(2-11) reproduced the pronociceptive but not the anti-allodynic action ^[1].

In the periphery, galanin(2-11) confirmed a GalR2-specific excitatory role in inflammation. Intraplantar galanin(2-11) mimicked galanin's ability to enhance capsaicin-evoked nociceptive behavior and nociceptor firing, and immunohistochemistry showed GalR2 co-expressed with the capsaicin receptor on sensory neurons, supporting the conclusion that peripheral GalR2 amplifies inflammatory pain and can modulate capsaicin-receptor function ^[2]. These studies made galanin(2-11) a standard reagent for attributing galanin effects to GalR2.

Galanin(2-11) has also been important in mood research. Because stimulation of GalR2 at the raphe level increases serotonin levels in the hippocampus and dorsal raphe, GalR2 agonism has been proposed as an antidepressant-relevant mechanism, and galanin(2-11) is the tool most often used to probe it; reviews of galanin receptor pharmacology in mood disorders explicitly discuss galanin(2-11) as the GalR2 agonist that raises serotonergic tone, contrasting it with GAL3 antagonists that act through disinhibition ^[3]. The fragment thus embodies the dual, subtype-dependent nature of galanin biology, being pronociceptive in one context and potentially mood-enhancing in another. It remains a preclinical peptide used for mechanistic dissection rather than a therapeutic candidate.

Galanin(2-11) is a research peptide with no human safety data. Its pronociceptive action in spinal and inflammatory pain models is a notable pharmacodynamic caution, indicating that GalR2 agonism is not uniformly beneficial and can amplify pain in some settings. No toxicology, pharmacokinetic, or reproductive safety studies in humans exist. It is used experimentally by direct central, intrathecal, or local administration and is not suitable for consumer use.

Galanin(2-11)/AR-M1896 was introduced in the early 2000s, notably in a 2001 study by Liu, Hokfelt, and colleagues that used it alongside a mixed GalR1/GalR2 agonist to separate the spinal actions of galanin by receptor subtype. It quickly became a workhorse reagent in galanin pain and mood pharmacology, cited across studies from Karolinska Institutet and collaborators, and it underpinned the conceptual split between GalR1 and GalR2 functions that guided later analog design.

Among galanin researchers galanin(2-11) is the default GalR2-preferring agonist and is trusted as a mechanistic tool, even as newer, more selective ligands have appeared. Its value lies in interpretation rather than therapy: it clarified that galanin's effects on pain and serotonin are subtype-specific. It is unknown in consumer and nootropic markets and available only as a research peptide.