Harnessing the Galanin paradox: A receptor- and circuit-based roadmap for precision neuromodulation

Galanin (GAL), a pleiotropic neuropeptide, presents a fascinating paradox in translational medicine. Acting through three distinct G protein-coupled receptors (GPCRs), it exerts profoundly context-dependent effects: in some neural circuits, it can exert either beneficial effects, such as neuroprotection or anti-tumor actions, or detrimental ones, including tumor progression or cognitive impairment, depending on the tissue context and receptor subtype involved. This functional diversity is underpinned by the specific anatomical distribution of GAL and its receptors, which are highly expressed in key brain regions regulating stress, emotion, and homeostasis, such as the locus coeruleus, hypothalamus, and amygdala. This review deconstructs the "Galanin Dilemma" by advancing a circuit- and receptor-context-centric framework for its resolution. We argue that this paradigm shift, moving beyond a simple ligand-based view, is essential for identifying novel therapeutic targets and for proactively navigating the inherent risks of GAL modulation. By establishing a clear framework that links receptor subtype to specific circuit and cellular contexts, we provide a translational roadmap for the rational design of safer, more precise therapies for a range of neurological and oncological disorders.