Gabapentin, α2δ-1 Modulation, and Neuroimmune Signaling in Chronic Pain: A Structured Narrative Review

Background/Objectives: Gabapentin is a first-line treatment for neuropathic pain, classically understood to reduce neuronal excitability through binding to the alpha-2-delta-1 (α2δ-1) subunit of voltage-gated calcium channels. However, this neuron-centric model does not fully explain its variable clinical efficacy across pain syndromes. In parallel, chronic pain is increasingly conceptualized as involving neuron–glia–immune interactions, in which microglial activation, astrocytic signaling, and inflammatory mediators may contribute to central sensitization. Methods: A structured narrative review was conducted using PubMed, Web of Science, and Google Scholar for articles available through December 2025. The search focused on gabapentin/gabapentinoids, chronic and neuropathic pain, α2δ-1 mechanisms, neuron–glia interactions, neuroinflammation, central and peripheral sensitization, nociplastic pain, cytokine/chemokine signaling, and neuroimmune modulation. Basic science studies, animal models, translational studies, clinical trials, reviews, meta-analyses, and guidelines were narratively synthesized. Results: Preclinical evidence indicates that gabapentin reduces neuronal hyperexcitability and may secondarily attenuate neuron-to-glia signaling, glial activation, and cytokine- and chemokine-related pathways. However, these neuroimmune effects remain predominantly preclinical, model-dependent, and incompletely validated in humans. Clinical evidence supports gabapentin for selected neuropathic pain conditions, but human studies rarely evaluate glial activation, cytokine signaling, or neuroimmune biomarkers. Conclusions: Gabapentin remains best understood as a neuronal α2δ-1 modulator. Although preclinical and translational evidence suggests biologically plausible secondary effects on neuroimmune signaling, these mechanisms have not been validated as biomarkers or prescribing targets in humans. The conceptual framework presented in this review supports mechanism-informed clinical reasoning and individualized pain management but should not be interpreted as a biomarker-guided prescribing algorithm. Clinically, gabapentin should be prescribed selectively for patients with neuropathic or sensitized pain features, using predefined functional goals, appropriate renal dose adjustment, careful safety monitoring, and discontinuation when meaningful benefit is not achieved.