Targeting the Gut-Brain Axis Through Insulin-like Growth Factors: Therapeutic Implications and Future Directions.

The gut-brain axis represents a sophisticated bidirectional communication network connecting the gastrointestinal tract and central nervous system through neural, endocrine, and immune pathways. Insulin-like growth factors (IGFs), particularly IGF-1 and IGF-2, function as pivotal mediators within this communication framework. These polypeptide growth factors regulate intestinal barrier integrity, microbiota homeostasis, neurogenesis, and synaptic plasticity mechanisms. Clinical evidence from 1989 to 2024 demonstrates that gut microbiota-derived short-chain fatty acids enhance IGF-1 production through novel molecular mechanisms. This narrative review examines IGF roles in gut-brain communication and evaluates therapeutic potential for neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, and depression, as well as inflammatory bowel disorders. Current clinical trials investigating IGF-based interventions show preliminary promising results, though studies remain limited in scope and patient numbers. Key therapeutic challenges include delivery mechanisms across biological barriers, oncogenic safety concerns related to cell proliferation, and substantial individual variability in treatment responses. Future directions emphasize development of tissue-specific IGF modulators, microbiome-targeted interventions, and precision medicine approaches utilizing advanced biomarkers. Understanding IGF-mediated gut-brain communication presents therapeutic opportunities for complex pathological conditions simultaneously affecting gastrointestinal and neurological systems.