Melatonin as a Pleiotropic Modulator of Mitochondrial Function and Cellular Signaling in Ischemic Brain Injury

Acute ischemic stroke is one of the leading causes of mortality and disability globally, characterized by a complex and temporally structured cascade of cellular and molecular events. Although reperfusion therapies have improved outcomes, their narrow therapeutic window and limited availability leave many patients without effective treatment, highlighting the need for effective neuroprotective strategies capable of targeting multiple interconnected pathways. Melatonin has been proposed as a potential adjunctive neuroprotective agent based on its pleiotropic properties, modulating cellular signaling networks including antioxidant, anti-inflammatory, mitochondrial stabilizing, and BBB-preserving effects. Melatonin regulates key signaling pathways, thereby coordinating cellular responses to injury in multiple stages of ischemic pathophysiology, positioning it as a potential adjunctive therapy. Preclinical studies consistently demonstrate reductions in infarct volume, preservation of neuronal architecture, and improvements in neurological outcomes. However, clinical evidence remains limited to a small number of clinical trials, which suggest safety and possible early neurological benefit but are underpowered to determine long-term efficacy. Importantly, translational gaps persist regarding optimal dosing, duration of administration, and alignment with the temporal dynamics of post-ischemic injury. This review integrates current knowledge on the cellular and molecular mechanisms underlying the potential neuroprotective actions and its role as a pleiotropic modulator of ischemic injury.