Melatonin induces mechanisms of brain resilience against neurodegeneration

Abstract

Melatonin is an endogenous pleiotropic molecule which orchestrates regulatory functions and protective capacity against age-related ailments. The increase in circulating levels of melatonin through dietary supplements intensifies its health benefits. Investigations in animal models have shown that melatonin protects against Alzheimer's disease (AD)-like pathology, although clinical studies have not been conclusive. We hypothesized that melatonin induces changes in the brain that prevent or attenuate AD by increasing resilience. Therefore, we treated healthy nontransgenic (NoTg) and AD transgenic (3xTg-AD) 6-month-old mice with a daily dose of 10 mg/kg of melatonin until 12 months of age. As expected, melatonin reversed cognitive impairment and dementia-associated behaviors of anxiety and apathy and reduced amyloid and tau burden in 3xTg-AD mice. Remarkably, melatonin induced cognitive enhancement and higher wellness level-related behavior in NoTg mice. At the mechanism level, NF-κB and proinflammatory cytokine expressions were decreased in both NoTg and 3xTg-AD mice. The SIRT1 pathway of longevity and neuroprotection was also activated in both mouse strains after melatonin dosing. Furthermore, we explored new mechanisms and pathways not previously associated with melatonin treatment such as the ubiquitin-proteasome proteolytic system and the recently proposed neuroprotective Gas6/TAM pathway. The upregulation of proteasome activity and the modulation of Gas6 and its receptors by melatonin were similarly displayed by both NoTg and 3xTg-AD mice. Therefore, these results confirm the potential of melatonin treatment against AD pathology, by way of opening new pathways in its mechanisms of action, and demonstrating that melatonin induces cognitive enhancement and brain resilience against neurodegenerative processes.

Melatonin alleviates cognition impairment by antagonizing brain insulin resistance in aged rats fed a high‐fat diet

“…Melatonin treatment was associated with weakened microglial and astrocyte activities. Moreover, consistent with a previous report, MLT reduced the levels of hippocampal inflammatory cytokines (such as TNF‐α) and pro‐inflammatory enzymes (such as iNOS and COX‐2), ultimately arresting neuroinflammation.…”

“…Besides helping to maintain circadian rhythms, MLT exhibits many other physiological effects that serve antioxidant, anti‐inflammatory, anti‐apoptotic, anti‐cancer, and analgesic functions. Intriguingly, MLT may exert beneficial effects on several CNS disorders, including cognitive impairments and Alzheimer's disease (AD) . It is also implicated as a neuroprotective agent in cases of traumatic brain injury and ischemic stroke .…”

Melatonin stabilizes rupture‐prone vulnerable plaques via regulating macrophage polarization in a nuclear circadian receptor RORα‐dependent manner

“…no. M5250, dissolved in PBS and given by gavage at a fixed time once a day) . The duration of melatonin administration was 9 weeks.…”

Pharmacologic Approaches for the Management of Apathy in Neurodegenerative Disorders

“…In a mice model of AD, the use of melatonin for 6 months (10 mg/kg) was efficient in reducing levels of apathy and anxiety as well amyloid and tau burden in transgenic AD mice, and could thus constitute a promising treatment opportunity in human research (Corpas et al, 2018).…”