Melatonin and risk of mortality in subjects with aneurysmal subarachnoid hemorrhage

A Novel Mechanism Linking Melatonin, Ferroptosis and Microglia Polarization via the Circodz3/HuR Axis in Subarachnoid Hemorrhage

A subarachnoid hemorrhage (SAH) is life-threatening bleeding into the subarachnoid space that causes brain damage. Growing evidence has suggested that melatonin provides neuroprotection following SAH. Exploring the mechanisms underlying melatonin-mediated neuroprotection contributes to its clinical application in SAH. The plasma and cerebrospinal fluid (CSF) were collected from SAH patients, and SAH mice were established via pre-chiasmatic injection. Circodz3 expression, levels of IL-1β and TNF-α, brain water content, neurological and beam-waling scores were determined. Ferroptosis was evaluated by analyzing levels of iron, lipid ROS, MDA, and GSH. The colocalization of circodz3 and Iba-1 was analyzed by immunofluorescence staining. Interaction of circodz3 and HuR was determined with RNA pull-down and RNA immunoprecipitation assays. Herein, we found that circodz3 was highly abundant in SAH patients and mice. Colocalization of circodz3 and Iba-1 in the left hemisphere of SAH mice suggested the implication of circodz3 in regulating microglia activation following SAH. Melatonin alleviated brain edema, neurological impairment, and microglia activation and inhibited circodz3 expression in SAH mice. Moreover, melatonin inhibited M1 polarization, oxidative stress and ferroptosis and restrained circodz3 expression in primary microglia following SAH. These effects were abrogated by circodz3 overexpression. Circodz3 knockdown inhibited ferroptosis and M1 polarization of BV2 microglia after SAH. Circodz3 interacted with HuR to facilitate β-Trcp1-mediated ubiquitination and degradation, thus restraining the expression of SLC7A11 and GPX4. Collectively, melatonin exerted neuroprotection following SAH via inhibiting ferroptosis and M1 polarization through the circodz3/HuR axis. Our study suggests potential application of melatonin in the treatment of SAH.

Melatonin as an Antioxidant Agent in Stroke: An Updated Review

Stroke is a devastating disease associated with high mortality and disability worldwide, and is generally classified as ischemic or hemorrhagic, which share certain similar pathophysiological processes. Oxidative stress is a critical factor involved in stroke-induced injury, which not only directly damages brain tissue, but also enhances a series of pathological signaling cascades, contributing to inflammation, brain edema, and neuronal death. To alleviate these serious secondary brain injuries, neuroprotective agents targeting oxidative stress inhibition may serve as a promising treatment strategy. Melatonin is a hormone secreted by the pineal gland, and has various properties, such as antioxidation, anti-inflammation, circadian rhythm modulation, and promotion of tissue regeneration. Numerous animal experiments studying stroke have confirmed that melatonin exerts considerable neuroprotective effects, partially via anti-oxidative stress. In this review, we introduce the possible role of melatonin as an antioxidant in the treatment of stroke based on the latest published studies of animal experiments and clinical research.

Melatonin as a Potential Neuroprotectant: Mechanisms in Subarachnoid Hemorrhage-Induced Early Brain Injury

Subarachnoid hemorrhage (SAH) is a common cerebrovascular disease with high mortality and disability rates. Despite progressive advances in drugs and surgical techniques, neurological dysfunction in surviving SAH patients have not improved significantly. Traditionally, vasospasm has been considered the main cause of death and disability following SAH, but anti-vasospasm therapy has not benefited clinical prognosis. Many studies have proposed that early brain injury (EBI) may be the primary factor influencing the prognosis of SAH. Melatonin is an indole hormone and is the main hormone secreted by the pineal gland, with low daytime secretion levels and high nighttime secretion levels. Melatonin produces a wide range of biological effects through the neuroimmune endocrine network, and participates in various physiological activities in the central nervous system, reproductive system, immune system, and digestive system. Numerous studies have reported that melatonin has extensive physiological and pharmacological effects such as anti-oxidative stress, anti-inflammation, maintaining circadian rhythm, and regulating cellular and humoral immunity. In recent years, more and more studies have been conducted to explore the molecular mechanism underlying melatonin-induced neuroprotection. The studies suggest beneficial effects in the recovery of intracerebral hemorrhage, cerebral ischemia-reperfusion injury, spinal cord injury, Alzheimer’s disease, Parkinson’s disease and meningitis through anti-inflammatory, antioxidant and anti-apoptotic mechanisms. This review summarizes the recent studies on the application and mechanism of melatonin in SAH.