Molecular Toxicology and Pathophysiology of Comorbid Alcohol Use Disorder and Post-Traumatic Stress Disorder Associated with Traumatic Brain Injury.

The increasing comorbidity of alcohol use disorder (AUD) and post-traumatic stress disorder (PTSD) associated with traumatic brain injury (TBI) is a serious medical, economic, and social issue. However, the molecular toxicology and pathophysiological mechanisms of comorbid AUD and PTSD are not well understood and the identification of the comorbidity state markers is significantly challenging. This review summarizes the main characteristics of comorbidity between AUD and PTSD (AUD/PTSD) and highlights the significance of a comprehensive understanding of the molecular toxicology and pathophysiological mechanisms of AUD/PTSD, particularly following TBI, with a focus on the role of metabolomics, inflammation, neuroendocrine, signal transduction pathways, and genetic regulation. Instead of a separate disease state, a comprehensive examination of comorbid AUD and PTSD is emphasized by considering additive and synergistic interactions between the two diseases. Finally, we propose several hypotheses of molecular mechanisms for AUD/PTSD and discuss potential future research directions that may provide new insights and translational application opportunities.

Melatonin and Autophagy in Aging-Related Neurodegenerative Diseases.

With aging, the nervous system gradually undergoes degeneration. Increased oxidative stress, endoplasmic reticulum stress, mitochondrial dysfunction, and cell death are considered to be common pathophysiological mechanisms of various neurodegenerative diseases (NDDs) such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), organophosphate-induced delayed neuropathy (OPIDN), and amyotrophic lateral sclerosis (ALS). Autophagy is a cellular basic metabolic process that degrades the aggregated or misfolded proteins and abnormal organelles in cells. The abnormal regulation of neuronal autophagy is accompanied by the accumulation and deposition of irregular proteins, leading to changes in neuron homeostasis and neurodegeneration. Autophagy exhibits both a protective mechanism and a damage pathway related to programmed cell death. Because of its "double-edged sword", autophagy plays an important role in neurological damage and NDDs including AD, PD, HD, OPIDN, and ALS. Melatonin is a neuroendocrine hormone mainly synthesized in the pineal gland and exhibits a wide range of biological functions, such as sleep control, regulating circadian rhythm, immune enhancement, metabolism regulation, antioxidant, anti-aging, and anti-tumor effects. It can prevent cell death, reduce inflammation, block calcium channels, etc. In this review, we briefly discuss the neuroprotective role of melatonin against various NDDs via regulating autophagy, which could be a new field for future translational research and clinical studies to discover preventive or therapeutic agents for many NDDs.

Electroacupuncture Improves M2 Microglia Polarization and Glia Anti-inflammation of Hippocampus in Alzheimer's Disease.

Background: Alzheimer's disease (AD) is a neurodegenerative disease characterized by loss of recognition and memory. Neuroinflammation plays pivotal roles in the pathology of AD and affects the progression of the disease. Astrocyte and microglia, as main immune executors in the central nervous system (CNS), participate into the inflammatory response in AD. Glia polarize into different phenotypes during neurodegeneration. Pro-inflammatory glia produce cytokines (IL-1ß, TNF-α, and IL-6) resulting into debris aggregates and neurotoxicity. Anti-inflammatory phenotypes produce cytokines (IL-4 and IL-10) to release the inflammation. Electroacupuncture is a useful treatment that has been found to slow the neurodegeneration in animals through experimentation and in humans through clinical trials. The aim of this study was to uncover the mechanisms of glia activation, microglia polarization, and cytokine secretion regulated by electroacupuncture as a treatment for AD. Methods: Twenty male Sprague-Dawley (SD) rats were randomly divided into four groups: Control group (Control), Normal saline group (NS), AD group (AD), and Electroacupuncture group (Acupuncture). The AD and Acupuncture groups were bilaterally injected with Aß1 - 42 into the CA1 field of the hippocampus. The Acupuncture group received electroacupuncture stimulation on the acupoint "Baihui" (GV20) for 6 days per week for a total of 3 weeks. The Morris Water Maze (MWM) was used to evaluate learning and memory capacity. Immunofluorescence was used to stain GFAP and Iba1 of the DG and CA1 in the hippocampus, which, respectively, expressed the activation of astrocyte and microglia. The M1 microglia marker, inducible nitric oxide synthase (iNOS), and M2 marker Arginase 1 (Arg1) were used to analyze the polarization of microglia. The pro-inflammatory cytokines (IL-1ß, TNF-α, and IL-6), anti-inflammatory cytokines (IL-4 and IL-10), and pathway-molecules (p65 and Stat6) were tested to analyze the glia inflammatory response by immunofluorescence and polymerase chain reaction (PCR). Results: The MWM results showed that electroacupuncture improves the escape latency time and the swimming distance of AD rats. The number of GFAP and Iba1 cells significantly increased in AD rats, but electroacupuncture decreased the cells. The iNOS-positive cells were significantly increased in AD, and electroacupuncture decreased the positive cells. Electroacupuncture elevated Arg1-positive cells in AD rats. Electroacupuncture decreased the glia pro-inflammatory cytokine expression and increased the anti-inflammatory cytokine expression in AD rats. Furthermore, electroacupuncture inhibited the NF-κB pathway molecule (p65) while raising the Stat6 pathway molecule (Stat6). Conclusion: These results provide evidence that electroacupuncture improves the recognition abilities and memory of AD rats. Electroacupuncture inhibits the activation of glia and polarizes microglia toward the M2 phenotype. Electroacupuncture decreased the pro-inflammatory cytokines (IL-1ß, TNF-α, and IL-6) and increased the anti-inflammatory cytokines (IL-4 and IL-10). Furthermore, electroacupuncture affects the immune responses through inhibition of NF-κB pathway but activation of Stat6 pathway.

Inflammatory factors and amyloid ß-induced microglial polarization promote inflammatory crosstalk with astrocytes.

The immunological responses are a key pathological factor in Alzheimer's disease (AD). We hypothesized that microglial polarization alters microglia-astrocyte immune interactions in AD. M1 and M2 microglia were isolated from primary rat microglia and were confirmed to secrete pro-inflammatory and anti-inflammatory factors, respectively. Primary rat astrocytes were co-cultured with M1 or M2 microglial medium. M1 microglial medium increased astrocyte production of pro-inflammatory factors (interleukin [IL]-1ß, tumor necrosis factor α and IL-6), while M2 microglial medium enhanced astrocyte production of anti-inflammatory factors (IL-4 and IL-10). To analyze the crosstalk between microglia and astrocytes after microglial polarization specifically in AD, we co-cultured astrocytes with medium from microglia treated with amyloid-ß (Aß) alone or in combination with other inflammatory substances. Aß alone and Aß combined with lipopolysaccharide/interferon-γ induced pro-inflammatory activity in M1 microglia and astrocytes, whereas IL-4/IL-13 inhibited Aß-induced pro-inflammatory activity. Nuclear factor κB p65 was upregulated in M1 microglia and pro-inflammatory astrocytes, while Stat6 was upregulated in M2 microglia and anti-inflammatory astrocytes. These results provide direct evidence that microglial polarization governs communication between microglia and astrocytes, and that AD debris alters this crosstalk.