Interleukin-1β Alters Hebbian Synaptic Plasticity in Multiple Sclerosis

Ginsenoside Rb1 protects hippocampal neurons in depressed rats based on mitophagy-regulated astrocytic pyroptosis

BACKGROUND

Astrocytes play a vital role in offering functional support for neurons, which are related to the pathogenic mechanism of depression. Ginsenoside Rb1 (GRb1) is demonstrated with antidepressant-like activities.

PURPOSE

We aimed to investigate whether GRb1 can inhibit mitophagy-mediated astrocytic pyroptosis to protect neurons in depression.

STUDY DESIGN

Model rats were subjected to chronic unpredictable mild stress (CUMS) for determining the in vivo antidepressant activity of GRb1.

METHODS

The mitophagy-mediated antipyroptosis role of GRb1 was assessed in lipopolysaccharide (LPS) + ATP-stimulated astrocytes. The mechanism by which GRb1 protects synaptic plasticity was investigated using hippocampal neurons incubated in an astrocyte medium. The rat depressive-like behaviors were determined through sucrose preference, forced swimming, and the open-field tests. Escitalopram was used in the anti-depression control of GRb1. Cyclosporin A (CsA), a mitophagy inhibitor, and interleukin (IL)-1β were used to reverse the role of GRb1 in mitophagy and pyroptosis, respectively.

RESULTS

GRb1 inhibited LPS-induced inflammation and activation in the astrocytes and repressed nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathway. Also, GRb1 repressed LPS + ATP-promoted astrocytic pyroptosis. During GRb1 treatment, the activation of mitophagy with a decrease in ROS was observed in LPS + ATPs-stimulated astrocytes. CsA enhanced GRb1-decreased ROS and promoted astrocytic pyroptosis. The GRb1-treated astrocyte medium suppressed neuron death and increased neuron viability and synaptic density. Escitalopram and GRb1 improved the depressive-like behaviors of the rats. GRb1 activated mitophagy and inhibited astrocytic activation and pyroptosis in rats with depression. It also reduced impairments in synaptic structures and increased synaptic density in depressive-like rats. IL-1β increased astrocytic pyroptosis and reversed GRb1-enhanced synaptic plasticity in the rats exposed to CUMS. There were no statistical changes in depressive-like behaviors between GRb1 and Escitalopram groups.

CONCLUSION

GRb1 modulates mitophagy and the NF-κB pathway to inhibit astrocytic pyroptosis, thereby maintaining neurological homeostasis by repressing inflammation and enhancing synaptic plasticity.

Molecular Mechanisms of Synaptic Plasticity 2.0: Dynamic Changes in Neurons Functions, Physiological and Pathological Process

Due to the success of the first Special Issue on synaptic plasticity, I endeavored to promote a new Special Issue with an emphasis on dynamic changes in neuronal functions and physiological and pathological processes [...].

Chelation Therapy Associated with Antioxidant Supplementation Can Decrease Oxidative Stress and Inflammation in Multiple Sclerosis: Preliminary Results

An imbalance of oxy-inflammation status has been involved in axonal damage and demyelination in multiple sclerosis (MS). The aim of this study was to investigate the efficacy of an antioxidant treatment (calcium disodium ethylenediaminetetracetic acid-EDTA) chelation therapy associated with a micronutrient complex in MS patients. A total of 20 MS patients and 20 healthy subjects, enrolled as a control group (CTR), were recruited. We measured the plasma ROS production and total antioxidant capacity (TAC) by a direct assessment using Electron Paramagnetic Resonance; activities of the antioxidant system (thiols' redox status and enzymes); and the urinary presence of biomarkers of oxidative stress by immunoenzymatic assays. We also evaluated the levels of inflammation by plasmatic cytokines (TNFα, IL-1β, and IL-6) and assessed the sICAM levels, as well as the nitric oxide (NO) catabolism and transthyretin (TTR) concentration. Comparing CTR and MS, in the latter ROS production, oxidative damage, inflammatory biomarkers, and NO metabolite concentrations results were significantly higher, while TAC was significantly lower. Treatment in MS induced significant (p < 0.05) down-regulating of pro-inflammatory sICAM1, TNF-α, IL6, as well as biomarkers of lipid peroxidation and DNA damage production. The protective effect exhibited may occur by decreasing ROS production and increasing antioxidant capacity, turning into a more reduced thiols' status.

Biology of cyclooxygenase-2: An application in depression therapeutics

Depressive Disorder is a common mood disorder or affective disorder that is dominated by depressed mood. It is characterized by a high incidence and recurrence. The onset of depression is related to genetic, biological and psychosocial factors. However, the pathogenesis is still unclear. In recent years, there has been an increasing amount of research on the inflammatory hypothesis of depression, in which cyclo-oxygen-ase 2 (COX-2), a pro-inflammatory cytokine, is closely associated with depression. A variety of chemical drugs and natural products have been found to exert therapeutic effects by modulating COX-2 levels. This paper summarizes the relationship between COX-2 and depression in terms of neuroinflammation, intestinal flora, neurotransmitters, HPA axis, mitochondrial dysfunction and hippocampal neuronal damage, which can provide a reference for further preventive control, clinical treatment and scientific research on depression.

Interleukin 10 Restores Lipopolysaccharide-Induced Alterations in Synaptic Plasticity Probed by Repetitive Magnetic Stimulation

Systemic inflammation is associated with alterations in complex brain functions such as learning and memory. However, diagnostic approaches to functionally assess and quantify inflammation-associated alterations in synaptic plasticity are not well-established. In previous work, we demonstrated that bacterial lipopolysaccharide (LPS)-induced systemic inflammation alters the ability of hippocampal neurons to express synaptic plasticity, i.e., the long-term potentiation (LTP) of excitatory neurotransmission. Here, we tested whether synaptic plasticity induced by repetitive magnetic stimulation (rMS), a non-invasive brain stimulation technique used in clinical practice, is affected by LPS-induced inflammation. Specifically, we explored brain tissue cultures to learn more about the direct effects of LPS on neural tissue, and we tested for the plasticity-restoring effects of the anti-inflammatory cytokine interleukin 10 (IL10). As shown previously, 10 Hz repetitive magnetic stimulation (rMS) of organotypic entorhino-hippocampal tissue cultures induced a robust increase in excitatory neurotransmission onto CA1 pyramidal neurons. Furthermore, LPS-treated tissue cultures did not express rMS-induced synaptic plasticity. Live-cell microscopy in tissue cultures prepared from a novel transgenic reporter mouse line [C57BL/6-Tg(TNFa-eGFP)] confirms that ex vivo LPS administration triggers microglial tumor necrosis factor alpha (TNFα) expression, which is ameliorated in the presence of IL10. Consistent with this observation, IL10 hampers the LPS-induced increase in TNFα, IL6, IL1β, and IFNγ and restores the ability of neurons to express rMS-induced synaptic plasticity in the presence of LPS. These findings establish organotypic tissue cultures as a suitable model for studying inflammation-induced alterations in synaptic plasticity, thus providing a biological basis for the diagnostic use of transcranial magnetic stimulation in the context of brain inflammation.