Natural Inhibitors on Over-Activation of Microglia from Herbals

Microglia and cognitive impairment in schizophrenia: translating scientific progress into novel therapeutic interventions

Cognitive impairment is a core clinical feature of schizophrenia, exerting profound adverse effects on social functioning and quality of life in a large proportion of patients with schizophrenia. However, the mechanisms underlying the pathogenesis of schizophrenia-related cognitive impairment are not well understood. Microglia, the primary resident macrophages in the brain, have been shown to play important roles in psychiatric disorders, including schizophrenia. Increasing evidence has revealed excessive microglial activation in cognitive deficits related to a broad range of diseases and medical conditions. Relative to that about age-related cognitive deficits, current knowledge about the roles of microglia in cognitive impairment in neuropsychiatric disorders, such as schizophrenia, is limited, and such research is in its infancy. Thus, we conducted this review of the scientific literature with a focus on the role of microglia in schizophrenia-associated cognitive impairment, aiming to gain insight into the roles of microglial activation in the onset and progression of such impairment and to consider how scientific advances could be translated to preventive and therapeutic interventions. Research has demonstrated that microglia, especially those in the gray matter of the brain, are activated in schizophrenia. Upon activation, microglia release key proinflammatory cytokines and free radicals, which are well-recognized neurotoxic factors contributing to cognitive decline. Thus, we propose that the inhibition of microglial activation holds potential for the prevention and treatment of cognitive deficits in patients with schizophrenia. This review identifies potential targets for the development of new treatment strategies and eventually the improvement of care for these patients. It might also help psychologists and clinical investigators in planning future research.

Dapsone Protects Against Lithium-Pilocarpine-Induced Status Epilepticus in Rats through Targeting Tumor Necrosis Factor-α and Nitrergic Pathway

Background and Purpose

Status epilepticus (SE) results in permanent neuronal brain damage in the central nervous system. One of the complex etiologies underlying SE pathogenesis is neuroinflammation. Dapsone has been recently considered as a potential neuroprotective agent in neuroinflammatory conditions. Therefore, the present study aims to investigate effects of dapsone on lithium-pilocarpine-induced SE in rats and assess whether tumor necrosis factor-alpha (TNF-α) and nitric oxide (NO) pathway participate in this effect.

Methods

SE was established by injecting lithium chloride (127 mg/kg, intraperitoneally [i.p.]) and pilocarpine (60 mg/kg, i.p.). The animals received pre-treatment dapsone (2, 5, 10, and 20 mg/kg, oral gavage) and post-treatment dapsone (10 mg/kg). Subsequently, seizure score and mortality rate were documented. To assess the underlying signaling pathway, L-Nω-Nitro-L-arginine methyl ester hydrochloride (a non-specific NO synthase [NOS] inhibitor), 7-nitroindazole (a specific neuronal NOS inhibitor), and aminoguanidine (a specific inducible NOS inhibitor) were administered 15 minutes before dapsone (10 mg/kg) pre- or post-treatment. Hippocampal tissue TNF-α and NO concentrations were quantified using the enzyme-linked immunosorbent assay method.

Results

Dapsone (10 mg/kg) pre-and post-treatment significantly attenuated the increased seizure score and mortality rate due to lithium-pilocarpine-induced SE. The development of SE in animals was associated with higher TNF-α and NO metabolites levels, which notably decreased in the dapsone-treated rats. Moreover, co-administration of NOS inhibitors with dapsone markedly reversed the anti-epileptic effects of dapsone and caused an escalation in TNF-α level but a significant reduction in NO concentration level.

Conclusions

It seems that dapsone may exert an anti-epileptic effect on lithium-pilocarpine-induced SE through TNF-α inhibition and modulation of the nitrergic pathway.

Natural therapeutic agents for neurodegenerative diseases from the shells of Xanthoceras sorbifolium

Neuroinflammation is linked to neurodegenerative diseases, manifested by the microglial-released over-production of nitric oxide (NO). However, so far there is no effective strategy regarding curing or preventing neurodegenerative diseases. Triterpene saponins from Xanthoceras sorbifolium were proved to be capable of eliciting a protective effect in neurodegenerative diseases. Thus, a systematic chemical study on the 70% ethanol extract of X. sorbifolium was conducted, leading to the identification of 22 compounds, including four previously undescribed triterpenes saponins and 14 known ones, along with four alkaloids. Their structures were elucidated by physicochemical and spectral methods. The in vivo anti-AD effects of 1-18 were predicted with a field-based 3D-QSAR model and anti-neuroinflammatory activities were assayed in BV-2 cells by assessing LPS-induced NO production and examine levels of iNOS, TNF-α, IL-1β, and IL-6 to support the predicted results. As a result, compounds 14, 16, 19, and 20 could have therapeutic potentials for neurodegenerative diseases due to their potent anti-neuroinflammatory activities.