sinomenine and Encephalitis

Astrocyte-mediated neuroinflammation plays a critical role in ischemic stroke-induced secondary cerebral injury. Previous studies have suggested that the dopamine D2 receptor (DRD2) acts as a key target in regulating the neuroinflammatory response. However, the underlying molecular mechanisms are still unknown, and effective DRD2 agonists are lacking. In the present study, we examined the anti-inflammatory and neuroprotective effects of sinomenine (Sino), a monomeric compound with potential immunoregulatory properties in nervous system.. TTC staining, apoptosis assay, evaluation of brain edema, and neurological assessment were performed in the middle cerebral artery occlusion (MCAO) mouse model. Primary astrocytes exposed to oxygen glucose deprivation (OGD) were used in the in vitro experiments. Quantitative PCR was applied to assess the levels of inflammatory cytokines. Multi-labeling immunofluorescence, Western blot, co-immunoprecipitation, and electrophoretic mobility shift assay (EMSA) were also used to investigate the molecular mechanisms underlying the Sino-mediated anti-inflammatory effects in vivo and in vitro.. Sino remarkably attenuated the cerebral infarction and neuronal apoptosis, reduced the levels of inflammatory cytokines, and alleviated neurological deficiency in MCAO mice. Sino significantly inhibited astrocytic activation and STAT3 phosphorylation as well as increased DRD2 and αB-crystallin (CRYAB) expression after MCAO. In vitro, Sino blocked OGD-induced activation of STAT3 and generation of pro-inflammatory cytokines in primary astrocytes, and these effects were significantly abolished by either DRD2 or CRYAB knockdown. Additionally, Sino induced up-regulation and nuclear translocation of CRYAB in astrocytes and enhanced the interaction between CRYAB and STAT3, which further inhibited the activation and DNA-binding activity of STAT3.. Our study demonstrates that Sino activates astrocytic DRD2 and thereby suppresses neuroinflammation via the CRYAB/STAT3 pathway, which sheds some light on a promising therapeutic strategy for ischemic stroke.

Topics: alpha-Crystallin B Chain; Animals; Animals, Newborn; Antirheumatic Agents; Astrocytes; Brain Edema; Cells, Cultured; Cerebral Infarction; Disease Models, Animal; Encephalitis; Hypoxia; Infarction, Middle Cerebral Artery; Mice; Mice, Inbred C57BL; Morphinans; Nervous System Diseases; Receptors, Dopamine D2; RNA Interference; Signal Transduction; STAT3 Transcription Factor

Microglia polarization plays a vital role in brain inflammatory injury following intracerebral hemorrhage (ICH). Previous studies have shown that sinomenine possesses potential immunoregulatory capabilities. However, microglia polarization's exact mechanisms in ICH remain uncertain. Therefore, we examined the role of sinomenine on microglia polarization and brain inflammation following ICH. For the experiment, autologous blood models were constructed in C57/BL6 mice. Markers of classically activated (M1) and alternatively activated (M2) microglia were detected by real-time polymerase chain reaction, immunofluorescence, and flow cytometry. Microglial toxicity was assessed using MTT and FACS assays. In addition, the neurological deficit and cerebral water content of ICH mice were also observed. Sinomenine attenuated M1 markers while promoting M2 markers of microglia. Sinomenine also protected hippocampal neurons from indirect toxicity mediated by ICH-treated microglia. Additionally, administration of sinomenine inhibited matrix metalloproteinase (MMP) 3/9 expression, cerebral water content, and neurological deficit. Therefore, sinomenine protected brain function following ICH, perhaps via M2 microglia phenotype induction and MMP 3/9 inhibition. This result suggests that sinomenine is a promising therapeutical strategy in ICH.

Topics: Animals; Brain Injuries; Cell Polarity; Cell Survival; Cells, Cultured; Cerebral Hemorrhage; Encephalitis; Male; Mice; Mice, Inbred C57BL; Microglia; Morphinans

The mechanisms involved in the induction and regulation of inflammation resulting in dopaminergic (DA) neurotoxicity in Parkinson's disease (PD) are complex and incompletely understood. Microglia-mediated inflammation has recently been implicated as a critical mechanism responsible for progressive neurodegeneration.. Mesencephalic neuron-glia cultures and reconstituted cultures were used to investigate the molecular mechanisms of sinomenine (SN)-mediated anti-inflammatory and neuroprotective effects in both the lipopolysaccharide (LPS)- and the 1-methyl-4-phenylpyridinium (MPP+)-mediated models of PD.. SN showed equivalent efficacy in protecting against DA neuron death in rat midbrain neuron-glial cultures at both micro- and sub-picomolar concentrations, but no protection was seen at nanomolar concentrations. The neuroprotective effect of SN was attributed to inhibition of microglial activation, since SN significantly decreased tumor necrosis factor-alpha (TNF-alpha, prostaglandin E2 (PGE2) and reactive oxygen species (ROS) production by microglia. In addition, from the therapeutic point of view, we focused on sub-picomolar concentration of SN for further mechanistic studies. We found that 10(-14) M of SN failed to protect DA neurons against MPP+-induced toxicity in the absence of microglia. More importantly, SN failed to show a protective effect in neuron-glia cultures from mice lacking functional NADPH oxidase (PHOX), a key enzyme for extracellular superoxide production in immune cells. Furthermore, we demonstrated that SN reduced LPS-induced extracellular ROS production through the inhibition of the PHOX cytosolic subunit p47phoxtranslocation to the cell membrane.. Our findings strongly suggest that the protective effects of SN are most likely mediated through the inhibition of microglial PHOX activity. These findings suggest a novel therapy to treat inflammation-mediated neurodegenerative diseases.

Topics: Animals; Animals, Newborn; Anti-Inflammatory Agents; Cell Death; Cell Line; Coculture Techniques; Dopamine; Dose-Response Relationship, Drug; Encephalitis; Enzyme Inhibitors; Mice; Mice, Inbred C57BL; Mice, Knockout; Microglia; Morphinans; NADPH Oxidases; Neurons; Neuroprotective Agents; Parkinson Disease; Rats; Rats, Inbred F344; Tumor Necrosis Factor-alpha