α-Asarone attenuates chronic sciatica by inhibiting peripheral sensitization and promoting neural repair

Inhalation of Acori Tatarinowii Rhizoma essential oil alleviates dyskinesia in Parkinson's disease rats through the regulation of neuroinflammation

ETHNOPHARMACOLOGICAL RELEVANCE

Acorus tatarinowii Rhizoma, a traditional Chinese medicine known for opening the orifices and transforming phlegm, is used in the treatment of brain disorders. It is listed as the top grade in the famous herbal monograph Shennong Materia Medica Classic. Traditional Chinese medicine believes that Acorus tatarinowii Rhizoma has a good advantage in the treatment of nervous system diseases, and modern research has also found that the essential oil of Acorus tatarinowii Rhizoma is the main component that plays a neuroprotective role and plays an important role in the treatment of Parkinson's disease.

AIM OF THE STUDY

This study aims to explore the effects and mechanisms of essential oil of Acorus tatarinowii Rhizoma (EOAT) on LPS-induced BV2 cell damage and Rotenone-induced Parkinson's disease (PD) rat models.

MATERIALS AND METHODS

In this experiment, the components of EOAT were identified by GC-MS. LPS was used to induce the overactivation of BV2 microglia, and rotenone was injected subcutaneously to induce Parkinson's disease in rats. Then, the expression of inflammatory factors and IBA-1 in cell was evaluated, and the effects of EOAT treatment were assessed on motor function, inflammatory factors, neurotransmitters, TH, α-Syn, and pathways and inflammation-related mRNA in rats.

RESULTS

GC-MS analysis obtained 24 components, among which β-Asarone and α-Asarone had the highest contents. In vitro experiments showed that after 2 h of EOAT intervention, the inflammatory factors TNF-α and IL-6 in the supernatant of LPS-induced BV2 cells were significantly reduced. The IF results showed that after EOAT intervention, the expression of IBA-1 protein in BV2 cells was significantly reduced. In animal experiments, rotenone injection in model rats led to a decrease in motor function, while inhalation of EOAT improved the motor ability of Parkinson's rats. In addition, Madopar and EOAT inhalation increased the levels of BDNF and DA in brain tissue and reduced the levels of IL-Iβ, TNF-α, and IL-6. IHC, IF, and WB analyses showed that the expression of TH protein in brain tissue of the Madopar group and the EOAT group was significantly increased, and the expression level of α-syn was reduced. RT-qPCR results showed that compared with the Model group, the levels of TLR2, MyD88, NF-κB, IL-1β, TNF-α, α-syn, and Bax in the substantia nigra and striatum of the Madopar group and the EOAT group were significantly down-regulated, and the levels of TH and Bcl-2 were significantly up-regulated.

CONCLUSION

These findings suggest that EOAT can prevent LPS from damaging BV2 cells and significantly improve the motor function of PD rats and lessen neuroinflammation. The anti-Parkinson's mechanism of EOAT is primarily dependent on the regulation of the TLR2/MyD88/NF-κB signaling pathway.

Cimifugin Alleviates Chronic Constriction Injury of the Sciatic Nerve by Suppressing Inflammatory Response and Schwann Cell Apoptosis

Inflammation and Schwann cell apoptosis play critical roles in neuropathic pain after sciatic nerve injury. This study aimed to explore the function and mechanism of cimifugin in lipopolysaccharide (LPS)-stimulated rat Schwann cells and sciatic nerves of rats treated with chronic constriction injury (CCI). Thermal, mechanical and cold hyperalgesia of rats in response to cimifugin or mecobalamin (the positive drug control) treatment were evaluated through behavioral tests. H&E staining of sciatic nerves was performed for pathological observation. ELISA was conducted to assess concentrations of inflammatory cytokines in rat serum and sciatic nerves. The intensity of S100β in sciatic nerves was determined using immunohistochemistry. Flow cytometry analysis was conducted for detection of Schwann cell apoptosis. RT-qPCR was performed to measure mRNA levels of inflammatory factors in Schwann cells. Immunofluorescence staining was performed to detect cellular p65/NF-κB activity. Western blotting was performed to quantify protein levels of apoptotic markers and factors associated with the NF-κB and MAPK pathways in rat nerves and Schwann cells. As shown by experimental data, cimifugin mitigated thermal, mechanical and cold hyperalgesia of CCI rats. Cimifugin repressed inflammatory cell infiltration, reduced proinflammatory cytokine levels while increasing anti-inflammatory factor (IL-10) level in serum or sciatic nerves of CCI rats. Cimifugin enhanced S100β expression and downregulated apoptotic markers in vivo. The anti-inflammatory and anti-apoptotic properties of cimifugin were verified in the LPS-stimulated Schwann cells. Moreover, cimifugin suppressed nuclear translocation of p65 NF-κB in vitro and repressed the phosphorylation of IκB, p65 NF-κB, p38 MAPK, ERK1/2, as well as JNK in CCI rats. In conclusion, cimifugin alleviates neuropathic pain after sciatica by suppressing inflammatory response and Schwann cell apoptosis via inactivation of NF-κB and MAPK pathways.

α-asarone activates mitophagy to relieve diabetic encephalopathy via inhibiting apoptosis and oxidative stress

Diabetic encephalopathy (DE) is a common complication of diabetes that may result in cognitive impairment. Currently, there is limited effective therapy for DE. Herein, we explored the beneficial effect of α-Asarone on DE and its potential mechanisms. DE was induced in Type 2 diabetes mellitus mice and high-glucose (HG)-exposed PC-12 cells. Cognitive function was evaluated by MWM test. Pathological changes in the brain tissues were observed by HE staining. Cell viability was detected by CCK-8. Apoptosis was assessed by Hoechst 33,342 staining, Annexin V/PI staining and TUNEL. Mitochondrial membrane potential was analyzed by JC-1 probe. ROS production was measured by DCFH-DA staining. Target protein levels were analyzed by Western blotting. Network pharmacology was used to elucidate the beneficial mechanisms of α-Asarone in DE. Our study showed that α-Asarone enhanced cell viability and suppressed apoptosis in HG-stimulated PC-12 cells. Furthermore, α-Asarone relieved HG-induced reduction in mitochondrial membrane potential and ROS overproduction. In addition, mitophagy was triggered by α-Asarone, which was responsible for the inhibitory effect of α-Asarone on apoptosis and oxidative stress. Consistently, the in vivo experiments showed that α-Asarone treatment relieved cognitive dysfunction, apoptosis, and oxidative stress of DE mice via mitophagy induction. However, inhibition of mitophagy by Mdivi-1 counteracted the beneficial action of α-Asarone. Mechanistically, network pharmacology analysis identified 10 key targets of α-Asarone. Molecular docking substantiated a strong affinity of α-Asarone with CASP3, EGFR, NFKB1, and ESR1 proteins. Taken together, α-Asarone protected against mitochondrial dysfunction, oxidative stress and apoptosis via activating mitophagy, thereby alleviating DE. Our findings suggest α-Asarone as a potential drug for DE.

Network pharmacology and experimental validation reveal the mechanisms of sniffing essential oil of Acori Tatarinowii rhizoma in treating olfactory dysfunction

ETHNOPHARMACOLOGICAL RELEVANCE

Acorus tatarinowii Rhizoma, a traditional Chinese medicine known for open the orifices and transform phlegm, is used in the treatment of brain disorders. The essential oil of Acorus tatarinowii Rhizoma (EOAT) has demonstrated neuroprotective properties clinically. However, research into its effect on Olfactory Dysfunction (OD) remains limited.

AIM OF THE STUDY

This study aimed to investigate the effects and mechanisms of sniffing EOAT on improving olfactory function in a 3-Methylindole (3-MI)-induced OD mouse model.

MATERIALS AND METHODS

The research involved intraperitoneal injection of 3-MI to induce OD in mice. The effects of EOAT treatment were assessed on olfactory function, olfactory bulb (OB) pathology, inflammatory factors, olfactory marker protein (OMP), microglial activation, and related pathway proteins and mRNA.

RESULTS

Based on the GC-MS analysis results of EOAT and network pharmacology studies, we predicted 18 targets associated with the treatment of OD. SLC6A3, MAOB, DRD1, and PTGS2 were identified as the core targets of EOAT against OD. Molecular docking and KEGG enrichment results indicated that EOAT may exert anti-inflammatory effects by acting on the core target PTGS2, with its anti-inflammatory mechanism possibly related to the PI3K/Akt signaling pathway. Subsequent animal experiments confirmed that inhalation of EOAT significantly increased the body weight of OD model mice, shortened the foraging time, enhanced the expression of OMP in OB, reduced damage to the OB cells, and improved olfactory function. Meanwhile, EOAT significantly alleviated the inflammatory response in OB of OD model mice, inhibited the activation of microglial cells, and suppressed the expression of PI3K/Akt signaling pathway proteins and mRNA.

CONCLUSION

EOAT inhalation could improve olfactory function in 3-MI-induced OD model. The underlying mechanism may be related to the modulation of the PI3K/Akt signaling pathway.

TLR4 induced TRPM2 mediated neuropathic pain

Ion channels play an important role in mediating pain through signal transduction, regulation, and control of responses, particularly in neuropathic pain. Transient receptor potential channel superfamily plays an important role in cation permeability and cellular signaling. Transient receptor potential channel Melastatin 2 (TRPM2) subfamily regulates Ca2+ concentration in response to various chemicals and signals from the surrounding environment. TRPM2 has a role in several physiological functions such as cellular osmosis, temperature sensing, cellular proliferation, as well as the manifestation of many disease processes such as pain process, cancer, apoptosis, endothelial dysfunction, angiogenesis, renal and lung fibrosis, and cerebral ischemic stroke. Toll-like Receptor 4 (TLR4) is a critical initiator of the immune response to inflammatory stimuli, particularly those triggered by Lipopolysaccharide (LPS). It activates downstream pathways leading to the production of oxidative molecules and inflammatory cytokines, which are modulated by basal and store-operated calcium ion signaling. The cytokine production and release cause an imbalance of antioxidant enzymes and redox potential in the Endoplasmic Reticulum and mitochondria due to oxidative stress, which results from TLR-4 activation and consequently induces the production of inflammatory cytokines in neuronal cells, exacerbating the pain process. Very few studies have reported the role of TRPM2 and its association with Toll-like receptors in the context of neuropathic pain. However, the molecular mechanism underlying the interaction between TRPM2 and TLR-4 and the quantum of impact in acute and chronic neuropathic pain remains unclear. Understanding the link between TLR-4 and TRPM2 will provide more insights into pain regulation mechanisms for the development of new therapeutic molecules to address neuropathic pain.

Danggui Sini Decoction normalizes the intestinal microbiota and serum metabolite levels to treat sciatica

ETHNOPHARMACOLOGICAL RELEVANCE

Danggui Sini Decoction (DGSD), which is commonly used to treat sciatica, has been shown to have an analgesic effect, but the underlying mechanisms are unclear. Here, Danggui Sini Decoction was shown to normalize the intestinal microbiota and serum metabolite levels to exert an analgesic effect.

AIM OF THE STUDY

This study aimed to elucidate the therapeutic effects of DGSD on sciatica and the underlying mechanisms involved.

METHODS

In this study, we conducted chronic constriction injury (CCI) model. Mecobalamin and DGSD were administered to CCI rats. Behavioural tests were used to examine the therapeutic effects of the drugs. UHPLC was used to identify DGSD components. 16S rRNA gene sequencing analysis of the intestinal flora was used to analyse the effect of DGSD on the intestinal microbiota. UHPLC‒MS/MS was used to identify blood metabolites. KEGG pathway analysis of differentially abundant metabolites was subsequently conducted. ELISA was used to measure the serum inflammatory factor levels, and correlation analysis between the serum inflammatory factor levels and intestinal microbe abundance was conducted. PCR, western blotting, and immunohistochemical staining were used to validate the results of the KEGG pathway analysis.

RESULTS

After CCI, the rats exhibited obvious thermal hyperalgesia; disruption of sciatic nerve structure; increased IL1α, SP, CCL5, and PGE2 levels; decreased IL10 levels in the blood; increased IL1β, IL6, COX2, MMP9, nNOS, and p-NF-κB levels; and decreased IL4 levels in the sciatic nerve. In addition, CCI led to increased abundances of Peptostreptococcaceae, Leuconostocaceae, Christensenellaceae, Akkermansiaceae, Staphylococcaceae, Romboutsia, Marvinbryantia, Turicibacter, Weissella, UCG-005, Christensenellaceae_R-7_group, Akkermansia, Staphylococcus, Romboutsia_ilealis, Weissella_paramesenteroides, and Akkermansia_muciniphila and decreased abundances of Lactobacillaceae, Lactobacillus, Lactobacillus_murinus, and Lactobacillus_johnsonii. Correlation analysis indicated that Turicibacter abundance was most strongly related to IL1α, PGE2, IL10, and CCL5 levels, while norank_o_Coriobacteriales abundance had the weakest relationship with SP levels. KEGG pathway analysis of the differentially abundant metabolites revealed that the 'NF-kappa B signalling pathway' was involved in sciatica. DGSD reduced the levels of inflammatory factors, including IL1α, SP, CCL5, PGE2, IL6, COX2, and MMP9, in the blood and sciatic nerve and inhibited nNOS and NF-κB phosphorylation. DGSD improved the abundance of probiotics, including Lactobacillus and Blautia, and lowered the abundance of harmful bacteria, including Romboutsia, Turicibacter, and Weissella. DGSD promoted the repair of the injured sciatic nerve.

CONCLUSIONS

DGSD can treat sciatica by inhibiting intestinal microbiota disorders induced by CCI in rats, normalizing inflammatory factor levels, and promoting nerve repair.

Dexborneol Amplifies Pregabalin's Analgesic Effect in Mouse Models of Peripheral Nerve Injury and Incisional Pain

Pregabalin is a medication primarily used in the treatment of neuropathic pain and anxiety disorders, owing to its gabapentinoid properties. Pregabalin monotherapy faces limitations due to its variable efficacy and dose-dependent adverse reactions. In this study, we conducted a comprehensive investigation into the potentiation of pregabalin's analgesic effects by dexborneol, a neuroprotective bicyclic monoterpenoid compound. We performed animal experiments where pain models were induced using two methods: peripheral nerve injury, involving axotomy and ligation of the tibial and common peroneal nerves, and incisional pain through a longitudinal incision in the hind paw, while employing a multifaceted methodology that integrates behavioral pharmacology, molecular biology, neuromorphology, and lipidomics to delve into the mechanisms behind this potentiation. Dexborneol was found to enhance pregabalin's efficacy by promoting its transportation to the central nervous system, disrupting self-amplifying vicious cycles via the reduction of HMGB1 and ATP release, and exerting significant anti-oxidative effects through modulation of central lipid metabolism. This combination therapy not only boosted pregabalin's analgesic property but also notably decreased its side effects. Moreover, this therapeutic cocktail exceeded basic pain relief, effectively reducing neuroinflammation and glial cell activation-key factors contributing to persistent and chronic pain. This study paves the way for more tolerable and effective analgesic options, highlighting the potential of dexborneol as an adjuvant to pregabalin therapy.

Spinal microglial M1 polarization contributes paclitaxel-induced neuropathic pain by triggering cells necroptosis

Paclitaxel (PTX) is a chemotherapeutic agent that is widely used for the treatment of several types of tumors. However, PTX-induced peripheral neuropathy (PIPN) is an adverse effect generally induced by long-term PTX use that significantly impairs the quality of life. Necroptosis has been implicated in various neurodegenerative disorders. Necroptosis of dorsal root ganglion neurons triggers the pathogenesis of PIPN. Therefore, the present study aims to investigate the role of spinal neuronal necroptosis in PIPN. It also explores the potential role of microglial polarization in necroptosis. We established rat models of PIPN via quartic PTX administration on alternate days (accumulated dose: 8 mg/kg). PTX induced obvious neuronal necroptosis and upregulated the expression of receptor-interacting protein kinase (RIP3) and mixed lineage kinase domain-like protein (MLKL) in the spinal dorsal horn. These effects were inhibited with a necroptosis pathway inhibitor, necrostatin-1 (Nec-1). The effect of microglial polarization on the regulation of spinal necroptosis was elucidated by administering minocycline to inhibit PTX-induced M1 polarization of spinal microglia caused by PTX. We observed a significant inhibitory effect of minocycline on PTX-induced necroptosis in spinal cord cells, based on the downregulation of RIP3 and MLKL expression, and suppression of tumor necrosis factor-α and IL-β synthesis. Additionally, minocycline improved hyperalgesia symptoms in PIPN rats. Overall, this study suggests that PTX-induced polarization of spinal microglia leads to RIP3/MLKL-regulated necroptosis, resulting in PIPN. These findings suggest a potential target for the prevention and treatment of neuropathic pain.

Stress/cell death pathways, neuroinflammation, and neuropathic pain

Neuropathic pain is a common and debilitating modality of chronic pain induced by a lesion or disease of the somatosensory nervous system. Albeit the elucidation of numerous pathophysiological mechanisms and the development of potential treatment compounds, safe and reliable therapies of neuropathic pain remain poor. Multiple stress/cell death pathways have been shown to be implicated in neuroinflammation during neuropathic pain. Here, we summarize the current knowledge of stress/cell death pathways and present an overview of the roles and molecular mechanisms of stress/cell death pathways in neuroinflammation during neuropathic pain, covering intrinsic and extrinsic apoptosis, autophagy, mitophagy, ferroptosis, pyroptosis, necroptosis, and phagoptosis. Small molecule compounds that modulate stress/cell death pathways in alleviating neuropathic pain are discussed mainly based on preclinical neuropathic pain models. These findings will contribute to in-depth understanding of the pathological processes during neuropathic pain as well as bridge the gap between basic and translational research to uncover new neuroprotective interventions.

Acorus calamus var. angustatus Besser: Insight into current research on ethnopharmacological use, phytochemistry, pharmacology, toxicology, and pharmacokinetics

A. calamus var. angustatus Besser is an important traditional medicinal herb commonly used in China and other Asian countries. This study is the first systematic review of the literature to thoroughly analyze the ethnopharmacological application, phytochemistry, pharmacology, toxicology and pharmacokinetic properties of A. calamus var. angustatus Besser and provides a rationale for future research and prospects for application in clinical treatment. Information on relevant studies investigating A. calamus var. angustatus Besser was collected from SciFinder, the Web of Science, PubMed, CNKI, Elsevier, ResearchGate, ACS, Flora of China, and Baidu Scholar, etc. up to December 2022. In addition, information was also obtained from Pharmacopeias, books on Chinese herbal classics, local books, as well as PhD and MS dissertations. A. calamus var. angustatus Besser has played an important role in the herbal treatment of coma, convulsion, amnesia, and dementia for thousands of years. Studies investigating the chemical constituents of A. calamus var. angustatus Besser have isolated and identified 234 small-molecule compounds and a few polysaccharides. Among them, simple phenylpropanoids represented by asarone analogues and lignans are the two main active ingredients, which can be considered characteristic chemotaxonomic markers of this herb. In vitro and in vivo pharmacological studies indicated that crude extracts and active compounds from A. calamus var. angustatus Besser display a wide range of pharmacological activities, especially as treatment for Alzheimer's disease (AD), and anticonvulsant, antidepressant-like, anxiolytic-like, anti-fatigue, anti-Parkinson, neuroprotection, and brain protection properties, providing more evidence to explain the traditional medicinal uses and ethnopharmacology. The clinical therapeutic dose of A. calamus var. angustatus Besser does not present any toxic effects, but its main active ingredients α-asarone and β-asarone at excessive dose may lead to toxicity, and in particular, their respective epoxide metabolites may exert potential toxicity to the liver. This review provides a reference and further information for the future development and clinical application of A. calamus var. angustatus Besser.

Proteomic and metabolomic approaches elucidate the molecular mechanism of emodin against neuropathic pain through modulating the gamma-aminobutyric acid (GABA)-ergic pathway and PI3K/AKT/NF-κB pathway

Neuropathic pain (NeP) is a major health concern. Due to the complex pathological mechanisms, management of NeP is challenging. Emodin, a natural anthraquinone derivative, exerts excellent analgesic effects. However, its mechanisms of action are still poorly understood. In this study, we investigated the mechanisms underlying pain-relief effects of emodin in the cerebral cortex using proteomic and metabolomic approaches. After 15 days of emodin administration, the mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) values in the emodin groups were significantly higher than those in the chronic constriction injury (CCI) group (p < .05), suggesting emodin treatment could reverse CCI-induced hyperalgesia. Emodin treatment evoked the expression alteration of 402 proteins (153 up-regulated and 249 down-regulated) in the CCI models, which were primarily involved in PI3K/AKT signaling pathway, gamma-aminobutyric acid (GABA) receptor signaling, complement and coagulation cascades, cGMP/PKG signaling pathway, MAPK signaling pathway, and calcium signaling pathway. In parallel, emodin intervention regulated the abundance alteration of 27 brain metabolites (20 up-regulated and 7 down-regulated) in the CCI rats, which were primarily implicated in carbon metabolism, biosynthesis of amino acids, pentose phosphate pathway, and glucagon signaling pathway. After a comprehensive analysis and western blot validation, we demonstrated that emodin alleviated NeP mainly through regulating GABAergic pathway and PI3K/AKT/NF-κB pathway.