Orientin and neuropathic pain in rats with spinal nerve ligation

Orientin Modulates Nrf2-ARE, PI3K/Akt, JNK-ERK1/2, and TLR4/NF-kB Pathways to Produce Neuroprotective Benefits in Parkinson's Disease

Parkinson's disease (PD) is characterized by oxidative stress and neuroinflammation as key pathological features. Emerging evidence suggests that nuclear factor erythroid 2 related factor 2-antioxidant response element (Nrf2-ARE), phosphatidylinositol 3‑kinase-protein kinase B (PI3K-Akt), c-Jun N-terminal kinase-extracellular signal-regulated kinase 1/2 (JNK-ERK1/2), and toll-like receptor 4/nuclear factor-kappa B (TLR4/NF-kB) pathways play pivotal roles in PD pathogenesis. Orientin, a phenolic phytoconstituent, has demonstrated modulatory potential on these pathways in various experimental conditions other than PD. In this study, we aimed to evaluate the neuroprotective effects of Orientin against rotenone-induced neurodegeneration in SH-SY5Y cell lines and the Swiss albino mice model of PD. Orientin was administered at doses 10 and 20 µM in cell lines and 10 and 20 mg/kg in mice, and its effects on rotenone-induced neurodegeneration were investigated. Oxidative stress markers including mitochondrial membrane potential (ΔΨm), reactive oxygen species (ROS), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), as well as inflammatory markers including interleukin-1β (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α), were measured. The expression levels of genes related to Nrf2-ARE (Nrf2), PI3K/Akt (Akt), JNK-ERK1/2 (TNF-α), and TLR4/NF-kB (TNF-α) pathways were measured to understand the modulatory effect of Orientin on these pathways. Additionally, behavioral studies assessing locomotor activity, muscle coordination, and muscle rigidity were conducted with mice. Our results indicate that Orientin dose-dependently attenuated rotenone-induced changes in oxidative stress markers, inflammatory markers, gene expression levels, and behavioral parameters. Therefore, our study concludes that Orientin exhibits significant neuroprotective benefits against rotenone-induced PD by modulating Nrf2-ARE, PI3K-Akt, JNK-ERK1/2, and TLR4/NF-kB pathways.

Effects of benidipine, paracetamol, and their combination on postoperative and normal tissue pain thresholds

Introduction: In clinical practice, inadequate pain inhibition leads to increased morbidity and mortality. Increased intracellular calcium, oxidants, and proinflammatory cytokines are known to play a role in the pathogenesis of postoperative pain. Therefore, we investigated the analgesic effects of benidipine, paracetamol, and benidipine-paracetamol combination (BPC) on postoperative and normal pain thresholds in rats. Material and methods: Sixty-four male albino Wistar rats weighing 285-295 g were used. The without-incision rats were divided into 4 subgroups: healthy control, benidipine alone, paracetamol alone, and BPC. The scalpel-incision rats were divided into 4 subgroups: scalpel incision, scalpel incision + benidipine, scalpel incision + paracetamol, and scalpel incision + BPC. Paw pain thresholds of rats were measured using a Basile algesimeter. Biochemical analyses were performed on the paw tissues of 6 rats randomly taken from the experimental groups, each containing 8 rats. Rats were sacrificed immediately after the measurements. After the pain threshold tests were finished, the paw tissues were removed and malondialdehyde (MDA), total glutathione (tGSH), cyclooxygenase (COX), and interleukin-6 (IL-6) levels were measured. Results: There was no significant difference between the groups in paw pain threshold and measured biochemical parameters in rats without incision. The decrease in the pain threshold of the incised paw was also best prevented by BPC, followed by benidipine and then paracetamol. Furthermore, increases in scalpel-incised paw tissue MDA, COX-2, and IL-6 levels and the decrease in tGSH were significantly suppressed by benidipine and BPC, while paracetamol could only significantly inhibit the increase in IL-6 production. Conclusion: The combination of the L-type Ca2+ channel blocker benidipine and paracetamol (BPC) may provide potent analgesia. Our experimental results support that BPC may be useful in the treatment of severe pain that cannot be adequately inhibited by paracetamol.

Orientin Reduces the Effects of Repeated Procedural Neonatal Pain in Adulthood: Network Pharmacology Analysis, Molecular Docking Analysis, and Experimental Validation

Background

Premature infants often undergo painful procedures and consequently experience repeated procedural neonatal pain. This can elicit hyperalgesia and cognitive impairment in adulthood. Treatments for neonatal pain are limited. Orientin is a flavonoid C-glycoside that has repeatedly been shown to have pharmacological effects in the past decades. The aim of this study was to systematically explore the effect of orientin on repeated procedural neonatal pain using network pharmacology, molecular docking analysis, and experimental validation.

Methods

Several compound-protein databases and disease-protein databases were employed to identify proteins that were both predicted targets of orientin and involved in neonatal pain. A protein-protein interaction (PPI) network was constructed, and Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed to explore the potential mechanism of action. Molecular docking analysis was employed to calculate the binding energy and visualize the interactions between orientin and potential target proteins. Finally, a mouse model of repeated procedural neonatal pain was established and orientin was administered for 6 days. The mechanical and thermal pain thresholds were assessed in neonates and adult mice. A Morris water maze was employed to investigate cognitive impairment in adult mice.

Results

A total of 286 proteins that were both predicted targets of orientin and involved in neonatal pain were identified. The hub proteins were SRC, HSP90AA1, MAPK1, RHOA, EGFR, AKT1, PTPN11, ESR1, RXRA, and HRAS. GO analysis indicated that the primary biological process (BP), molecular function (MF), and cellular component (CC) were protein phosphorylation, protein kinase activity, and vesicle lumen, respectively. KEGG analysis revealed that the mitogen-activated protein kinase (MAPK) signaling pathway may be the key to the mechanism of action. Molecular docking analysis showed the high binding affinities of orientin for MAPK1, MAPK8, and MAPK14. In mice, orientin inhibited the hyperalgesia in the pain threshold tests in neonates and adult mice and cognitive impairment in adult mice. Immunofluorescence showed that phosphorylated MAPK1 (p-ERK) protein levels in the hippocampus and spinal dorsal horn were downregulated by orientin.

Conclusion

The findings suggested that orientin alleviates neonatal pain, and the MAPK signaling pathway is involved.

Anti-Inflammatory Effects of Phytochemical Components of Clinacanthus nutans

Recent studies on the ethnomedicinal use of Clinacanthus nutans suggest promising anti-inflammatory, anti-tumorigenic, and antiviral properties for this plant. Extraction of the leaves with polar and nonpolar solvents has yielded many C-glycosyl flavones, including schaftoside, isoorientin, orientin, isovitexin, and vitexin. Aside from studies with different extracts, there is increasing interest to understand the properties of these components, especially regarding their ability to exert anti-inflammatory effects on cells and tissues. A major focus for this review is to obtain information on the effects of C. nutans extracts and its phytochemical components on inflammatory signaling pathways in the peripheral and central nervous system. Particular emphasis is placed on their role to target the Toll-like receptor 4 (TLR4)-NF-kB pathway and pro-inflammatory cytokines, the antioxidant defense pathway involving nuclear factor erythroid-2-related factor 2 (NRF2) and heme oxygenase 1 (HO-1); and the phospholipase A₂ (PLA₂) pathway linking to cyclooxygenase-2 (COX-2) and production of eicosanoids. The ability to provide a better understanding of the molecular targets and mechanism of action of C. nutans extracts and their phytochemical components should encourage future studies to develop new therapeutic strategies for better use of this herb to combat inflammatory diseases.

Antinociceptive effects of minor cannabinoids, terpenes and flavonoids in Cannabis

Cannabis has been used for centuries for its medicinal properties. Given the dangerous and unpleasant side effects of existing analgesics, the chemical constituents of Cannabis have garnered significant interest for their antinociceptive, anti-inflammatory and neuroprotective effects. To date, Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) remain the two most widely studied constituents of Cannabis in animals. These studies have led to formulations of THC and CBD for human use; however, chronic pain patients also use different strains of Cannabis (sativa, indica and ruderalis) to alleviate their pain. These strains contain major cannabinoids, such as THC and CBD, but they also contain a wide variety of cannabinoid and noncannabinoid constituents. Although the analgesic effects of Cannabis are attributed to major cannabinoids, evidence indicates other constituents such as minor cannabinoids, terpenes and flavonoids also produce antinociception against animal models of acute, inflammatory, neuropathic, muscle and orofacial pain. In some cases, these constituents produce antinociception that is equivalent or greater compared to that produced by traditional analgesics. Thus, a better understanding of the extent to which these constituents produce antinociception alone in animals is necessary. The purposes of this review are to (1) introduce the different minor cannabinoids, terpenes, and flavonoids found in Cannabis and (2) discuss evidence of their antinociceptive properties in animals.

Orientin Prolongs the Longevity of Caenorhabditis elegans and Postpones the Development of Neurodegenerative Diseases via Nutrition Sensing and Cellular Protective Pathways

Age is the major risk factor for most of the deadliest diseases. Developing small molecule drugs with antiaging effects could improve the health of aged people and retard the onset and progress of aging-associated disorders. Bioactive secondary metabolites from medicinal plants are the main source for development of medication. Orientin is a water-soluble flavonoid monomer compound widely found in many medicinal plants. Orientin inhibits fat production, antioxidation, and anti-inflammatory activities. In this study, we explored whether orientin could affect the aging of C. elegans. We found that orientin improved heat, oxidative, and pathogenic stress resistances through activating stress responses, including HSF-1-mediated heat shock response, SKN-1-mediated xenobiotic and oxidation response, mitochondria unfolded responses, endoplasmic unfolded protein response, and increased autophagy activity. Orientin also could activate key regulators of the nutrient sensing pathway, including AMPK and insulin downstream transcription factor FOXO/DAF-16 to further improve the cellular health status. The above effects of orientin reduced the accumulation of toxic proteins (α-synuclein, β-amyloid, and poly-Q) and delayed the onset of neurodegenerative disorders in AD, PD, and HD models of C. elegans and finally increased the longevity and health span of C. elegans. Our results suggest that orientin has promising antiaging effects and could be a potential natural source for developing novel therapeutic drugs for aging and its related diseases.

Revealing the Mechanism of Friedelin in the Treatment of Ulcerative Colitis Based on Network Pharmacology and Experimental Verification

Objectives

Ulcerative colitis (UC) is a chronic inflammatory disease affecting the colon, and its incidence is rising worldwide. This study was designed to uncover the healing effect of friedelin, a bioactive compound against UC through bioinformatics of network pharmacology and experimental verification of UC model mice.

Materials and Methods

Targets of friedelin and potential mechanism of friedelin on UC were predicted through target searching, PPI network establishing, and enrichment analyzing. We explored effects of friedelin on dextran sulfate sodium (DSS)-induced colitis. Severity of UC was investigated by body weight, disease activity index (DAI), and length of the colon. Inflammation severity was examined by determination of proinflammatory and anti-inflammatory cytokines. The numbers of autophagosome around the epithelial cells were observed by autophagy inhibition via a transmission electron microscope. The expressions of autophagy-related ATG5 protein and AMPK-mTOR signaling pathway were determined by immunofluorescence staining.

Results

In this study, 17 potential targets of friedelin and 1111 UC-related targets were identified. 10 therapeutic targets of friedelin against UC were acquired from overlapped targets of UC and friedelin. PPI network construction filtered 14 core targets through target amplification and confidence enhancement. The results of molecular docking showed that the docking scores of the top 5 active targets were higher than the threshold values. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were carried out, showing friedelin alleviates UC through anti-inflammatory pathways and molecular function of autophagy. Subsequently, animal-based experiments revealed the intraperitoneal injection of friedelin ameliorated DSS-induced body weight loss, DAI decrease, colon length shortening and colonic pathological damage with lower myeloperoxidase and proinflammatory cytokines (IL-1β and IL-6) and higher IL-10 levels, and more autophagosomes in transmission electron microscope results. The AMPK-mTOR signaling pathway plays important role in the friedelin's effect in autophagy as KEGG pathway result and experiment verification. Furthermore, the 3 ma validated the role of autophagy as an improvement in the friedelin's pharmacologic effect to UC model mice.

Conclusions

Friedelin ameliorated DSS-induced colitis in mice through of inflammatory inhibition and regulation of autophagy.

CCR1 enhances SUMOylation of DGCR8 by up-regulating ERK phosphorylation to promote spinal nerve ligation-induced neuropathic pain

Neuropathic pain is a somatosensory nervous system dysfunction that remains a threatening health problem globally. Recent studies have highlighted the involvement of C-C motif chemokine receptor 1 (CCR1) in neuropathic pain. Herein, the current study set out to explore the modulatory role of CCR1 in spinal nerve ligation (SNL)-induced neuropathic pain and its underlying molecular mechanism. First, it was found that CCR1 was highly expressed in spinal cord tissues and microglial cells of SNL rats. On the other hand, CCR1 knockdown attenuated nerve pain in SNL rats and repressed microglial cell activation in SNL rats and also in the LPS-induced microglial cell model of nerve injury, as evidenced by elevated microglial cell markers OX-42 and IL-1β, IL-6 and TNF-α. Mechanistically, CCR1 enhanced small ubiquitin-like modifier 1 (SUMO1) modification of DiGeorge syndrome critical region gene 8 (DGCR8) in LPS-treated microglial cells by phosphorylating ERK. Moreover, CCR1 silencing brought about elevations in mechanical withdrawal threshold and thermal withdrawal latency. To conclude, our findings indicated that CCR1 enhanced the modification of DGCR8 by SUMO1 through phosphorylation of ERK, thereby promoting the activation and inflammatory response of spinal cord microglial cells and increasing the sensitivity of SNL rats to pain. Thus, this study offers a promising therapeutic target for the management of neuropathic pain.

Ferroptosis is involved in the development of neuropathic pain and allodynia

Neuropathic pain (NP) is chronic, intractable, and typically not alleviated using analgesics. Ferroptosis is a new type of cell death characterized by mitochondrial damage, oxidative stress, and mitochondrial dysfunction, affecting specific types of synaptic plasticity in the spinal cord. Here, we evaluated the role of ferroptosis in NP using chronic contractile injury (CCI) in rats. The CCI and control groups were subjected to sciatic nerve ligation. The mechanical withdrawal threshold and thermal withdrawal reflex latency were used to detect changes in mechanical pain threshold and thermal pain threshold in rats, respectively. Notably, CCI caused mechanical and thermal stimulation of the injured hind paw, reduced levels of glutathione peroxidase 4 (GPX4), and increased acyl-CoA synthetase long-chain family member 4 (ACSL4). Treatment with the ferroptosis inhibitor ferrostatin-1 (10 mg/kg) 1 h after surgery upregulated GPX4 expression and downregulated ACSL4 expression, whereas the ferroptosis inducer, erastin (10 mg/kg), exerted opposite effects. Treatment with ferrostatin-1 upregulated NeuN expression and downregulated GPX4 expression, whereas erastin reversed these effects. CCI increased the number of damaged mitochondria and decreased the mean planar mitochondrial area, and treatment with erastin further exacerbated these effects. The iron ion content in the spinal cords of CCI-induced rats increased. Treatment with ferrostatin-1 decreased, whereas treatment with erastin increased iron ion content in the CCI-induced rat model. Taken together, our results showed that ferroptosis is involved in the development of NP in male rats by blocking neuron and astrocyte activation in the spinal dorsal horn.

Toll-like receptor 7 contributes to neuropathic pain by activating NF-κB in primary sensory neurons

Toll like receptor 7 (TLR7) is expressed in neurons of the dorsal root ganglion (DRG), but whether it contributes to neuropathic pain is elusive. We found that peripheral nerve injury caused by ligation of the fourth lumbar (L₄) spinal nerve (SNL) or chronic constriction injury of sciatic nerve led to a significant increase in the expression of TLR7 at mRNA and protein levels in mouse injured DRG. Blocking this increase through microinjection of the adeno-associated virus (AAV) 5 expressing TLR7 shRNA into the ipsilateral L₄ DRG alleviated the SNL-induced mechanical, thermal and cold pain hypersensitivities in both male and female mice. This microinjection also attenuated the SNL-induced increases in the levels of phosphorylated extracellular signal-regulated kinase ½ (p-ERK1/2) and glial fibrillary acidic protein (GFAP) in L₄ dorsal horn on the ipsilateral side during both development and maintenance periods. Conversely, mimicking this increase through microinjection of AAV5 expressing full-length TLR7 into unilateral L_3/4 DRGs led to elevations in the amounts of p-ERK1/2 and GFAP in the dorsal horn, augmented responses to mechanical, thermal and cold stimuli, and induced the spontaneous pain on the ipsilateral side in the absence of SNL. Mechanistically, the increased TLR7 activated the NF-κB signaling pathway through promoting the translocation of p65 into the nucleus and phosphorylation of p65 in the nucleus from the injured DRG neurons. Our findings suggest that DRG TLR7 contributes to neuropathic pain by activating NF-κB in primary sensory neurons. TLR7 may be a potential target for therapeutic treatment of this disorder.

Crotoxin Conjugated to SBA-15 Nanostructured Mesoporous Silica Induces Long-Last Analgesic Effect in the Neuropathic Pain Model in Mice

Neuropathic pain is a disease caused by structural and functional plasticity in central and peripheral sensory pathways that produce alterations in nociceptive processing. Currently, pharmacological treatment for this condition remains a challenge. Crotoxin (CTX), the main neurotoxin of Crotalus durissus terrificus rattlesnake venom, has well described prolonged anti-inflammatory and antinociceptive activities. In spite of its potential benefits, the toxicity of CTX remains a limiting factor for its use. SBA-15 is an inert nanostructured mesoporous silica that, when used as a vehicle, may reduce toxicity and potentiate the activity of different compounds. Based on this, we propose to conjugate crotoxin with SBA-15 (CTX:SBA-15) in order to investigate if when adsorbed to silica, CTX would have its toxicity reduced and its analgesic effect enhanced in neuropathic pain induced by the partial sciatic nerve ligation (PSNL) model. SBA-15 enabled an increase of 35% of CTX dosage. Treatment with CTX:SBA-15 induced a long-lasting reduction of mechanical hypernociception, without modifying the previously known pathways involved in antinociception. Moreover, CTX:SBA-15 reduced IL-6 and increased IL-10 levels in the spinal cord. Surprisingly, the antinociceptive effect of CTX:SBA-15 was also observed after oral administration. These data indicate the potential use of the CTX:SBA-15 complex for neuropathic pain control and corroborates the protective potential of SBA-15.

Fn14 Participates in Neuropathic Pain Through NF-κB Pathway in Primary Sensory Neurons

Fibroblast growth factor-inducible-14 (Fn14), a receptor for tumor necrosis-like weak inducer of apoptosis, is expressed in the neurons of dorsal root ganglion (DRG). Its mRNA is increased in the injured DRG following peripheral nerve injury. Whether this increase contributes to neuropathic pain is unknown. We reported here that peripheral nerve injury caused by spinal nerve ligation (SNL) increased the expression of Fn14 at both protein and mRNA levels in the injured DRG. Blocking this increase attenuated the development of SNL-induced mechanical, thermal, and cold pain hypersensitivities. Conversely, mimicking this increase produced the increases in the levels of phosphorylated extracellular signal-regulated kinase ½ and glial fibrillary acidic protein in ipsilateral dorsal horn and the enhanced responses to mechanical, thermal, and cold stimuli in the absence of SNL. Mechanistically, the increased Fn14 activated the NF-κB pathway through promoting the translocation of p65 into the nucleus of the injured DRG neurons. Our findings suggest that Fn14 may be a potential target for the therapeutic treatment of peripheral neuropathic pain.

The Genus Adonis as an Important Cardiac Folk Medicine: A Review of the Ethnobotany, Phytochemistry and Pharmacology

The genus Adonis L. (Ranunculaceae), native to Europe and Asia, comprises 32 annual or perennial herbaceous species. Due to their cardiac-enhancing effects, Adonis spp. have long been used in European and Chinese folk medicine. These plants have been widely investigated since the late 19th century, when the cardiovascular activity of Adonis vernalis L. was noted in Europe. The present paper provides a review of the phytochemistry, biological activities and toxicology in order to highlight the future prospects of the genus. More than 120 chemical compounds have been isolated, with the most important components being cardiac glycosides as well as flavones, carotenoids, coumarins and other structural types. Plants of the genus, especially A. vernalis L. and A. amurensis Regel & Radde, their extracts and their active constituents possess broad pharmacological properties, including cardiovascular, antiangiogenic, antibacterial, antioxidant, anti-inflammatory and acaricidal activities, and exhibit both diuretic effects and effects on the central nervous system. However, most plants within the 32 species have not been comprehensively studied, and further clinical evaluation of their cardiovascular activity and toxicity should be conducted after addressing the problem of the rapidly decreasing resources. This review provides new insight into the genus and lays a solid foundation for further development of Adonis.

Translocation Associated Membrane Protein 1 Contributes to Chronic Constriction Injury-Induced Neuropathic Pain in the Dorsal Root Ganglion and Spinal Cord in Rats

Neuropathic pain is a severe debilitating state caused by injury or dysfunction of somatosensory nervous system, and the clinical treatment is still challenging. Translocation associated membrane protein 1 (TRAM1), an adapter protein, participates in a variety of transduction pathways and mediates the biological functions such as cell proliferation, activation, and differentiation. However, whether TRAM1 is involved in the pathogenesis of neuropathic pain is still unclear. In our study, we reported the role of TRAM1 in the maintenance of neuropathic pain induced by chronic constriction injury (CCI) on rats. By western blot and staining, we found that TRAM1 increased in the dorsal root ganglion (DRG) neurons and spinal cord (SC) neurons after CCI. Being similar to IB4-, CGRP-positive expressed area, TRAM1 also expressed in the superficial laminae of the spinal cord dorsal horn (SCDH), suggesting it was related to the innervations of the primary afferents. Moreover, intrathecal injection of TRAM1 siRNA or Toll-like receptor 4 (TLR4) inhibitor induced low expression of TRAM1 in SC, which alleviated the pain response induced by CCI. The upregulation of p-NF-κB expression was reversed by TRAM1 siRNA in SC and DRG, and intrathecal injection of p-NF-κB inhibitor relieved neuropathic pain. All the data indicated that TRAM1 could take part in CCI-induced pain and might be a potential treatment for chronic neuropathic pain.