Neuroprotective Effect of Anethole Against Neuropathic Pain Induced by Chronic Constriction Injury of the Sciatic Nerve in Mice

Identification of Matrine as a Kirsten rats Arcomaviral oncogene homolog inhibitor alleviating chemotherapy-induced neuropathic pain

BACKGROUND

Chemotherapy-induced peripheral neuropathy (CIPN) represents a prevailing and severe clinical concern, characterized by limited availability of clinically effective treatment strategies. Current evidence endorses matrine's potential as a neuroprotective and analgesic agent for CIPN. Nevertheless, the precise targets and mechanisms of action of matrine remain insufficiently explored, impeding comprehensive pharmacological investigation and clinical application.

OBJECTIVE

This study endeavors to elucidate the analgesic and neuroprotective effects of matrine in mice with vincristine-induced neuropathic pain. A focal point is the identification of matrine's specific target and the underlying molecular mechanisms governing its analgesic and neuroprotective actions.

METHODS

To discern matrine's analgesic effects in CIPN mice, we conducted behavioral experiments encompassing the Von Frey filament test and Hargreaves Test. Furthermore, we conducted electrophysiological and histopathological assessments involving HE staining, Nissl staining, and Fluoro-Jade B staining to evaluate matrine's effects on neuroprotection within dorsal root ganglia and the spinal cord of CIPN mice. Sequentially, thermal shift assay, GTP hydrolysis assay, and nucleotide exchange assay were executed to validate matrine's inhibitory effects on KRAS. Molecular docking and site-directed mutagenesis experiments were implemented to identify the precise binding pocket of matrine on KRAS. Lastly, matrine's inhibitory effects on downstream signaling pathways of KRAS were confirmed through experiments conducted at animal model.

RESULTS

Matrine exhibited a notable increase in mechanical withdrawal threshold and thermal withdrawal latency in vincristine-treated mice. This compound substantially ameliorated the neurofunctional blockade associated with sensory and motor functions induced by vincristine. Moreover, matrine mitigated pathological damage within DRG and the L4-L5 spinal cord regions. The study's MST experiments indicated matrine's substantial elevation of KRAS's melting temperature. The GTP hydrolysis and nucleotide exchange assays revealed concentration-dependent inhibition of KRAS activity by matrine. Molecular docking provided insight into the binding mode of matrine with KRAS, while site-directed mutagenesis verified the specific binding site of matrine on KRAS. Lastly, matrine's inhibition of downstream Raf/Erk1/2 and PI3K/Akt/mTOR signaling pathways of KRAS was confirmed in VCR mice.

CONCLUSION

Compared to previous studies, our research has identified matrine as a natural inhibitor of the elusive protein KRAS, often considered "undruggable." Furthermore, this study has revealed that matrine exerts its therapeutic effects on chemotherapy-induced peripheral neuropathy (CIPN) by inhibiting KRAS activation, subsequently suppressing downstream signaling pathways such as Raf/Erk1/2 and PI3K/Akt/mTOR. This investigation signifies the discovery of a novel target for matrine, thus expanding the potential scope of its involvement in KRAS-related biological functions and diseases. These findings hold the promise of providing a crucial experimental foundation for forthcoming drug development initiatives centered around matrine, thereby advancing the field of pharmaceutical research.

Anethole Prevents the Alterations Produced by Diabetes Mellitus in the Sciatic Nerve of Rats

Anethole is a terpenoid with antioxidant, anti-inflammatory, and neuronal blockade effects, and the present work was undertaken to study the neuroprotective activity of anethole against diabetes mellitus (DM)-induced neuropathy. Streptozotocin-induced DM rats were used to investigate the effects of anethole treatment on morphological, electrophysiological, and biochemical alterations of the sciatic nerve (SN). Anethole partially prevented the mechanical hyposensitivity caused by DM and fully prevented the DM-induced decrease in the cross-sectional area of the SN. In relation to electrophysiological properties of SN fibers, DM reduced the frequency of occurrence of the 3rd component of the compound action potential (CAP) by 15%. It also significantly reduced the conduction velocity of the 1st and 2nd CAP components from 104.6 ± 3.47 and 39.8 ± 1.02 to 89.9 ± 3.03 and 35.4 ± 1.56 m/s, respectively, and increased the duration of the 2nd CAP component from 0.66 ± 0.04 to 0.82 ± 0.09 ms. DM also increases oxidative stress in the SN, altering values related to thiol, TBARS, SOD, and CAT activities. Anethole was capable of fully preventing all these DM electrophysiological and biochemical alterations in the nerve. Thus, the magnitude of the DM-induced neural effects seen in this work, and the prevention afforded by anethole treatment, place this compound in a very favorable position as a potential therapeutic agent for treating diabetic peripheral neuropathy.

Anethole via increase in the gene expression of PI3K/AKT/mTOR mitigates the autistic-like behaviors induced by maternal separation stress in mice

Autism spectrum disorder (ASD) is a neurodegenerative disease with increasing incidence in the world. The maternal separation (MS) stress at early life with its own neuroendocrine and neurostructural changes can provide the basis for development of ASD. Previously it has been reported neuroprotective characteristics for anethole. The PI3K/AKT/mTOR signaling pathway has pivotal role in the function of central nervous system (CNS). This study aimed to evaluate the possible effects of anethole on the autistic-like behaviors in the maternally separated (MS) mice focusing on the potential role of the PI3K/AKT/mTOR pathway. Forty male Naval Medical Research Institute (NMRI) mice were assigned to five groups (n = 8) comprising a control group (treated with normal saline) and four groups subjected to MS and treated with normal saline and or anethole at doses of 31.25, 62.5 and 125 mg/kg, respectively. All gents were administrated via intraperitoneal (i.p.) route for 14 constant days. Behavioral tests were conducted, including the three-chamber test, shuttle box and resident-intruder test. The gene expression of the PI3K, AKT and mTOR assessed in the hippocampus by qRT-PCR. Findings indicated that MS is associated with autistic-like behaviors. Anethole increased the sociability and social preference indexes in the three-chamber test, increased duration of secondary latency in the shuttle box test and decreased aggressive behaviors in the resident-intruder test. Also, anethole increased the gene expression of PI3K, AKT and mTOR in the hippocampus of MS mice. We concluded that anethole through increase in the gene expression of PI3K/ AKT/mTOR mitigated autistic-like behaviors induced by MS in mice.

Mitigation of sciatica injury-induced neuropathic pain through active metabolites derived from medicinal plants

Sciatica characterized by irritation, inflammation, and compression of the lower back nerve, is considered one of the most common back ailments globally. Currently, the therapeutic regimens for sciatica are experiencing a paradigm shift from the conventional pharmacological approach toward exploring potent phytochemicals from medicinal plants. There is a dire need to identify novel phytochemicals with anti-neuropathic potential. This review aimed to identify the potent phytochemicals from diverse medicinal plants capable of alleviating neuropathic pain associated with sciatica. This review describes the pathophysiology of sciatic nerve pain, its cellular mechanisms, and the pharmacological potential of various plants and phytochemicals using animal-based models of sciatic nerve injury-induced pain. Extensive searches across databases such as Medline, PubMed, Web of Science, Scopus, ScienceDirect, and Google Scholar were conducted. The findings highlights 39 families including Lamiaceae, Asteraceae, Fabaceae, and Apocyanaceae and Cucurbitaceae, effectively treating sciatic nerve injury-induced pain. Flavonoids made up 53% constituents, phenols and terpenoids made up 15%, alkaloids made up 13%, and glycosides made up 6% to be used in neuorpathic pain. Phytochemicals derived from various medicinal plants can serve as potential therapeutic targets for both acute and chronic sciatic injury-induced neuropathic pain.

Trans-anethole pretreatment ameliorates hepatic ischemia-reperfusion injury via regulation of soluble epoxide hydrolase

Hepatic ischemia reperfusion injury (IRI) is a risk factor for early graft nonfunction and graft rejection after liver transplantation (LT). The process of liver IRI involves inflammatory response, oxidative stress, apoptosis and other pathophysiological processes. So far, there is still a lack of effective drugs to ameliorate liver IRI. Trans-anethole (TA) is an aromatic compound. Many medications as well as natural foods contain TA. TA has multiple effects such as anti-inflammation, anti-oxidative stress and anti-apoptosis. However, the mechanism of TA pretreatment in liver IRI is unclear. The mice hepatic IRI model was constructed after gavage pretreatment with TA (10 mg/kg, 20 mg/kg, 40 mg/kg) for 7 consecutive days. Our study confirmed that TA pretreatment significantly improve liver function and reduce serum AST, ALT in hepatic IRI. HE staining showed that TA pretreatment alleviated liver injury. Meanwhile, TA (20 mg/kg) pretreatment attenuated hepatocyte apoptosis in hepatic IRI. In addition, TA (20 mg/kg) pretreatment reduced the inflammatory factors TNF-α, IL-6 and infiltration of CD11b positive cells in liver tissues during hepatic IRI in mice. TA pretreatment also alleviated oxidative stress in mice hepatic IRI. Our study further indicated that TA pretreatment attenuated mice hepatic IRI through inhibiting NLRP3 inflammasome activation via regulation of soluble epoxide hydrolase (sEH). This study provides a novel and effective potential drug with few side effects for easing liver IRI.

Anti-inflammatory, anti-apoptotic, and neuroprotective potentials of anethole in Parkinson's disease-like motor and non-motor symptoms induced by rotenone in rats

Parkinson's disease (PD) is a complex neurological disorder characterized by a combination of motor and non-motor symptoms (NMS). Antioxidant and anti-inflammatory compounds are considered a potential therapeutic strategy against PD. The present study examined the neuroprotective effects of anethole as a potent antioxidant and anti-inflammatory agent against motor and non-motor deficits induced by rotenone toxicity. Rats were treated with anethole (62.5, 125, and 250 mg/kg, i.g) concomitantly with rotenone (2 mg/kg, s.c) for 5 weeks. After the treatment, behavioral tests were performed to evaluate motor function and depression-/anxiety-like behaviors. After the behavioral tests, rats were decapitated and brains were removed for histological analysis. Striatum samples were also isolated for neurochemical, and molecular analysis. Our data showed that rotenone-induced motor deficit, anxiety-and depression-like behaviors were significantly improved in rats treated with anethole. Furthermore, anethole treatment reduced inflammatory cytokines tumor necrosis factor α (TNFα) and Interleukin 6 (IL-6), and increased anti-inflammatory cytokine IL-4 in the striatum of rotenone-induced PD rats. Western blot analysis showed that treatment with anethole markedly suppressed caspase-3 activation induced by rotenone. Moreover, histological examination of striatum showed an increase in the number of surviving neurons after treatment with anethole. Anethole also significantly enhanced the striatal levels of dopamine in rotenone-induced PD rats. In addition, treatment with L-Dopa as a positive control group had effects similar to those of anethole on histological, neurochemical, and molecular parameters in rotenone-induced parkinsonian rats. Our results suggested the neuroprotective effects of anethole through anti-inflammatory, anti-apoptotic, and antioxidant mechanisms against rotenone-induced toxicity in rats.

Analgesic effect of nobiletin against neuropathic pain induced by the chronic constriction injury of the sciatic nerve in mice

Neuropathic pain is chronic pain resulting from central or peripheral nerve damage that remains difficult to treat. Current evidence suggests that nobiletin, isolated from Citrus reticulata Blanco, possesses analgesic and neuroprotective effects. However, its effect on neuropathic pain has not been reported. This study evaluated the analgesic effect of nobiletin on neuropathic pain induced by chronic constriction injury (CCI) in mice. In vivo, mice were intragastrically administered with nobiletin (30, 60, 120 mg/kg) for eight consecutive days, respectively. Our study indicated that nobiletin ameliorated mechanical allodynia, cold allodynia and thermal hyperalgesia on CCI mice at doses that do not induce significant sedation. Moreover, nobiletin could ameliorate axonal and myelin injury of the sciatic nerve and further restore abnormal sciatic nerve electrical activity on CCI mice. In vitro studies indicated that nobiletin could suppress the proteins and mRNA expression of the IRF5/P2X4R/BDNF signalling pathway in fibronectin-induced BV2 cells. Overall, our results indicated that nobiletin might exert an analgesic effect on CCI-induced neuropathic pain in mice by inhibiting the IRF5/P2X4R/BDNF signalling pathway in spinal microglia. This study provided a novel potential therapeutic drug for neuropathic pain and new insights into the pharmacological action of nobiletin.

Co-Combination of Pregabalin and Withaniacoagulans-Extract-Loaded Topical Gel Alleviates Allodynia and Hyperalgesia in the Chronic Sciatic Nerve Constriction Injury for Neuropathic Pain in Animal Model

The current study reports the fabrication of co-combination gel using Pregabalin and Withania coagulans fruit extract to validate its effectiveness for neuropathic pain in chronic constriction injury (CCI) rat models. Three topical gels were prepared using Carbopol 934 through a pseudo-ternary phase diagram incorporating the Pregabalin (2.5%), Withania coagulans extract (2%), and co-combination of both Pregabalin (2.5%) and Withania coagulans extract (2%). Gels were characterized. FTIR showed a successful polymeric network of the gel without any interaction. The drug distribution at the molecular level was confirmed by XRD. The AFM images topographically indicated the rough surface of gels with a size range from 0.25 to 330 nm. DSC showed the disappearance of sharp peaks of the drug and extract, showing successful incorporation into the polymeric network of gels. The in vitro drug release of co-combination gel was 73% over 48 h. The mechanism of drug release by combination gel was Higuchi+ fickian with values of n (0.282) and R2 (0.947). An in vivo study for pain assessment via four methods: (i) heat hyperalgesia, (ii) cold allodynia, (iii) mechano-hyperalgesia, and (iv) dynamic mechano-allodynia, confirmed that topical treatment with co-combination gel reduced the pain significantly as indicated by the p value: R1 (p < 0.001), R2 (p < 0.001), R3 (p < 0.015), and R4 (p < 0.0344). The significance order was R2 (****) > R1 (***) > R3 (**) > R4 (*) > R5 (ns).

Protein Tyrosine Phosphatase Receptor Type D Regulates Neuropathic Pain After Nerve Injury via the STING-IFN-I Pathway

Neuropathic pain is usually caused by injury or dysfunction of the somatosensory system, and medicine is a common way of treatment. Currently, there are still no satisfactory drugs, like opioids and lidocaine, which carry a high risk of addiction. Protein tyrosine phosphatase receptor type D (PTPRD) is a known therapeutic target in addiction pathways and small molecule inhibitors targeting it, such as 7-butoxy illudalic acid analog (7-BIA), have recently been developed to tackle addition. PTPRD is also upregulated in the dorsal root ganglion (DRG) in a rat model of neuropathic pain, but is not yet clear whether PTPRD contributes to the development of neuropathic pain. Here, we established a chronic constriction injury (CCI) and evaluated PTPRD expression and its association with neuropathic pain. PTPRD expression was found to gradually increase after CCI in DRGs, and its expression was concomitant with the progressive development of hypersensitivity as assessed by both mechanical and thermal stimuli. Both PTPRD knockdown and administration of PTPRD inhibitor 7-BIA alleviated CCI-induced neuropathic pain while upregulating STING and IFN-α in the DRG. Treatment with H-151, a STING inhibitor, abolished the analgesic effects of PTPRD knockdown. Taken together, our study suggests that increased levels of PTPRD in the DRG following CCI are involved in the development of neuropathic pain via the STING-IFN-I pathway. 7-BIA, a small molecule inhibitor of PTPRD with anti-addiction effects, may represent a novel and safe therapeutic strategy for the clinical management of neuropathic pain without the risk of addiction.

Anethole inhibits RANKL-induced osteoclastogenesis by downregulating ERK/AKT signaling and prevents ovariectomy-induced bone loss in vivo

Postmenopausal osteoporosis is a chronic population health hazard systemic metabolic disease caused by excessive bone resorption and reduced bone formation. The activity between osteoblast and osteoclast, with their mutual effects, influence the procedure of normal bone remodeling. Over-activated osteoclast differentiation and function play a crucial role in excessive bone resorption. Hence, therapy strategies targeting osteoclast activity may promote the bone mass preservation and delay the osteoporosis process. Natural compound (anethole) is emerging as potential therapeutics for various metabolic diseases. The purpose of this study is to investigate the potential effects of anethole on RANKL-induced osteoclast formation and function in vitro and in vivo. Here, in vitro TRAP staining assay was performed to investigate the inhibitory effect of anethole on osteoclast differentiation. Bone pits resorption assay revealed that osteoclast-mediated bone resorption was inhibited by anethole. At mRNA and protein levels, anethole significantly reduced the expression of osteoclast-specific genes expression in a concentration- or time-dependent manner, including NFATc1, MMP-9, DC-STAMP, c-F, TRAP, CTR, Cathepsin K, and V-ATPase d2. Furthermore, intracellular signaling transduction assay indicated that anethole inhibited osteoclast formation via blocking ERK and AKT signaling. GSK3β, the downstream signal of AKT, is simultaneously suppressed with anethole treatment. Based on ovariectomized (OVX) mice model, micro-CT and histological staining results suggested that anethole prevented estrogen deficiency-induced bone mass loss and increased osteoclast activity in vivo. In conclusion, our results show significant indications that anethole exhibits an osteoprotective effect and may be potential for the treatment of osteoporosis.

Neuroprotective effect of l-theanine in a rat model of chronic constriction injury of sciatic nerve-induced neuropathic pain

BACKGROUND/PURPOSE

We investigated the protective efficacy of _l-theanine (LT), the major amino acid components of green tea, on chronic constriction injury (CCI) of sciatic nerve-induced neuropathic pain (NP) development and neuronal functional changes in rats.

METHODS

Rats with NP induced by CCI of the left sciatic nerve and sham-operated rats received LT or saline solution, with pain sensitive tests of thermal hyperalgesia and mechanical allodynia. Motor and sensory nerve conduction velocities were measured after surgery. Subsequently, the rats were sacrificed; the sciatic nerve was excised, homogenized, prepared and subjected for estimation of nitric oxide (NO), malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), myeloperoxidase (MPO), and caspase-3.

RESULTS

CCI produced a significant increase in hyperalgesia and allodynia, an increase in SFI, a decrease in nerve conduction velocity, increases in NO, MDA, TNF-α, IL-1β, IL-6, MPO, and caspase-3 levels, as well as reduction of GSH, SOD, and CAT in the rat sciatic nerve. LT treatment significantly and dose-dependently alleviated CCI-induced nociceptive pain thresholds and ameliorated abnormal nerve conduction and functional loss in rats with CCI. Moreover, LT treatment reduced NO and MDA levels, increased antioxidative strength, and markedly suppressed the levels of neuroinflammatory and apoptotic markers in injured sciatic nerves.

CONCLUSION

This is the first report on the ameliorative effect of LT in CCI-induced NP in rats. This effect might be attributed to its anti-oxidative, anti-inflammatory, anti-apoptotic, and neuroprotective, thus making it potentially useful as an adjuvant to conventional treatment.

Essential Oil of Croton zehntneri Prevents Conduction Alterations Produced by Diabetes Mellitus on Vagus Nerve

Autonomic diabetic neuropathy (ADN) is a complication of diabetes mellitus (DM), to which there is no specific treatment. In this study, the efficacy of the essential oil of Croton zehntneri (EOCz) in preventing ADN was evaluated in the rat vagus nerve. For the two fastest conducting myelinated types of axons of the vagus nerve, the conduction velocities and rheobase decreased, whilst the duration of the components of the compound action potential of these fibers increased. EOCz completely prevented these DM-induced alterations of the vagus nerve. Unmyelinated fibers were not affected. In conclusion, this investigation demonstrated that EOCz is a potential therapeutic agent for the treatment of ADN.

Protection by rhynchophylline against MPTP/MPP+-induced neurotoxicity via regulating PI3K/Akt pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Isolated from Uncaria rhynchophylla (U. rhynchophylla), rhynchophylline (Rhy) has been applied for treating diseases related to central nervous system such as Parkinson's disease. Nevertheless, the molecular mechanism of the neuroprotective effect has not been well interpreted.

AIM OF THE STUDY

To investigate the effects of Rhy on MPTP/MPP + -induced neurotoxicity in C57BL/6 mice or PC12 cells and study the mechanisms involved.

MATERIALS AND METHODS

The neuroprotective effect of Rhy on MPTP-induced neurotoxicity was evaluated by spontaneous motor activity test, as well as a test of rota-rod on a rat model of Parkinson's disease. The numbers of TH-positive neurons in the substantia nigra pars compacta (SNpc) was assessed by immunohistological. CCK-8, lactate dehydrogenase (LDH), reactive oxygen species (ROS), the concentration of intracellular calcium ([Ca²⁺]i) and flow cytometry analysis were performed to evaluate the pharmacological property of Rhy on 1-methyl-4-phenylpyridinium (MPP⁺) induced neurotoxicity in PC12 cells. Besides, LY294002, a PI3K inhibitor was employed to determine the underlying molecular signaling pathway revealing the effect of Rhy by western-blot analysis.

RESULTS

The results showed that Rhy exhibited a protective effect against the MPTP-induced decrease in tyrosine hydroxylase (TH)-positive fibers in the substantia nigra at 30 mg/kg, demonstrated by the immunohistological and behavioral outcomes. Furthermore, it has been indicated that cell viability was improved and the MPP⁺-induced apoptosis was inhibited after the treatment of Rhy at 20 μM, which were severally analyzed by the CCK-8 and the Annexin V/propidium iodide staining method. In addition, Rhy treatment attenuated MPP⁺-induced up-regulation of LDH, ([Ca²⁺]i), and the levels of ROS. Besides, it can be revealed from the Western blot assay that LY294002, as a selective Phosphatidylinositol 3-Kinase (PI3K) inhibitor, effectively inhibited the Akt phosphorylation caused by Rhy, which suggested that Rhy showed its protective property through the activated the PI3K/Akt signaling pathway. Moreover, the Rhy-induced decreases of Bax and caspase-3 as the proapoptotic markers and the increase of Bcl-2 as the antiapoptotic marker, were blocked by LY294002 in the MPP⁺-treated PC12 cells.

CONCLUSIONS

Rhy exerts a neuroprotective effect is partly mediated by activating the PI3K/Akt signaling pathway.

Review of aromatherapy essential oils and their mechanism of action against migraines

ETHNOPHARMACOLOGICAL RELEVANCE

Migraines have become a major threat to human health, as they significantly affect human health and quality of life due to a high prevalence rate, attack rate and pain intensity. Aromatherapy, with its comfortable and pleasant natural characteristics and rapid and efficient characteristics, is widely favored by patients in the folk. Chinese folk also have the application history and related records of aromatic plants in the treatment of migraine.

AIM OF THE STUDY

This study was conducted to review the pathogenesis of migraine, the application of plant essential oils in the treatment of migraine, and further explore the material basis and mechanism of action of plant essential oils against migraine.

MATERIALS AND METHODS

Search the electronic literature of essential oils with anti-migraine effect in Google Scholar, PubMed and China National Knowledge Infrastructure, and further search the research situation of the monomer components of essential oils in migraine, inflammation, pain and other aspects.

RESULTS

studies show that there are 10 types of plant essential oils that could relieve migraine symptoms, and that 16 monomers may play a role in migraine treatment by effectively inhibiting neurogenic inflammation, hyperalgesia and balancing vasorelaxation.

CONCLUSION

Aromatic plant essential oils can relieve migraine effectively, these findings can be used as an important part of the development of anti-migraine drugs.

New generation of supramolecular mixtures: Characterization and solubilization studies

In this work, a series of novel low melting mixtures (LMM) based on cyclodextrins (CD) and levulinic acid and inspired by the deep eutectic solvents (DES), were prepared. These supramolecular mixtures are the first reported CD-based mixtures that are liquid at room temperature. Density, viscosity and rheological measurements as well as differential scanning calorimetry and thermogravimetric analysis were performed to characterize these new LMM. Nuclear magnetic resonance (NMR) spectroscopy was used to monitor their stability. Furthermore, their ability to solubilize trans-anethole (AN) and related essentials oils were evaluated by static headspace-gas chromatography (SH-GC), in comparison with water. AN was up to 1300 times more soluble in the CD-based LMM than in water. Finally, multiple headspace extraction (MHE) was used to monitor the release of AN from these LMM. After 10 extractions, 20 to 40% of AN was released from the studied LMM, while 70% was released from water. The new CD-based LMM have potential applications for solubilization and delivery of poorly soluble drugs.

Roles of tumor necrosis factor-α and interleukin-6 in regulating bone cancer pain via TRPA1 signal pathway and beneficial effects of inhibition of neuro-inflammation and TRPA1

Background

Pain is one of the most common and distressing symptoms suffered by patients with progression of bone cancer; however, the mechanisms responsible for hyperalgesia are not well understood. The purpose of our current study was to determine contributions of the sensory signaling pathways of inflammatory tumor necrosis factor-α and interleukin-6 and downstream transient receptor potential ankyrin 1 (TRPA1) to neuropathic pain induced by bone cancer. We further determined whether influencing these pathways can improve bone cancer pain.

Methods

Breast sarcocarcinoma Walker 256 cells were implanted into the tibia bone cavity of rats to induce mechanical and thermal hyperalgesia. ELISA and western blot analysis were used to examine (1) the levels of tumor necrosis factor-α and interleukin-6 in dorsal root ganglion and (2) protein expression of tumor necrosis factor-α and interleukin-6 receptors (TNFR1 and IL-6R) and TRPA1 as well as intracellular signals (p38-MAPK and JNK).

Results

Tumor necrosis factor-α and interleukin-6 were elevated in the dorsal root ganglion of bone cancer rats, and expression of TNFR1, IL-6R, and TRPA1 was upregulated. In addition, inhibition of TNFR1 and IL-6R alleviated mechanical and thermal hyperalgesia in bone cancer rats, accompanied with downregulated TRPA1 and p38-MAPK and JNK.

Conclusions

We revealed specific signaling pathways leading to neuropathic pain during the development of bone cancer, including tumor necrosis factor-α-TRPA1 and interleukin-6-TRPA1 signal pathways. Overall, our data suggest that blocking these signals is beneficial to alleviate bone cancer pain.

The blockade of CC chemokine receptor type 1 influences the level of nociceptive factors and enhances opioid analgesic potency in a rat model of neuropathic pain

A growing body of evidence has indicated that the release of nociceptive factors, such as interleukins and chemokines, by activated immune and glial cells has crucial significance for neuropathic pain generation and maintenance. Moreover, changes in the production of nociceptive immune factors are associated with low opioid efficacy in the treatment of neuropathy. Recently, it has been suggested that CC chemokine receptor type 1 (CCR1) signaling is important for nociception. Our study provides evidence that the development of hypersensitivity in rats following chronic constriction injury (CCI) of the sciatic nerve is associated with significant up-regulation of endogenous CCR1 ligands, namely, CCL2, CCL3, CCL4, CCL6, CCL7 and CCL9 in the spinal cord and CCL2, CCL6, CCL7 and CCL9 in dorsal root ganglia (DRG). We showed that single and repeated intrathecal administration of J113863 (an antagonist of CCR1) attenuated mechanical and thermal hypersensitivity. Moreover, repeated administration of a CCR1 antagonist enhanced the analgesic properties of morphine and buprenorphine after CCI. Simultaneously, repeated administration of J113863 reduced the protein levels of IBA-1 in the spinal cord and MPO and CD4 in the DRG and, as a consequence, the level of pronociceptive factors, such as interleukin-1β (IL-1β), IL-6 and IL-18. The data obtained provide evidence that CCR1 blockade reduces hypersensitivity and increases opioid-induced analgesia through the modulation of neuroimmune interactions.

Effect of Ficus glomerata leaf extract in streptozotocin-induced early diabetic complications and its characterization by LC-MS

Diabetes mellitus is a complex metabolic disorder that leads to various micro-vascular complications. The present study elucidated the effect of chloroform extract of leaves of Ficus glomerata (CHFG) in streptozotocin-induced early diabetic renal and neural complications. Wistar rats were injected with STZ (55 mg/kg, i.p.) to produce experimental diabetes. Two weeks after the stabilization of diabetes, CHFG extract at the dose of 200 and 400 mg/kg (CHFG 200 and CHFG 400) and metformin at the dose of 250 mg/kg (Met 250) was administered to the diabetic rats for further two weeks. Diabetic rats showed an increase in blood glucose, plasma urea, uric acid, creatinine, triglyceride, and total cholesterol level. The change in behavioral parameters such as thermal hyperalgesia and cold allodynia with compromised sciatic nerve and kidney antioxidant status were seen in diabetic rats. Diabetic rats treated with CHFG 200, CHFG 400, and Met 250 showed a decrease in blood glucose, plasma urea, uric acid, creatinine, triglyceride, and total cholesterol level. Also, it improved altered behavioral parameters such as thermal hyperalgesia and cold allodynia. It also restored the sciatic nerve and kidney antioxidant status. The results of kidney and sciatic nerves histopathological study were in line with the results of biochemical parameters that confirmed the favorable role of CHFG. Characterization of CHFG by LC-MS revealed the presence of diverse phytoconstituents, which might be responsible for its protective effect.

Effect of Geraniol and Citronellol Essential Oils on the Biophysical Gating Properties of AMPA Receptors

Essential oils have been advertised endlessly to be very beneficial for the health of humans, and an extensive amount of research examines the validity of such claims. In contribution, the current study evaluates the neuroprotective properties of Citronellol and Geraniol essential oils (EOs). In relationship to the biophysical gating properties of different the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) subunits, the EOs were administered to HEK293 (Human embryonic kidney 293) cells and examined for any inhibition and effect on desensitization or deactivation rates, using whole-cell patch-clamp electrophysiology. Our results demonstrated the highest levels of inhibition from Citronellol oil by four-fold on all AMPARs subunits. Likewise, Geraniol oil had a similar inhibiting impact on the receptors, and both oils decreased the desensitization and deactivation rates of the inhibited receptors. Thus, the examined EOs of this study portray neuroprotective qualities by targeting AMPARs activation and reducing desensitization and deactivation rates. Finally, the results of the current study entail a better understanding of AMPARs, provides a natural template for future drug synthesis to treat neurological diseases associated with excessive AMPAR activation, and offers a possible mechanism by which these essential oils deploy their ‘calming’ effect.