Knockdown siRNA Targeting GPR55 Reveals Significant Differences Between the Anti-inflammatory Actions of KLS-13019 and Cannabidiol.

KLS-13019 was reported previously to reverse paclitaxel-induced mechanical allodynia in a mouse model of chemotherapy-induced peripheral neuropathy (CIPN). Recent studies demonstrated that paclitaxel-induced increases in inflammatory markers (GPR55, NLRP3, and IL-1ß) of dorsal root ganglion (DRG) cultures were shown to be reversed by KLS-13019 treatment. The mechanism of action for KLS-13019-mediated reversal of paclitaxel-induced neuroinflammation now has been explored using GPR55 siRNA. Pre-treatment of DRG cultures with GPR55 siRNA produced a 21% decrease of immunoreactive (IR) area for GPR55 in cell bodies and a 59% decrease in neuritic IR area, as determined by high-content imaging. Using a 24-h reversal treatment paradigm, paclitaxel-induced increases in the inflammatory markers were reversed back to control levels after KLS-3019 treatment. Decreases in these inflammatory markers produced by KLS-13019 were significantly attenuated by GPR55 siRNA co-treatment, with mean IR area responses being attenuated by 56% in neurites and 53% in cell bodies. These data indicate that the percentage decreases in siRNA-mediated attenuation of KLS-13019-related efficacy on the inflammatory markers were similar to the percentage knockdown observed for neuritic GPR55 IR area. Similar studies conducted with cannabidiol (CBD), the parent compound of KLS-13019, produced low efficacy (25%) reversal of all inflammatory markers that were poorly attenuated (29%) by GPR55 siRNA. CBD was shown previously to be ineffective in reversing paclitaxel-induced mechanical allodynia. The present studies indicated significant differences between the anti-inflammatory properties of KLS-13019 and CBD which may play a role in their observed differences in the reversibility of mechanical allodynia in a mouse model of CIPN.

Spinal HMGB1 participates in the early stages of paclitaxel-induced neuropathic pain via microglial TLR4 and RAGE activation.

Introduction: Chemotherapy-induced neuropathic pain (CINP) is one of the main adverse effects of chemotherapy treatment. At the spinal level, CINP modulation involves glial cells that upregulate Toll-like receptor 4 (TLR4) and signaling pathways, which can be activated by pro-inflammatory mediators as the high mobility group box-1 (HMGB1). Objective: To evaluate the spinal role of HMGB1 in the paclitaxel-induced neuropathic pain via receptor for advanced glycation end products (RAGE) and TLR4 activation expressed in glial cells. Methods: Male C57BL/6 Wild type and TLR4 deficient mice were used in the paclitaxel-induced neuropathic pain model. The nociceptive threshold was measured using the von Frey filament test. In addition, recombinant HMGB1 was intrathecally (i.t.) injected to confirm its nociceptive potential. To evaluate the spinal participation of RAGE, TLR4, NF-kB, microglia, astrocytes, and MAPK p38 in HMGB1-mediated nociceptive effect during neuropathic pain and recombinant HMGB1-induced nociception, the drugs FPS-ZM1, LPS-RS, PDTC, minocycline, fluorocitrate, and SML0543 were respectively administrated by i.t. rout. Microglia, astrocytes, glial cells, RAGE, and TLR4 protein expression were analyzed by Western blot. ELISA immunoassay was also used to assess HMGB1, IL-1ß, and TNF-α spinal levels. Results: The pharmacological experiments demonstrated that spinal RAGE, TLR4, microglia, astrocytes, as well as MAPK p38 and NF-kB signaling are involved with HMGB1-induced nociception and paclitaxel-induced neuropathic pain. Furthermore, HMGB1 spinal levels were increased during the early stages of neuropathic pain and associated with RAGE, TLR4 and microglial activation. RAGE and TLR4 blockade decreased spinal levels of pro-inflammatory cytokines during neuropathic pain. Conclusion: Taken together, our findings indicate that HMGB1 may be released during the early stages of paclitaxel-induced neuropathic pain. This molecule activates RAGE and TLR4 receptors in spinal microglia, upregulating pro-inflammatory cytokines that may contribute to neuropathic pain.

Expression of MHC II in DRG neurons attenuates paclitaxel-induced cold hypersensitivity in male and female mice.

Chemotherapy is often a life-saving treatment, but the development of intractable pain caused by chemotherapy-induced peripheral neuropathy (CIPN) is a major dose-limiting toxicity that restricts cancer survival rates. Recent reports demonstrate that paclitaxel (PTX) robustly increases anti-inflammatory CD4+ T cells in the dorsal root ganglion (DRG), and that T cells and anti-inflammatory cytokines are protective against CIPN. However, the mechanism by which CD4+ T cells are activated, and the extent cytokines released by CD4+ T cells target DRG neurons are unknown. Here, we are the first to detect major histocompatibility complex II (MHCII) protein in mouse DRG neurons and to find CD4+ T cells breaching the satellite glial cell barrier to be in close proximity to neurons, together suggesting CD4+ T cell activation and targeted cytokine release. MHCII protein is primarily expressed in small nociceptive neurons in male and female mouse DRG but increased after PTX in small nociceptive neurons in only female DRG. Reducing one copy of MHCII in small nociceptive neurons decreased anti-inflammatory IL-10 and IL-4 producing CD4+ T cells in naïve male DRG and increased their hypersensitivity to cold. Administration of PTX to male and female mice that lacked one copy of MHCII in nociceptive neurons decreased anti-inflammatory CD4+ T cells in the DRG and increased the severity of PTX-induced cold hypersensitivity. Collectively, our results demonstrate expression of MHCII protein in mouse DRG neurons, which modulates cytokine producing CD4+ T cells in the DRG and attenuates cold hypersensitivity during homeostasis and after PTX treatment.

Protective effect of misoprostol against paclitaxel-induced cardiac damage in rats.

OBJECTIVE: One of the most critical reasons for limiting cancer treatment is the toxic effects of anti-cancer drugs on healthy tissues and organs. This study aims to investigate the possible protective effects of misoprostol (MS) against the damage that arises from paclitaxel (PT), an anti-cancer pharmacological agent, in the rat heart using histopathological and biochemical analyses. METHODS: In this study, four groups, each containing seven animals, were formed by random selection from 28 Sprague Dawley female rats. Control group rats were administered 1 ml of normal saline orally and intraperitoneally (i.p.) for six days. While the PT group rats were administered PT at a dose of 2 mg/kg intraperitoneally (i.p.) on days 0, 2, 4, and 6, the MS group was administered MS at a dose of 0.2 mg/kg in 1 ml normal saline by oral gavage for six days. PT and MS were administered to the PT + MS group rats in the same dose and route as the previous groups. RESULTS: Administration of PT increased serum lactate dehydrogenase (LDH), cardiac troponin I (cTn-I), creatine kinase isoenzyme MB (CK-MB), and brain natriuretic peptide (BNP) levels. PT administration also decreased the levels of glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT) in the heart tissue while increasing the level of malondialdehyde (MDA) (p < 0.05). In histopathological examinations, pathological changes, such as edema, congestion, hemorrhage, apoptosis, and degeneration, occurred in the heart tissue of PT-treated rats. The negative changes in histopathological and biochemical parameters that occurred in the PT group were almost not observed in the PT + MS group (p < 0.005). CONCLUSION: When the findings were evaluated, it was concluded that MS protects the heart tissue from the harmful effects of PT, probably due to its antioxidant, anti-apoptotic and TNF-alpha suppressive effects.

Protective Effects of Glatiramer Acetate Against Paclitaxel-Induced Peripheral Neuropathy in Rats: A Role for Inflammatory Cytokines and Oxidative Stress.

Chemotherapy-induced peripheral neuropathy (CIPN) is a major challenge for cancer patients who undergo chemotherapy with paclitaxel. Therefore, finding effective therapies for CIPN is crucial. Glatiramer acetate is used to treat multiple sclerosis that exerts neuroprotective properties in various studies. We hypothesized that glatiramer acetate could also improve the paclitaxel-induced peripheral neuropathy. We used a rat model of paclitaxel (2 mg/kg/every other day for 7 doses)-induced peripheral neuropathy. Rats were treated with either different doses of glatiramer acetate (1, 2, 4 mg/kg/day) or its vehicle for 14 days in separate groups. The mechanical and thermal sensitivity of the rats by using the Von Frey test and the Hot Plate test, respectively, were assessed during the study. The levels of oxidative stress (malondialdehyde and superoxide dismutase), inflammatory markers (TNF-α, IL-10, NF-kB), and nerve damage (H&E and S100B staining) in the sciatic nerves of the rats were also measured at the end of study. Glatiramer acetate (2 and 4 mg/kg) exerted beneficial effects on thermal and mechanical allodynia tests. It also modulated the inflammatory response by reducing TNF-α and NF-κB levels, enhancing IL-10 production, and improving the oxidative stress status by lowering malondialdehyde and increasing superoxide dismutase activity in the sciatic nerve of the rats. Furthermore, glatiramer acetate enhanced nerve conduction velocity in all treatment groups. Histological analysis revealed that glatiramer acetate (2 and 4 mg/kg) prevented paclitaxel-induced damage to the nerve structure. These results suggest that glatiramer acetate can alleviate the peripheral neuropathy induced by paclitaxel.

Peripheral mu-opioid receptor activation by dermorphin [D-Arg2, Lys4] (1-4) amide alleviates behavioral and neurobiological aberrations in rat model of chemotherapy-induced neuropathic pain.

Paclitaxel, a frequently utilized chemotherapeutic agent, often gives rise to severe and distressing sensory neuropathy in patients undergoing chemotherapy. Unfortunately, current therapeutics for chemotherapy-induced neuropathic pain (CINP) demonstrate limited effectiveness and are burdened with the potential for central side effects such as sedation, respiratory depression, cognitive impairment, and addiction, posing substantial clinical challenges. In light of these limitations, present study is designed to investigate the therapeutic potential of Dermorphin [D-Arg2, Lys4] (1-4) amide (DALDA), a preferential peripherally acting mu-opioid receptor agonist, in rat model of CINP. The primary objective was to assess the analgesic properties of DALDA and elucidate the underlying mechanisms governing its therapeutic activity. Our findings revealed that DALDA treatment significantly ameliorated paclitaxel-induced evoked and spontaneous ongoing pain in rats without causing drug addiction and other central side effects. Molecular analyses further unveiled that paclitaxel administration resulted in increased expression of TRP channels, NR2B, voltage-gated sodium channels (VGSCs) and neuroinflammatory markers in both the dorsal root ganglion (DRG) and the spinal cord (L4-L5 region) of rats. DALDA treatment significantly downregulated ion channels (TRPs, VGSCs) and NR2B expressions, concomitant with the inhibition of microglial activation, resulting in the suppression of oxido-nitrosative stress and neuroinflammatory cascade. Findings from the current study suggests that peripheral mu-opioid receptors may offer a potential target for the treatment of patients suffering from CINP, offering new avenues for improved pain relief while minimizing central side effects.

Morphofunctional characterisation of axonal damage in different rat models of chemotherapy-induced peripheral neurotoxicity: The role of nerve excitability testing.

BACKGROUND AND AIMS: Chemotherapy-induced peripheral neurotoxicity (CIPN) is a common and long-lasting adverse event of several anticancer compounds, for which treatment has not yet been developed. To fill this gap, preclinical studies are warranted, exploiting highly translational outcome measure(s) to transfer data from bench to bedside. Nerve excitability testing (NET) enables to test in vivo axonal properties and can be used to monitor early changes leading to axonal damage. METHODS: We tested NET use in two different CIPN rat models: oxaliplatin (OHP) and paclitaxel (PTX). Animals (female) were chronically treated with either PTX or OHP and compared to respective control animals. NET was performed as soon as the first injection was administered. At the end of the treatment, CIPN onset was verified via a multimodal and robust approach: nerve conduction studies, nerve morphometry, behavioural tests and intraepidermal nerve fibre density. RESULTS: NET showed the typical pattern of axonal hyperexcitability in the 72 h following the first OHP administration, whereas it showed precocious signs of axonal damage in PTX animals. At the end of the month of treatment, OHP animals showed a pattern compatible with a mild axonal sensory polyneuropathy. Instead, PTX cohort was characterised by a rather severe sensory axonal polyneuropathy with minor signs of motor involvement. INTERPRETATION: NET after the first administration demonstrated the ongoing OHP-related channelopathy, whereas in PTX cohort it showed precocious signs of axonal damage. Therefore, NET could be suggested as an early surrogate marker in clinical trials, to detect precocious changes leading to axonal damage.

Effect of vitamin E on doxorubicin and paclitaxel-induced memory impairments in male rats.

PURPOSE: In addition to peripheral neuronal dysfunction, conventional chemotherapy can be associated with other neurological treatment-limiting adverse effects, including cognitive dysfunction, memory impairment, and anxiety, which are referred to as "chemobrain". This study aimed to investigate the effects of doxorubicin (DOX) and paclitaxel (PAC) on learning and memory in rats using radial arm water maze (RAWM) and investigated a potential beneficial effect of vitamin E (Vit. E). METHODS: Adult male rats were injected with four doses of 2 mg/kg/week DOX, or 2 mg/kg PAC every other day intraperitoneally. Vit. E was co-administered with these drugs in other groups to study its antioxidative effects. Using the RAWM, each rat was assessed for learning and memory performance through two sets of six trials separated by a 5-min rest period evaluating both short- and long-term effects on memory. RESULTS: There was no deficit in learning or long-term memory in both drug groups compared to control. However, rats in both drug groups made significantly more errors in all short-term memory trials. This effect was mitigated when Vit. E was co-administered with either drug. Moreover, PAC (but not DOX) induced hippocampal lipid peroxidation by increasing the levels of standard biomarker thiobarbituric acid reactive substances (TBARS). Interestingly, Vit. E prevented PAC-induced hippocampal oxidative stress. Furthermore, both DOX and PAC were correlated with reduction in Brain-Derived Neurotrophic Factor (BDNF) expression levels in the hippocampus, which was overcome by the co-administration of Vit. E. CONCLUSION: There is a potential role of Vit. E in alleviating short-term memory impairment in rats exposed to chemotherapy, possibly by reducing hippocampal oxidative stress and neurodegeneration.

Effect of age on metabolomic changes in a model of paclitaxel-induced peripheral neurotoxicity.

BACKGROUND AND AIMS: Chemotherapy-induced peripheral neurotoxicity (CIPN) is one of the most common dose-limiting side effects of paclitaxel (PTX) treatment. Many age-related changes have been hypothesized to underlie susceptibility to damage or impaired regeneration/repair after nerve injury. The results of these studies, however, are inconclusive and other potential biomarkers of nerve impairment need to be investigated. METHODS: Twenty-four young (2 months) and 24 adult (9 months) Wistar male rats were randomized to either PTX treatment (10 mg/kg i.v. once/week for 4 weeks) or vehicle administration. Neurophysiological and behavioral tests were performed at baseline, after 4 weeks of treatment and 2-week follow-up. Skin biopsies and nerve specimens collected from sacrificed animals were examined for intraepidermal nerve fiber (IENF) density assessment and nerve morphology/morphometry. Blood and liver samples were collected for targeted metabolomics analysis. RESULTS: At the end of treatment, the neurophysiological studies revealed a reduction in sensory nerve action potential amplitude (p < .05) in the caudal nerve of young PTX-animals, and in both the digital and caudal nerve of adult PTX-animals (p < .05). A significant decrease in the mechanical threshold was observed only in young PTX-animals (p < .001), but not in adult PTX-ones. Nevertheless, both young and adult PTX-rats had reduced IENF density (p < .0001), which persisted at the end of follow-up period. Targeted metabolomics analysis showed significant differences in the plasma metabolite profiles between PTX-animals developing peripheral neuropathy and age-matched controls, with triglycerides, diglycerides, acylcarnitines, carnosine, long chain ceramides, sphingolipids, and bile acids playing a major role in the response to PTX administration. INTERPRETATION: Our study identifies for the first time multiple related metabolic axes involved in PTX-induced peripheral neurotoxicity, and suggests age-related differences in CIPN manifestations and in the metabolic profile.

Fabrication of Dual pH/Reduction-Responsive P(CL-co-ACL)-Based Cross-Linked Polymeric Micelles for PTX Delivery.

To enhance the stability of the polymeric micelles and optimize their drug-controlled release ability, three disulfide-linked polyethylene glycol methyl ether methacrylate-disulfide-poly(ε-caprolactone-co-γ-amine-ε-caprolactone) (PPEGMA-SS-P(CL-co-ACL)) polymers were synthesized and characterized by 1H NMR, GPC, and FT-IR successfully, and their dual pH/reduction-responsive cross-linked polymeric micelles were prepared for paclitaxel (PTX) delivery by using 2,3-dimethylmaleic anhydride (DMMA) as the cross-linking agent. The PTX loading capacity (LC) and encapsulation efficiency (EE) values of the cross-linked micelles formed by PPEGMA8-SS-P(CL47-co-ACL15) achieved were 23.96% and 71.58%, slightly higher than those of un-cross-linked micelles. Both particle sizes of blank micelles and in vitro drug release of PTX-loaded micelles confirmed that compared with those un-cross-linked micelles, the cross-linked micelles were more stable at pH 7.4 + 0 mM DTT, with a PTX cumulative release of 13% at 120 h, while the PTX cumulative release of the cross-linked micelles at pH 5.0 + 10 mM DTT were close to that of un-cross-linked micelles after 60 h, indicating the successful reversible cross-linking and smooth drug release of the cross-linked micelles. The cytotoxicity assay showed that PPEGMA8-SS-P(CL47-co-ACL15) and its cross-linked micelles had low cell cytotoxicity, and both PTX-loaded micelles revealed a certain inhibitory effect on HepG2 cells. These results revealed that the dual pH/reduction-responsive cross-linked polymeric micelles prepared from PPEGMA8-SS-P(CL47-co-DCL15) were a promising candidate for PTX delivery.

Thymoquinone Alleviates Paclitaxel-Induced Peripheral Neuropathy through Regulation of the TLR4-MyD88 Inflammatory Pathway.

Paclitaxel-induced peripheral neuropathy (PIPN) is one of the common adverse effects during the paclitaxel (PTX) treatment of cancer. In this study, we investigated the neuroprotective effects and mechanisms of thymoquinone (TQ) in the PIPN model. Through pain behavioral assays and histological assessment, we demonstrated that TQ significantly alleviated the nociceptive behavior, modulated the pathological changes in peripheral nerves, and decreased the expression of inflammatory factors TNF-α, IL-1ß, and IL-6 induced by PIPN in mice. In addition, TQ significantly reversed the reduced viability and inflammatory response of primary DRG neurons caused by PTX. Moreover, the gene expression of related pathways was detected by Western blot, qPCR, and immunofluorescence, and the results showed that TQ exerts neuroprotective effects by regulating TLR4/MyD88 and its downstream NF-κB and MAPKs inflammatory pathways in vivo and in vitro. The treatment with TLR4 antagonist TAK-242 further indicated the important role of the TLR4/MyD88 signaling pathway in PIPN. Furthermore, molecular docking and a cellular thermal shift assay were used to confirm the interaction of TQ with TLR4. In summary, our study shows that TQ can inhibit inflammatory responses against PIPN by regulating TLR4 and MyD88 and its downstream inflammatory pathways.

Broad-spectrum neuroprotection exerted by DDD-028 in a mouse model of chemotherapy-induced neuropathy.

ABSTRACT: Neurotoxicity of chemotherapeutics involves peculiar alterations in the structure and function, including abnormal nerve signal transmission, of both the peripheral and central nervous system. The lack of effective pharmacological approaches to prevent chemotherapy-induced neurotoxicity necessitates the identification of innovative therapies. Recent evidence suggests that repeated treatment with the pentacyclic pyridoindole derivative DDD-028 can exert both pain-relieving and glial modulatory effects in mice with paclitaxel-induced neuropathy. This work is aimed at assessing whether DDD-028 is a disease-modifying agent by protecting the peripheral nervous tissues from chemotherapy-induced damage. Neuropathy was induced in animals by paclitaxel injection (2.0 mg kg -1 i.p). DDD-028 (10 mg kg -1 ) and the reference drug, pregabalin (30 mg kg -1 ), were administered per os daily starting concomitantly with the first injection of paclitaxel and continuing 10 days after the end of paclitaxel treatment. The behavioural tests confirmed the antihyperalgesic efficacy of DDD-028 on paclitaxel-induced neuropathic pain. Furthermore, the electrophysiological analysis revealed the capacity of DDD-028 to restore near-normal sensory nerve conduction in paclitaxel-treated animals. Histopathology evidence indicated that DDD-028 was able to counteract effectively paclitaxel-induced peripheral neurotoxicity by protecting against the loss of intraepidermal nerve fibers, restoring physiological levels of neurofilament in nerve tissue and plasma, and preventing morphological alterations occurring in the sciatic nerves and dorsal root ganglia. Overall, DDD-028 is more effective than pregabalin in preventing chemotherapy-induced neurotoxicity. Thus, based on its potent antihyperalgesic and neuroprotective efficacy, DDD-028 seems to be a viable prophylactic medication to limit the development of neuropathies consequent to chemotherapy.

Intrathecal rapamycin attenuates the mechanical hyperalgesia of paclitaxel-induced peripheral neuropathy in mice.

Paclitaxel is an extensively used chemotherapy antitumor drug and paclitaxel-induced peripheral neuropathy (PIPN) is one of the most common side effect. Rapamycin, originally used as an adjuvant drug for chemotherapy, has recently been found to possess potential neuroprotective activities. Our purposes of this study are to verify the effect of rapamycin on PIPN, which contributes to a new target for PIPN treatment. Mice were given paclitaxel or rapamycin with different injection methods. Paw withdrawal threshold was tested at different time points for mechanical sensitivity assessment. Administration of paclitaxel, both 2 mg/kg and 5 mg/kg, could induce mechanical hypersensitivity. 0.01 mg intrathecal injection of rapamycin showed the best effect on attenuate the mechanical hyperalgesia of PIPN. Intrathecal injection of only rapamycin would not induce the mechanical hyperalgesia while when rapamycin and paclitaxel were used together the mechanical hyperalgesia induced by paclitaxel could be attenuated. Paclitaxel could induce mechanical hyperalgesia in mice and rapamycin could attenuate such mechanical hyperalgesia of PIPN.

Silymarin, an antioxidant flavonoid, protects the liver from the toxicity of the anticancer drug paclitaxel.

One of the biggest factors that negatively affect the cancer treatment plan is the toxic effects of chemotherapeutics on non-target cells and tissues. This information prompted us to investigate the protective effects of silymarin (SL), a hepatoprotective agent, against the hepatotoxic effects of the anticancer drug paclitaxel (PAC). Four groups were formed from 28 rats as control, PAC (2 mg/kg), SL (100 mg/kg) and PAC + SL (combination of PAC with SL). After completing the experimental procedures, the tissues collected after anesthesia were analyzed by Western blot, qRT-PCR, biochemical, stereological, immunohistochemical, and histopathological techniques. Administration of PAC significantly increased the expression of tumor necrosis factor-alpha (TNF-α), Bax, cytochrome-c (cyt-c), and active caspase-3, as well as malondialdehyde (MDA) levels in liver tissue and decreased glutathione (GSH) levels compared with the control group. PAC also resulted in a significant increase in serum triglyceride (TG), cholesterol (CH), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels compared with the control group. Pathological changes such as microvesicular steatosis, the formation of Councilman bodies, an increase in total sinusoidal volume, and a decrease in the total number of hepatocytes were observed in the liver tissue of the PAC group. Almost all analysis results in the PAC + SL group were similar to those in the control group, and no significant pathological alterations were observed in this group. The data obtained show that SL protects the liver from the harmful effects of PAC, especially thanks to its TNF-α suppressor, anti-inflammatory, anti-apoptotic and antioxidant effects. Based on this result, in cases where PAC is used in cancer treatment, it can be recommended to be used together with SL to prevent harmful effects on healthy liver tissue and to continue treatment uninterruptedly and effectively.

Naringin and naringenin counteract taxol-induced liver injury in Wistar rats via suppression of oxidative stress, apoptosis and inflammation.

This research aimed to evaluate the preventing effects of naringin, naringenin, and their combination on liver injury induced by Taxol (paclitaxel) in Wistar rats. Male Wistar rats received 2 mg/kg Taxol intraperitoneal injections twice weekly on the second and fifth days of each week for 6 weeks. During the same period as Taxol administration, rats were given naringin, naringenin, or a combination of the two (10 mg/kg b.wt) every other day. Treatment with naringin and/or naringenin reduced the abnormally high serum levels of total bilirubin, aspartate transaminase, alanine transaminase, alkaline phosphatase, lactate dehydrogenase, and gamma-glutamyl transferase in Taxol-treated rats. It also significantly increased the level of serum albumin, indicating an improvement in the liver. The perturbed histological liver changes were markedly improved due to the naringin and/or naringenin treatment in Taxol-administered rats. Additionally, the treatments reduced high hepatic lipid peroxidation and increased liver glutathione content as well as the activities of superoxide dismutase and glutathione peroxidase. Furthermore, the treatments reduced the levels of alpha-fetoprotein and caspase-3, a pro-apoptotic mediator. The naringin and naringenin mixture appeared more effective in improving organ function and structural integrity. In conclusion, naringin and naringenin are suggested to employ their hepatoprotective benefits via boosting the body's antioxidant defense system, reducing inflammation, and suppressing apoptosis.

Parthenolide as a potential analgesic in the treatment of paclitaxel-induced neuropathic pain: the rat modeling.

In this study, we determined the therapeutic effect of parthenolide (PTL), the active component of Tanacetum parthenium, on neuropathic pain caused by paclitaxel (PTX), a chemotherapeutic drug frequently used in cancer treatment, at the gene and protein levels. To this end, 6 groups were formed: control, PTX, sham, 1 mg/PTL, 2 mg/kg PTL, and 4 mg/kg PTL. Pain formation was tested by Randall-Selitto analgesiometry and locomotor activity behavioral analysis. Then, PTL treatment was performed for 14 days. After the last dose of PTL was taken, Hcn2, Trpa1, Scn9a, and Kcns1 gene expressions were measured in rat brain (cerebral cortex/CTX) tissues. In addition, changes in the levels of SCN9A and KCNS1 proteins were determined by immunohistochemical analysis. Histopathological hematoxylin-eosin staining was also performed to investigate the effect of PTL in treating tissue damage on neuropathic pain caused by PTX treatment. When the obtained data were analyzed, pain threshold and locomotor activity decreased in PTX and sham groups and increased with PTL treatment. In addition, it was observed that the expression of the Hcn2, Trpa1, and Scn9a genes decreased while the Kcns1 gene expression increased. When protein levels were examined, it was determined that SCN9A protein expression decreased and the KCNS1 protein level increased. It was determined that PTL treatment also improved PTX-induced tissue damage. The results of this study demonstrate that non-opioid PTL is an effective therapeutic agent in the treatment of chemotherapy-induced neuropathic pain, especially when used at a dose of 4 mg/kg acting on sodium and potassium channels.

Duloxetine prevents bortezomib and paclitaxel large-fiber chemotherapy-induced peripheral neuropathy (LF-CIPN) in sprague dawley rats.

Chemotherapy-induced peripheral neuropathy (CIPN) is a debilitating, treatment-limiting, side-effect of several classes of chemotherapy drugs. While negatively impacting oncology patients' quality of life, chemotherapy-induced large-fiber (LF) neuropathy is amongst the least well understood components of CIPN, and one for which there is currently no established therapy. Preliminary clinical observations have led to the suggestion that Duloxetine, which is used for the treatment of pain associated with small-fiber CIPN (SF-CIPN), may be effective against LF-CIPN. In the present experiments we developed a model of LF-CIPN and studied the effect of Duloxetine on LF-CIPN induced by two neurotoxic chemotherapy agents: the proteasome inhibitor, Bortezomib, a first-line treatment of multiple myeloma; and, the anti-microtubule taxane, Paclitaxel, used in the treatment of solid tumors. Since there are currently no models for selective the study of LF-CIPN, our first aim was to establish a pre-clinical model in the rat. LF-CIPN was evaluated with the Current Perception Threshold (CPT) assay, which uses a high frequency (1000 Hz) electrical stimulus protocol that selectively activates large-fiber myelinated afferents. Our second aim was to use this model to test the hypothesis that Duloxetine can prevent LF-CIPN. We report that Bortezomib and Paclitaxel induce elevation of CPT, compatible with loss of large-fiber function, which are prevented by Duloxetine. Our findings support the clinical observation that Duloxetine may be an effective treatment for the large-fiber CIPN. We also suggest that CPT could be used as a biomarker for LF-CIPN in patients receiving neurotoxic chemotherapy.

SAFit2 ameliorates paclitaxel-induced neuropathic pain by reducing spinal gliosis and elevating pro-resolving lipid mediators.

BACKGROUND: Chemotherapy-induced neuropathic pain (CIPN) describes a pathological pain state that occurs dose-dependently as a side effect and can limit or even impede an effective cancer therapy. Unfortunately, current treatment possibilities for CIPN are remarkably confined and mostly inadequate as CIPN therapeutics themselves consist of low effectiveness and may induce severe side effects, pointing out CIPN as pathological entity with an emerging need for novel treatment targets. Here, we investigated whether the novel and highly specific FKBP51 inhibitor SAFit2 reduces paclitaxel-induced neuropathic pain. METHODS: In this study, we used a well-established multiple low-dose paclitaxel model to investigate analgesic and anti-inflammatory properties of SAFit2. For this purpose, the behavior of the mice was recorded over 14 days and the mouse tissue was then analyzed using biochemical methods. RESULTS: Here, we show that SAFit2 is capable to reduce paclitaxel-induced mechanical hypersensitivity in mice. In addition, we detected that SAFit2 shifts lipid levels in nervous tissue toward an anti-inflammatory and pro-resolving lipid profile that counteracts peripheral sensitization after paclitaxel treatment. Furthermore, SAFit2 reduced the activation of astrocytes and microglia in the spinal cord as well as the levels of pain-mediating chemokines. Its treatment also increased anti-inflammatory cytokines levels in neuronal tissues, ultimately leading to a resolution of neuroinflammation. CONCLUSIONS: In summary, SAFit2 shows antihyperalgesic properties as it ameliorates paclitaxel-induced neuropathic pain by reducing peripheral sensitization and resolving neuroinflammation. Therefore, we consider SAFit2 as a potential novel drug candidate for the treatment of paclitaxel-induced neuropathic pain.

Fluocinolone Acetonide Enhances Anterograde Mitochondria Trafficking and Promotes Neuroprotection against Paclitaxel-Induced Peripheral Neuropathy.

Paclitaxel (PTX)-induced peripheral neuropathy (PIPN) is a debilitating health condition which is a result of degeneration of peripheral nerves found in extremities. Currently, there are no established treatment methods that can prevent or protect from PIPN. Fluocinolone acetonide (FA) has been recently identified as a potential candidate for protection from PIPN. However, the fundamental mechanism of action is still unknown. In this study, we showed that enhanced anterograde mitochondrial movement in dorsal root ganglion (DRG) cells has a major role in FA-mediated neuroprotection in PIPN. In this study, cells were treated with PTX or FA along with their combination followed by mitochondrial fluorescence staining. Somal (proximal) and axonal (distal) mitochondria were selectively stained using a microfluidic compartmentalized chamber with different MitoTrackers blue and red, respectively, which we termed, the two-color staining approach. Results revealed that axons were protected from degeneration by the PTX effect when treated along with FA. PTX exposure alone resulted in low mitochondrial mobility in DRG cells. However, cotreatment with PTX and FA showed significant enhancement of anterograde trafficking of somal (proximal) mitochondria to distal axons. Similarly, cotreatment with FA restored mitochondrial mobility significantly. Overall, this study affirms that increasing mitochondrial recruitment into the axon by cotreatment with FA can be a worthwhile strategy to protect or prevent PIPN. The proposed two-color staining approach can be extended to study trafficking for other neuron-specific subcellular organelles.

Cannabidiol and mitragynine exhibit differential interactive effects in the attenuation of paclitaxel-induced mechanical allodynia, acute antinociception, and schedule-controlled responding in mice.

BACKGROUND: For many chemotherapy patients peripheral neuropathy is a debilitating side effect. Mitragyna speciosa (kratom) contains the alkaloid mitragynine (MG), which produces analgesia in multiple preclinical pain models. In humans, anecdotal reports suggest cannabidiol (CBD) may enhance kratom-related analgesia. We examined the interactive activity of MG and CBD in a mouse chemotherapy-induced peripheral neuropathy (CIPN) model. We also examined MG + CBD in acute antinociception and schedule-controlled responding assays, as well as examined underlying receptor mechanisms. METHODS: Male and female C57BL/6J mice received a cycle of intraperitoneal (ip) paclitaxel injections (cumulative dose 32 mg/kg). The von Frey assay was utilized to assess CIPN allodynia. In paclitaxel-naïve mice, schedule-controlled responding for food was conducted under a fixed ratio (FR)-10, and hot plate antinociception was examined. RESULTS: MG dose-relatedly attenuated CIPN allodynia (ED50 102.96 mg/kg, ip), reduced schedule-controlled responding (ED50 46.04 mg/kg, ip), and produced antinociception (ED50 68.83 mg/kg, ip). CBD attenuated allodynia (ED50 85.14 mg/kg, ip) but did not decrease schedule-controlled responding or produce antinociception. Isobolographic analysis revealed 1:1, 3:1 MG + CBD mixture ratios additively attenuated CIPN allodynia. All combinations decreased schedule-controlled responding and produced antinociception. WAY-100635 (serotonin 5-HT1A receptor antagonist) pretreatment (0.01 mg/kg, ip) antagonized CBD anti-allodynia. Naltrexone (pan opioid receptor antagonist) pretreatment (0.032 mg/kg, ip) antagonized MG anti-allodynia and acute antinociception but produced no change in MG-induced decreased schedule-controlled behavior. Yohimbine (α2 receptor antagonist) pretreatment (3.2 mg/kg, ip) antagonized MG anti-allodynia and produced no change in MG-induced acute antinociception or decreased schedule-controlled behavior. CONCLUSIONS: Although more optimization is needed, these data suggest CBD combined with MG may be useful as a novel CIPN therapeutic.