Vincristine increased spinal cord substance P levels in a peripheral neuropathy rat model

The dual role of VEGF-A in a complex in vitro model of oxaliplatin-induced neurotoxicity: Pain-related and neuroprotective effects

Vascular endothelial growth factor (VEGF)-A is a main player in the development of neuropathic pain induced by chemotherapy and the pharmacological blockade of VEGF receptor (VEGFR) subtype 1 is a pain killer strategy. Interestingly, VEGF-A has been demonstrated to have also neuroprotective properties. The aim of the study was to investigate the neuroprotective role of VEGF-A against oxaliplatin neurotoxicity, attempting to discriminate pain-related and restorative signaling pathways. We used rat organotypic spinal cord slices treated with oxaliplatin, as an in vitro model to study chemotherapy-induced toxicity. In this model, 10 ​μM oxaliplatin caused a time-dependent release of VEGF-A, which was reduced by the astrocyte inhibitor fluorocitrate. Moreover, glia inhibition exacerbated oxaliplatin-induced cytotoxicity in a VEGF-A sensitive manner. Treatment with VEGF165b, the main isoform of VEGF-A, prevented the oxaliplatin-induced neuronal damage (indicated by NeuN staining) and astrocyte activation (indicated by GFAP staining). In addition, the blockade of VEGFR-2 by the selective antibody DC101 blunted the protective action of VEGF165b. In the same model, VEGF165b increased the release of molecules relevant in pain signaling, like substance P and CGRP, as well as the mRNA expression of glutamate transporters (EAAT1 and EAAT2), similarly to oxaliplatin and these effects were prevented by the selective VEGFR-1 blocker antibody D16F7. In conclusion, VEGF-A plays a dichotomic role in an in vitro model of chemotherapy-induced toxicity, either promoting neuroprotection or triggering pain mediators release, depending on which of its two receptors is activated. The selective management of VEGF-A signaling is suggested as a therapeutic approach.

Aprepitant mitigates paclitaxel-induced neuropathic pain in rats via suppressing inflammatory pathways in dorsal root ganglia

Neuropathic pain is the crucial dose-limiting side effect of paclitaxel in chemotherapy patients that negatively impacts the quality of life and survival. Currently, no effective treatment option is available. Aprepitant, a well-established chemotherapy antiemetic performing neurokinin-1 receptor antagonism, shows analgesic effects in some pain models. We studied aprepitant analgesic effects on the paclitaxel-induced neuropathic pain model in rats besides inflammatory markers assessment. Rats intraperitoneally received paclitaxel, reaching the cumulative paclitaxel dose of 8 mg/kg. Aprepitant was orally administered every alternate day between days 2 and 14, with a prescribed dosage of 10 or 20 mg/kg. The evaluation of mechanical allodynia and cold hyperalgesia involved the measurement of paw withdrawal threshold and acetone test score on days 0, 7, and 14. On day 14, paw licking latency was measured using a hot plate test before scarification and tissue collection for interleukin 1β, tumor necrosis factor α, and nuclear factor kappa B (NF-kB) evaluation. Paclitaxel induced neuropathy as indicated by a lowered hind paw withdrawal threshold in the Von Frey test, a higher score in the acetone test, and shortened hot plate latency. Aprepitant effectively alleviated cold and thermal hyperalgesia as well as mechanical allodynia. Moreover, aprepitant administration significantly reversed paclitaxel-mediated elevation of proinflammatory cytokines levels in dorsal root ganglia. In addition, aprepitant application suppressed the protein expression of NF-kB in the dorsal root ganglia of paclitaxel-treated rats, as revealed by western blot analysis. Aprepitant treatment ameliorates neuropathy induced by paclitaxel, which is associated with decreasing proinflammatory cytokines and NF-kB expression.

Melatonin mitigates vincristine-induced peripheral neuropathy by inhibiting TNF-α/astrocytes/microglial cells activation in the spinal cord of rats, while preserving vincristine's chemotherapeutic efficacy in lymphoma cells

Vincristine (VCR), an anti-tubulin chemotherapy agent, is known to cause peripheral and central nerve damage, inducing severe chemotherapy-induced peripheral neuropathy (CIPN). Although melatonin has been recently recognized for its potential anti-neuropathic effects, its efficacy in countering VCR-induced neuropathy remains unclear. This study examines the neuroprotective potential of melatonin against VCR-induced neuropathy using a rat model. Neuropathic pain was induced through 10 VCR injections (0.1 mg/kg/day i.p.), administered in two five-day cycles with a two-day break. Melatonin treatment started two days before VCR administration and continued daily throughout the experiment. Rats were assigned to five groups: control, VCR, and three melatonin-treated groups receiving VCR with melatonin (5, 10, or 20 mg/kg/day i.p.). We assessed mechanical (von-Frey and Randall-Selitto tests) and thermal (hot-plate and tail-flick tests) hyperalgesia, motor coordination (rotarod test), and sciatic nerve conduction velocity (NCV). Changes in body weight, spinal cord histopathology (H&E), and proinflammatory markers (TNF-α, IL-1β, and IL-6), reactive astrocytes (GFAP) and microglial cells (IBA-1) were also assessed, as well as spinal cord degeneration (Nissl stain) and demyelination (LFB stain and MBP). Finally, the effect of melatonin on the cytotoxic activity of VCR against EL4 lymphoma cells was assessed using an MTT assay. Our results indicated that melatonin coadministration with VCR preserved spinal cord architecture, elevated nociceptive thresholds, improved motor coordination, enhanced NCV, and maintained normal body weight gain. Melatonin also reduced inflammation, decreased reactive astrocytes and microglia, and prevented neurodegeneration and demyelination in the spinal cord. Importantly, melatonin did not affect VCR's cytotoxic activity in cancer cells.

5,7-Dimethoxycoumarin ameliorates vincristine induced neuropathic pain: potential role of 5HT3 receptors and monoamines

Vincristine is the drug of choice for Hodgkin's lymphoma, acute lymphoblastic leukemia, and non-Hodgkin lymphoma. Despite its significant anticancer effects, it causes dose-dependent neuropathy, leading to compulsive dose reduction. The available drugs used for vincristine-induced neuropathic pain (VINP) have a range of safety, efficacy, and tolerability issues prompting a search for new therapies. 5,7-Dimethoxycoumarin (5,7-DMC) also known as citropten, is a natural coumarin found in the essential oils of citrus plants such as lime, lemons, and bergamots, and it possesses both antidepressant and anti-inflammatory effects. This study was designed to investigate the possible analgesic and antiallodynic effects of 5,7-DMC in a murine model of VINP. Vincristine was administered to groups of BALB/c male mice (0.1 mg/kg intraperitoneally) once daily for 14 days to induce VINP. Thermal hyperalgesia and mechanical allodynia were quantified using the tail immersion test and von Frey filament application method. The levels of monoamine neurotransmitters and vitamin C in frontal cortical, striatal and hippocampal tissues, as well as the TNF-α level in plasma, were quantified using high performance liquid chromatography and ELISA respectively. On day 15 of the protocol, acute treatment with 5,7-DMC clearly reversed VINP thermal hyperalgesia, mechanical static allodynia, mechanical dynamic allodynia, and cold allodynia. The activity of 5,7-DMC against hyperalgesia and allodynia was inhibited by pretreatment with ondansetron but not naloxone, implicating a 5-HT3 receptor involvement. VINP vitamin C levels were restored by 5,7-DMC in the frontal cortex, and changes in serotonin, dopamine, adenosine, inosine and hypoxanthine levels caused by vincristine were reversed either fully or partially. Additionally, the vincristine-induced rise in hippocampal serotonin, dopamine, inosine and striatal serotonin was appreciably reversed by 5,7-DMC. 5,7-DMC also reversed the vincristine-induced increase in the plasma level of TNF-α. In negating the changes in the levels of some neurotransmitters in the brain caused by vincristine, 5,7-DMC showed stronger effects than gabapentin. It was concluded that, there is a potential role of 5-HT3 receptors and monoamines in the amelioration of VINP induced by 5,7-DMC, and the use of this compound warrants further investigation.

Neuropathy, its Profile and Experimental Nerve Injury Neuropathic Pain Models: A Review

Neuropathy is a terrible disorder that has a wide range of etiologies. Drug-induced neuropathy, which happens whenever a chemical agent damages the peripheral nerve system, has been linked here to the iatrogenic creation of some drugs. It is potentially permanent and causes sensory impairments and paresthesia that typically affects the hands, feet, and stockings; motor participation is uncommon. It might appear suddenly or over time, and the long-term outlook varies. The wide range of chronic pain conditions experienced by people has been one of the main obstacles to developing new, more effective medications for the treatment of neuropathic pain. Animal models can be used to examine various neuropathic pain etiologies and symptoms. Several models investigate the peripheral processes of neuropathic pain, whereas some even investigate the central mechanisms, such as drug induce models like vincristine, cisplatin, bortezomib, or thalidomide, etc., and surgical models like sciatic nerve chronic constriction injury (CCI), sciatic nerve ligation through spinal nerve ligation (SNL), sciatic nerve damage caused by a laser, SNI (spared nerve injury), etc. The more popular animal models relying on peripheral nerve ligatures are explained. In contrast to chronic sciatic nerve contraction, which results in behavioral symptoms of less reliable stressful neuropathies, (SNI) spared nerve injury generates behavioral irregularities that are more feasible over a longer period. This review summarizes the latest methods models as well as clinical ideas concerning this mechanism. Every strongest current information on neuropathy is discussed, along with several popular laboratory models for causing neuropathy.

Quercetin provides protection against the peripheral nerve damage caused by vincristine in rats by suppressing caspase 3, NF-κB, ATF-6 pathways and activating Nrf2, Akt pathways

In the present study, the protective effects of quercetin on peripheral neurotoxicity caused by vincristine, which is used effectively in the treatment of various types of cancers, were investigated by using different techniques. In the study, for 12 days, male Sprague Dawley rats were given 25 and 50 mg/kg doses of quercetin orally and were administered a 0.1 mg/kg dose of vincristine (a total cumulative dose of 1.2 mg/kg) intraperitoneally 30 min later. The protein levels of nuclear factor erythroid 2-related factor-2 (Nrf2), heme oxygenase-1 (HO-1), NAD(P)H quinone dehydrogenase-1 (NQO1), glial fibrillary acidic protein (GFAP), and nuclear factor kappa B (NF-κB) were measured with ELISA; the immunopositivity of 8-hydroxy-2'-deoxyguanosine (8-OHdG) and caspase 3 were determined with immunohistochemistry; the mRNA transcript levels of double-stranded RNA-activated protein kinase (PKR)-like ER kinase (PERK), inositol-requiring enzyme-1 (IRE1), activating transcription factor-6 (ATF-6), glucose-regulated protein 78 (GRP78), Bcl-2-associated X protein (Bax), B-cell lymphoma-2 (Bcl-2), caspase 3, protein kinase B1/2 (Akt-1/2), and forkhead box transcription factor, class O1 (FOXO1) were determined with RT-PCR. The reduction of Nrf2 levels and HO-1 and NQO1 activities in the sciatic nerve tissue, the increase in the levels of 8-OHdG, and the increase in the levels of GFAP and NF-κB caused by vincristine was observed to cause oxidative stress, oxidative DNA damage, neuronal cell damage, and inflammation, respectively. Additionally, vincristine was determined to cause ER stress and apoptosis by increasing PERK, IRE1, ATF-6, and GRP78 and caspase 3 and Bax expressions and by decreasing Bcl-2 expressions. Vincristine causing Akt inhibition also shows that it prevents neuronal survival. However, quercetin was determined to relieve oxidative stress, oxidative DNA damage, neuronal cell damage, inflammation, ER stress, and apoptosis caused by vincristine and enable Akt activation. These results show that in rats, quercetin may have a protective effect against peripheral neurotoxicity caused by vincristine.