Selenium partially prevents cisplatin-induced neurotoxicity: a preliminary study

Dental Pulp-Derived Mesenchymal Stem Cells Increase Axon Numbers in Mental Nerve Repair

Aim

The mental nerve, the extended part of the inferior alveolar nerve, is often injured during dentoalveolar, orthognathic, or tumor surgery. Numerous therapeutic interventions, including surgery and pharmacotherapy, have been used to enhance the recovery of nerve injuries. Dental pulp stem cells (DPSCs) represent an easily accessible source of adult stem cells that can be isolated from the pulp of extracted teeth. This study evaluated the effect of DPSCs on the regeneration of the mental nerve injury model of rabbits.

Methods

In this presented study, DPSCs were cultured and cell characterizations were performed by using flow cytometry and immunostainings. Bilateral mental nerve injury models of rabbits were created. In the control group (n = 10), saline was applied, and in the study group (n = 10), 2 × 106 DPSCs were applied to the repaired nerve areas. After 3 weeks, animals were killed and histological examination was obtained by using Masson's trichrome staining. An unpaired Student's t test was used when comparing the groups. Differences were considered to be statistically significant at P values of less than 0.05.

Results

The DPSCs demonstrated a homogeneous population of mesenchymal stromal cells which expressed cluster of differentiation CD44, CD73, CD90, and CD105 and lack of CD34, CD45, and HLA-DR. Our finding clearly demonstrated that a lower number of cross-sectioned axons were founded in the control group (60.18 ± 2.52) compared to the study group (72.96 ± 2.43) (p = 0.00).

Conclusions

DPSCs promote mental nerve axonal regeneration. These results suggest that DPSCs provide an important accessible source of adult stem cells for mental nerve regeneration.

The effect of different treatment protocols with diode laser on regeneration in axonetmesis ınjuries of the ınferior alveolar nerve: an animal study

The inferior alveolar nerve can be damaged during dental procedures, leading to symptoms, such as tingling, numbness, and reduced quality of life. Recovery depends on factors such as medications, surgery, and photobiomodulation therapy. Photobiomodulation therapy has shown the potential to improve nerve function and reduce regeneration time; however, there is no standard treatment protocol yet. This study aimed to examine the effect of diode lasers on nerve regeneration in patients with axonetmesis injuries. In this experiment on animals, Wistar rats' damaged sensory systems were treated with lasers to restore them. Animals were randomly divided into six groups: a sham group, a control group, and four laser treatment groups(1st group: performed every day, 10 sessions; 2nd group: performed every 2 days, 10 sessions; 3rd group: performed every day, 20 sessions; and 4th group: performed every 2 days, 20 sessions). Sensory function was determined using the Semmes-Weinstein monofilament test, which was repeated after the surgical procedure. The results showed that the 20-session group had the best improvement, most closely resembling the group without sensory test damage. The histomorphometric results showed that the number of axons was significantly lower in the group that received 10 daily sessions and in the control group than in the undamaged nerve. Axon diameter was lower in all groups than in the sham group. In conclusion, the remarkable aspect of this study is that consecutive-day 20-session laser treatment showed better improvement than the over-the-day 20-session treatment protocol.

The Therapeutic Potential of Antioxidants in Chemotherapy-Induced Peripheral Neuropathy: Evidence from Preclinical and Clinical Studies

As cancer therapies advance and patient survival improves, there has been growing concern about the long-term adverse effects that patients may experience following treatment, and concerns have been raised about such persistent, progressive, and often irreversible adverse effects. Chemotherapy is a potentially life-extending treatment, and chemotherapy-induced peripheral neuropathy (CIPN) is one of its most common long-term toxicities. At present, strategies for the prevention and treatment of CIPN are still an open problem faced by medicine, and there has been a large amount of previous evidence that oxidative damage is involved in the process of CIPN. In this review, we focus on the lines of defense involving antioxidants that exert the effect of inhibiting CIPN. We also provide an update on the targets and clinical prospects of different antioxidants (melatonin, N-acetylcysteine, vitamins, α-lipoic acid, mineral elements, phytochemicals, nutritional antioxidants, cytoprotectants and synthetic compounds) in the treatment of CIPN with the help of preclinical and clinical studies, emphasizing the great potential of antioxidants as adjuvant strategies to mitigate CIPN.

The effect of pulsed radiofrequency application on nerve healing after sciatic nerve anastomosis in rats

The Effect of Pulsed Radiofrequency Application on Nerve Healing After Sciatic Nerve Anastomosis in Rats. In this study, we aimed to evaluate the histomorphological and functional effect of Pulsed Radiofrequency (PRF) application on regeneration after experimental nerve damage in rats. Forty Sprague-Dawley male rats were used in the study. Sciatic nerve incision was applied to all rats and then anastomosis was performed. Twenty rats were separated as the control group, and the remaining 20 rats underwent PRF every day at 42oC, for 120 seconds. The groups were divided into two further subgroups to be sacrificed on the 15th and 30th days. Tissue samples were obtained from all groups at 24 hours and 72 hours after the injury. Sections of sciatic nerve samples were stained with hematoxylin-eosin for light microscopic investigation and prepared for evaluation of ultrastructural changes with transmission electron microscopy. In the evaluation of axon numbers and diameters were seen that the 30th-day RF group had an increase compared to the control group. In the electron microscopic examination, it was observed that myelinated and unmyelinated nerve fiber sheaths had borders that are more regular in the RF group, the nucleus structures of schwann cells were better preserved, mitochondrial damage was less, and the extensions of fibroblast and collagen fibers were smoother than the control group. The findings suggested that PRF application has a positive contribution histologically on nerve healing in the early period after full-layer incision nerve injury anastomosis surgery.

Surgical Procedures Required for Measurement Reduce Nerve Conduction Velocity: An In Vivo and In Vitro Comparative Study

Background: Although in vitro methods have disadvantages, they are still commonly used to measure nerve conduction velocity (NCV) in experimental studies. Therefore, this study was designed to demonstrate the effect of the surgical procedures required for in vitro methods on nerve fibers and the effect of in vivo and in vitro methods on the results of electrophysiological measurements.Methods: Rats were assigned to the in vivo (control-1, injury-1, and diabetic-1) and in vitro (control-2, injury-2, and diabetic-2) groups. The NCV and compound action potential amplitudes were measured, and the nerve fibers were histologically examined.Results: Damaged axons and myelin sheaths were observed in the control-2 group. The electrophysiological values of the in vitro groups were lower than those of the in vivo groups. Furthermore, these values were lower for the diabetic and injury groups than for the control groups.Conclusions: This study showed that the surgical procedures required for the in vitro method reduced the measured values. Owing to the previous and current disadvantages of the in vitro method, the in vivo method was more sensitive for the NCV measurement. Moreover, measurements can be performed using the current in vivo method for small nerve fibers.

Efficacy and safety of intravenous administration of high-dose selenium for preventing chemotherapy-induced peripheral neuropathy in platinum-sensitive recurrent ovarian, fallopian or primary peritoneal cancer: study protocol for a phase III, double-blind, randomized study

Background

The second-line chemotherapy using paclitaxel, carboplatin, and bevacizumab for treating platinum-sensitive recurrent ovarian, fallopian or primary peritoneal cancer frequently cause chemotherapy-induced peripheral neuropathy (CIPN), which is significantly associated with deterioration of quality of life. Despite the potential of some agents to prevent and treat CIPN, and there is still a lack of evidence of the effect. Although selenium has been suggested as an antioxidant candidate to prevent CIPN, there are insufficient data regarding its effect due to its low dose by oral administration. Thus, we hypothesized intravenous administration of high-dose selenium (2,000 µg/day) at each cycle of the second-line chemotherapy would prevent and reduce CIPN in patients with platinum-sensitive recurrent ovarian, fallopian or primary peritoneal cancer.

Method

This trial is an investigator-initiated, phase III, double-blinded, randomized controlled trial to evaluate the efficacy and safety of intravenous administration of high-dose selenium (2,000 µg/day) for preventing CIPN in patients with platinum-sensitive recurrent ovarian, fallopian or primary peritoneal cancer who receive paclitaxel, carboplatin, and bevacizumab. A total of 68 patients will be randomly assigned to the experimental and control groups at a 1:1 ratio. As the primary endpoint, the incidence rate of CIPN three months after six cycles of chemotherapy will be compared between the two groups according to the combined criteria of neuropathy using the World Health Organization-CIPN criteria and Common Terminology Criteria for Adverse Events version 5.0. As secondary endpoints, we will compare adverse events, patient-reported quality of life, and requirement of concomitant drugs for reducing CIPN between the two groups.

Trial Registration

ClinicalTrials.gov Identifier: NCT04201561

The effect of erythropoietin and umbilical cord-derived mesenchymal stem cells on nerve regeneration in rats with sciatic nerve injury

OBJECTIVE

We aimed to investigate the effects of umbilical cord-derived mesenchymal stem cells and erythropoietin on nerve regeneration in the sciatic nerve 'crush injury' in a rat model.

METHODS

Experimental animals were randomly divided into 5 groups: Crush Injury, Sham, Crush Injury + Erythropoietin, Crush Injury + Mesenchymal Stem Cell, Crush Injury + Erythropoietin + Mesenchymal Stem Cell groups. Crush injury made with bulldog clamp. Mesencyhmal stem cells delivered by enjection locally. Erythropoietin administered by intraperitoneally. On the 0th, 14th and 28th days, all groups underwent a sciatic functional index test. On 28th day, sciatic nerves were harvested and histopathological appearance, axon number and axon diameter of the sciatic nerves were evaluated with Oil Red O staining. Immunoreactivity of nerve growth factor, neurofilament-H and caspase-3 were determined by immunofluorescence staining in nerve tissue.

RESULTS

In histopathological examination, axons and nerve bundles exhibiting normal nerve architecture in the Sham group. Crush Injury + Mesenchymal Stem Cell group has similar histological appearance to the Sham group. The number of axons were higher in the Mesenchymal Stem Cell groups compared to the Crush Injury group. Nerve growth factor immunoreactivity intensity was significantly lower in Crush Injury + Mesenchymal Stem Cell group compared to Crush Injury group. Neurofilament-H density was higher in the treatment groups when compared to the Crush Injury group.

CONCLUSIONS

In this study, it was found that umbilical cord-derived mesenchymal stem cells and erythropoietin treatments effects positively regeneration of crush injury caused by bulldog clamp in the sciatic nerve of rats.

Behavioral, Histopathologic, and Molecular Biological Responses of Nanoparticle- and Solution-Based Formulations of Vincristine in Mice

Clinical use of the chemotherapeutic agent vincristine (VCR) is limited by chemotherapy-induced peripheral neuropathy (CiPN). A new formulation of VCR encapsulated by nanoparticles has been proposed and developed to alleviate CiPN. We hypothesized in nonclinical animals that the nanoparticle drug would be less neurotoxic due to different absorption and distribution properties to the peripheral nerve from the unencapsulated free drug. Here, we assessed whether VCR encapsulation in nanoparticles alleviates CiPN using behavioral gait analysis (CatWalk), histopathologic and molecular biological (RT-qPCR) approaches. Adult male C57BL/6 mice were assigned to 3 groups (empty nanoparticle, nano-VCR, solution-based VCR, each n = 8). After 15 days of dosing, animals were euthanized for tissue collection. It was shown that intraperitoneal administration of nano-VCR (0.15 mg/kg, every other day) and the empty nanoparticle resulted in no changes in gait parameters; whereas, injection of solution-based VCR resulted in decreased run speed and increased step cycle and stance (P < 0.05). There were no differences in incidence and severity of degeneration in the sciatic nerves between the nano-VCR-dosed and solution-based VCR-dosed animals. Likewise, decreased levels of a nervous tissue-enriched microRNA-183 in circulating blood did not show a significant difference between the nano- and solution-based VCR groups (P > 0.05). Empty nanoparticle administration did not cause any behavioral, microRNA, or structural changes. In conclusion, this study suggests that the nano-VCR formulation may alleviate behavioral changes in CiPN, but it does not improve the structural changes of CiPN in peripheral nerve. Nanoparticle properties may need to be optimized to improve biological observations.

Antioxidant Supplementation in the Treatment of Neurotoxicity Induced by Platinum-Based Chemotherapeutics-A Review

Cancer represents one of the most pernicious public health problems with a high mortality rate among patients worldwide. Chemotherapy is one of the major therapeutic approaches for the treatment of various malignancies. Platinum-based drugs (cisplatin, oxaliplatin, carboplatin, etc.) are highly effective chemotherapeutic drugs used for the treatment of several types of malignancies, but their application and dosage are limited by their toxic effects on various systems, including neurotoxicity. Simultaneously, researchers have tried to improve the survival rate and quality of life of cancer patients and decrease the toxicity of platinum-containing drugs by combining them with non-chemotherapy-based drugs, dietary supplements and/or antioxidants. Additionally, recent studies have shown that the root cause for the many side effects of platinum chemotherapeutics involves the production of reactive oxygen species (ROS) in naive cells. Therefore, suppression of ROS generation and their inactivation with antioxidants represents an appropriate approach for platinum drug-induced toxicities. The aim of this paper is to present an updated review of the protective effects of different antioxidant agents (vitamins, dietary antioxidants and supplements, medicaments, medicinal plants and their bioactive compounds) against the neurotoxicity induced by platinum-based chemotherapeutics. This review highlights the high potential of plant antioxidants as adjuvant strategies in chemotherapy with platinum drugs.

Neurotoxicity of antineoplastic drugs: Mechanisms, susceptibility, and neuroprotective strategies

This review summarizes the adverse effects on the central and/or peripheral nervous systems that may occur in response to antineoplastic drugs. In particular, we describe the neurotoxic side effects of the most commonly used drugs, such as platinum compounds, doxorubicin, ifosfamide, 5-fluorouracil, vinca alkaloids, taxanes, methotrexate, bortezomib and thalidomide. Neurotoxicity may result from direct action of compounds on the nervous system or from metabolic alterations produced indirectly by these drugs, and either the central nervous system or the peripheral nervous system, or both, may be affected. The incidence and severity of neurotoxicity are principally related to the dose, to the duration of treatment, and to the dose intensity, though other factors, such as age, concurrent pathologies, and genetic predisposition may enhance the occurrence of side effects. To avoid or reduce the onset and severity of these neurotoxic effects, the use of neuroprotective compounds and/or strategies may be helpful, thereby enhancing the therapeutic effectiveness of antineoplastic drug.

Fabrication and transplantation of chitosan-selenium biodegradable nanocomposite conduit on transected sciatic nerve: a novel study in rat model

Purpose: The improvement of techniques using conduits that connects the ends of damaged nerves and guides the growth of nerve fibers between the stumps, including adoption of natural or synthetic materials still is a challenge in peripheral nerve repair. The aim of the present novel study was to fabricate and transplant chitosan-selenium biodegradable nanocomposite conduit on transected sciatic nerve in rat model.Methods: In NORMAL group, the left sciatic nerve was exposed through a gluteal muscle incision and after careful hemostasis skin was closed. In TRANSECTED group left sciatic nerve was transected and stumps were fixed in adjacent muscle. In CHITOSAN and CSBNC groups, 10-mm sciatic nerve defects were bridged using a chitosan and chitosan-selenium biodegradable nanocomposite conduits, respectively. The regenerated fibers were studied 4, 8 and 12 weeks after surgery. Assessment of nerve regeneration was based on behavioral, functional, biomechanical, histomorphometric and immunohistochemical criteria.Results: The behavioral, functional and biomechanical studies confirmed significant recovery of regenerated axons in CSBNC group (P < 0.05). Quantitative morphometric analyses of regenerated fibers showed the number and diameter of myelinated fibers in CSBNC group were significantly higher than in the CHITOSAN group (P < 0.05).Discussion: This demonstrates the potential of using CSBNC in peripheral nerve regeneration without limitations of donor-site morbidity associated with isolation autograft. It is also cost saving and may have clinical implications for the surgical management of patients after facial nerve transection.

The effect of thiamine and its metabolites on peripheral neuropathic pain induced by cisplatin in rats

Thiamine pyrophosphate (TPP) is the active metabolite of thiamine. This study aimed to investigate the effects of thiamine and TPP on cisplatin-induced peripheral neuropathic pain (PNP). Male albino Wistar type Rattus norvegicus were divided into six groups (n=6) that received 2 mg/kg cisplatin (CIS), 25 mg/kg thiamine (TM), 2 mg/kg cisplatin+25 mg/kg thiamine (CTM), 25 mg/kg TPP (TPP), 2 mg/kg cisplatin+25 mg/kg TPP (CTPP), or distilled water (healthy group; HG) for 8 days intraperitoneally. Analgesic effect was measured with a Basile Algesimeter. IL-1β, malondialdehyde (MDA), total glutathione (tGSH), thiamine, and TPP were determined in blood samples. Histopathological examinations were performed on removed sciatic nerves. The percent analgesic effects of the CTM and CTPP groups were calculated to be 21.3% and 82.9%, respectively. Increased production of IL-1β and MDA by cisplatin was inhibited by TPP, while it was not inhibited by thiamine. Conversion of thiamine to TPP significantly decreased in the CIS group. Histopathological and biochemical investigations demonstrated that hyperalgesia and sciatic nerve damage developed in the CIS and CTM groups with low TPP levels. These results indicate that cisplatin inhibits the formation of TPP from thiamine, leading to severe PNP. This finding suggests that TPP may be more beneficial than thiamine for the treatment of cisplatin-induced PNP.

Chemical Speciation of Selenium and Mercury as Determinant of Their Neurotoxicity

The antagonism of mercury toxicity by selenium has been well documented. Mercury is a toxic metal, widespread in the environment. The main target organs (kidneys, lungs, or brain) of mercury vary depending on its chemical forms (inorganic or organic). Selenium is a semimetal essential to mammalian life as part of the amino acid selenocysteine, which is required to the synthesis of the selenoproteins. This chapter has the aim of disclosing the role of selenide or hydrogen selenide (Se^-2 or HSe^-) as central metabolite of selenium and as an important antidote of the electrophilic mercury forms (particularly, Hg²⁺ and MeHg). Emphasis will be centered on the neurotoxicity of electrophile forms of mercury and selenium. The controversial participation of electrophile mercury and selenium forms in the development of some neurodegenerative disease will be briefly presented. The potential pharmacological use of organoseleno compounds (Ebselen and diphenyl diselenide) in the treatment of mercury poisoning will be considered. The central role of thiol (-SH) and selenol (-SeH) groups as the generic targets of electrophile mercury forms and the need of new in silico tools to guide the future biological researches will be commented.

Impact of electrical stimulation of the stomach on gastric distension-induced emesis in the musk shrew

BACKGROUND

Gastric electrical stimulation (GES) is implicated as a potential therapy for difficult-to-treat nausea and vomiting; however, there is a lack of insight into the mechanisms responsible for these effects. This study tested the relationship between acute GES and emesis in musk shrews, an established emetic model system.

METHODS

Urethane-anesthetized shrews were used to record emetic responses (monitoring intra-tracheal pressure and esophageal contractions), respiration rate, heart rate variability, blood pressure, and gastrointestinal electromyograms. We investigated the effects of acute GES pulse duration (0.3, 1, 5, and 10 ms), current amplitude (0.5, 1, and 2 mA), pulse frequency (8, 15, 30, and 60 Hz), and electrode placement (antrum, body, and fundus) on emesis induced by gastric stretch, using a balloon.

KEY RESULTS

There were four outcomes: (i) GES did not modify the effects of gastric stretch-induced emesis; (ii) GES produced emesis, depending on the stimulation parameters, but was less effective than gastric stretch; (iii) other physiological changes were closely associated with emesis and could be related to a sub-threshold activation of the emetic system, including suppression of breathing and rise in blood pressure; and (iv) a control experiment showed that 8-OH-DPAT, a reported 5-HT1A receptor agonist that acts centrally as an antiemetic, blocked gastric stretch-induced emesis.

CONCLUSIONS AND INFERENCES

These results do not support an antiemetic effect of acute GES on gastric distension-induced emesis within the range of conditions tested, but further evaluation should focus on a broader range of emetic stimuli and GES stimulation parameters.

Ameliorative effect of selenium in cisplatin-induced testicular damage in rats

In this study, we investigated the protective effect of selenium (Se) on cisplatin (Cis) induced testicular damage using histopathological, immunohistochemical and biochemical approaches. Twenty-one male Wistar rats were equally divided into three groups of seven rats each: control (C), Cis, and Cis+Se. Cis and Cis+Se group rats received Cis at a dose of 12mg/kg b.w./day, intraperitoneally for 3 consecutive days. Cis+Se group rats received selenium via oral gavage 3mg/kg/day (twice-a day as 1.5mg/kg) until 11th consecutive days starting at 5 days before cisplatin injection. C group received only 0.9% NaCl intraperitoneally and orally at same time and at equal volume. After the treatment, the histopathological, immunohistochemical and biochemical examinations were performed. In seminiferous tubules of Cis treated rats were observed the most consistent findings characterized with vacuolization, desquamation, disorganization, and also was a considerable reduction in elongated spermatids, however the Cis+Se group exhibited improved histopathologic changes. In the immunohistochemical examinations, caspase-3 immunopositive cells displayed higher in the Cis group according to C and Cis+Se groups. Bcl-2 and NF-κB staining revealed a moderate number in the C group and significantly fewer in the Cis group compared to the Cis+Se groups. Additionally, MDA levels were also significantly increased in the Cis group in comparison to Control group, but pretreatment with selenium prevented elevation of MDA levels significantly in Cis+Se group rats. This study indicates that Cis-treatment induced testicular apoptosis and lipid peroxidation, and combined treatment with selenium prevented severity of the toxicity in rats.

Curcumin alleviates cisplatin-induced learning and memory impairments

The present study has been designed to investigate the role of curcumin on cisplatin-inducedcognitive impairment and to reveal mechanisms of cisplatin's detrimental actions on cognition in rats. Animals were treated with cisplatin (5mg/kg/week) and/or curcumin (300mg/kg/day) for 5weeks. Morris water maze test was used to assess spatial learning and memory. Enzymatic activities of acetylcholinesterase (AChE) and superoxide dismutase (SOD) were evaluated from hippocampus and plasma samples, and malondialdehyde (MDA), which is the end-product of lipid peroxidation, was determined by a colorimetric method. Our results showed that cisplatin (5mg/kg/week, 5weeks) caused learning and memory deficits, elevated MDA content, decreased SOD activity in the hippocampus and plasma, and AChE activity in the hippocampus. Curcumin improved learning and memory in rats with administration of cisplatin. In addition, curcumin significantly reduced the level of MDA and increased the activities of SOD and AChE. Taken together, our findings indicate that curcumin ameliorates cisplatin-induced spatial learning and memory impairment, possibly through restored cholinergic function and enhanced oxidative status.