Oxaliplatin is a platinum-organic drug with antineoplastic properties used for colorectal cancer. With respect to the other platinum derivates oxaliplatin induces only a mild hematological and ...gastrointestinal toxicity. Its limiting side effect is its neurotoxicity, which results in a sensory neuropathy. Repeated oxaliplatin treatment in the rat led to a neuropathic pain characterized by a significant oxidative damage throughout the nervous system. The natural antioxidants silibinin and α-tocopherol reduce redox alteration and prevent pain. Starting from the “oxidative hypothesis” as a molecular basis of chemotherapy-induced neurotoxicity, we decided to explore deep inside the mechanisms of oxaliplatin neurotoxicity and search for a cellular system useful for screening antioxidant compounds that can reduce oxaliplatin neurotoxicity. Focusing on various constituents of the central nervous system, we used the neuronal-derived cell line SH-SY5Y and primary cultures of rat cortical astrocytes. Oxaliplatin significantly increased superoxide anion production and induced lipid peroxidation (malonyldialdehyde levels) and protein (carbonylated proteins) and DNA oxidation (8-OH-dG levels). Silibinin and α-tocopherol (10µM) were able to reduce the oxidative damage in both cell types. These antioxidants fully protected astrocytes from the caspase 3 apoptotic signaling activation induced by oxaliplatin. The damage prevention effects of silibinin and α-tocopherol on nervous system-derived cells did not interfere with the oxaliplatin antineoplastic in vitro mechanism as evaluated on a human colon adenocarcinoma cell line (HT29). Moreover, neither silibinin nor α-tocopherol modified the oxaliplatin-induced apoptosis in HT29 cells, suggesting a different antiapoptotic profile in normal vs tumoral cells for these antioxidant compounds. In conclusion, because data obtained in in vitro cellular models parallel the in vivo study we propose cell models to investigate oxaliplatin neurotoxicity and to screen possible therapeutic adjuvant agents.
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•Natural antioxidants reduce oxaliplatin-dependent neuropathic pain.•Oxaliplatin induces characteristic redox alterations in astrocyte cultures.•Silibinin and α-tocopherol protect glial cells from oxidative and apoptotic damage.•These antioxidants do not influence oxaliplatin anticancer activity on HT29 cells.•A cell model of neuropathy to screen therapeutic adjuvant agents is proposed.
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A solid lipid nanoparticle (SLN) formulation was developed with the aim of improving the oral bioavailability and the therapeutic effectiveness of glibenclamide (GLI), a poorly ...water-soluble drug used in the treatment of type 2 diabetes. The SLN was prepared using different lipid components (Precirol® and Compritol®) and preparation procedures. Precirol-based SLN, obtained with the emulsion of solvent evaporation technique gave the best results and was selected for drug loading. Addition of lecithin to the SLN core or PEG coating was effective in increasing the nanoparticles stability in simulated gastric solution. Both such formulations were stable after one month storage at 5±3°C, exhibited the absence of in vitro cytotoxicity, and presented a similar in vitro prolonged-release, reaching 100% release after 24h. The lecithin-containing GLI-loaded SLN formulation, selected for in vivo studies in virtue of its higher EE% than the PEG-coated formulation (70.3% vs 19.6%), showed a significantly stronger hypoglycemic effect with respect to the drug alone, in terms of both shorter onset time and longer duration of the effect. These positive results indicated that the proposed SLN approach was successful in improving GLI oral bioavailability, confirming its potential as an effective delivery system for a suitable therapy of diabetes.
Chemotherapy-Induced Peripheral Neuropathy (CIPN) is the most frequent adverse effect of pharmacological cancer treatments. The occurrence of neuropathy prevents the administration of fully-effective ...drug regimen, affects negatively the quality of life of patients, and may lead to therapy discontinuation. CIPN is currently treated with anticonvulsants, antidepressants, opioids and non-opioid analgesics, all of which are flawed by insufficient anti-hyperalgesic efficacy or addictive potential. Understandably, developing new drugs targeting CIPN-specific pathogenic mechanisms would dramatically improve efficacy and tolerability of anti-neuropathic therapies. Neuropathies are associated to aberrant excitability of DRG neurons due to the alteration in the expression or function of a variety of ion channels. In this regard, Hyperpolarization-activated Cyclic Nucleotide-gated (HCN) channels are overexpressed in inflammatory and neuropathic pain states, and HCN blockers have been shown to reduce neuronal excitability and to ameliorate painful states in animal models. However, HCN channels are critical in cardiac action potential, and HCN blockers used so far in pre-clinical models do not discriminate between cardiac and non-cardiac HCN isoforms. In this work, we show an HCN current gain of function in DRG neurons from oxaliplatin-treated rats. Biochemically, we observed a downregulation of HCN2 expression and an upregulation of the HCN regulatory beta-subunit MirP1. Finally, we report the efficacy of the selective HCN1 inhibitor MEL57A in reducing hyperalgesia and allodynia in oxaliplatin-treated rats without cardiac effects. In conclusion, this study strengthens the evidence for a disease-specific role of HCN1 in CIPN, and proposes HCN1-selective inhibitors as new-generation pain medications with the desired efficacy and safety profile.
•Nociceptive neurons from oxaliplatin-treated rats show Ih gain of function.•Increased current density is mediated by HCN1-specific kinetic enhancement.•Acceleration of HCN1 kinetics is associated to increased MiRP1 expression.•Pan HCN blockers effectively revert neuropathy in vivo but cause bradycardia.•HCN1-selective blocker MEL57A shows intact analgesic efficacy without cardiac effects.
Neuropathic syndromes which are evoked by lesions to the peripheral or central nervous system are extremely difficult to treat, and available drugs rarely joint an antihyperalgesic with a ...neurorestorative effect. N-Palmitoylethanolamine (PEA) exerts antinociceptive effects in several animal models and inhibits peripheral inflammation in rodents. Aimed to evaluate the antineuropathic properties of PEA, a damage of the sciatic nerve was induced in mice by chronic constriction injury (CCI) and a subcutaneous daily treatment with 30 mg kg−1 PEA was performed. On the day 14, PEA prevented pain threshold alterations. Histological studies highlighted that CCI induced oedema and an important infiltrate of CD86 positive cells in the sciatic nerve. Moreover, osmicated preparations revealed a decrease in axon diameter and myelin thickness. Repeated treatments with PEA reduced the presence of oedema and macrophage infiltrate, and a significant higher myelin sheath, axonal diameter, and a number of fibers were observable. In PPAR-α null mice PEA treatment failed to induce pain relief as well as to rescue the peripheral nerve from inflammation and structural derangement. These results strongly suggest that PEA, via a PPAR-α-mediated mechanism, can directly intervene in the nervous tissue alterations responsible for pain, starting to prevent macrophage infiltration.
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Hydrogen sulfide (H2S) is a gasotransmitter deeply involved in cardiovascular homeostasis and implicated in the myocardial protection against ischemia/reperfusion. The ...post-translational persulfidation of cysteine residues has been identified as the mechanism through which H2S regulates a plethora of biological targets. Erucin (ERU) is an isothiocyanate produced upon hydrolysis of the glucosinolate glucoerucin, presents in edible plants of Brassicaceae family, such as Eruca sativa Mill., and it has emerged as a slow and long-lasting H2S-donor.
In this study the cardioprotective profile of ERU has been investigated and the action mechanism explored, focusing on the possible role of the recently identified mitochondrial Kv7.4 (mitoKv7.4) potassium channels.
Interestingly, ERU showed to release H2S and concentration-dependently protected H9c2 cells against H2O2-induced oxidative damage. Moreover, in in vivo model of myocardial infarct ERU showed protective effects, reducing the extension of ischemic area, the levels of troponin I and increasing the amount of total AnxA1, as well as co-related inflammatory outcomes. Conversely, the pre-treatment with XE991, a blocker of Kv7.4 channels, abolished them. In isolated cardiac mitochondria ERU exhibited the typical profile of a mitochondrial potassium channels opener, in particular, this isothiocyanate produced a mild depolarization of mitochondrial membrane potential, a reduction of calcium accumulation into the matrix and finally a flow of potassium ions. Finally, mitoKv7.4 channels were persulfidated in ERU-treated mitochondria.
ERU modulates the cardiac mitoKv7.4 channels and this mechanism may be relevant for cardioprotective effects.
The effect of “prophylactic” environmental stimulation on clinical symptoms and presynaptic defects in mice suffering from the experimental autoimmune encephalomyelitis (EAE) at the acute stage of ...disease (21 ± 1 days post immunization, d.p.i.) was investigated. In EAE mice raised in an enriched environment (EE), the clinical score was reduced when compared to EAE mice raised in standard environment (SE).Concomitantly, gain of weight and increased spontaneous motor activity and curiosity were observed, suggesting increased well-being in mice. Impaired glutamate exocytosis and cyclic adenosine monophosphate (cAMP) production in cortical terminals of SE-EAE mice were evident at 21 ± 1 d.p.i.. Differently, the 12 mM KCl-evoked glutamate exocytosis from cortical synaptosomes of EE-EAE mice was comparable to that observed in SE and EE-control mice, but significantly higher than that in SE-EAE mice. Similarly, the 12 mM KCl-evoked cAMP production in EE-EAE mice cortical synaptosomes recovered to the level observed in SE and EE-control mice. MUNC-18 and SNAP25 contents, but not Syntaxin-1a and Synaptotagmin 1 levels, were increased in cortical synaptosomes from EE-EAE mice when compared to SE-EAE mice. Circulating IL-1β was increased in the spinal cord, but not in the cortex, of SE-EAE mice, and it did not recover in EE-EAE mice. Inflammatory infiltrates were reduced in the cortex but not in the spinal cord of EE-EAE mice. Demyelination was observed in the spinal cord; EE significantly diminished it. We conclude that “prophylactic” EE is beneficial to synaptic derangements and preserves glutamate transmission in the cortex of EAE mice.
This article is part of the Special Issue entitled “Neurobiology of Environmental Enrichment”.
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•Enriched environment (EE) ameliorates clinical score and behaviours in EAE mice.•Inflammatory infiltrates and spinal demyelination are reduced in EE-EAE mice.•EE preserves glutamate exocytosis efficiency from cortical terminals.•cAMP production from cortical synaptosomes is unaltered in trained EAE mice.•EE increases the expression of MUNC-18 and SNAP-25 in the cortex.
Fabry disease (FD) is an X-linked metabolic disease caused by a deficiency in α-galactosidase A (α-Gal A) activity. This causes accumulation of glycosphingolipids, especially globotriaosylceramide ...(Gb3), in different cells and organs. Neuropathic pain and gastrointestinal (GI) symptoms, such as abdominal pain, nausea, diarrhea, constipation, and early satiety, are the most frequent symptoms reported by FD patients and severely affect their quality of life. It is generally accepted that Gb3 and lyso-Gb3 are involved in the symptoms; nevertheless, the origin of these symptoms is complex and multifactorial, and the exact mechanisms of pathogenesis are still poorly understood. Here, we used a murine model of FD, the male α-Gal A (-/0) mouse, to characterize functionality, behavior, and microbiota in an attempt to elucidate the microbiota-gut-brain axis at three different ages. We provided evidence of a diarrhea-like phenotype and visceral hypersensitivity in our FD model together with reduced locomotor activity and anxiety-like behavior. We also showed for the first time that symptomology was associated with early compositional and functional dysbiosis of the gut microbiota, paralleled by alterations in fecal short-chain fatty acid levels, which partly persisted with advancing age. Interestingly, most of the dysbiotic features suggested a disruption of gut homeostasis, possibly contributing to accelerated intestinal transit, visceral hypersensitivity, and impaired communication along the gut-brain axis.
Abstract The γ isoform of protein kinase C (PKCγ) is an injury-activated intracellular modulator that boosts neuronal activity in algesic and neuroregenerative signalling pathways. Acetyl- l ...-carnitine (ALCAR), a physiological compound with role in bioenergetic functions, shows an antihyperalgesic effect and at the same time can exert neuroregenerative and neuroprotective effects. Aimed to explore the link between pain and neuroregeneration, the effect of ALCAR treatment (100 mg kg−1 i.p. twice daily for 15 days) on PKCγ and mitogen-activated protein kinases (MAPKs) expression has been evaluated in CCI (chronic constriction injury) rats. The sciatic nerve and the lumbar tract of the spinal cord were processed to evaluate the levels of the phosphorylated form of PKCγ, ERK 1,2, SAP/JNK, p-38 and c-Jun; furthermore, the mRNA expression of the early genes c-Jun and c-Fos has been investigated. Fifteen days after injury, the analysis in the sciatic nerves highlighted a bilateral increase of the activated forms of PKCγ, ERK 1,2 and SAP/JNK, whereas c-Jun showed an increase only ipsilaterally. ALCAR completely prevented mechanical hyperalgesia and provoked in the nerve a c-Jun increment only. In the lumbar tract of the spinal cord, higher levels of activated PKCγ, ERK 1,2, p38, SAP/JNK and c-Jun proteins were detected in the ipsilateral side in respect of sham. ALCAR was able to stimulate this expression profile. At the transcriptional level c-Jun mRNA was increased in the ipsilateral side of spinal cord of CCI saline-treated rats, whereas c-Fos mRNA was unchanged. ALCAR had a stimulatory effect on both these early genes. These findings may represent a different approach in the study of the complex balance between pain and neuroregeneration and could constitute the basis for developing new disease modifying agents in the treatment of neuropathic pain.
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