Mario Maresca

The α9α10 nicotinic receptor antagonist α-conotoxin RgIA prevents neuropathic pain induced by oxaliplatin treatment.

Oxaliplatin, a third-generation diaminocyclohexane platinum drug, is widely used alone or in combination with 5-fluorouracil and leucovorin to treat metastatic colorectal, ovarian, and pancreatic cancers. Oxaliplatin long-term treatment is associated with the development of a dose-limiting painful neuropathy that dramatically impairs the patients quality of life and therapy possibility. To study novel strategies to treat oxaliplatin-induced neuropathy, we evaluated α-conotoxin RgIA, a peptide that potently blocks the α9α10 nicotinic acetylcholine receptor (nAChR) subtype in a rat model of oxaliplatin-dependent neurotoxicity (2.4mgkg(-1) oxaliplatin intraperitoneally daily for 21days). The administration of RgIA (2 and 10nmol injected intramuscularly once a day concomitantly with oxaliplatin treatment), reduced the oxaliplatin-dependent hypersensitivity to mechanical and thermal noxious and non-noxious stimuli. Moreover, morphological modifications of L4-L5 dorsal root ganglia were significantly prevented. In the spinal cord the numerical increase of astrocyte cell density present in oxaliplatin-treated rats is partially prevented by RgIA treatment. Nevertheless, the administration of the α-conotoxin is able per se to elicit a numerical increase and a morphological activation of microglia and astrocytes in specific brain areas.

Astragali radix : could it be an adjuvant for oxaliplatin-induced neuropathy?

Neurotoxicity is a major side effect of platinum derivatives both during and after treatment. In the absence of effective pharmacological compounds, the opportunity to identify safe adjuvant treatments among medicinal plants seems appropriate. Astragali radix is an adaptogenic herbal product recently analyzed in platinum-treated cancer patients. With the aim of evaluating the anti-neuropathic profile of Astragali radix, a previously characterized aqueous (Aqu) and two hydroalcoholic (20%HA and 50%HA) extracts were tested in a rat model of oxaliplatin-induced neuropathy. Repeated administrations significantly reduced oxaliplatin-dependent hypersensitivity with 50%HA, the most effective, fully preventing mechanical and thermal hypersensitivity. Ex vivo, 50%HA reduced morphometric and molecular alterations induced by oxaliplatin in peripheral nerve and dorsal-root-ganglia. In the spinal cord and in brain areas, 50%HA significantly decreased activation of microglia and astrocytes. Furthermore, 50%HA prevented the nephro- and hepato-toxicity induced by the anticancer drug. The protective effect of 50%HA did not alter oxaliplatin-induced apoptosis in colon tumors of Pirc rats, an Apc-driven model of colon carcinogenesis. The hydroalcoholic extract (50%HA) of Astragali radix relieves pain and promotes the rescue mechanisms that protect nervous tissue from the damages triggering chronic pain. A safe profile strongly suggests the usefulness of this natural product in oxaliplatin-induced neuropathy.

A model of neuropathic pain induced by sorafenib in the rat: Effect of dimiracetam.

BACKGROUND Sorafenib is a kinase inhibitor anticancer drug whose repeated administration causes the onset of a peripheral painful neuropathy. Notably, the efficacy of common analgesic drugs is not adequate and this often leads pre-mature discontinuation of anticancer therapy. The aim of this study was to establish a rat model of sorafenib-induced neuropathic pain, and to assess the effect of the new anti-neuropathic compound dimiracetam in comparison with gabapentin, pregabalin and duloxetine. METHODS Male Sprague-Dawley rats were treated i.v. (10 mg kg(-1)), i.p. (10 and 30 mg kg(-1)) or p.o. (80 and 160 mg kg(-1)) with sorafenib once daily for 21 days. Pain behaviour measurements (cold plate, paw pressure, electronic von Frey) were performed on days 0, 7, 14 and 21. RESULTS Sorafenib lowered the paw-licking threshold to non-noxious cold stimuli on day 14 of all protocols evaluated. The i.p. administration resulted in greater efficacy than the other administration routes. Sorafenib treatments did not affect paw-withdrawal responses to non-noxious or to noxious mechanical stimuli. On day 14, dimiracetam (300 mg kg(-1)), gabapentin (100 mg kg(-1)), pregabalin (30 mg kg(-1)) and duloxetine (30 mg kg(-1)) were acutely administered p.o. in sorafenib i.p.-treated rats. A single oral dose of dimiracetam induced a statistically significant increase of the pain threshold 15 min after administration. Pregabalin induced a comparable effect, whereas gabapentin and duloxetine were ineffective. Repeated twice-daily administration of dimiracetam (150 mg kg(-1) p.o.), starting on the first day of i.p sorafenib administration, significantly protected rats from sorafenib-induced decrease in the paw-licking threshold. CONCLUSIONS A rat model of sorafenib-induced hypersensitivity to cold stimulation has been established. Dimiracetam and pregabalin are effective in prevention of sorafenib-induced neuropathy in this model.

Anti-neuropathic effects of Rosmarinus officinalis L. terpenoid fraction: relevance of nicotinic receptors.

Traditional uses and current results highlight the neuroprotective properties of Rosmarinus officinalis L. The compelling need for novel strategies able to relieve neuropathic pain encouraged us to analyze different rosemary leaf extracts in rats following chronic constriction injury (CCI) of sciatic nerve. Ethanol, acetone, and the innovative ultrasound-hexane extractive methods were used to obtain: EE, AE, and for hexane extracts UREprel and URE. Extracts were characterized in terms of typical constituents and repeatedly administered to CCI-rats (13-days treatment, from the day of surgery). URE showed the best efficacy and potency in reducing hypersensitivity to noxious- and non-noxious stimuli and spontaneous pain. URE contained the higher quantity of the terpenoid carnosic acid (CA) and its efficacy was compared to pure CA. Histological analysis of the sciatic nerve revealed that URE prevented axon and myelin derangement, edema and inflammatory infiltrate. In the dorsal horn of the spinal cord, URE did not reduce astrocyte activation. Both the pain reliever and the neuroconservative effects of URE were significantly prevented by the nicotinic receptor (nAChR) antagonist mecamylamine. In conclusion, the hexane-ultrasound rosemary extract is able to reduce neuropathic hypersensitivity and protect nervous tissues. Effectiveness is mainly related to the terpenoid fraction by mechanisms involving nAChRs.

Pain relieving and protective effects of Astragalus hydroalcoholic extract in rat arthritis models

The evaluation of the pharmacological profile of the dried 50% hydroalcoholic extract (50%HA) of Astragali radix in two different animal models of articular damage resembling osteoarthritis and rheumatoid arthritis.

Effects of the neutrophil elastase inhibitor EL-17 in rat adjuvant-induced arthritis

OBJECTIVES Neutrophil elastase (NE), a granule-associated enzyme, participates in connective tissue breakdown and promotes cytokine release and specific receptor activation during various inflammatory diseases like RA. NE is increased in the SF and cartilage of RA patients and represents a target for the development of new therapeutic possibilities. The present research aimed to evaluate the preclinical pharmacological profile of the N-benzoylpyrazole derivative EL-17, a potent and selective NE inhibitor, in a rat model of RA. METHODS Complete Freunds Adjuvant (CFA) was injected in the tibiotarsal joint and the effect of acute or repeated treatments with EL-17 (1-30 mg/kg by mouth) were evaluated. RESULTS On day 14 after CFA injection, a single administration of EL-17 significantly reduced CFA-dependent hypersensitivity to mechanical noxious stimuli and the postural unbalance related to spontaneous pain. To evaluate the preventive efficacy, EL-17 was administered daily starting from the day of CFA treatment. Behavioural measurements performed on days 7 and 14 showed a progressive efficacy of EL-17 against hypersensitivity to mechanical noxious and non-noxious stimuli, as well as a decrease of hind limb weight-bearing alterations. Histological evaluation of the tibiotarsal joint (day 14) demonstrated significant prevention of articular derangement after EL-17 (30 mg/kg) treatment. The protective effects of EL-17 directly correlated with a complete reversion of the plasma NE activity increase induced by CFA. CONCLUSIONS The NE inhibitor EL-17 relieved articular pain after acute administration. Furthermore, repeated treatment reduced the development of hypersensitivity and protected joint tissue, revealing a disease-modifying profile.

Effects of a water extract of Lepidium meyenii root in different models of persistent pain in rats

Abstract Lepidium meyenii (Walp.), commonly called maca, is an Andean crop belonging to the Brassicaceae family. Maca hypocotils are habitually consumed as customary food as well as traditional remedies for pathological conditions such as infertility. Moreover, the characterization of maca extracts revealed the presence of compounds that are able to modulate the nervous system. Aimed to evaluate the efficacy of L. meyenii in persistent pain, the present study analyzed the effects of a commercial root extract from maca in different animal models reproducing the most common causes of chronic painful pathologies. A qualitative characterization of this commercial extract by high performance liquid chromatography-mass spectrometry and tandem mass spectrometry analyses allowed us to confirm the presence of some macamides known as bioactive constituents of this root and the absence of the main aromatic glucosinolates. The acute oral administration of maca extract is able to reduce mechanical hypersensitivity and postural unbalance induced by the intra-articular injection of monoiodoacetate and the chronic-constriction injury of the sciatic nerve. Furthermore, L. meyenii extract reverts pain threshold alterations evoked by oxaliplatin and paclitaxel. A good safety profile in mice and rats was shown. In conclusion, the present maca extract could be considered as a therapeutic opportunity to relieve articular and neuropathic pain.

Selenium and zinc: Two key players against cadmium-induced neuronal toxicity

Cadmium (Cd), a worldwide occupational pollutant, is an extremely toxic heavy metal, capable of damaging several organs, including the brain. Its toxicity has been related to neurodegenerative diseases such as Alzheimers and Parkinsons diseases. The neurotoxic potential of Cd has been attributed to the changes induced in the brain enzyme network involved in counteracting oxidative stress. On the other hand, it is also known that trace elements, such as zinc (Zn) and selenium (Se), required for optimal brain functions, appears to have beneficial effects on the prevention of Cd intoxication. Based on this protective effect of Zn and Se, we aimed to investigate whether these elements could protect neuronal cells from Cd-induced excitotoxicity. The experiments, firstly carried out on SH-SY5Y catecholaminergic neuroblastoma cell line, demonstrated that the treatment with 10 μM cadmium chloride (CdCl2) for 24 h caused significant modifications both in terms of oxidative stress and neuronal sprouting, triggered by endoplasmic reticulum (ER) stress. The evaluation of the effectiveness of 50 μM of zinc chloride (ZnCl2) and 100 nM sodium selenite (Na2SeO3) treatments showed that both elements were able to attenuate the Cd-dependent neurotoxicity. However, considering that following induction with retinoic acid (RA), the neuroblastoma cell line undergoes differentiation into a cholinergic neurons, our second aim was to verify the zinc and selenium efficacy also in this neuronal phenotype. Our data clearly demonstrated that, while zinc played a crucial role on neuroprotection against Cd-induced neurotoxicity independently from the cellular phenotype, selenium is ineffective in differentiated cholinergic cells, supporting the notion that the molecular events occurring in differentiated SH-SY5Y cells are critical for the response to specific stimuli.

Therapeutic option by synergistic administration of the β-hydroxy-β-methyl butyrate and R(+) Lipoic Acid in a cellular model of dexamethasone-dependent sarcopenia

The decline of muscle mass and strength, known as sarcopenia, is a clinical problem associated with osteo-articular diseases, muscle disuse, cancer, renal failure, postmemenopause, age and corticosteroid treatments [1,2]. In this scenario, alterations in mitochondrial function [3] and accelerated apoptosis in skeletal muscle [4] are considered a major factor underlying sarcopenia and muscle atrophy. These evidences suggests that targeting myonuclear apoptosis as well as reducing the oxidative stress might provide novel and effective therapeutic tools to combat sarcopenia. Alpha-lipoic acid (1,2-dithiolane- 3-pentanoic acid), is a natural antioxidant with two optical isomers of which the (+)- possess a more pronounced effect (R (+) LA) [7]. Beta-hydroxy-beta-methylbutyrate (HMB), a leucine catabolite, has been shown to prevent muscle damage directly enhancing myogenic cells (satellite cells) proliferation and attenuating apoptosis [8]. Aim of the present research was the evaluation of the pharmacological profile of the HMB associated with the natural R(+)LA in a cellular model of muscle wasting. Material and Methods. C2C12 cell line was used as myoblasts or differentiated in miotubes by 7 day culture with 2% horse serum. Cell damage was induced by dexamethasone. Results. Dexamethasone toxicity was evaluated measuring cell viability (MTT assay) and apoptosis induction (caspase 3 activity) after 24h and 48h incubation of myoblasts with the glucocorticoid (0.01–300 μM concentration range). One μM dexamethasone (48h) decreased cell viability by about 50% and increased caspase 3 activity by 80%. R(+)LA (100 and 300 μM) or HMB (1 and 3 mM) significantly prevented dexamethasone-induced cell mortality; the efficacy was improved when 100 μM R(+)LA was combined with 1mM HMB, demonstrating the synergistic effect of R(+)LA and HMB in preventing cell mortality and caspase 3 activation. Similarly, the evaluation of dexamethasone evoked O2-. production and protein carbonylation demonstrated the efficacy of the combination of R(+)LA with HMB. In the early phase of myotube differentiation (72h) the combination of R(+)LA and HMB preserved the number of myogenin-positive cells as well as in the later (7 days) phase of differentiation the dexamethasone-dependent damage (evaluated as cell diameter and percentage of multinucleated cells). These data offer a rational to candidate the mixture as a therapeutic option for sarcopenia treatment.

Oxaliplatin-induced blood brain barrier loosening: a new point of view on chemotherapy-induced neurotoxicity

Oxaliplatin is a key drug in the treatment of advanced metastatic colorectal cancer. Despite its beneficial effects in tumor reduction, the most prevalent side-effect of oxaliplatin treatment is a chemotherapy-induced neuropathy that frequently forces to discontinue the therapy. Indeed, along with direct damage to peripheral nerves, the chemotherapy-related neurotoxicity involves also the central nervous system (CNS) as demonstrated by pain chronicity and cognitive impairment (also known as chemobrain), a newly described pharmacological side effect. The presence of the blood brain barrier (BBB) is instrumental in preventing the entry of the drug into the CNS; here we tested the hypothesis that oxaliplatin might enter the endothelial cells of the BBB vessels and trigger a signaling pathway that induce the disassembly of the tight junctions, the critical components of the BBB integrity. By using a rat brain endothelial cell line (RBE4) we investigated the signaling pathway that ensued the entry of oxaliplatin within the cell. We found that the administration of 10 μM oxaliplatin for 8 and 16 h induced alterations of the tight junction (TJs) proteins zonula occludens-1 (ZO-1) and of F-actin, thus highlighting BBB alteration. Furthermore, we reported that intracellular oxaliplatin rapidly induced increased levels of reactive oxygen species and endoplasmic reticulum stress, assessed by the evaluation of glucose-regulated protein GRP78 expression levels. These events were accompanied by activation of caspase-3 that led to extracellular ATP release. These findings suggested a possible novel mechanism of action for oxaliplatin toxicity that could explain, at least in part, the chemotherapy-related central effects.