Browsing by Author "Gomez, Marcus Vinicius"

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    Analgesic and side effects of intravenous recombinant Phα1β.
    (2020) Rigo, Flavia Karine; Rossato, Mateus Fortes; Borges, Vanessa; Silva, Juliana Figueira da; Pereira, Elizete Maria Rita; Ávila, Ricardo Andrez Machado de; Trevisan, Gabriela; Astoni, Duana Carvalho dos Santos; Diniz, Danuza Montijo; Silva, Marco Aurélio Romano; Castro Junior, Célio José de; Cunha, Thiago Mattar; Ferreira, Juliano; Gomez, Marcus Vinicius
    Background: Intrathecal injection of voltage-sensitive calcium channel blocker peptide toxins exerts analgesic effect in several animal models of pain. Upon intrathecal administration, recombinant Phα1β exerts the same analgesic effects as the those of the native toxin. However, from a clinical perspective, the intrathecal administration limits the use of anesthetic drugs in patients. Therefore, this study aimed to investigate the possible antinociceptive effect of intravenous recombinant Phα1β in rat models of neuropathic pain, as well as its side effects on motor, cardiac (heart rate and blood pressure), and biochemical parameters. Methods: Male Wistar rats and male Balb-C mice were used in this study. Giotto Biotech® synthesized the recombinant version of Phα1β using Escherichia coli expression. In rats, neuropathic pain was induced by chronic constriction of the sciatic nerve and paclitaxel-induced acute and chronic pain. Mechanical sensitivity was evaluated using von Frey filaments. A radiotelemeter transmitter (TA11PA-C10; Data Sciences, St. Paul, MN, USA) was placed on the left carotid of mice for investigation of cardiovascular side effects. Locomotor activity data were evaluated using the open-field paradigm, and serum CKMB, TGO, TGP, LDH, lactate, creatinine, and urea levels were examined. Results: Intravenous administration of recombinant Phα1β toxin induced analgesia for up to 4 h, with ED50 of 0.02 (0.01-0.03) mg/kg, and reached the maximal effect (Emax = 100% antinociception) at a dose of 0.2 mg/kg. No significant changes were observed in any of the evaluated motor, cardiac or biochemical parameters. Conclusion: Our data suggest that intravenous administration of recombinant Phα1β may be feasible for drug-induced analgesia, without causing any severe side effects.
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    Analgesic effects of Phα1β toxin : a review of mechanisms of action involving pain pathways.
    (2021) Silva, Juliana Figueira da; Binda, Nancy Scardua; Pereira, Elizete Maria Rita; Lavor, Mário Sérgio Lima de; Vieira, Luciene Bruno; Souza, Alessandra Hubner de; Rigo, Flávia Karine; Ferrer, Hèlia Tenza; Castro Júnior, Célio José de; Ferreira, Juliano; Gomez, Marcus Vinicius
    Phα1β is a neurotoxin purified from spider venom that acts as a high-voltage-activated (HVA) calcium channel blocker. This spider peptide has shown a high selectivity for N-type HVA calcium channels (NVACC) and an analgesic effect in several animal models of pain. Its activity was associated with a reduction in calcium transients, glutamate release, and reactive oxygen species production from the spinal cord tissue and dorsal ganglia root (DRG) in rats and mice. It has been reported that intrathecal (i.t.) administration of Phα1β to treat chronic pain reverted opioid tolerance with a safer profile than ω-conotoxin MVIIA, a highly selective NVACC blocker. Following a recent development of recombinant Phα1β (CTK 01512-2), a new molecular target, TRPA1, the structural arrangement of disulphide bridges, and an effect on glial plasticity have been identified. CTK 01512-2 reproduced the antinociceptive effects of the native toxin not only after the intrathecal but also after the intravenous administration. Herein, we review the Phα1β antinociceptive activity in the most relevant pain models and its mechanisms of action, highlighting the impact of CTK 01512-2 synthesis and its potential for multimodal analgesia.
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    Antiarrhythmogenic effects of a neurotoxin from the spider Phoneutria nigriventer.
    (2011) Almeida, Alvair Pinto de; Andrade, Alexandre Barbosa; Ferreira, Anderson José; Pires, Andrea Cristina Gomes; Damasceno, Dênis Derly; Alves, Márcia Netto Magalhães; Gomes, Enéas Ricardo de Morais; Kushmerick, Christopher; Lima, Ricardo de Freitas; Prado, Marco Antônio Maximo; Prado, Vânia Ferreira; Richardson, Michael; Cordeiro, Marta do Nascimento; Guatimosim, Silvia; Gomez, Marcus Vinicius
    In this study, we evaluated the effects of PhKv, a 4584 Da peptide isolated from the spider Phoneutria nigriventer venom, in the isolated rat heart and in isolated ventricular myocytes. Ventricular arrhythmias were induced by occlusion of the left anterior descending coronary artery for 15 min followed by 30 min of reperfusion. Administration of native PhKv (240 nM) 1 min before or after reperfusion markedly reduced the duration of arrhythmias. This effect was blocked by atropine, thereby indicating the participation of muscarinic receptors in the antiarrhythmogenic effect of PhKv. Notably, recombinant PhKv (240 nM) was also efficient to attenuate the arrhythmias (3.8 0.9 vs. 8.0 1.2 arbitrary units in control group). Furthermore, PhKv induced a significant reduction in heart rate. This bradycardia was partially blunted by atropine and potentiated by pyridostigmine. To further evaluate the participation of acetylcholine on the PhKv effects, we examined the release of this neurotransmitter from neuromuscular junctions. It was found that Phkv (200 nM) significantly increased the release of acetylcholine in this preparation. Moreover, PhKv (250 nM) did not cause any significant change in action potential or Ca2þ transient parameters in isolated cardiomyocytes. Altogether, these findings show an important acetylcholine-mediated antiarrhythmogenic effect of the spider PhKv toxin in isolated hearts.
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    Calcium channels blockers toxins attenuate abdominal hyperalgesia and inflammatory response associated with the cerulein-induced acute pancreatitis in rats.
    (2021) Carvalho, Vanice Paula Ricardo; Silva, Juliana Figueira da; Buzelin, Marcelo Araújo; Silva Júnior, Cláudio Antônio da; Santos, Duana Carvalho dos; Diniz, Danuza Montijo; Binda, Nancy Scardua; Borges, Marcia Helena; Guimarães, André Luiz Senna; Pereira, Elizete Maria Rita; Gomez, Marcus Vinicius
    Agents that modulate the activity of high-voltage gated calcium channels (HVCCs) exhibit experimentally and clinically significant effect by relieving visceral pain. Among these agents, the toxins Phα1β and ω-conotoxin MVIIA effectively reduce chronic pain in rodent models. The molecular mechanisms underlying the chronic pain associated with acute pancreatitis (AP) are poorly understood. Hypercalcemia is a risk factor; the role of cytosolic calcium is considered to be a modulator of pancreatitis. Blockade of Ca2+ signals may be useful as a prophylactic treatment of pancreatitis. We explored the pathophysiological roles of three peptide toxins: Phα1β and its re- combinant form CTK 01512-2—blockers of TRPA1 receptor and HVCCs and ω-conotoxin MVIIA, a specific blocker of N-type calcium channels in cerulein-induced AP. Cerulein injection elicits AP in rats, evidenced by an increase in hyperalgesic pain, inflammatory infiltration, amylase and lipase secretion, and reactive oxygen species, TNF-α, and p65 NF-κB levels. These effects of cerulein-induced AP were abolished by Phα1β and its recombinant form CTK 01512-2, whereas ω-conotoxin MVIIA had no effect on the induced increase in pancreatic enzyme secretion. Our results demonstrate that Phα1β and CTK 01512-2 toxins—antagonists of HVCCs and TRPA1 receptor presented an effective response profile, in the control of nociception and inflammatory process in the AP model in rats, without causing changes in spontaneous locomotion of the rats.
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    Choline oxidase chemiluminéscent assay, after removal of eserine from medium, of acetylcholine released in vitro from brain slices.
    (1990) Prado, Marco Antônio Maximo; Santos, T. Moraes; Freitas, Renata Nascimento de; Silva, Marco Aurélio Romano; Gomez, Marcus Vinicius
    A chemiluminescent method has been used recently for the determination of acetylcholine with limitations such as the presence of a cholinesterase inhibitor in the incubation medium, which is indispensable for the study of acetylcholine release by various agents. A modified procedure is presented in which the cholinesterase inhibitor eserine (physostigmine) is extracted from the medium. The results showed complete recovery when labelled acetylcholine was used. This modified procedure was used to determine the release of acetylcholine evoked by tityustoxin and ouabain. The results were comparable to those obtained by bioassay using a strip of guinea pig ileum.
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    Conotoxin MVIIA improves cell viability and antioxidant system after spinal cord injury in rats.
    (2018) Oliveira, Karen Maciel de; Binda, Nancy Scardua; Lavor, Mário Sérgio Lima de; Silva, Carla Maria Osório; Rosado, Isabel Rodrigues; Alves, Endrigo Gabellini Leonel; Silva, Juliana Figueira da; Oliveira, Camila M.; Melo, Marilia Martins; Gomez, Marcus Vinicius; Melo, Eliane Gonçalves de
    This study evaluates whether intrathecal MVIIA injection after spinal cord injury (SCI) elicits neuroprotective effects. The test rats were randomly distributed into six groups— sham, placebo, MVIIA 2.5 μM, MVIIA 5 μM, MVIIA 10 μM, and MVIIA 20 μM—and were administered the treatment four hours after SCI. After the optimal MVIIA dose (MVIIA 10 μM) was defined, the best time for application, one or four hours, was analyzed. Locomotor hind limb function and side effects were assessed. Forty-eight hours after the injury and immediately after euthanasia, spinal cord segments were removed from the test rats. Cell viability, reactive oxygen species, lipid peroxidation, and glutamate release were investigated. To examine the MVIIA mechanism of action, the gene expressions of pro-apoptotic (Bax, nNOS, and caspase-3, -8, -9, -12) and anti-apoptotic (Bcl-xl) factors in the spinal cord tissue samples were determined by real-time PCR, and the activities of antioxidant enzymes were also investigated. Application of intrathecal MVIIA 10 μM four hours after SCI prompted a neuroprotective effect: neuronal death decreased (22.46%), oxidative stress diminished, pro-apoptotic factors (Bax, nNOS, and caspase-3, -8) were expressed to a lesser extent, and mitochondrial viability as well as anti-apoptotic factor (Bcl-xl) expression increased. These results suggested that MVIIA provided neuroprotection through antioxidant effects. Indeed, superoxide dismutase (188.41%), and glutathione peroxidase (199.96%), reductase (193.86%), and transferase (175.93%) expressions increased. Therefore, intrathecal MVIIA (MVIIA 10 μM, 4 h) application has neuroprotective potential, and the possible mechanisms are related to antioxidant agent modulation and to intrinsic and extrinsic apoptotic pathways.
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    Dysautonomia due to reduced cholinergic neurotransmission causes cardiac remodeling and heart failure.
    (2010) Gomes, Aline Alves Lara; Damasceno, Dênis Derly; Pires, Rita Gomes Wanderley; Gros, Robert; Gomes, Enéas Ricardo de Morais; Gavioli, Mariana; Lima, Ricardo de Freitas; Guimarães, Diogo Aparecido da Silva; Lima, Patrícia Maria d'Almeida; Bueno Júnior, Carlos Roberto; Vasconcelos, Anilton Cesar; Campos, Danilo Roman; Menezes, Cristiane Alves da Silva; Sirvente, Raquel de Assis; Salemi, Vera Maria Cury; Mady, Charles; Caron, Marc G.; Ferreira, Anderson José; Brum, Patricia Chakur; Resende, Rodrigo Ribeiro; Cruz, Jader dos Santos; Gomez, Marcus Vinicius; Prado, Vânia Ferreira; Almeida, Alvair Pinto de; Prado, Marco Antônio Maximo; Fonseca, Silvia Carolina Guatimosim
    Overwhelming evidence supports the importance of the sympathetic nervous system in heart failure. In contrast, much less is known about the role of failing cholinergic neurotransmission in cardiac disease. By using a unique genetically modified mouse line with reduced expression of the vesicular acetylcholine transporter (VAChT) and consequently decreased release of acetylcholine, we investigated the consequences of altered cholinergic tone for cardiac function. M-mode echocardiography, hemodynamic experiments, analysis of isolated perfused hearts, and measurements of cardiomyocyte contraction indicated that VAChT mutant mice have decreased left ventricle function associated with altered calcium handling. Gene expression was analyzed by quantitative reverse transcriptase PCR and Western blotting, and the results indicated that VAChT mutant mice have profound cardiac remodeling and reactivation of the fetal gene program. This phenotype was attributable to reduced cholinergic tone, since administration of the cholinesterase inhibitor pyridostigmine for 2 weeks reversed the cardiac phenotype in mutant mice. Our findings provide direct evidence that decreased cholinergic neurotransmission and underlying autonomic imbalance cause plastic alterations that contribute to heart dysfunction.
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    Mapping of brain activity in the analgesia induced by Phα1β and morphine.
    (2022) Diniz, Danuza Montijo; Malamut, Carlos; Araújo, Marina Rios; Ferreira, Andréa Vidal; Silva, Juliana Figueira; Cordeiro, Marta do Nascimento; Borges, Marcia Helena; Silva, Marco Aurélio Romano; Gomez, Marcus Vinicius; Castro Junior, Célio José de
    Preclinical evidence suggests the potential of Phα1β, a toxin obtained from the venom of spider Phoneutria nigriventer, as a new analgesic drug. Molecular brain imaging techniques have afforded exciting opportunities to examine brain processes in clinical pain conditions. This paper aims to study the brain regions involved in the analgesic effects of Phα1β compared with Morphine, in a model of acute pain induced by formalin in Sprague Dawley rats. We used 18F-fluorodeoxyglucose as a metabolic radiotracer to perform brain imaging of rats pretreated with Phα1β or Morphine in a model of acute inflammatory pain caused by intraplantar injection of formalin. The rats’ hind paw’s formalin stimulation resulted in a brain metabolic increase at the bilateral motor cortex, visual cortex, somatosensory cortex, thalamus, and cingulate cortex.In rats treated with Phα1β, selective inhibition of unilateral motor cortex and cingulate cortex was observed. Morphine treatment leads to small and selective inhibition at the bilateral amygdala striatum and accumbens. Our results indicate that the analgesic effect of Phα1β and Morphine possesses a differential profile of central processing in the pain state.
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    Phoneutria toxin PnTx3-5 inhibits TRPV1 channel with antinociceptive action in an orofacial pain model.
    (2020) Pereira, Elizete Maria Rita; Souza, Jéssica Mabelle; Carobin, Natália Virtude; Silva, Juliana Figueira da; Astoni, Duana Carvalho dos Santos; Silva Júnior, Cláudio Antônio da; Binda, Nancy Scardua; Borges, Marcia Helena; Nagem, Ronaldo Alves Pinto; Kushmerick, Christopher; Ferreira, Juliano; Castro Junior, Célio José de; Ribeiro, Fabiola Mara; Gomez, Marcus Vinicius
    Capsaicin, an agonist of TRPV1, evokes intracellular [Ca2+] transients and glutamate release from perfused trigeminal ganglion. The spider toxin PnTx3-5, native or recombinant is more potent than the selective TRPV1 blocker SB-366791 with IC50 of 47 ± 0.18 nM, 45 ± 1.18 nM and 390 ± 5.1 nM in the same experimental conditions. PnTx3-5 is thus more potent than the selective TRPV1 blocker SB-366791. PnTx3-5 (40 nM) and SB-366791 (3 μM) also inhibited the capsaicin-induced increase in intracellular Ca2+ in HEK293 cells transfected with TRPV1 by 75 ± 16% and 84 ± 3.2%, respectively. In HEK293 cells transfected with TRPA1, cinnamaldehyde (30 μM) generated an increase in intracellular Ca2+ that was blocked by the TRPA1 antagonist HC-030031 (10 μM, 89% inhibition), but not by PnTx3-5 (40 nM), indicating selectivity of the toxin for TRPV1. In whole-cell patch-clamp experiments on HEK293 cells transfected with TRPV1, capsaicin (10 μM) generated inward currents that were blocked by SB-366791 and by both native and recombinant PnTx3-5 by 47 ± 1.4%; 54 ± 7.8% and 56 ± 9.0%, respectively. Intradermal injection of capsaicin into the rat left vibrissa induced nociceptive behavior that was blocked by pre-injection with either SB-366791 (3 nmol/site i.d., 83.3 ± 7.2% inhibition) or PnTx3-5 (100 fmol/site, 89 ± 8.4% inhibition). We conclude that both native and recombinant PnTx3-5 are potent TRPV1 receptor antagonists with antinociceptive action on pain behavior evoked by capsaicin.
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    The inhibitory efect of Phα1β toxin on diabetic neuropathic pain involves the CXCR4 chemokine receptor.
    (2020) Silva Júnior, Cláudio Antônio da; Castro Junior, Célio José de; Pereira, Elizete Maria Rita; Binda, Nancy Scardua; Silva, Juliana Figueira da; Cordeiro, Marta do Nascimento; Diniz, Danuza Montijo; Santa Cecília, Flávia Viana; Ferreira, Juliano; Gomez, Marcus Vinicius
    Background: Diabetic neuropathy is a common cause of painful diabetic neuropathy (PDN). C-X-C chemokine receptor type 4 (CXCR4) expression is increased in peripheral nerve samples from diabetes patients, suggesting a role for CXCR4 in PDN. Therefore, we evaluated the effects of Phα1β, ω-conotoxin MVIIA, and AMD3100 in a model of streptozotocin (STZ)-induced PDN in rodents and naïve model of rats with the activation of the CXCR4/stromal cell-derived factor 1 (SDF-1) signal. Methods: Diabetic neuropathy was induced by intraperitoneal (ip) injection of STZ in Wistar rats. Naïve rats were intrathecally injected with SDF-1 to test the CXCR4/SDF-1 signal. The effects of Phα1β intrathecal (it), ω-conotoxin MVIIA intrathecal (it), and AMD3100 intraperitoneal (ip) on rat hypersensitivity, IL-6, and the intracellular calcium [Ca2+]i content of diabetic synaptosomes were studied. Results: The drugs reduced the hypersensitivity in diabetic rats. SDF-1 (1.0 µg/it) administration in naïve rats induced hypersensitivity. Phα1β (100 pmol/it) or AMD3100 (2.5 µg/ip) reduced this hypersensitivity after 2 h treatments, while ω-conotoxin MVIIA did not have an effect. IL-6 and [Ca2+]i content increased in the spinal cord synaptosomes in diabetic rats. The drug treatments reduced IL-6 and the calcium influx in diabetic synaptosomes. Conclusions: Phα1β, ω-conotoxin MVIIA, and AMD3100, after 2 h of treatment of STZ-induced PDN, reduced hypersensitivity in diabetic rats. In naïve rats with CXCR4/SDF-1 activation, the induced hypersensitivity decreased after 2 h treatments with Phα1β or AMD-3100, while ω-conotoxin MVIIA did not affect. The inhibitory effects of Phα1β on PDN may involve voltage-dependent calcium channels.