RESUMO
PURPOSE: Musculoskeletal injuries are common, and peripheral nerve injury (PNI) causes significant muscle and bone loss within weeks. After PNI, 4-aminopyridine (4-AP) improves functional recovery and muscle atrophy. However, it is unknown whether 4-AP has any effect on isolated traumatic muscle injury and PNI-induced bone loss. METHODS: A standardized crush injury was performed on the sciatic nerve and muscles in mice, and the mice were assigned to receive normal saline or 4-AP treatment daily for 21 days. The postinjury motor and sensory function recovery was assessed, injured muscles were processed for histomorphometry, and the tibial bone was scanned for bone density. RESULTS: 4-Aminopyridine significantly accelerated the postinjury motor and sensory function recovery, improved muscle histomorphometry, increased muscle satellite cell numbers, and shifted muscle fiber types after combined nerve and muscle injury. Importantly, the 4-AP treatment significantly reduced PNI-induced bone loss. In contrast, in the case of isolated muscle injury, 4-AP had no effect on functional recovery and bone density, but it improved muscle-specific histomorphometry to a limited extent. CONCLUSIONS: These findings demonstrate the potential beneficial effects of 4-AP on the recovery of muscle morphology and bone density after combined muscle and nerve injury. CLINICAL RELEVANCE: Nerve injuries frequently involve muscle and result in rapid muscle and bone atrophy. In this scenario, 4-AP, in addition to accelerating nerve functional recovery, might work as an adjunctive agent to improve the recovery of injured muscle and attenuate PNI-induced bone loss.
Assuntos
Doenças Ósseas Metabólicas , Traumatismos dos Nervos Periféricos , Camundongos , Animais , 4-Aminopiridina/farmacologia , 4-Aminopiridina/metabolismo , 4-Aminopiridina/uso terapêutico , Nervo Isquiático/lesões , Atrofia Muscular , Músculos , Recuperação de Função Fisiológica , Regeneração NervosaRESUMO
Study design: Systematic review. Objective: To provide current evidence on the efficacy of 4-aminopyridine (4-AP) to bring about functional improvement in individuals with chronic traumatic spinal cord injury (SCI). Methods: The Medline (PubMed), Web of Science and SCOPUS databases were systematically searched for relevant articles on the efficacy of 4-AP to treat SCI, from the dates such articles were first published until May 2022. Full-text versions of all the articles selected were examined independently by two reviewers. Methodological quality was rated using the Modified Jadad Scale, and risk of bias was assessed with the RoB-2 test. Data extracted included human models/types, PRISMA assessment protocols, and the results of each study. Descriptive syntheses are provided. Results: In total, 28 articles were initially identified, 10 of which were included after screening. Most of the studies reviewed reported some degree of patient improvement in one or more of the following parameters: motor, sensitivity and sexual function, sphincter control, spasticity, ability to function independently, quality of life, central motor conduction, pain, and pulmonary function. Conclusions: This review confirms the efficacy of 4-AP in improving several conditions resulting from SCI but further research on this topic is warranted. Additional randomized clinical trials with 4-AP involving larger sample sizes are needed, as are consistent outcome measures in order to obtain adequate data for analysis with a view to enhance treatment benefits. Systematic review registration: https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=334835, PROSPERO CRD42022334835.
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The GABAergic and glutamatergic neurotransmission systems are involved in seizures and other disorders of the central nervous system (CNS). Benzofuran derivatives often serve as the core in drugs used to treat such neurological disorders. The aim of this study was to synthesize new γ-amino acids structurally related to GABA and derived from 2,3-disubstituted benzofurans, analyze in silico their potential toxicity, ADME properties, and affinity for the GluN1-GluN2A NMDA receptor, and evaluate their potential activity and neuronal mechanisms in a murine model of pentylenetetrazol (PTZ)- and 4-aminopyridine (4-AP)-induced seizures. The in silico analysis evidenced a low risk of toxicity for the test compounds as well as the probability that they can cross the blood-brain barrier (BBB) to reach their targets in the CNS. According to docking simulations, these compounds bind at the active site of the NMDA glutamate receptor with high affinity. The in vivo assays demonstrated that 4 protects against 4-AP-induced seizure episodes, suggesting negative allosteric modulation (NAMs) at the glutamatergic NMDA receptor. Contrarily, 3 (the regioisomer of 4) and its racemic derivatives (cis-2,3-dihydrobenzofurans) were previously described to exacerbate such episodes, pointing to their positive allosteric modulation (PAMs) of the same receptor.
Assuntos
Benzofuranos , Receptores de N-Metil-D-Aspartato , Aminoácidos , Animais , Benzofuranos/farmacologia , Ligantes , Camundongos , Pentilenotetrazol , Receptores de N-Metil-D-Aspartato/metabolismoRESUMO
Diruthenium(II,III) metal-metal multiply bonded paddlewheel complexes bearing non-steroidal anti-inflammatory drugs are promising anticancer metallodrugs. The [Ru2(Ibp)4Cl] (Ibp, ibuprofenate anion from HIbp ibuprofen drug), free or encapsulated, shows anticancer activity against glioblastoma (in vitro, in vivo), and against human breast and prostate cancer cells. Herein we report the interaction of [Ru2(Ibp)4Cl] and of [Ru2(Ac)4(H2O)2]PF6 (Ac, acetate) with the 4-aminopyridine (4Apy) drug. The N-ligand was capable of cleaving the paddlewheel unit with oxidation of Ru2(II,III) to Ru2(III,III)O µ-oxo core in the ibuprofen complex while the acetate complex underwent axial substitution of water by 4Apy. Carefully designed synthetic and chromatographic methods succeeded in giving the novel [Ru2O(Ibp)2(4Apy)6]Cl2 metallodrug, the first diruthenium(III,III) µ-oxo having chloride as counterion. Characterization was performed by elemental analysis, mass spectrometry, thermogravimetric analysis, electronic absorption and vibrational spectroscopies, molar conductivity and cyclic voltammetry. Kinetic studies for the µ-oxo complex (in 50:50 v/v ethanol:water) suggested an aquation/complexation equilibrium in consecutive step reactions with the exchange of the two 4Apy trans to the µ-oxo bridge by water (aquation) and the back coordination of 4Apy in excess of the N-ligand (complexation). Trypan blue assays for the novel compound showed time- and dose- dependent antiproliferative effects (at 5-50 µmol L-1) and cytotoxicity (> 20 µmol L-1), and MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide) assays gave IC50 value of 7.6 ± 1.5 µmol L-1 (at 48 h, 1-20 µmol L-1) against U87MG human glioblastoma cells (aggressive brain glioma cancer) pointing the metallodrug as potential candidate for novel therapies in gliomas.
Assuntos
Antineoplásicos/farmacologia , Complexos de Coordenação/farmacologia , Ibuprofeno/análogos & derivados , Ibuprofeno/farmacologia , Antineoplásicos/síntese química , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Complexos de Coordenação/síntese química , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Cinética , Rutênio/químicaRESUMO
Accumulation of amyloid-beta (Aß) in temporal lobe structures, including the hippocampus, is related to a variety of Alzheimer's disease symptoms and seems to be involved in the induction of neural network hyperexcitability and even seizures. Still, a direct evaluation of the pro-epileptogenic effects of Aß in vivo, and of the underlying mechanisms, is missing. Thus, we tested whether the intracisternal injection of Aß modulates 4-aminopyridine (4AP)-induced epileptiform activity, hippocampal network function, and its synaptic coupling. When tested 3 weeks after its administration, Aß (but not its vehicle) reduces the latency for 4AP-induced seizures, increases the number of generalized seizures, exacerbates the time to fully recover from seizures, and favors seizure-induced death. These pro-epileptogenic effects of Aß correlate with a reduction in the power of the spontaneous hippocampal network activity, involving all frequency bands in vivo and only the theta band (4-10 Hz) in vitro. The pro-epileptogenic effects of Aß also correlate with a reduction of the Schaffer-collateral CA1 synaptic coupling in vitro, which is exacerbated by the sequential bath application of 4-AP and Aß. In summary, Aß produces long-lasting pro-epileptic effects that can be due to alterations in the hippocampal circuit, impacting its coordinated network activity and its synaptic efficiency. It is likely that normalizing synaptic coupling and/or coordinated neural network activity (i.e., theta activity) may contribute not only to improve cognitive function in Alzheimer's disease but also to avoid hyperexcitation in conditions of amyloidosis.
Assuntos
4-Aminopiridina/toxicidade , Peptídeos beta-Amiloides/toxicidade , Hipocampo/fisiopatologia , Fragmentos de Peptídeos/toxicidade , Convulsões/induzido quimicamente , Convulsões/fisiopatologia , Sinapses/fisiologia , Animais , Cisterna Magna/efeitos dos fármacos , Cisterna Magna/fisiopatologia , Potenciais Pós-Sinápticos Excitadores/efeitos dos fármacos , Potenciais Pós-Sinápticos Excitadores/fisiologia , Hipocampo/efeitos dos fármacos , Masculino , Rede Nervosa/efeitos dos fármacos , Rede Nervosa/fisiopatologia , Técnicas de Cultura de Órgãos , Bloqueadores dos Canais de Potássio/toxicidade , Ratos , Ratos Wistar , Sinapses/efeitos dos fármacosRESUMO
Studies have indicated that epilepsy, an important neurological disease, can generate oxidative stress and mitochondrial dysfunction, among other damages to the brain. In this context, the use of antioxidant compounds could provide neuroprotection and help to reduce the damage caused by epileptic seizures and thereby the use of anticonvulsant drugs. Rosmarinic acid (RA) is an ester of caffeic acid and 3,4-dihydroxyphenylactic acid that prevents cell damage caused by free radicals, acting as an antioxidant. It also presents anti-inflammatory, antimutagenic, and antiapoptotic properties. In this work, we used two models of acute seizure, 4-aminopyridine (4-AP) and picrotoxin (PTX)-induced seizures in mice, to investigate the anticonvulsant, antioxidant, and neuroprotective profile of RA. Diazepam and valproic acid, antiepileptic drugs already used in the treatment of epilepsy, were used as positive controls. Although RA could not prevent seizures in the models used in this study, neither enhance the latency time to first seizure at the tested doses, it exhibited an antioxidant and neuroprotective effect. RA (8 and 16 mg/kg) decreased reactive oxygen species production, superoxide dismutase activity, and DNA damage, measured in hippocampus, after seizures induced by PTX and 4-AP. Catalase activity was decreased by RA only after seizures induced by 4-AP. The activity of the mitochondrial complex II was increased by RA in hippocampus samples after both seizure models. The results obtained in this study suggest that RA is able to reduce cell damage generated by the 4-AP and PTX seizures and therefore could represent a potential candidate in reducing pathophysiological processes involved in epilepsy.
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Anticonvulsivantes/farmacologia , Cinamatos/farmacologia , Depsídeos/farmacologia , Complexo II de Transporte de Elétrons/metabolismo , Mitocôndrias/efeitos dos fármacos , Fármacos Neuroprotetores/farmacologia , Estresse Oxidativo/efeitos dos fármacos , Convulsões/tratamento farmacológico , 4-Aminopiridina/farmacologia , Animais , Antioxidantes/metabolismo , Comportamento Animal/efeitos dos fármacos , Dano ao DNA , Modelos Animais de Doenças , Complexo II de Transporte de Elétrons/genética , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Camundongos , Mitocôndrias/metabolismo , Estresse Oxidativo/genética , Picrotoxina/farmacologia , Convulsões/metabolismo , Ácido RosmarínicoRESUMO
BACKGROUND: Benzofurans are heterocyclic compounds with neurotropic activity. Some have been developed for the treatment of acute and degenerative neuronal injuries. OBJECTIVE: The study aimed to evaluate the in silico binding of some promising benzofurans on the GABA receptors, and the in vivo neurotropic activity of benzofuran analogues (BZF 6-10) of gamma-aminobutyric acid (GABA) on a seizure model. METHODS: The ligands with the best physicochemical attributes were docked on two GABA receptors (the alpha-1 subunit of GABAA-R and GBR1 subunit of GABAB-R). Selected benzofuran derivatives were synthesized by a multistep procedure and characterized. To examine the neurotropic effects, mice were pretreated with different concentrations of the compounds prior to PTZ- or 4- AP-induced seizures. We assessed acute toxicity, motor behavior, and the effects on seizures. RESULTS: The tested ligands that complied with Lipinski's rule of five were tested in silico with GABAA-R (ΔG = -5.51 to -5.84 kcal/mol) at the allosteric site for benzodiazepines. They bound to a similar cluster of residues as the reference compound (gaboxadol, ΔG = -5.51 kcal/mol). Synthesis was achieved with good overall yields (42-9.7%). Two compounds were selected for biological tests (BZF-7 and rac-BZF-10) on a mouse model of seizures, induced by pentylenetetrazol (PTZ) or 4-aminopyridine (4-AP). PTZ-induced seizures are associated with GABA receptors, and those 4-AP-induced with the blockage of the delayed rectifier-type potassium channel, which promotes the release of the NMDA-sensitive glutamatergic ionotropic receptor and other neurotransmitters. The biological assays demonstrated that BZF-7 and rac-BZF-10 do not protect against seizures. Indeed, BZF-7 increased the number of PTZ-induced seizures and decreased latency time. The 4-AP model apparently showed a potentiation of seizure effects after administration of the BZF-analogues, evidenced by the incidence and severity of the seizures and reduced latency time. CONCLUSION: The results suggest that the test compounds are GABAergic antagonists with stimulatory activity on the CNS.
Assuntos
Benzofuranos/farmacologia , Estimulantes do Sistema Nervoso Central/farmacologia , Antagonistas de Receptores de GABA-A/farmacologia , Antagonistas de Receptores de GABA-B/farmacologia , Animais , Benzofuranos/síntese química , Benzofuranos/química , Benzofuranos/toxicidade , Estimulantes do Sistema Nervoso Central/síntese química , Estimulantes do Sistema Nervoso Central/química , Estimulantes do Sistema Nervoso Central/toxicidade , Antagonistas de Receptores de GABA-A/síntese química , Antagonistas de Receptores de GABA-A/química , Antagonistas de Receptores de GABA-A/toxicidade , Antagonistas de Receptores de GABA-B/síntese química , Antagonistas de Receptores de GABA-B/química , Antagonistas de Receptores de GABA-B/toxicidade , Humanos , Ligantes , Masculino , Camundongos , Simulação de Acoplamento Molecular , Receptores de GABA-A/química , Receptores de GABA-B/químicaRESUMO
BACKGROUND: Gamma-Decanolactone (GD) is a monoterpene compound that presents anticonvulsant effect in acute and chronic models of epilepsy and it acts as a noncompetitive glutamate antagonist. OBJECTIVE: This study evaluated the anticonvulsant profile and the possible mechanism of action of GD in seizures induced by isoniazid (INH; 250 mg/kg), picrotoxin (PCT; 5 mg/kg) and 4- aminopyridine (4-AP; 13 mg/kg) in male mice. METHOD: Thirty minutes before the convulsants administration, animals received a single administration of saline, GD (100 or 300 mg/kg) or the positive control diazepam (DZP; 2 mg/kg). The parameters evaluated were the latency to the first seizure and the occurrence of clonic forelimb seizures. The rotarod performance test was used to evaluate the neurotoxicity of GD (300 mg/kg). Also, the DZPinduced sleep test was used. RESULTS: DZP increased the latency to the first seizure on all used models and decreased the percentage of seizures in two of the three behavioral models. GD was able to prolong the latency to the first seizure and decreased the percentage of seizures induced by INH and 4-AP, but not by PCT. It reduced the latency to fall off the rotarod test only at the time of 30 min. In the DZP-induced sleep test, GD shortened the onset and prolonged the time of sleep. CONCLUSION: Our findings suggested that GD reduced the convulsive behavior in the seizure models used here and it could modulate GABA pathways and affect potassium channels directly or indirectly, involving more than one cellular target in the central nervous system.
RESUMO
Epilepsy is a highly prevalent neurological disorder. Additionally, a percentage of patients do not respond to conventional antiepileptic drugs. Therefore, drugs for epilepsy control are still being developed. In the present study, the effect of propylparaben (PPB) in the epileptiform activity induced by 4-aminopyridine in hippocampal CA1 pyramidal neurons was evaluated using individual recordings in current-clamp mode. Results indicated that PPB suppressed the epileptiform activity in registered neurons. This effect disappeared when PPB was removed from the solution of incubation. In contrast, phenytoin only reduced the firing frequency without abolishing epileptiform activity. Our results indicate that PPB exerts an antiepileptic effect on CA1 pyramidal neurons in vitro. Therefore, PPB may represent an effective antiepileptic compound.
Assuntos
Anticonvulsivantes/farmacologia , Região CA1 Hipocampal/efeitos dos fármacos , Epilepsia/tratamento farmacológico , Parabenos/farmacologia , Células Piramidais/efeitos dos fármacos , 4-Aminopiridina , Animais , Região CA1 Hipocampal/fisiopatologia , Relação Dose-Resposta a Droga , Epilepsia/fisiopatologia , Masculino , Técnicas de Patch-Clamp , Células Piramidais/fisiologia , Ratos Wistar , Técnicas de Cultura de TecidosRESUMO
Despite the large number of reported crystalline structures of coordination complexes bearing pyridines as ligands, the relevance of π-π interactions among these hereroaromatic systems in the stabilization of their supramolecular structures and properties is not very well documented in the recent literature. The title compound, [CoCl2(C5H6N2)2], was obtained as bright-blue crystals suitable for single-crystal X-ray diffraction analysis from the reaction of 4-aminopyridine with cobalt(II) chloride in ethanol. The new complex was fully characterized by a variety of spectroscopic techniques and single-crystal X-ray diffraction. The crystal structure showed a tetrahedral complex stabilized mainly by bidimensional motifs constructed by π-π interactions with large horizontal displacements between the 4-aminopyridine units, and N-H...Cl hydrogen bonds. Other short contacts, such as C-H...Cl interactions, complete the three-dimensional arrangement. The supramolecular investigation was extended by statistical studies using the Cambridge Structural Database and a Hirshfeld surface analysis.
RESUMO
Autonomic nerves release ATP, which is processed into adenosine in the synaptic cleft. Adenosine and ATP exert a negative chronotropic effect in the heart. This study aims to evaluate adenosine and P2 receptors and cellular signalling in cardiac arrest produced by purines in the heart. Right atria of adult Wistar rats were used to evaluate the effects of adenosine, ATP and CPA (an adenosine A1 receptor agonist), in the presence and absence of DPCPX, an adenosine A1 receptor antagonist. Effects of adenosine A2 and A3 receptors agonists and antagonists were also investigated. Finally, involvement of calcium and potassium channels in these responses was assessed using BayK 8644 and 4-Aminopyridine. Cumulative concentration-effect curves of adenosine and CPA resulted in a negative chronotropic effect culminating in cardiac arrest at 1000µM (adenosine) and 1µM (CPA). Furthermore, ATP produced a negative chronotropic effect at 1-300µM and cardiac arrest at 1000µM in the right atrium. ATPγS (a non-hydrolysable analogue of ATP) reduced chronotropism only. The effects of adenosine, CPA and ATP were inhibited by DPCPX, a selective adenosine A1 receptor antagonist. The selective adenosine A2 and A3 receptors antagonists did not alter the chronotropic response of adenosine. 4-Aminopyridine, a blocker of potassium channels at 10mM, prevented the cardiac arrest produced by adenosine and ATP, while BayK 8644, activator of calcium channels, did not prevent cardiac arrest. Adenosine A1 receptor activation by adenosine and ATP produces cardiac arrest in the right atrium of Wistar rats predominantly through activation of potassium channels.
Assuntos
Trifosfato de Adenosina/farmacologia , Adenosina/farmacologia , Canais de Cálcio/metabolismo , Parada Cardíaca/induzido quimicamente , Parada Cardíaca/metabolismo , Átrios do Coração/efeitos dos fármacos , Canais de Potássio/metabolismo , Animais , Relação Dose-Resposta a Droga , Parada Cardíaca/patologia , Parada Cardíaca/fisiopatologia , Átrios do Coração/metabolismo , Átrios do Coração/patologia , Átrios do Coração/fisiopatologia , Frequência Cardíaca/efeitos dos fármacos , Masculino , Agonistas do Receptor Purinérgico P1/farmacologia , Ratos , Ratos Wistar , Receptores Purinérgicos P1/metabolismoRESUMO
Flavonoid galetin 3,6-dimethyl ether (FGAL) has been isolated from the aerial parts of Piptadenia stipulaceae and has shown a spasmolytic effect in guinea pig ileum. Thus, we aimed to characterize its relaxant mechanism of action. FGAL exhibited a higher relaxant effect on ileum pre-contracted by histamine (EC50=1.9±0.4×10(-7) M) than by KCl (EC50=2.6±0.5×10(-6) M) or carbachol (EC50=1.8±0.4×10(-6) M). The flavonoid inhibited the cumulative contractions to histamine, as well as to CaCl2 in depolarizing medium nominally Ca(2+)-free. The flavonoid relaxed the ileum pre-contracted by S-(-)-Bay K8644 (EC50=9.5±1.9×10(-6) M) but less potently pre-contracted by KCl or histamine. CsCl attenuated the relaxant effect of FGAL (EC50=1.1±0.3×10(-6) M), but apamin or tetraethylammonium (1mM) had no effect (EC50=2.6±0.2×10(-7) and 1.6±0.3×10(-7) M, respectively), ruling out the involvement of small and big conductance Ca(2+)-activated K(+) channels (SKCa and BKCa, respectively). Either 4-aminopyridine or glibenclamide attenuated the relaxant effect of FGAL (EC50=1.8±0.2×10(-6) and 1.5±0.5×10(-6) M, respectively), indicating the involvement of voltage- and ATP-sensitive K(+) channels (KV and KATP, respectively). FGAL did not alter the viability of intestinal myocytes in the MTT assay and decreased (88%) Fluo-4 fluorescence, indicating a decrease in cytosolic Ca(2+) concentration. Therefore, the relaxant mechanism of FGAL involves pseudo-irreversible noncompetitive antagonism of histaminergic receptors, KV and KATP activation and blockade of CaV1, thus leading to a reduction in cytosolic Ca(2+) levels.
Assuntos
Cálcio/metabolismo , Flavonoides/farmacologia , Íleo/efeitos dos fármacos , Contração Muscular/efeitos dos fármacos , Canais de Potássio/agonistas , Éster Metílico do Ácido 3-Piridinacarboxílico, 1,4-Di-Hidro-2,6-Dimetil-5-Nitro-4-(2-(Trifluormetil)fenil)/farmacologia , 4-Aminopiridina/farmacologia , Animais , Apamina/farmacologia , Cloreto de Cálcio/antagonistas & inibidores , Cloreto de Cálcio/farmacologia , Carbacol/antagonistas & inibidores , Carbacol/farmacologia , Sobrevivência Celular/efeitos dos fármacos , Césio/farmacologia , Cloretos/farmacologia , Flavonoides/antagonistas & inibidores , Glibureto/farmacologia , Cobaias , Histamina/farmacologia , Antagonistas dos Receptores Histamínicos/farmacologia , Íleo/fisiologia , Células Musculares/efeitos dos fármacos , Bloqueadores dos Canais de Potássio/farmacologia , Cloreto de Potássio/antagonistas & inibidores , Cloreto de Potássio/farmacologia , TetraetilamônioRESUMO
The intrinsic properties of spherical neurons play a fundamental role in the sensory processing of self-generated signals along a fast electrosensory pathway in electric fish. Previous results indicate that the spherical neuron's intrinsic properties depend mainly on the presence of two resonant currents that tend to clamp the voltage near the resting potential. Here we show that these are: a low-threshold potassium current blocked by 4-aminopyridine and a mixed cationic current blocked by cesium chloride. We also show that the low-threshold potassium current also causes the long refractory period, explaining the necessary properties that implement the dynamic filtering of the self-generated signals previously described. Comparative data from other fish and from the auditory system indicate that other single spiking onset neurons might differ in the channel repertoire observed in the spherical neurons of Gymnotus omarorum.