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1.
Life Sci ; 239: 116878, 2019 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-31669736

RESUMO

AIMS: We previously demonstrated that iron-overload in non-thalassemic rats induced neurotoxicity and cognitive decline. However, the effect of iron-overload on the brain of thalassemic condition has never been investigated. An iron chelator (deferiprone) provides neuroprotective effects against metal toxicity. Furthermore, a T-type calcium channels blocker (efonidipine) effectively attenuates cardiac dysfunction in thalassemic mice with iron-overload. However, the effects of both drugs on brain of iron-overload thalassemia has not been determined. We hypothesize that iron-overload induces neurotoxicity in Thalassemic and wild-type mice, and not only deferiprone, but also efonidipine, provides neuroprotection against iron-overload condition. MAIN METHODS: Mice from both wild-type (WT) and ß-thalassemic type (HT) groups were assigned to be fed with a standard-diet or high-iron diet containing 0.2% ferrocene/kg of diet (HFe) for 4 months consecutively. After three months of HFe, 75-mg/kg/d deferiprone or 4-mg/kg/d efonidipine were administered to the HFe-fed WT and HT mice for 1 month. KEY FINDINGS: HFe consumption caused an equal impact on circulating iron-overload, oxidative stress, and inflammation in WT and HT mice. Brain iron-overload and iron-mediated neurotoxicity, such as oxidative stress, inflammation, glial activation, mitochondrial dysfunction, and Alzheimer's like pathologies, were observed to an equal degree in HFe fed WT and HT mice. These pathological conditions were mitigated by both deferiprone and efonidipine. SIGNIFICANCE: These findings indicate that iron-overload itself caused neurotoxicity, and T-type calcium channels may play a role in this condition.


Assuntos
Deferiprona/farmacologia , Di-Hidropiridinas/farmacologia , Ferro/toxicidade , Nitrofenóis/farmacologia , Animais , Bloqueadores dos Canais de Cálcio/farmacologia , Canais de Cálcio Tipo T/efeitos dos fármacos , Deferiprona/metabolismo , Di-Hidropiridinas/metabolismo , Modelos Animais de Doenças , Ferro/metabolismo , Quelantes de Ferro/farmacologia , Sobrecarga de Ferro/patologia , Camundongos , Camundongos Endogâmicos C57BL , Síndromes Neurotóxicas/tratamento farmacológico , Síndromes Neurotóxicas/metabolismo , Nitrofenóis/metabolismo , Compostos Organofosforados/metabolismo , Compostos Organofosforados/farmacologia , Talassemia/patologia
2.
Exp Neurol ; 317: 226-243, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-30872136

RESUMO

The T-type calcium channels Cav3.2, one of the low voltage-activated (LVA) calcium channels, have been found to play important roles in the neuronal excitability. Recently, we and others have demonstrated that accumulation of Cav3.2 channels in the dorsal root ganglion (DRG) neurons and sensory nerves contributes to neuropathic pain after peripheral nerve injury. In the present study, we aimed to further investigate the regulation of Cav3.2 channels by interleukin-6 (IL-6) in DRG neurons in neuropathic pain rats after spinal nerve ligation (SNL). The results showed that Cav3.2 channel protein expression in L5 DRG neurons was upregulated and blockade of this channel decreased the hyperexcitability of DRG neurons and mechanical allodynia in SNL neuropathic pain rats. Furthermore, inhibition of IL-6 trans-signaling reduced the upregulation of Cav3.2 T-type channel induced by FIL-6 (a fusion protein of IL-6 and sIL-6R) in primary cultured DRG neurons in vitro. In vivo, inhibition of IL-6 trans-signaling reversed the upregulation of Cav3.2, reduced the hyperexcitability of L5 DRG neurons and alleviated mechanical allodynia in SNL rats. Our results suggest that IL-6 upregulates Cav3.2 T-type channels expression and function through the IL-6/sIL-6R trans-signaling pathway in DRG neurons, thus contributes to the development of neuropathic pain in SNL rats.


Assuntos
Canais de Cálcio Tipo T/metabolismo , Gânglios Espinais/metabolismo , Interleucina-6/biossíntese , Neuralgia/metabolismo , Neurônios/metabolismo , Nervos Espinhais/lesões , Animais , Bloqueadores dos Canais de Cálcio/farmacologia , Canais de Cálcio Tipo T/efeitos dos fármacos , Células Cultivadas , Hiperalgesia/metabolismo , Hiperalgesia/patologia , Interleucina-6/antagonistas & inibidores , Ligadura , Masculino , Neuralgia/fisiopatologia , Técnicas de Patch-Clamp , Ratos , Ratos Sprague-Dawley , Regulação para Cima
3.
Br J Anaesth ; 122(5): 643-651, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30916017

RESUMO

BACKGROUND: Hypnotics and general anaesthetics impair memory by altering hippocampal synaptic plasticity. We recently reported on a neurosteroid analogue with potent hypnotic activity [(3ß,5ß,17ß)-3-hydroxyandrostane-17-carbonitrile; 3ß-OH], which does not cause developmental neurotoxicity in rat pups. Here, we investigated the effects of 3ß-OH on neuronal excitability in the subiculum, the major output structure of the hippocampal formation, and synaptic plasticity at two key hippocampal synapses in juvenile rats. METHODS: Biophysical properties of isolated T-type calcium currents (T-currents) in the rat subiculum were investigated using acute slice preparations. Subicular T-type calcium channel (T-channel) subtype mRNA expression was compared using qRT-PCR. Using electrophysiological recordings, we examined the effects of 3ß-OH and an endogenous neuroactive steroid, allopregnanolone (Allo), on T-currents and burst firing properties of subicular neurones, and on the long-term potentiation (LTP) in CA3-CA1 and CA1-subiculum pathways. RESULTS: Biophysical and molecular studies confirmed that CaV3.1 channels represent the dominant T-channel isoform in the subiculum of juvenile rats. 3ß-OH and Allo inhibited rebound burst firing by decreasing the amplitude of T-currents in a voltage-dependent manner with similar potency, with 30-80% inhibition. Both neurosteroids suppressed LTP at the CA1-subiculum, but not at the CA3-CA1 Schaffer collateral synapse. CONCLUSIONS: Neurosteroid effects on T-channels modulate hippocampal output and provide possible molecular mechanisms for the amnestic action of the novel hypnotic 3ß-OH. Effects on T-channels in the subiculum provide a novel target for amnestic effects of hypnotics.


Assuntos
Androstanóis/farmacologia , Canais de Cálcio Tipo T/efeitos dos fármacos , Hipocampo/efeitos dos fármacos , Hipnóticos e Sedativos/farmacologia , Potenciação de Longa Duração/efeitos dos fármacos , Plasticidade Neuronal/efeitos dos fármacos , Nitrilos/farmacologia , Animais , Bloqueadores dos Canais de Cálcio/farmacologia , Canais de Cálcio Tipo T/biossíntese , Canais de Cálcio Tipo T/genética , Feminino , Regulação da Expressão Gênica/efeitos dos fármacos , Hipocampo/fisiologia , Potenciação de Longa Duração/fisiologia , Masculino , RNA Mensageiro/genética , Ratos Sprague-Dawley
4.
Neuropharmacology ; 149: 1-12, 2019 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-30695710

RESUMO

Limited information exists on the link between purinergic class P2X7 receptors (P2X7Rs) and calcium ion channels in epilepsy; no data has been reported regarding the interaction between P2X7Rs and T-type calcium ion channels in epilepsy. Thus, this study is an evaluation of the role that T-type calcium ion channels play in the effect of P2X7Rs on penicillin-induced epileptiform activity. In the first set of experiments, P2X7R agonist BzATP (at 25-, 50-, 100- and 200-µg doses), P2X7R antagonist A-438079 (at 5-, 10-, 20- and 40-µg doses) and T-type calcium ion channel antagonist, NNC-550396 were administered for electrophysiological analyses 30 min after penicillin injection (2.5 µl, 500 IU). In the second set of experiments, the effective doses of these substances were used for biochemical analyses. Malondialdehyde (MDA), advanced oxidation protein product (AOPP), glutathione (GSH), glutathione reductase (GR), glutathione peroxide (GPx), catalase (CAT) and superoxide dismutase (SOD) levels were measured in the cerebrum, cerebellum and brainstem of rats. BzATP (100 µg, icv) increased the mean frequency of epileptiform activity, whereas A-438079 (40 µg, icv) and NNC-550396 (30 µg, ic) reduced it. Both A-438079 and NNC-550396 reversed BzATP's proconvulsant action. BzATP increased lipid peroxidation and protein oxidation; it also altered other antioxidant enzymes measured in this study, which were all then reversed via A-438079 and NNC-550396, at least in the cerebrum. The electrophysiological and biochemical analysis of present study suggest that P2X7Rs and its interaction with T-type calcium ion channels play an important role in the experimental model of epilepsy.


Assuntos
Canais de Cálcio Tipo T/efeitos dos fármacos , Canais de Cálcio Tipo T/metabolismo , Epilepsia/metabolismo , Receptores Purinérgicos P2X7/efeitos dos fármacos , Receptores Purinérgicos P2X7/metabolismo , Trifosfato de Adenosina/análogos & derivados , Trifosfato de Adenosina/farmacologia , Animais , Antioxidantes/metabolismo , Benzimidazóis/farmacologia , Tronco Encefálico/efeitos dos fármacos , Tronco Encefálico/metabolismo , Cerebelo/efeitos dos fármacos , Cerebelo/metabolismo , Cérebro/efeitos dos fármacos , Cérebro/metabolismo , Ciclopropanos/farmacologia , Modelos Animais de Doenças , Epilepsia/induzido quimicamente , Naftalenos/farmacologia , Penicilinas/farmacologia , Agonistas do Receptor Purinérgico P2X/farmacologia , Antagonistas do Receptor Purinérgico P2X/farmacologia , Piridinas/farmacologia , Ratos , Ratos Wistar , Tetrazóis/farmacologia
5.
J Asian Nat Prod Res ; 21(1): 17-24, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29373928

RESUMO

Three new Lycopodium alkaloids (1-3), together with 15 known alkaloids, were isolated from club moss Lycopodium japonicum. Their structures were determined by extensive spectroscopic analysis, including 1D and 2D NMR spectra. Compound 1 has an unusual ß-oriented methyl group substituted at C-15 and an α-hydroxy cyclopentenone moiety. All new alkaloids were evaluated for the inhibition of T-type calcium channel.


Assuntos
Alcaloides/isolamento & purificação , Lycopodium/química , Alcaloides/química , Alcaloides/farmacologia , Bloqueadores dos Canais de Cálcio/isolamento & purificação , Canais de Cálcio Tipo T/efeitos dos fármacos , Células HEK293 , Humanos , Espectroscopia de Ressonância Magnética
6.
Am J Physiol Gastrointest Liver Physiol ; 316(2): G291-G303, 2019 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-30540489

RESUMO

The P-STS human ileal neuroendocrine tumor cells, as a model for gut enterochromaffin cells, are strongly and synergistically activated by histamine plus acetylcholine (ACh), presumably via histamine 4 receptors, and weakly activated by histamine alone. Sensing these signals, enterochromaffin cells could participate in intestinal intolerance or allergic reactions to food constituents associated with elevated histamine levels. In this study we aimed to analyze the underlying molecular mechanisms. Inhibition by mepyramine and mibefradil indicated that histamine alone caused a rise in intracellular calcium concentration ([Ca2+]i) via histamine 1 receptors involving T-type voltage-gated calcium channels (VGCCs). Sensitivity to histamine was enhanced by pretreatment with the inflammatory cytokine tumor necrosis factor-α (TNF-α). In accordance with the relief it offers some inflammatory bowel disease patients, otilonium bromide, a gut-impermeable inhibitor of T-type (and L-type) VGCCs and muscarinic ACh receptors, efficiently inhibited the [Ca2+]i responses induced by histamine plus ACh or by histamine alone in P-STS cells. It will take clinical studies to show whether otilonium bromide has promise for the treatment of adverse food reactions. The cells did not react to the nutrient constituents glutamate, capsaicin, cinnamaldehyde, or amylase-trypsin inhibitors and the transient receptor potential channel vanilloid 4 agonist GSK-1016790A. The bacterial product butyrate evoked a rise in [Ca2+]i only when added together with ACh. Lipopolysaccharide had no effect on [Ca2+]i despite the presence of Toll-like receptor 4 protein. Our results indicate that inflammatory conditions with elevated levels of TNF-α might enhance histamine-induced serotonin release from intestinal neuroendocrine cells. NEW & NOTEWORTHY We show that histamine synergistically enhances the intracellular calcium response to the physiological agonist acetylcholine in human ileal enterochromaffin tumor cells. This synergistic activation and cell activation by histamine alone largely depend on T-type voltage-gated calcium channels and are inhibited by the antispasmodic otilonium bromide. The cells showed no response to wheat amylase-trypsin inhibitors, suggesting that enterochromaffin cells are not directly involved in nongluten wheat sensitivity.


Assuntos
Canais de Cálcio Tipo L/efeitos dos fármacos , Canais de Cálcio Tipo T/efeitos dos fármacos , Células Enterocromafins/efeitos dos fármacos , Histamina/farmacologia , Cálcio/metabolismo , Bloqueadores dos Canais de Cálcio/farmacologia , Canais de Cálcio Tipo L/metabolismo , Células Enterocromafins/metabolismo , Histamina/metabolismo , Humanos , Potenciais da Membrana/efeitos dos fármacos , Potenciais da Membrana/fisiologia
7.
Behav Brain Res ; 361: 54-64, 2019 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-30550952

RESUMO

Abnormalities in social behavior are a co-morbid symptom of idiopathic generalized epilepsies such as childhood absence epilepsy. The Genetic Absence Epilepsy Rats from Strasbourg (GAERS) model is a spontaneously occurring absence epilepsy phenotype closely correlated to that of human absence epilepsies. Similar to the human conditions, GAERS display social abnormalities. Previous studies have only demonstrated social abnormalities in female GAERS, whereas social problems are observed in male and female patients. Seizures in GAERS result in part due to a gain-of-function missense mutation in the Cav3.2 T-type calcium channel gene. This study examined the effects of the pan-T-type calcium channel antagonist, Z944, on social interaction behaviors in male and female GAERS using an open field social interaction test. A second objective of this study was to examine the effects of Z944 on anxiety-like behavior in an open field locomotion test and elevated plus maze. Results showed a decrease in social activity in GAERS relative to non-epileptic control (NEC) rats. Acute, systemic Z944 (5 mg/kg; i.p.) consistently reduced introductory and aggressive behaviors in both GAERS and NECs whereas strain effects were observed for over-and-under crawl behaviors. In the open field locomotion test and elevated plus maze, Z944 increased anxiety-like behaviors in GAERS, whereas, Z944 produced inconsistent effects on anxiety-like behaviors in NECs. The results of this study suggest that the regulation of T-type calcium channel activity may be a useful strategy for the development of new therapeutic approaches for the treatment of social and affective abnormalities observed in absence epilepsy disorders.


Assuntos
Comportamento Animal/efeitos dos fármacos , Epilepsia Tipo Ausência/genética , Piperidinas/farmacologia , Animais , Ansiedade/genética , Encéfalo/metabolismo , Bloqueadores dos Canais de Cálcio/farmacologia , Canais de Cálcio Tipo T/efeitos dos fármacos , Modelos Animais de Doenças , Eletroencefalografia , Epilepsia Generalizada/genética , Feminino , Locomoção/efeitos dos fármacos , Masculino , Ratos , Ratos Wistar , Convulsões/tratamento farmacológico , Comportamento Social
8.
Expert Opin Ther Pat ; 28(12): 883-901, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30372652

RESUMO

INTRODUCTION: T-type calcium channels are attractive targets for potential treatment of epilepsy inflammatory or neuropathic pain, insomnia, Parkinson's disease, and cancer. Three isoforms having different biophysical functions are expressed in peripheral and central nerve. Since the withdrawal of mibefradil, the first compound marketed for selective T-type calcium channel blockade, extensive efforts have been made to identify more selective T-type calcium channel blockers. AREAS COVERED: This review covers the 43 patents describing 'organic small molecules as T-type calcium channel blockers'-published since 2012. The most recent similar patent review was published in 2011. Information from a recent review article and relevant research papers has been included, as well as biological data and clinical trial results where available. EXPERT OPINION: Triazinone derivatives, carbazole compounds, and aryl triazole/imidazole amide derivatives display potent blockade activity α1H, α1G, and pan T-type calcium channel subtypes, respectively, though the specificity of the letter is still unsatisfactory. Nonetheless, improvements seen in the efficacy of compounds targeting α1H T-type calcium channels indicate significant progress. Ongoing clinical trials are for the candidates Z944 (Phase II) and ACT-709478 (Phase II) appear promising. These studies may lead to a new generation of inhibitors with higher selectivity, improved physicochemical properties, and reduced side effects.


Assuntos
Bloqueadores dos Canais de Cálcio/farmacologia , Canais de Cálcio Tipo T/efeitos dos fármacos , Desenho de Drogas , Animais , Bloqueadores dos Canais de Cálcio/efeitos adversos , Bloqueadores dos Canais de Cálcio/química , Canais de Cálcio Tipo T/metabolismo , Humanos , Patentes como Assunto
9.
Learn Mem ; 25(7): 317-324, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29907639

RESUMO

The roles of low-voltage-activated (T-type) calcium channels in brain diseases have been studied extensively. Less is known regarding the involvement of T-type channels in cognition and behavior. Sensory integration (SI) is a cognitive process whereby the brain uses unimodal or multimodal sensory features to create a comprehensive representation of the environment. The multisensory object oddity (MSO) task assesses SI using combinations of sensory features of objects, either in the same or different sensory modalities. The regulation of SI involves the orbitofrontal cortex (OFC), an area which shows high levels of T-type calcium channel expression. We tested the effects of blocking T-type calcium channels on the MSO task with the selective T-type antagonist, Z944 (5 mg/kg; i.p. systemic; 100 or 500 µM OFC infusion), in male Long Evans rats. With systemic treatment, Z944 impaired the visual and visual-olfactory versions of the task. Infusion of 100 and 500 µM Z944 produced deficits in the olfactory version of the task. In addition, only vehicle-infused, but not Z944-infused, rats showed significant performance above chance for all task variants. Thus, the present results suggest that T-type calcium channels in OFC are involved in SI of features in an oddity task. Given that unimodal SI was disrupted by OFC infusions of Z944, the deficits in the multimodal task must be interpreted with caution. As SI is disrupted in psychiatric disorders, further investigations elucidating the brain regions implicated in SI regulation by T-type calcium channels may help inform therapeutic development for those suffering from SI impairments.


Assuntos
Bloqueadores dos Canais de Cálcio/farmacologia , Canais de Cálcio Tipo T/fisiologia , Percepção Olfatória/fisiologia , Córtex Pré-Frontal/fisiologia , Desempenho Psicomotor/fisiologia , Percepção Visual/fisiologia , Animais , Bloqueadores dos Canais de Cálcio/administração & dosagem , Canais de Cálcio Tipo T/efeitos dos fármacos , Masculino , Percepção Olfatória/efeitos dos fármacos , Piperidinas/farmacologia , Córtex Pré-Frontal/efeitos dos fármacos , Desempenho Psicomotor/efeitos dos fármacos , Ratos , Ratos Long-Evans , Percepção Visual/efeitos dos fármacos
10.
Eur Rev Med Pharmacol Sci ; 22(12): 4025-4031, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29949180

RESUMO

OBJECTIVE: Lercanidipine is a calcium antagonist with no cardiodepressant activity, long lasting antihypertensive action and reno-protective effect. Our previous data demonstrated that lercanidipine blocks L-type calcium channels (CaL). However, no data are available concerning its effects on T-type calcium channels (CaT). The aim of this study was to evaluate the effect on both CaL and CaT and the selectivity ratio of R-lercanidipine, S-lercanidipine and RS-lercanidipine. A comparison with other dihydropyridines (amlodipine and lacidipine) and the CaT blocker mibefradil was also performed. MATERIALS AND METHODS: In patch-clamped guinea-pig ventricular myocytes, a voltage protocol was applied mimicking a normal action potential: HP of -90 mV, 200 ms depolarizing steps to -50/+50 mV. Lercanidipine was tested at concentrations (1-10 µM) able to block ≈ 50% CaL evoked from a HP in the range of -50 to -30 mV. Cells were superfused with a Na+ and K+ free solution pre-warmed to 35°C to abolish overlapping currents. RESULTS: Using the described voltage protocol, all dihydropyridines at 1 µM blocked less than 20% CaL, with the exception of lacidipine, that reduced CaL >60% of control. All calcium channel blockers (CCBs) blocked a significant amount of CaT, varying from 28% (mibefradil) to 4.3% (amlodipine). Based on the ratio between CaT and CaL blockade in each cell (T/L), mibefradil, as expected, showed the highest T affinity (T/L=1.3). Lercanidipine, either racemate or enantiomers, showed a noticeable T selectivity, T/L varying from 1.05 (S-lercanidipine) to 1.15 (R-lercanidipine). CONCLUSIONS: All CCBs examined in this study showed both T- and L-channel blocking activities and can be differentiated based on their relative affinity. Among tested dihydropyridines, lercanidipine showed the highest T/L selectivity.


Assuntos
Anti-Hipertensivos/farmacologia , Bloqueadores dos Canais de Cálcio/farmacologia , Canais de Cálcio Tipo T/efeitos dos fármacos , Di-Hidropiridinas/farmacologia , Potenciais de Ação/efeitos dos fármacos , Animais , Canais de Cálcio Tipo T/fisiologia , Cobaias , Miócitos Cardíacos/efeitos dos fármacos , Miócitos Cardíacos/fisiologia
11.
Curr Pharm Des ; 24(16): 1772-1779, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29732965

RESUMO

Otilonium bromide (OB) is a drug with spasmolytic activity belonging to quaternary ammonium derivatives and extensively used to treat patients affected by the Irritable Bowel Syndrome (IBS). Thanks to its peculiar pharmacokinetic, OB concentrates in the large bowel wall and acts locally. From the pharmacodynamics point of view, OB is able to inhibit i) the main patterns of human colonic motility in vitro; ii) the contractility caused by excitatory motor neurons stimulation (pre-synaptic action) and iii) the contractility caused by the direct action of excitatory neurotransmitters (post-synaptic action). Interestingly, these effects derive from a complex interaction between the drug and several cellular targets. The main action consists in the blockade of Ca2+ entry through L-type Ca2+ channels and interference with intracytoplasmatic Ca2+ mobilization necessary for SMC contraction, thus preventing excessive bowel contractions and abdominal cramps. Further, OB blocks the T-type Ca2+ channels and interferes with the muscarinic responses; it interacts, directly or indirectly, with the tachykinin receptors on SMC and on primary afferent neurons whose combined effects may result in the reduction of motility and abdominal pain. In summary, a revision of this complex picture of OB activity could help to better address its therapeutic use.


Assuntos
Bloqueadores dos Canais de Cálcio/farmacologia , Síndrome do Intestino Irritável/tratamento farmacológico , Compostos de Amônio Quaternário/farmacologia , Animais , Cálcio/metabolismo , Canais de Cálcio Tipo T/efeitos dos fármacos , Canais de Cálcio Tipo T/metabolismo , Humanos , Síndrome do Intestino Irritável/metabolismo
12.
Artigo em Inglês | MEDLINE | ID: mdl-29684576

RESUMO

Daphnia magna heartbeat is myogenic-originating within the animal's heart. However, the mechanism for this myogenic automaticity is unknown. The mechanism underlying the automaticity of vertebrate myogenic hearts involves cells (pacemaker cells), which have a distinct set of ion channels that include hyperpolarization activated cyclic nucleotide-gated (HCN) and T-type calcium ion channels. We hypothesized that these ion channels also underlie the automatic myogenic heartbeat of Daphnia magna. The drugs, ZD7288 and mibefradil dihydrochloride, block HCN and T-type calcium ion channels respectively. Application of these drugs, in separate experiments, show that they inhibit the heartbeat of Daphnia magna in a dose-dependent manner. Calculation of the percent difference between the heart rate of pretreatment (before drug application) and heart rate following drug application (post-treatment) allowed us to graph a dose-response curve for both ZD7288 and mibefradil, revealing that ZD7288 produces a greater effect on decreasing heart rate. This indicates the HCN ion channels play a foremost role in generating Daphnia magna heartbeat. Our results show conclusively that HCN and T-type calcium ion channels underlie the automatic myogenic heartbeat in Daphnia magna-and suggest a conserved mechanism for generating myogenic heartbeat within the animal kingdom. Thus, Daphnia magna represents a credible model system for further exploration of cardiac physiology.


Assuntos
Bloqueadores dos Canais de Cálcio/farmacologia , Canais de Cálcio Tipo T/efeitos dos fármacos , Cardiotônicos/farmacologia , Canais de Cátion Regulados por Nucleotídeos Cíclicos/efeitos dos fármacos , Daphnia/fisiologia , Frequência Cardíaca/efeitos dos fármacos , Mibefradil/farmacologia , Pirimidinas/farmacologia , Animais , Bloqueadores dos Canais de Cálcio/administração & dosagem , Cardiotônicos/administração & dosagem , Relação Dose-Resposta a Droga , Mibefradil/administração & dosagem , Pirimidinas/administração & dosagem
13.
Bioorg Med Chem ; 26(11): 3046-3059, 2018 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-29622412

RESUMO

Both N- and T-type calcium ion channels have been implicated in pain transmission and the N-type channel is a well-validated target for the treatment of neuropathic pain. An SAR investigation of a series of substituted aminobenzothiazoles identified a subset of five compounds with comparable activity to the positive control Z160 in a FLIPR-based intracellular calcium response assay measuring potency at both CaV2.2 and CaV3.2 channels. These compounds may form the basis for the development of drug leads and tool compounds for assessing in vivo effects of variable modulation of CaV2.2 and CaV3.2 channels.


Assuntos
Benzimidazóis/síntese química , Benzotiazóis/síntese química , Bloqueadores dos Canais de Cálcio/farmacologia , Canais de Cálcio Tipo N/química , Canais de Cálcio Tipo T/química , Ciclopropanos/síntese química , Naftalenos/síntese química , Piperidinas/síntese química , Benzimidazóis/química , Benzimidazóis/farmacologia , Benzotiazóis/química , Benzotiazóis/farmacologia , Bloqueadores dos Canais de Cálcio/síntese química , Bloqueadores dos Canais de Cálcio/química , Canais de Cálcio Tipo N/efeitos dos fármacos , Canais de Cálcio Tipo T/efeitos dos fármacos , Ciclopropanos/química , Ciclopropanos/farmacologia , Estrutura Molecular , Naftalenos/química , Naftalenos/farmacologia , Piperazinas/síntese química , Piperazinas/química , Piperazinas/farmacologia , Piperidinas/química , Piperidinas/farmacologia , Relação Estrutura-Atividade
14.
Pharmacology ; 101(5-6): 309-321, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29597200

RESUMO

Hypothyroidism is a common disorder that is associated with psychological disturbances such as dementia, depression, and psychomotor disorders. We recently found that chronic treatment with the T-type calcium channel enhancer SAK3 prevents the cholinergic neurodegeneration induced by a single intraperitoneal (i.p.) injection of methimazole (MMI; 75 mg/kg), thereby improving cognition. Here, we evaluated the acute effect of SAK3 on cognitive impairments and its mechanism of action following the induction of hypothyroidism. Hypothyroidism was induced by 2 injections of MMI (75 mg/kg, i.p.) administered once per week. Four weeks after the final MMI treatment, MMI-treated mice showed reduced serum thyroxine (T4) levels and cognitive impairments without depression-like behaviors. Although acute SAK3 (1.0 mg/kg, p.o.) administration failed to ameliorate the decreased T4 levels and histochemical destruction of the glomerular structure, acute SAK3 (1.0 mg/kg, p.o.) administration significantly reduced cognitive impairments in MMI-treated mice. Importantly, the α7 nicotinic acetylcholine receptor (nAChR)-selective inhibitor methyllycaconitine (MLA; 12 mg/kg, i.p.) and T-type calcium channel-specific blocker NNC 55-0396 (25 mg/kg, i.p.) antagonized the acute effect of SAK3 on memory deficits in MMI-treated mice. We also confirmed that acute SAK3 administration does not rescue reduced olfactory marker protein or choline acetyltransferase immunoreactivity levels in the olfactory bulb or medial septum. Taken together, these results suggest that SAK3 has the ability to improve the cognitive decline caused by hypothyroidism directly through activation of nAChR signaling and T-type calcium channels.


Assuntos
Disfunção Cognitiva/prevenção & controle , Hipotireoidismo/complicações , Imidazóis/farmacologia , Metimazol/toxicidade , Compostos de Espiro/farmacologia , Acetilcolina/metabolismo , Animais , Antitireóideos/toxicidade , Benzimidazóis/farmacologia , Canais de Cálcio Tipo T/efeitos dos fármacos , Canais de Cálcio Tipo T/metabolismo , Disfunção Cognitiva/etiologia , Ciclopropanos/farmacologia , Feminino , Hipotireoidismo/induzido quimicamente , Camundongos , Naftalenos/farmacologia , Bulbo Olfatório/efeitos dos fármacos , Bulbo Olfatório/metabolismo , Transdução de Sinais/efeitos dos fármacos
15.
J Pineal Res ; 64(4): e12476, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29437250

RESUMO

Recent studies implicate melatonin in the antinociceptive activity of sensory neurons. However, the underlying mechanisms are still largely unknown. Here, we identify a critical role of melatonin in functionally regulating Cav3.2 T-type Ca2+ channels (T-type channel) in trigeminal ganglion (TG) neurons. Melatonin inhibited T-type channels in small TG neurons via the melatonin receptor 2 (MT2 receptor) and a pertussis toxin-sensitive G-protein pathway. Immunoprecipitation analyses revealed that the intracellular subunit of the MT2 receptor coprecipitated with Gαo . Both shRNA-mediated knockdown of Gαo and intracellular application of QEHA peptide abolished the inhibitory effects of melatonin. Protein kinase C (PKC) antagonists abolished the melatonin-induced T-type channel response, whereas inhibition of conventional PKC isoforms elicited no effect. Furthermore, application of melatonin increased membrane abundance of PKC-eta (PKCη ) while antagonism of PKCη or shRNA targeting PKCη prevented the melatonin-mediated effects. In a heterologous expression system, activation of MT2 receptor strongly inhibited Cav3.2 T-type channel currents but had no effect on Cav3.1 and Cav3.3 current amplitudes. The selective Cav3.2 response was PKCη dependent and was accompanied by a negative shift in the steady-state inactivation curve. Furthermore, melatonin decreased the action potential firing rate of small TG neurons and attenuated the mechanical hypersensitivity in a mouse model of complete Freund's adjuvant-induced inflammatory pain. These actions were inhibited by T-type channel blockade. Together, our results demonstrated that melatonin inhibits Cav3.2 T-type channel activity through the MT2 receptor coupled to novel Gßγ -mediated PKCη signaling, subsequently decreasing the membrane excitability of TG neurons and pain hypersensitivity in mice.


Assuntos
Canais de Cálcio Tipo T/efeitos dos fármacos , Melatonina/farmacologia , Proteína Quinase C/metabolismo , Células Receptoras Sensoriais/efeitos dos fármacos , Animais , Canais de Cálcio Tipo T/metabolismo , Hiperalgesia/metabolismo , Potenciais da Membrana/efeitos dos fármacos , Camundongos Endogâmicos ICR , Receptor MT2 de Melatonina/metabolismo , Células Receptoras Sensoriais/metabolismo , Transdução de Sinais/efeitos dos fármacos , Gânglio Trigeminal/efeitos dos fármacos , Gânglio Trigeminal/metabolismo
16.
Life Sci ; 192: 144-150, 2018 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-29183797

RESUMO

AIMS: Ca2+ and cAMP are important intracellular modulators. In order to generate intracellular signals with various amplitudes, as well as different temporal and spatial properties, a tightly and precise control of these modulators in intracellular compartments is necessary. The aim of this study was to evaluate the effects of elevated and sustained cAMP levels on voltage-dependent Ca2+ currents and proliferation in pituitary tumor GH3 cells. MAIN METHODS: Effect of long-term exposure to forskolin and dibutyryl-cyclic AMP (dbcAMP) on Ca2+ current density and cell proliferation rate were determined by using the whole-cell patch-clamp technique and real time cell monitoring system. The cAMP levels were assayed, after exposing transfected GH3 cells with the EPAC-1 cAMP sensor to forskolin and dbcAMP, by FRET analysis. KEY FINDINGS: Sustained forskolin treatment (24 and 48h) induced a significant increase in total Ca2+ current density in GH3 cells. Accordingly, dibutyryl-cAMP incubation (dbcAMP) also elicited increase in Ca2+ current density. However, the maximum effect of dbcAMP occurred only after 72h incubation, whereas forskolin showed maximal effect at 48h. FRET-experiments confirmed that the time-course to elevate intracellular cAMP was distinct between forskolin and dbcAMP. Mibefradil inhibited the fast inactivating current component selectively, indicating the recruitment of T-type Ca2+ channels. A significant increase on cell proliferation rate, which could be related to the elevated and sustained intracellular levels of cAMP was observed. SIGNIFICANCE: We conclude that maintaining high levels of intracellular cAMP will cause an increase in Ca2+ current density and this phenomenon impacts proliferation rate in GH3 cells.


Assuntos
Canais de Cálcio/metabolismo , AMP Cíclico/metabolismo , Animais , Bucladesina/farmacologia , Bloqueadores dos Canais de Cálcio/farmacologia , Canais de Cálcio Tipo L/efeitos dos fármacos , Canais de Cálcio Tipo T/efeitos dos fármacos , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Colforsina/farmacologia , Mibefradil/farmacologia , Técnicas de Patch-Clamp , Neoplasias Hipofisárias/metabolismo , Ratos , Vasodilatadores/farmacologia
17.
JCI Insight ; 2(22)2017 11 16.
Artigo em Inglês | MEDLINE | ID: mdl-29202456

RESUMO

Amyotrophic lateral sclerosis (ALS) is a rapidly progressing, fatal disorder with no effective treatment. We used simple genetic models of ALS to screen phenotypically for potential therapeutic compounds. We screened libraries of compounds in C. elegans, validated hits in zebrafish, and tested the most potent molecule in mice and in a small clinical trial. We identified a class of neuroleptics that restored motility in C. elegans and in zebrafish, and the most potent was pimozide, which blocked T-type Ca2+ channels in these simple models and stabilized neuromuscular transmission in zebrafish and enhanced it in mice. Finally, a short randomized controlled trial of sporadic ALS subjects demonstrated stabilization of motility and evidence of target engagement at the neuromuscular junction. Simple genetic models are, thus, useful in identifying promising compounds for the treatment of ALS, such as neuroleptics, which may stabilize neuromuscular transmission and prolong survival in this disease.


Assuntos
Esclerose Amiotrófica Lateral/tratamento farmacológico , Antipsicóticos/farmacocinética , Antipsicóticos/uso terapêutico , Doenças da Junção Neuromuscular/tratamento farmacológico , Animais , Caenorhabditis elegans , Canais de Cálcio/efeitos dos fármacos , Canais de Cálcio Tipo T/efeitos dos fármacos , Proteínas de Ligação a DNA/metabolismo , Modelos Animais de Doenças , Avaliação Pré-Clínica de Medicamentos , Tolerância a Medicamentos , Feminino , Camundongos , Junção Neuromuscular/efeitos dos fármacos , Pimozida/farmacologia , Peixe-Zebra , Proteínas de Peixe-Zebra/metabolismo
18.
Chimia (Aarau) ; 71(10): 722-729, 2017 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-29070417

RESUMO

We describe the discovery and optimization of new, brain-penetrant T-type calcium channel blockers. We present optimized compounds with excellent efficacy in a rodent model of generalized absence-like epilepsy. Along the fine optimization of a chemical series with a pharmacological target located in the CNS (target potency, brain penetration, and solubility), we successfully identified an Ames negative aminopyrazole as putative metabolite of this compound series. Our efforts culminated in the selection of compound 20, which was elected as a preclinical candidate.


Assuntos
Bloqueadores dos Canais de Cálcio/uso terapêutico , Canais de Cálcio Tipo T/efeitos dos fármacos , Descoberta de Drogas , Epilepsia Generalizada/tratamento farmacológico , Animais , Canais de Cálcio Tipo T/fisiologia , Modelos Animais de Doenças , Humanos , Camundongos , Ratos
19.
PLoS One ; 12(10): e0186864, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29073181

RESUMO

Medicinal plants represent a significant reservoir of unexplored substances for early-stage drug discovery. Of interest, two flowering Mediterranean plants have been used for thousands of years for their beneficial effects on nervous disorders, including anxiety and mood. However, the therapeutic potential of these plants regarding their ability to target ion channels and neuronal excitability remains largely unknown. Towards this goal, we have investigated the ability of Lavender and Rosemary to modulate T-type calcium channels (TTCCs). TTCCs play important roles in neuronal excitability, neuroprotection, sensory processes and sleep. These channels are also involved in epilepsy and pain. Using the whole-cell patch-clamp technique, we have characterized how Lavender and Rosemary extracts, as well as their major active compounds Linalool and Rosmarinic acid, modulate the electrophysiological properties of recombinant TTCCs (CaV3.2) expressed in HEK-293T cells. Both the methanolic and essential oil extracts as well as the active compounds of these plants inhibit Cav3.2 current in a concentration-dependent manner. In addition, these products also induce a negative shift of the steady-state inactivation of CaV3.2 current with no change in the activation properties. Taken together, our findings reveal that TTCCs are a molecular target of the Lavender and Rosemary compounds, suggesting that inhibition of TTCCs could contribute to the anxiolytic and the neuroprotective effects of these plants.


Assuntos
Canais de Cálcio Tipo T/efeitos dos fármacos , Lavandula/química , Extratos Vegetais/farmacologia , Rosmarinus/química , Animais , Bloqueadores dos Canais de Cálcio/farmacologia , Canais de Cálcio Tipo T/fisiologia , Células HEK293 , Humanos , Metanol/química , Neurônios/efeitos dos fármacos , Técnicas de Patch-Clamp
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