Synaptic downscaling is a homeostatic mechanism that allows neurons to reduce firing rates during chronically elevated network activity. Although synaptic downscaling is important in neural circuit ...development and epilepsy, the underlying mechanisms are poorly described. We performed small RNA profiling in picrotoxin (PTX)‐treated hippocampal neurons, a model of synaptic downscaling. Thereby, we identified eight microRNAs (miRNAs) that were increased in response to PTX, including miR‐129‐5p, whose inhibition blocked synaptic downscaling in vitro and reduced epileptic seizure severity in vivo. Using transcriptome, proteome, and bioinformatic analysis, we identified the calcium pump Atp2b4 and doublecortin (Dcx) as miR‐129‐5p targets. Restoring Atp2b4 and Dcx expression was sufficient to prevent synaptic downscaling in PTX‐treated neurons. Furthermore, we characterized a functional crosstalk between miR‐129‐5p and the RNA‐binding protein (RBP) Rbfox1. In the absence of PTX, Rbfox1 promoted the expression of Atp2b4 and Dcx. Upon PTX treatment, Rbfox1 expression was downregulated by miR‐129‐5p, thereby allowing the repression of Atp2b4 and Dcx. We therefore identified a novel activity‐dependent miRNA/RBP crosstalk during synaptic scaling, with potential implications for neural network homeostasis and epileptogenesis.
Synopsis
A systematic approach using small RNA and mRNA profiling in combination with proteomics is used to delineate post‐transcriptional regulatory pathways involved in synaptic scaling. This led to the identification of a pathway consisting of the miRNA miR‐129‐5p and the RNA‐binding protein Rbfox that controls excitatory synapse function in neurons and epileptic seizure activity in the brain.
8 microRNAs, including miR‐129‐5p, are upregulated during homeostatic synaptic downscaling in hippocampal neurons.
miR‐129‐5p inhibition blocks synaptic downscaling in vitro and kainic acid‐induced epileptic seizures in vivo.
A combination of transcriptomics, proteomics and bioinformatics was used to identify miR‐129‐5p target mRNAs, including Atp2b4, Dcx and Rbfox1/3.
Activity‐dependent downregulation of Rbfox1 by miR‐129‐5p is required for the repression of synaptic genes during homeostatic synaptic downscaling.
Combining miRNA and mRNA profiling with proteomics reveals roles for miR‐129‐5p and the RNA‐binding protein Rbfox in excitatory synapse function and epileptic seizure.
Summary
Purpose: Methylmalonic acidemias are inherited metabolic disorders characterized by methylmalonate (MMA) accumulation and neurologic dysfunction, including seizures. It is known that ...metabolic crises in affected patients are precipitated by infections. Although growing evidence supports that inflammation facilitates seizures, it is not known whether inflammatory mediators facilitate MMA‐induced seizures. Therefore, in this study we investigate the involvement of cyclooxygenase‐2 (COX‐2) and prostaglandin E2 (PGE2) in MMA‐induced seizures.
Methods: Adult male Wistar rats were implanted with electrodes over the parietal cortex for electroencephalography (EEG) recording and a cannula in the right lateral ventricle. Animals were injected with PGE2 (100 ng/2 μl, i.c.v.) or phosphate‐buffered saline (PBS) (2 μl, i.c.v.), 15 min before MMA (2.5 μmol/2.5 μl, i.c.v.) or NaCl (2.5 μmol/2.5 μl, i.c.v.). The anticonvulsant effect of celecoxib (0.2; 2 or 20 mg/kg, p.o., 60 min before MMA) on MMA‐induced seizures, and whether PGE2 (10 or 100 ng/2 μl, i.c.v.) prevented the anticonvulsant effect of celecoxib (2 mg/kg, p.o.) were also investigated.
Key Findings: PGE2 decreased the latency to MMA‐induced jerks and generalized seizures, and increased the amplitude of generalized seizure EEG recordings. The selective COX‐2 inhibitor celecoxib at the dose 2 mg/kg, but not at the dose 20 mg/kg, completely prevented MMA‐induced seizures. The protective effect of celecoxib (2 mg/kg) against MMA‐induced seizures was prevented by PGE2.
Significance: These results support a role for PGE2 in the seizures elicited by MMA, which is in agreement with the view that infections may precipitate and exacerbate neurologic dysfunction in patients with MMA acidemic.
Immune System and Chronic Diseases 2018 Bagatini, Margarete Dulce; Cardoso, Andréia Machado; Reschke, Cristina Ruedell ...
Journal of Immunology Research,
01/2018, Volume:
2018
Journal Article
Peer reviewed
Open access
Immunological research involving cancer, rheumatoid arthritis, inflammatory bowel disease, asthma, multiple sclerosis diabetes, heart diseases, and others has not only enabled the understanding of ...the mechanisms that underlie these diseases but also suggested new therapies that may impact positively on patients minimizing morbidity and mortality. ...after PSE, an increase in counts for platelets, neutrophils, lymphocytes, and monocytes was verified. ...PLA triggered apoptosis in NCI-H292 cells and altered the signaling pathways ERK1/2 and Bcl2/Bax.
Evidences show that purinergic signaling is involved in processes associated with health and disease, including noncommunicable, neurological, and degenerative diseases. These diseases strike from ...children to elderly and are generally characterized by progressive deterioration of cells, eventually leading to tissue or organ degeneration. These pathological conditions can be associated with disturbance in the signaling mediated by nucleotides and nucleosides of adenine, in expression or activity of extracellular ectonucleotidases and in activation of P2X and P2Y receptors. Among the best known of these diseases are atherosclerosis, hypertension, cancer, epilepsy, Alzheimer’s disease (AD), Parkinson’s disease (PD), and multiple sclerosis (MS). The currently available treatments present limited effectiveness and are mostly palliative. This review aims to present the role of purinergic signaling highlighting the ectonucleotidases E-NTPDase, E-NPP, E-5′-nucleotidase, and adenosine deaminase in noncommunicable, neurological, and degenerative diseases associated with the cardiovascular and central nervous systems and cancer. In conclusion, changes in the activity of ectonucleotidases were verified in all reviewed diseases. Although the role of ectonucleotidases still remains to be further investigated, evidences reviewed here can contribute to a better understanding of the molecular mechanisms of highly complex diseases, which majorly impact on patients’ quality of life.
Aluminum (Al) is ubiquitously present in the environment and known to be a neurotoxin for humans. The trivalent free Al anion (Al3+) can cross the blood-brain barrier (BBB), accumulate in the brain, ...and elicit harmful effects to the central nervous system (CNS) cells. Thus, evidence has suggested that Al increases the risk of developing neurodegenerative diseases, particularly Alzheimer’s disease (AD). Purinergic signaling has been shown to play a role in several neurological conditions as it can modulate the functioning of several cell types, such as microglial cells, the main resident immune cells of the CNS. However, Al effects on microglial cells and the role of the purinergic system remain elusive. Based on this background, this study is aimed at assessing the modulation of Al on purinergic system parameters of microglial cells. An in vitro study was performed using brain microglial cells exposed to Al chloride (AlCl3) and lipopolysaccharide (LPS) for 96 h. The uptake of Al, metabolism of nucleotides (ATP, ADP, and AMP) and nucleoside (adenosine), and the gene expression and protein density of purinoceptors were investigated. The results showed that both Al and LPS increased the breakdown of adenosine, whereas they decreased nucleotide hydrolysis. Furthermore, the findings revealed that both Al and LPS triggered an increase in gene expression and protein density of P2X7R and A2AR receptors, whereas reduced the A1R receptor expression and density. Taken together, the results showed that Al and LPS altered the setup of the purinergic system of microglial cells. Thus, this study provides new insights into the involvement of the purinergic system in the mechanisms underlying Al toxicity in microglial cells.
Summary
Purpose:
Methylmalonic acidemias are inherited metabolic disorders characterized by methylmalonate (MMA) accumulation and neurologic dysfunction, including seizures. It is known that ...metabolic crises in affected patients are precipitated by infections. Although growing evidence supports that inflammation facilitates seizures, it is not known whether inflammatory mediators facilitate MMA‐induced seizures. Therefore, in this study we investigate the involvement of cyclooxygenase‐2 (COX‐2) and prostaglandin E
2
(PGE
2
) in MMA‐induced seizures.
Methods:
Adult male Wistar rats were implanted with electrodes over the parietal cortex for electroencephalography (EEG) recording and a cannula in the right lateral ventricle. Animals were injected with PGE
2
(100 ng/2 μl, i.c.v.) or phosphate‐buffered saline (PBS) (2 μl, i.c.v.), 15 min before MMA (2.5 μmol/2.5 μl, i.c.v.) or NaCl (2.5 μmol/2.5 μl, i.c.v.). The anticonvulsant effect of celecoxib (0.2; 2 or 20 mg/kg, p.o., 60 min before MMA) on MMA‐induced seizures, and whether PGE
2
(10 or 100 ng/2 μl, i.c.v.) prevented the anticonvulsant effect of celecoxib (2 mg/kg, p.o.) were also investigated.
Key Findings:
PGE
2
decreased the latency to MMA‐induced jerks and generalized seizures, and increased the amplitude of generalized seizure EEG recordings. The selective COX‐2 inhibitor celecoxib at the dose 2 mg/kg, but not at the dose 20 mg/kg, completely prevented MMA‐induced seizures. The protective effect of celecoxib (2 mg/kg) against MMA‐induced seizures was prevented by PGE
2
.
Significance:
These results support a role for PGE
2
in the seizures elicited by MMA, which is in agreement with the view that infections may precipitate and exacerbate neurologic dysfunction in patients with MMA acidemic.
Summary Methylmalonic acidemias are inherited metabolic disorders characterized by methylmalonate (MMA) accumulation and neurological dysfunction, including seizures. Dietary fatty acids are known as ...an important energy source and reduce seizure activity in selected acute animal models. This study investigated whether chronic treatment with fish oil or with oleic acid attenuates MMA-induced seizures and whether maintenance of Na+ ,K+ -ATPase activity was involved in such an effect. Adult male Wistar rats were given fish oil (85 mg/kg), oleic acid (85 mg/kg) or vehicle (0.42% aqueous Cremophor EL™, 4 mL/kg/body weight/day), p.o., for 75 days. On the 73th day a cannula was implanted in the right lateral ventricle with electrodes over the parietal cortex for EEG recording. On the 76th day the animals were injected with NaCl (2.5 μmol/2.5 μL, i.c.v.), or with MMA (2.5 μmol/2.5 μL, i.c.v.), and seizure activity was measured by electroencephagraphic (EEG) recording with concomitant behavior monitoring. The effect of prostaglandin E2 (PGE2 ) on Na+ ,K+ -ATPase activity of slices of cerebral cortex from NaCl-injected animals was determined. Fish oil increased the latency to MMA-induced tonic-clonic seizures, reduced the mean amplitude of ictal EEG recordings, and prevented PGE2 -induced decrease of Na+ ,K+ -ATPase activity in cortical slices in vitro . Oleic acid decreased mean amplitude of ictal EEG recordings. The results support that fish oil decreases MMA-induced seizures. The decreased sensitivity of Na+ ,K+ -ATPase to the inhibitory effect of PGE2 in fish oil-treated animals may be related to the currently reported anticonvulsant activity.
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Epilepsy is one of the most common neurologic disorders. It has been suggested that
seizures may be facilitaded by inflammation. PGE2 is ...one of the most important inflammatory
mediators, and facilitates pentylenetetrazol (PTZ)-induced seizures by stimulating EP1 and
EP3 receptors. However, up to the present moment, no study has investigated whether EP1
and EP3 receptors blocking attenuate seizures induced by convulsants other than PTZ. It is
also unknown whether Na+,K+-ATPase activity alterations are involved in such an effect.
Therefore, in the current study we investigated whether EP1 and EP3 ligands (agonists and
antagonists) modulate PTZ- and kainic acid (KA)-induced seizures, and whether alterations
in Na+,K+-ATPase activity mediate such a protective effect, in mice. EP1 and EP3
antagonists (ONO-8713 and ONO-AE3-240, respectively, 10 Og/kg, s.c.) attenuated PTZ (60
mg/kg, i.p.)- and KA (20 mg/kg, i.p.)-induced seizures. The respective agonists (ONO-DI-004
and ONO-AE-248, 10 Og/kg, s.c.) facilitated seizures in both acute models, and at noneffective
doses, prevented the protective effects of the antagonists. Animals injected with
PTZ presented decreased Na+,K+-ATPase activity in the cerebral cortex and hippocampus.
On the other hand, animals injected with KA presented increased Na+,K+-ATPase activity in
the same cerebral structures at the end of the experiment. These divergent findings suggest
that alterations in Na+,K+-ATPase activity in both acute models depends on the convulsant
agent used and make difficult to establish a relationship between Na+,K+-ATPase activity and
seizure development. Moreover, EP1 and EP3 antagonists administration abolished Na+,K+-
ATPase activity alterations induced by PTZ and KA, in such a way that these alterations
seem to be related more to the presence of ictal phenomenon itself than to the seizure
induction mechanisms. Notwithstanding, the currrent results clearly show that EP1 and EP3
receptors might constitute novel targets for anticonvulsants development, since EP1 and
EP3 decreased seizures, regardless of the convulsant agent used.
A epilepsia é uma das disfunções neurológicas mais comuns. Tem sido sugerido que as
crises epilépticas podem ser facilitadas pela ocorrência de inflamação. A PGE2 é um dos
mediadores inflamatórios mais importantes que, agindo por meio dos receptores EP1 e EP3,
facilita as convulsões induzidas por pentilenotetrazol (PTZ). Contudo, até a presente data,
nenhum estudo investigou, de maneira sistêmica, se a ativação ou bloqueio de receptores
EP1 e EP3 facilitam as convulsões induzidas por outros agentes; tampouco se alterações na
atividade da Na+,K+-ATPase estão envolvidas nesse efeito. Assim, no presente estudo,
investigamos se ligantes (agonistas e antagonistas) de receptores EP1 e EP3 modificam as
crises induzidas por PTZ e ácido caínico (KA), e se tais efeitos estão associados a
alterações na atividade da enzima Na+,K+-ATPase, em camundongos. Os antagonistas EP1
e EP3 (ONO-8713 e ONO-AE3-240, respectivamente, 10 Og/Kg, s.c.) atenuaram as
convulsões induzidas por PTZ (60 mg/Kg, i.p.) e KA (20 mg/Kg). Os seus respectivos
agonistas (ONO-DI-004 e ONO-AE-248 de 10 Og/Kg, s.c.) facilitaram as convulsões em
ambos modelos agudos de crises epilépticas e, em doses não efetivas para gerar crises,
preveniram os efeitos dos antagonistas. Os animais submetidos à administração de PTZ
apresentaram, ao final do experimento, a atividade Na+,K+-ATPásica diminuída no córtex
cerebral e hipocampo. Por outro lado, animais tratados com KA apresentaram um aumento
na atividade Na+,K+-ATPásica nestas mesmas estruturas, que se correlacionou
positivamente com a vigência de status epilepticus no momento do sacrifício. Os achados
divergentes no que diz respeito à alteração da atividade da Na+,K+-ATPase nos dois
modelos de crises agudas sugere que tais alterações estejam relacionadas ao tipo de
agente convulsivante utilizado, e dificultam estabelecer, de forma inequívoca, uma relação
entre atividade desta ATPase e sensibilidade à crises agudas. Ademais, a administração de
antagonistas EP1 e EP3 aboliu as alterações da atividade da Na+,K+-ATPase induzidas tanto
por PTZ como por KA, de tal forma que estas parecem estar mais associadas com o
fenômeno ictal em si, do que com os mecanismos de indução da crise. Contudo, os
resultados mostram de forma clara que os receptores EP1 e EP3 podem se constituir
possíveis novos alvos para o desenvolvimento de drogas antiepilépticas, pois antagonistas
EP1 e EP3 diminuíram as crises, independente do agente convulsivante utilizado.
Methylmalonic acidemias are inherited metabolic disorders characterized by methylmalonate (MMA) accumulation and neurologic dysfunction, including seizures. It is known that metabolic crises in ...affected patients are precipitated by infections. Although growing evidence supports that inflammation facilitates seizures, it is not known whether inflammatory mediators facilitate MMA-induced seizures. Therefore, in this study we investigate the involvement of cyclooxygenase-2 (COX-2) and prostaglandin E(2) (PGE(2)) in MMA-induced seizures.
Adult male Wistar rats were implanted with electrodes over the parietal cortex for electroencephalography (EEG) recording and a cannula in the right lateral ventricle. Animals were injected with PGE(2) (100 ng/2 μl, i.c.v.) or phosphate-buffered saline (PBS) (2 μl, i.c.v.), 15 min before MMA (2.5 μmol/2.5 μl, i.c.v.) or NaCl (2.5 μmol/2.5 μl, i.c.v.). The anticonvulsant effect of celecoxib (0.2; 2 or 20 mg/kg, p.o., 60 min before MMA) on MMA-induced seizures, and whether PGE(2) (10 or 100 ng/2 μl, i.c.v.) prevented the anticonvulsant effect of celecoxib (2 mg/kg, p.o.) were also investigated.
PGE(2) decreased the latency to MMA-induced jerks and generalized seizures, and increased the amplitude of generalized seizure EEG recordings. The selective COX-2 inhibitor celecoxib at the dose 2 mg/kg, but not at the dose 20 mg/kg, completely prevented MMA-induced seizures. The protective effect of celecoxib (2 mg/kg) against MMA-induced seizures was prevented by PGE(2).
These results support a role for PGE(2) in the seizures elicited by MMA, which is in agreement with the view that infections may precipitate and exacerbate neurologic dysfunction in patients with MMA acidemic.
Conselho Nacional de Desenvolvimento Científico e Tecnológico
Methylmalonic acidemias are inherited metabolic disorders characterized by methylmalonate (MMA) accumulation and neurological ...dysfunction, including seizures. Dietary fatty acids are known as an important energy source and reduce seizure activity in selected acute animal models. This study investigates whether the chronic treatment with;
fish oil or with oleic acid attenuates MMA-induced seizures. Adult male Wistar rats were treated with fish oil (85 mg/kg), oleic acid (85 mg/kg) or vehicle (0.42 % aqueous Cremophor EL , 4 mL/kg/body weight/day), p.o., for 75 days. In the 73th day were implanted a cannula;
in the right lateral ventricle with electrodes over the parietal cortex for EEG recording. In the 76th day half the animals from each group were injected with NaCl (2.5 μmol/2.5 μL, i.c.v.), and the other half with MMA (2.5 μmol/2.5 μL, i.c.v.), and seizure activity was measured by;
EEG recording with concomitant behavior monitoring. The effect of prostaglandin E2 (PGE2) on Na+,K+-ATPase activity of slices of cerebral cortex from NaCl-injected (control) animals was determined. Fish oil administration increased the latency for MMA-induced tonic-clonic;
seizures and reduced the mean amplitude of ictal EEG recordings. Oleic acid decreased mean amplitude of ictal EEG recordings. Treatment with fish oil prevented PGE2-induced decrease of Na+,K+-ATPase activity in cortical slices in vitro. The results support a major anticonvulsant role for fish oil against MMA-induced seizures. The decreased sensitivity of Na+,K+-ATPase from fish oil-treated animals to the inhibitory effect of PGE2 may be related to its currently reported anticonvulsant activity.
A acidemia metilmalônica é um erro inato do metabolismo caracterizado pelo acúmulo tecidual de ácido metilmalônico (MMA) e disfunção neurológica, incluindo convulsões. Os ácidos graxos dietéticos são conhecidos como fonte de energia e reduzem a atividade convulsivante em determinados modelos experimentais agudos de convulsão. Este;
estudo investiga se o tratamento crônico com óleo de peixe ou com ácido oléico atenua as convulsões induzidas por MMA. Ratos Wistar machos adultos foram tratados com óleo de;
peixe (85 mg / kg), ácido oléico (85 mg / kg) ou veículo (solução aquosa de Cremophor EL® 0,42%, 4 mL / kg de peso corporal / dia), via oral, por 75 dias. No 73º dia foi implantada uma cânula no ventrículo lateral direito e dois eletrodos sobre o córtex parietal para o registro eletroencefalográfico. No 76º dia metade dos animais de cada grupo foi injetada com NaCl;
(2,5 Smol / 2,5 SL, i.c.v.), e outra metade com MMA (2,5 Smol / 2,5 SL, i.c.v.), e a atividade convulsiva foi medida por EEG e monitoramento comportamental concomitantemente. O;
efeito da prostaglandina E2 (PGE2) na atividade Na+, K+-ATPase foi determinada em fatias de córtex cerebral dos animais injetados com NaCl (controle). A administração de óleo de peixe aumentou a latência para as convulsões tônico-clônicas induzidas por MMA e reduziu a amplitude média dos registros ictais de EEG. O ácido oléico diminuiu a amplitude média dos registros ictais de EEG. O tratamento com óleo de peixe preveniu a diminuição da atividade da Na+, K+-ATPase induzida por PGE2 em fatias corticais in vitro. Os resultados;
suportam um papel importante anticonvulsivante do óleo de peixe sobre as convulsões induzidas por MMA. A prevenção da redução da Na+, K+-ATPase induzida por PGE2 nos;
animais tratados com óleo de peixe pode estar relacionada à sua atividade anticonvulsivante atualmente relatada.
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