Mitochondrial brain proteome acetylation levels and behavioural responsiveness to amphetamine are altered in mice lacking Sirt3.

Post-translational modification of mitochondrial proteins represents one mechanism by which the functional activity of mitochondria can be regulated. In the brain, these modifications can influence the functional properties of different neural circuitries. Given that the sirtuin family member Sirt3 represents the primary protein deacetylase enzyme in mitochondria, we tested whether brain mitochondrial proteome acetylation would increase in male or female mice lacking Sirt3. Our results confirm that whole brain mitochondrial proteome acetylation levels are indeed elevated in both sexes of Sirt3-KO mice relative to controls. Consistently, we found the mitochondria of mouse embryonic fibroblast (MEF) cells derived from Sirt3-KO mice were smaller in size, and fewer in number than in wild-type MEFs, and that mitochondrial free calcium levels were elevated within the mitochondria of these cells. As protein acetylation can influence mitochondrial function, and changes in mitochondrial function have been linked to alterations in neural circuit function regulating motor activity and anxiety-like behavior, we tested whether Sirt3-deficient mice would display sensitized responsiveness to the stimulant amphetamine. Both male and female Sirt3-KO mice displayed hyper-locomotion and attenuated anxiety-like behavior in response to a dose of amphetamine that was insufficient to promote any behavioural responses in wild-type mice. Collectively, these results confirm that Sirt3 regulates mitochondrial proteome acetylation levels in brain tissue, and that the absence of Sirt3 increases the sensitivity of neural systems to amphetamine-induced behavioural responses.

Antiseizure effects of the cannabinoids in the amygdala-kindling model.

OBJECTIVE: Focal impaired awareness seizures (FIASs) are the most common seizure type in adults and are often refractory to medication. Management of FIASs is clinically challenging, and new interventions are needed for better seizure control. The amygdala-kindling model is a preclinical model of FIASs with secondary generalization. The present study assessed the efficacy of cannabidiol (CBD), ∆9-tetrahydrocannabinol (THC), and a combination of CBD and THC in a 15:1 ratio at suppressing focal and secondarily generalized seizures in the amygdala-kindled rat. METHODS: Fully kindled, male Sprague Dawley rats, with bipolar electrodes implanted in the right amygdala, were given either CBD (0-320 mg/kg), THC (0-40 mg/kg), or a combination of CBD and THC (15:1 ratio, multiple doses) intraperitoneally. Suprathreshold kindling stimulation was administered 1 h (THC) or 2 h (CBD) after drug injection, and outcomes were assessed using focal electroencephalographic recording and the Racine seizure scale. RESULTS: CBD alone produced a partial suppression of both generalized seizures (median effective dose [ED50 ] = 283 mg/kg) and focal seizures (ED40 = 320 mg/kg) at doses that did not produce ataxia. THC alone also produced partial suppression of generalized (ED50 = 10 mg/kg) and focal (ED50 = 30 mg/kg) seizures, but doses of 10 mg/kg and above produced hypolocomotion, although not ataxia. The addition of a low dose of THC to CBD (15:1) left-shifted the CBD dose-response curve, producing much lower ED50 s for both generalized (ED50 = 26 + 1.73 mg/kg) and focal (ED50 = 40 + 2.66 mg/kg) seizures. No ataxia or hypolocomotion was seen at these doses of the CBD + THC combination. SIGNIFICANCE: CBD and THC both have antiseizure properties in the amygdala-kindling model, although THC produces suppression of the amygdala focus only at doses that produce hypolocomotion. The addition of small amounts of THC greatly improves the effectiveness of CBD. A combination of CBD and THC might be useful for the management of FIASs.

Seizures in Mouse Models of Rare Neurodevelopmental Disorders.

Genetic neurodevelopmental disorders - that often include epilepsy as part of their phenotype - are a heterogeneous and clinically challenging spectrum of disorders in children. Although seizures often contribute significantly to morbidity in these affected populations, the mechanisms of epileptogenesis in these conditions remain poorly understood. Different model systems have been developed to aid in unraveling these mechanisms, which include a number of specific mutant mouse lines which genocopy specific general types of mutations present in patients. These mouse models have not only allowed for assessments of behavioral and electrographic seizure phenotypes to be ascertained, but also have allowed effects on the neurodevelopmental alterations and cognitive impairments associated with these disorders to be examined. In addition, these models play a role in advancing our understanding of these epileptic processes and developing preclinical therapeutics. The concordance of seizure phenotypes - in a select group of rare, genetic, neurodevelopmental disorders and epileptic encephalopathies - found between human patients and their model counterparts will be summarized. This review aims to assess whether models of Rett syndrome, CDKL5 deficiency disorder, Fragile-X syndrome, Dravet syndrome, and Ohtahara syndrome phenocopy the seizures seen in human patients.

Impaired Regulation of Histone Methylation and Acetylation Underlies Specific Neurodevelopmental Disorders.

Epigenetic processes are critical for governing the complex spatiotemporal patterns of gene expression in neurodevelopment. One such mechanism is the dynamic network of post-translational histone modifications that facilitate recruitment of transcription factors or even directly alter chromatin structure to modulate gene expression. This is a tightly regulated system, and mutations affecting the function of a single histone-modifying enzyme can shift the normal epigenetic balance and cause detrimental developmental consequences. In this review, we will examine select neurodevelopmental conditions that arise from mutations in genes encoding enzymes that regulate histone methylation and acetylation. The methylation-related conditions discussed include Wiedemann-Steiner, Kabuki, and Sotos syndromes, and the acetylation-related conditions include Rubinstein-Taybi, KAT6A, genitopatellar/Say-Barber-Biesecker-Young-Simpson, and brachydactyly mental retardation syndromes. In particular, we will discuss the clinical/phenotypic and genetic basis of these conditions and the model systems that have been developed to better elucidate cellular and systemic pathological mechanisms.

Interpreting the Tests of Focal Cortical Dysplasia for Epilepsy Surgery Referral.

OBJECTIVE: Focal cortical dysplasia (FCD) is a common cause of refractory, focal onset epilepsy in children. Interictal, scalp electroencephalograph (EEG) markers have been associated with these pathologies and epilepsy surgery may be an option for some patients. We aim to study how scalp EEG and magnetic resonance imaging (MRI) markers of FCD affect referral of these patients for surgical evaluation. METHODS: A single-center, retrospective review of children with focal onset epilepsy. Patients were included if they were between 1 month and 18 years of age, had focal onset seizures, prolonged scalp EEG monitoring, and an MRI conducted after 2 years of age. Statistics were carried out using the chi-squared and student's t-test, as well as a logistic regression model. RESULTS: Sixty-eight patients were included in the study. Thirty-seven of these patients were referred to a comprehensive pediatric epilepsy program (CPEP) for surgical evaluation, and of these 22% showed FCD EEG markers, 32% FCD MRI markers, and 10% had both. These markers were also present in patients not referred to a CPEP. The MRI markers were significantly associated with CPEP referral, whereas EEG markers were not. Neither marker type was associated with epilepsy surgery. CONCLUSION: This study found that children with focal onset epilepsy were more likely to be referred for surgical evaluation if they were medically refractory, or were diagnosed with FCD or tumor on MRI. Scalp EEG markers of FCD were not associated with CPEP referral. The online tool CASES may be a useful physician guide for identifying appropriate children for epilepsy surgery referral.

Interpréter les tests de détection de la dysplasie corticale focale en vue d'une évaluation préopératoire du traitement de l'épilepsie.Objectif: La dysplasie corticale focale (DCF) constitue une des causes communes des crises convulsives partielles réfractaires chez l'enfant. À la suite d'EEG effectués au niveau du cuir chevelu, des marqueurs de l'activité épileptique interictale ont été associés avec ce trouble pour lequel une intervention chirurgicale peut constituer, dans le cas de certains patients, une option. Nous voulons nous pencher sur la façon dont ces marqueurs et les marqueurs utilisés lors d'examens d'IRM pour la DCF peuvent affecter l'aiguillage de ces patients en vue d'une évaluation préopératoire. Méthodes: Dans un seul établissement hospitalier, nous avons effectué une analyse rétrospective de cas d'enfants chez qui sont apparues des crises convulsives partielles. Pour être inclus, les patients devaient être âgés de 1 mois à 18 ans, avoir été victimes de telles crises convulsives, avoir bénéficié de surveillance prolongée par EEG et avoir subi un examen d'IRM après l'âge de deux ans. Nous avons enfin effectué une analyse statistique à l'aide d'un modèle de régression logistique et des tests du X2 et de Student. Résultats: Au total, nous avons inclus soixante-huit patients dans cette étude. Trente-sept d'entre eux ont été redirigés vers un programme pédiatrique complet de traitement de l'épilepsie (comprehensive pediatric epilepsy program) en vue d'une évaluation préopératoire. Sur ces trente-sept patients, on a observé chez 22 % d'entre eux les marqueurs électroencéphalographiques associés à la DCF ; ce pourcentage atteignait 32 % dans le cas des marqueurs de la DCF utilisés en imagerie ; enfin, on a pu détecter ces deux types de marqueurs chez 10 % de ces trente-sept patients. Fait à souligner, ces marqueurs étaient aussi présents chez des patients n'ayant pas été orientés vers le type de programme cité ci-dessus. En outre, les marqueurs utilisés en imagerie se sont avérés étroitement associés au fait d'orienter des patients vers ce programme tandis que les marqueurs électroencéphalographiques ne l'étaient pas. Finalement, aucun de ces types de marqueurs n'a pu être associé à une intervention chirurgicale visant à traiter l'épilepsie. Conclusion: Cette étude a donc permis de constater que les enfants atteints de crises convulsives partielles étaient plus susceptibles d'être orientés en vue d'une évaluation préopératoire si leur trouble était de nature réfractaire ou s'ils avaient reçu un diagnostic de DCF ou de tumeur cancéreuse à la suite d'un examend'IRM. Les marqueurs électroencéphalographiques de la DCF n'ont pas été associés à un aiguillage vers un programme pédiatrique complet de traitement de l'épilepsie. Il se pourrait à cet égard que l'outil en ligne CASES soit un guide utile pour les médecins souhaitant identifier les enfants convenant à un aiguillage en vue d'un traitement chirurgical de l'épilepsie.

Atypical Antipsychotics for Irritability in Pediatric Autism: A Systematic Review and Network Meta-Analysis.

OBJECTIVE: Irritability is common in pediatric autism spectrum disorder (ASD) patients. This can have major implications in child development, receptivity to behavioral therapy, as well as child and caregiver well-being. A systematic review and network meta-analysis were conducted to assess the efficacy and safety of atypical antipsychotics in treating irritability in these patients. METHODS: Studies were identified from Medline, Embase, and PsycINFO from inception to March 2018. The clinical trials database was reviewed. Studies were included if they were a double-blind, randomized controlled trial utilizing the Aberrant Behavior Checklist Irritability (ABC-I) to measure the efficacy of atypical antipsychotic monotherapy. Data extraction was carried out following the Preferred Reporting Items for Systematic Reviews and Meta-analyses for network meta-analysis guidelines. The main outcome was the reduction in irritability score using the ABC-I subscale from baseline. RESULTS: Eight trials comparing four interventions-risperidone, aripiprazole, lurasidone, and placebo in 878 patients, were included. Both risperidone and aripiprazole had significantly reduced ABC-I scores than placebo. Estimates of mean differences (95% credible intervals) were risperidone, -6.89 (-11.14, -2.54); aripiprazole, -6.62 (-10.88, -2.22); and lurasidone, -1.61 (-9.50, 6.23). Both risperidone and aripiprazole had similar safety. There were only eight studies included in the analysis, however, sample sizes were not small. Variance in reporting of adverse effects limited the quality of safety analysis. CONCLUSION: Risperidone and aripiprazole were the two best drugs, with comparable efficacy and safety in pediatric ASD patients. These two medications could be beneficial in improving irritability in these patients.