Background
Recently, the adenosine triphosphate (ATP) sensitive potassium channel opener levcromakalim was shown to induce migraine attacks with a far higher incidence than any previous provoking ...agent such as calcitonin gene-related peptide. Here, we show efficacy of ATP sensitive potassium channel inhibitors in two validated rodent models of migraine.
Methods
In female spontaneous trigeminal allodynic rats, the sensitivity of the frontal region of the head was tested by an electronic von Frey filament device. In mice, cutaneous hypersensitivity was induced by repeated glyceryl trinitrate or levcromakalim injections over nine days, as measured with von Frey filaments in the hindpaw. Release of calcitonin gene-related peptide from dura mater and trigeminal ganglion was studied ex vivo.
Results
The ATP sensitive potassium channel inhibitor glibenclamide attenuated the spontaneous cephalic hypersensitivity in spontaneous trigeminal allodynic rats and glyceryl trinitrate-induced hypersensitivity of the hindpaw in mice. It also inhibited CGRP release from dura mater and the trigeminal ganglion isolated from spontaneous trigeminal allodynic rats. The hypersensitivity was also diminished by the structurally different ATP sensitive potassium channel inhibitor gliquidone. Mice injected with the ATP sensitive potassium channel opener levcromakalim developed a progressive hypersensitivity that was completely blocked by glibenclamide, confirming target engagement.
Conclusion
The results suggest that ATP sensitive potassium channel inhibitors could be novel and highly effective drugs in the treatment of migraine.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The integral synaptic vesicle (SV) protein synaptophysin forms ∼10% of total SV protein content, but has no known function in SV physiology. Synaptobrevin (sybII) is another abundant integral SV ...protein with an essential role in SV exocytosis. Synaptophysin and sybII form a complex in nerve terminals, suggesting this interaction may have a key role in presynaptic function. To determine how synaptophysin controls sybII traffic in nerve terminals, we used a combination of optical imaging techniques in cultures derived from synaptophysin knock-out mice. We show that synaptophysin is specifically required for the retrieval of the pH-sensitive fluorescent reporter sybII-pHluorin from the plasma membrane during endocytosis. The retrieval of other SV protein cargo reporters still occurred; however, their recapture proceeded with slower kinetics. This slowing of SV retrieval kinetics in the absence of synaptophysin did not impact on global SV turnover. These results identify a specific and selective requirement for synaptophysin in the retrieval of sybII during SV endocytosis and suggest that their interaction may act as an adjustable regulator of SV retrieval efficiency.
Treatment with the dopamine (DA) precursor l‐3,4‐dihydroxyphenylalanine (l‐DOPA) provides symptomatic relief arising from DA denervation in Parkinson's disease. Mounting evidence that DA ...autooxidation to neurotoxic quinones is involved in Parkinson's disease pathogenesis has raised concern about potentiation of oxidative stress by l‐DOPA. The rate of DA quinone formation increases in the presence of excess redox‐active iron (Fe), which is a pathological hallmark of Parkinson's disease. Conversely, l‐DOPA has pH‐dependent Fe‐chelating properties, and may act to ‘redox silence’ Fe and partially allay DA autoxidation. We examined the effects of l‐DOPA in three murine models of parkinsonian neurodegeneration: early‐life Fe overexposure in wild‐type mice, transgenic human (h)A53T mutant α‐synuclein (α‐syn) over‐expression, and a combined ‘multi‐hit’ model of Fe‐overload in hA53T mice. We found that l‐DOPA was neuroprotective and prevented age‐related Fe accumulation in the substantia nigra pars compacta (SNc), similar to the mild‐affinity Fe chelator clioquinol. Chronic l‐DOPA treatment showed no evidence of increased oxidative stress in wild‐type midbrain and normalized motor performance, when excess Fe was present. Similarly, l‐DOPA also did not exacerbate protein oxidation levels in hA53T mice, with or without excess nigral Fe, and showed evidence of neuroprotection. The effects of l‐DOPA in Fe‐fed hA53T mice were somewhat muted, suggesting that Fe‐chelation alone is insufficient to attenuate neuron loss in an animal model also recapitulating altered DA metabolism. In summary, we found no evidence in any of our model systems that l‐DOPA treatment accentuated neurodegeneration, suggesting DA replacement therapy does not contribute to oxidative stress in the Parkinson's disease brain.
l‐DOPA is the most commonly used treatment for alleviating symptoms of Parkinson's disease, though as a precursor to dopamine there are concerns it may in fact increase risk of neurotoxicity by promoting dopamine autooxidation. We used three models of parkinsonism: hA53T over‐expressing transgenic mice, mice exposed to high levels of dietary iron during the neonatal period, and a combined model with both risk factors. We found evidence that the iron‐chelating properties of l‐DOPA mitigate any possible contribution to neuron loss and provide the first in vivo substantiation that l‐DOPA does not contribute to oxidative stress via dopamine auto‐oxidation.
Baker, Gordon et al. present the first international case series describing the neurodevelopmental disorder associated with Synaptotagmin 1 (SYT1) de novo missense mutations. Key features include ...movement abnormalities, severe intellectual disability, and hallmark EEG alterations. Expression of patients' SYT1 mutations in mouse neurons disturbs presynaptic vesicle dynamics in a mutation-specific manner.
Abstract
Synaptotagmin 1 (SYT1) is a critical mediator of fast, synchronous, calcium-dependent neurotransmitter release and also modulates synaptic vesicle endocytosis. This paper describes 11 patients with de novo heterozygous missense mutations in SYT1. All mutations alter highly conserved residues, and cluster in two regions of the SYT1 C2B domain at positions Met303 (M303K), Asp304 (D304G), Asp366 (D366E), Ile368 (I368T) and Asn371 (N371K). Phenotypic features include infantile hypotonia, congenital ophthalmic abnormalities, childhood-onset hyperkinetic movement disorders, motor stereotypies, and developmental delay varying in severity from moderate to profound. Behavioural characteristics include sleep disturbance and episodic agitation. Absence of epileptic seizures and normal orbitofrontal head circumference are important negative features. Structural MRI is unremarkable but EEG disturbance is universal, characterized by intermittent low frequency high amplitude oscillations. The functional impact of these five de novo SYT1 mutations has been assessed by expressing rat SYT1 protein containing the equivalent human variants in wild-type mouse primary hippocampal cultures. All mutant forms of SYT1 were expressed at levels approximately equal to endogenous wild-type protein, and correctly localized to nerve terminals at rest, except for SYT1M303K, which was expressed at a lower level and failed to localize at nerve terminals. Following stimulation, SYT1I368T and SYT1N371K relocalized to nerve terminals at least as efficiently as wild-type SYT1. However, SYT1D304G and SYT1D366E failed to relocalize to nerve terminals following stimulation, indicative of impairments in endocytic retrieval and trafficking of SYT1. In addition, the presence of SYT1 variants at nerve terminals induced a slowing of exocytic rate following sustained action potential stimulation. The extent of disturbance to synaptic vesicle kinetics is mirrored by the severity of the affected individuals' phenotypes, suggesting that the efficiency of SYT1-mediated neurotransmitter release is critical to cognitive development. In summary, de novo dominant SYT1 missense mutations are associated with a recognizable neurodevelopmental syndrome, and further cases can now be diagnosed based on clinical features, electrophysiological signature and mutation characteristics. Variation in phenotype severity may reflect mutation-specific impact on the diverse physiological functions of SYT1.
ABSTRACT
In the western United States, climate warming poses a unique threat to water and snow hydrology because much of the snowpack accumulates at temperatures near 0 °C. As the climate continues ...to warm, much of the region's precipitation is expected to switch from snow to rain, causing flashier hydrographs, earlier inflow to reservoirs, and reduced spring and summer snowpack. This study investigates historical variability in snow to precipitation proportion (Sf) and maps areas in the western United States that have demonstrated higher Sf sensitivity to warming in the past. Projected changes in Sf under 1.1, 1.8, and 3.0 °C future warming scenarios are presented in relation to historical variability and sensitivity. Our findings suggest that Sf in this region has primarily varied based on winter temperature rather than precipitation. The difference in Sf between cold and warm winters at low‐ and mid‐elevations during 1916–2003 ranged from 31% in the Pacific Northwest to 40% in the California Sierra Nevada. In contrast, the difference in Sf between wet and dry winters was statistically not significant. Overall, in the northern Sierra, Klamath, and western slopes of the Cascade Mountains Ranges, Sf was most sensitive to temperature where winter temperature ranged between −5 to 5 °C. Results from our trend analysis show a regional shift in both Sf and signal‐to‐noise ratios during 1960–2003 as compared with 1916–2003. Our findings indicate that natural variability in Sf over 1916–2003 across all regions except for the Great Basin most closely resembles the projected 2040‐warming scenario (+1.8 °C).
Although adolescent mental health interventions are widely implemented, little consensus exists about elements comprising successful models.
We aimed to identify effective program components of ...interventions to promote mental health and prevent mental disorders and risk behaviors during adolescence and to match these components across these key health outcomes to inform future multicomponent intervention development.
A total of 14 600 records were identified, and 158 studies were included.
Studies included universally delivered psychosocial interventions administered to adolescents ages 10 to 19. We included studies published between 2000 and 2018, using PubMed, Medline, PsycINFO, Scopus, Embase, and Applied Social Sciences Index Abstracts databases. We included randomized controlled, cluster randomized controlled, factorial, and crossover trials. Outcomes included positive mental health, depressive and anxious symptomatology, violence perpetration and bullying, and alcohol and other substance use.
Data were extracted by 3 researchers who identified core components and relevant outcomes. Interventions were separated by modality; data were analyzed by using a robust variance estimation meta-analysis model, and we estimated a series of single-predictor meta-regression models using random effects.
Universally delivered interventions can improve adolescent mental health and reduce risk behavior. Of 7 components with consistent signals of effectiveness, 3 had significant effects over multiple outcomes (interpersonal skills, emotional regulation, and alcohol and drug education).
Most included studies were from high-income settings, limiting the applicability of these findings to low- and middle-income countries. Our sample included only trials.
Three program components emerged as consistently effective across different outcomes, providing a basis for developing future multioutcome intervention programs.
Introduction
Rodent disease models can play an indispensable role in drug development. Confirming that translationally-relevant disease mechanisms are engaged in such models is a crucial facet of ...this process. Accordingly, we have validated the role of calcitonin gene-related peptide signaling in a mouse model of glyceryl trinitrate-provoked migraine-like pain and a spontaneous rat model of migraine-like pain by assessing their pharmacological responsiveness to the small molecule calcitonin gene-related peptide receptor antagonist olcegepant, and the humanised monoclonal calcitonin gene-related peptide antibody ALD405.
Methods
Cutaneous sensitivity to hind paw, and periorbital mechanical stimulation were used as surrogate markers of activation of relevant pain pathways in each respective model. Separate experiments were performed to identify the time-course of treatment response to olcegepant (1 mg/kg i.p.) and ALD405 (10 mg/kg i.p.).
Results
Olcegepant and ALD405 significantly alleviated cutaneous mechanical hypersensitivity in both models compared with corresponding control treatments (saline and IgG control antibody respectively). As expected, the duration of anti-nociceptive action obtained with ALD405 was considerably longer than that associated with olcegepant. Surprisingly, in the spontaneous rat model the onset of action of ALD405 occurred within just 4 hours after administration.
Discussion
The current data clearly show that calcitonin gene-related peptide-mediated signaling is critically involved in the manifestation of cutaneous hypersensitivity in distinct rodent models of migraine-like pain and emphasise their translational relevance. Moreover, the unexpected rapidity of onset observed for ALD405 supports i) a probable site of action outside the blood-brain barrier, and ii) a potential clinical utility of specific monoclonal calcitonin gene-related peptide antibodies in the abortive treatment of migraine.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Synaptophysin is an integral synaptic vesicle (SV) protein that accounts for ∼10% of total SV protein cargo. Deletion of synaptophysin results in the defective retrieval of synaptobrevin II (sybII) ...from the plasma membrane during endocytosis, coupled with a slowing in the speed of endocytosis. Synaptophysin has been implicated in X-linked intellectual disability, with a recent study identifying four separate synaptophysin gene mutations in families affected by the disorder. To determine how these mutations may affect synaptophysin function, we expressed them in cultured neurons derived from synaptophysin knock-out mice. Two distinct truncating mutants were mislocalized throughout the axon and phenocopied the arrest of sybII retrieval in synaptophysin knock-out cultures. The remaining two mutants displayed a nerve terminal localization but did not support efficient sybII retrieval. Interestingly, one mutant fully rescued SV endocytosis kinetics, suggesting that sybII retrieval and endocytosis speed are independent from each other. These studies suggest that the efficient retrieval of sybII by synaptophysin may be key to maintaining synaptic health and perturbation of this event may contribute to the pathogenesis underlying neurodevelopmental disorders such as X-linked intellectual disability.
Mutations in RAB18 have been shown to cause the heterogeneous autosomal recessive disorder Warburg Micro syndrome (WARBM). Individuals with WARBM present with a range of clinical symptoms, including ...ocular and neurological abnormalities. However, the underlying cellular and molecular pathogenesis of the disorder remains unclear, largely owing to the lack of any robust animal models that phenocopy both the ocular and neurological features of the disease. We report here the generation and characterisation of a novel Rab18-mutant mouse model of WARBM. Rab18-mutant mice are viable and fertile. They present with congenital nuclear cataracts and atonic pupils, recapitulating the characteristic ocular features that are associated with WARBM. Additionally, Rab18-mutant cells exhibit an increase in lipid droplet size following treatment with oleic acid. Lipid droplet abnormalities are a characteristic feature of cells taken from WARBM individuals, as well as cells taken from individuals with other neurodegenerative conditions. Neurological dysfunction is also apparent in Rab18-mutant mice, including progressive weakness of the hind limbs. We show that the neurological defects are, most likely, not caused by gross perturbations in synaptic vesicle recycling in the central or peripheral nervous system. Rather, loss of Rab18 is associated with widespread disruption of the neuronal cytoskeleton, including abnormal accumulations of neurofilament and microtubule proteins in synaptic terminals, and gross disorganisation of the cytoskeleton in peripheral nerves. Global proteomic profiling of peripheral nerves in Rab18-mutant mice reveals significant alterations in several core molecular pathways that regulate cytoskeletal dynamics in neurons. The apparent similarities between the WARBM phenotype and the phenotype that we describe here indicate that the Rab18-mutant mouse provides an important platform for investigation of the disease pathogenesis and therapeutic interventions.
Single-nucleotide variations in C13orf31 (LACC1) that encode p.C284R and p.I254V in a protein of unknown function (called 'FAMIN' here) are associated with increased risk for systemic juvenile ...idiopathic arthritis, leprosy and Crohn's disease. Here we set out to identify the biological mechanism affected by these coding variations. FAMIN formed a complex with fatty acid synthase (FASN) on peroxisomes and promoted flux through de novo lipogenesis to concomitantly drive high levels of fatty-acid oxidation (FAO) and glycolysis and, consequently, ATP regeneration. FAMIN-dependent FAO controlled inflammasome activation, mitochondrial and NADPH-oxidase-dependent production of reactive oxygen species (ROS), and the bactericidal activity of macrophages. As p.I254V and p.C284R resulted in diminished function and loss of function, respectively, FAMIN determined resilience to endotoxin shock. Thus, we have identified a central regulator of the metabolic function and bioenergetic state of macrophages that is under evolutionary selection and determines the risk of inflammatory and infectious disease.
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