RESUMEN
Cannabidiol (CBD) is a major phytocannabinoid in Cannabis sativa. CBD is being increasingly reported as a clinical treatment for neurological diseases. Febrile seizure is one of the most common diseases in children with limited therapeutic options. We investigated possible therapeutic effects of CBD on febrile seizures and the underlying mechanism. Use of a hyperthermia-induced seizures model revealed that CBD significantly prolonged seizure latency and reduced the severity of thermally-induced seizures. Hippocampal neuronal excitability was significantly decreased by CBD. Further, CBD significantly reduced the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) mediated evoked excitatory postsynaptic currents (eEPSCs) and the amplitude and frequency of miniature EPSCs (mEPSCs). Furthermore, CBD significantly accelerated deactivation in GluA1 and GluA2 subunits. Interestingly, CBD slowed receptor recovery from desensitization of GluA1, but not GluA2. These effects on kinetics were even more prominent when AMPAR was co-expressed with γ-8, the high expression isoform 8 of transmembrane AMPAR regulated protein (TARPγ8) in the hippocampus. The inhibitory effects of CBD on AMPAR depended on its interaction with the distal N-terminal domain of GluA1/GluA2. CBD inhibited AMPAR activity and reduced hippocampal neuronal excitability, thereby improving the symptoms of febrile seizure in mice. The putative binding site of CBD in the N-terminal domain of GluA1/GluA2 may be a drug target for allosteric gating modulation of AMPAR.
Asunto(s)
Anticonvulsivantes/farmacología , Ondas Encefálicas/efectos de los fármacos , Región CA1 Hipocampal/efectos de los fármacos , Cannabidiol/farmacología , Antagonistas de Aminoácidos Excitadores/farmacología , Hipertermia/complicaciones , Receptores AMPA/antagonistas & inhibidores , Convulsiones Febriles/prevención & control , Animales , Anticonvulsivantes/metabolismo , Región CA1 Hipocampal/metabolismo , Región CA1 Hipocampal/fisiopatología , Cannabidiol/metabolismo , Modelos Animales de Enfermedad , Antagonistas de Aminoácidos Excitadores/metabolismo , Potenciales Postsinápticos Excitadores/efectos de los fármacos , Células HEK293 , Humanos , Activación del Canal Iónico/efectos de los fármacos , Cinética , Ratones , Ratones Endogámicos C57BL , Potenciales Postsinápticos Miniatura/efectos de los fármacos , Modelos Moleculares , Unión Proteica , Tiempo de Reacción/efectos de los fármacos , Receptores AMPA/genética , Receptores AMPA/metabolismo , Convulsiones Febriles/etiología , Convulsiones Febriles/metabolismo , Convulsiones Febriles/fisiopatologíaRESUMEN
The RIIß subunit of cAMP-dependent protein kinase A (PKA) is expressed in the brain and adipose tissue. RIIß-knockout mice show leanness and increased UCP1 in brown adipose tissue. The authors have previously reported that RIIß reexpression in hypothalamic GABAergic neurons rescues the leanness. However, whether white adipose tissue (WAT) browning contributes to the leanness and whether RIIß-PKA in these neurons governs WAT browning are unknown. Here, this work reports that RIIß-KO mice exhibit a robust WAT browning. RIIß reexpression in dorsal median hypothalamic GABAergic neurons (DMH GABAergic neurons) abrogates WAT browning. Single-cell sequencing, transcriptome sequencing, and electrophysiological studies show increased GABAergic activity in DMH GABAergic neurons of RIIß-KO mice. Activation of DMH GABAergic neurons or inhibition of PKA in these neurons elicits WAT browning and thus lowers body weight. These findings reveal that RIIß-PKA in DMH GABAergic neurons regulates WAT browning. Targeting RIIß-PKA in DMH GABAergic neurons may offer a clinically useful way to promote WAT browning for treating obesity and other metabolic disorders.
Asunto(s)
Tejido Adiposo Pardo , Subunidad RIIbeta de la Proteína Quinasa Dependiente de AMP Cíclico , Hipotálamo , Animales , Ratones , Tejido Adiposo Pardo/metabolismo , Subunidad RIIbeta de la Proteína Quinasa Dependiente de AMP Cíclico/metabolismo , Proteínas Quinasas Dependientes de AMP Cíclico/metabolismo , Neuronas GABAérgicas/metabolismo , Hipotálamo/metabolismo , Obesidad/metabolismo , Delgadez/metabolismoRESUMEN
ETHNOPHARMACOLOGICAL RELEVANCE: Febrile seizure is a common neurologic disorder with limited treatment occurring in infants and children under the age of five. Jujuboside B (JuB) is a main bioactive saponin component isolated from the Chinese anti-insomnia herbal medicine Ziziphi Spinosae Semen (ZSS), seed of Ziziphus jujuba Mill, which has been proved to exhibit neuroprotective effects recently. AIM OF THE STUDY: In this study, we aimed at elucidating the effect of JuB on suppressing febrile seizure and the potential mechanisms. METHODS: Electroencephalogram (EEG) recording was used to monitor the severity of febrile seizures. The JuB in the brain was identified by mass spectrometry. Neuronal excitability was investigated using patch clamp. RESULTS: JuB (30 mg/kg) significantly prolonged seizure latency and reduced the severity in hyperthermia-induced seizures model mice. Hippocampal neuronal excitability was significantly decreased by JuB. And JuB significantly reduced the excitatory synaptic transmission mediated by α-amino-3-hydroxy-5-methyl-4-iso-xazolepropionic acid receptor (AMPAR), including evoked excitatory postsynaptic currents (eEPSCs), and miniature EPSCs (mEPSCs) in hippocampal neurons. Furthermore, JuB also significantly inhibited recombinant GluA1 and GluA2 mediated AMPA current in HEK293 cell and decreased the upregulation of [Ca2+]i induced by AMPA in primary cultured cortex neurons. CONCLUSIONS: JuB suppressed the excitability of hippocampal neurons by inhibiting the activity of AMPAR and reducing the intracellular free calcium, thereby relieving febrile seizures.
Asunto(s)
Saponinas , Convulsiones Febriles , Ratones , Humanos , Animales , Convulsiones Febriles/tratamiento farmacológico , Receptores AMPA , Células HEK293 , Ácido alfa-Amino-3-hidroxi-5-metil-4-isoxazol Propiónico , Saponinas/farmacología , Saponinas/uso terapéuticoRESUMEN
Attention-deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder prevalent in school-age children. At present, however, its etiologies and risk factors are unknown. Transmembrane α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor regulatory protein γ-8 (TARP γ-8, also known as calcium voltage-gated channel auxiliary subunit gamma 8 (CACNG8)) is an auxiliary AMPA receptor (AMPAR) subunit. Here, we report an association between TARP γ-8 and ADHD, whereby adolescent TARP γ-8 knockout (KO) mice exhibited ADHD-like behaviors, including hyperactivity, impulsivity, anxiety, impaired cognition, and memory deficits. Human single-nucleotide polymorphism (SNP) analysis also revealed strong associations between intronic alleles in CACNG8 genes and ADHD susceptibility. In addition, synaptosomal proteomic analysis revealed dysfunction of the AMPA glutamate receptor complex in the hippocampi of TARP γ-8 KO mice. Proteomic analysis also revealed dysregulation of dopaminergic and glutamatergic transmissions in the prefrontal cortices of TARP γ-8 KO mice. Methylphenidate (MPH), which is commonly used to treat ADHD, significantly rescued the major behavioral deficits and abnormal synaptosomal proteins in TARP γ-8 KO mice. Notably, MPH significantly reversed the up-regulation of Grik2 and Slc6a3 in the prefrontal cortex. MPH also significantly improved synaptic AMPAR complex function by up-regulating other AMPAR auxiliary proteins in hippocampal synaptosomes. Taken together, our results suggest that TARP γ-8 is involved in the development of ADHD in humans. This study provides a useful alternative animal model with ADHD-like phenotypes related to TARP γ-8 deficiency, which has great potential for the development of new therapies.
Asunto(s)
Trastorno por Déficit de Atención con Hiperactividad , Canales de Calcio , Animales , Trastorno por Déficit de Atención con Hiperactividad/genética , Canales de Calcio/genética , Humanos , Ratones , Ratones Noqueados , ProteómicaRESUMEN
The two most common aging-related diseases, Alzheimer's disease and type 2 diabetes mellitus, are associated with accumulation of amyloid proteins (ß-amyloid and amylin, respectively). This amylin aggregation is reportedly cytotoxic to neurons. We found that aggregation of human amylin (hAmylin) induced neuronal apoptosis without obvious microglial infiltration in vivo. High concentrations of hAmylin irreversibly aggregated on the surface of the neuronal plasma membrane. Long-term incubation with hAmylin induced morphological changes in neurons. Moreover, hAmylin permeabilized the neuronal membrane within 1 min in a manner similar to Triton X-100, allowing impermeable fluorescent antibodies to enter the neurons and stain intracellular antigens. hAmylin also permeabilized the cell membrane of astrocytes, though more slowly. Under scanning electron microscopy, we observed that hAmylin destroyed the integrity of the cell membranes of both neurons and astrocytes. Additionally, it increased intracellular reactive oxygen species generation and reduced the mitochondrial membrane potential. Thus, by aggregating on the surface of neurons, hAmylin impaired the cell membrane integrity, induced reactive oxygen species production, reduced the mitochondrial membrane potential, and ultimately induced neuronal apoptosis.