Outward depolarization of the microglia mitochondrial membrane potential following lipopolysaccharide exposure: a novel screening tool for microglia metabolomics.

Microglia are non-electrogenic immune cells that respond rapidly to protect the central nervous system (CNS) from infections, injuries, or other forms of damage. Microglia mitochondria are essential for providing the requisite energy resources for immune regulation. While fluctuations in energy metabolism are regulated by mitochondria and are reflected in the mitochondrial membrane potential (ΔΨm), there remains a lack of innovation in microglia-centric tools that capitalize on this.

Comparative Assessment of TSPO Modulators on Electroencephalogram Activity and Exploratory Behavior.

Network communication in the CNS relies upon multiple neuronal and glial signaling pathways. In addition to synaptic transmission, other organelles such as mitochondria play roles in cellular signaling. One highly conserved mitochondrial signaling mechanism involves the 18 kDa translocator protein (TSPO) of the outer mitochondrial membrane.

Human ARHGEF9 intellectual disability syndrome is phenocopied by a mutation that disrupts collybistin binding to the GABA receptor α2 subunit.

Intellectual disability (ID) is a common neurodevelopmental disorder that can arise from genetic mutations ranging from trisomy to single nucleotide polymorphism. Mutations in a growing number of single genes have been identified as causative in ID, including ARHGEF9. Evaluation of 41 ARHGEF9 patient reports shows ubiquitous inclusion of ID, along with other frequently reported symptoms of epilepsy, abnormal baseline EEG activity, behavioral symptoms, and sleep disturbances.

Influence of Previous COVID-19 and Mastitis Infections on the Secretion of Brain-Derived Neurotrophic Factor and Nerve Growth Factor in Human Milk.

Background: Brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) play a critical role in neurodevelopment, where breast milk is a significant dietary source. The impact of previous COVID-19 infection and mastitis on the concentration of BDNF and NGF in human milk was investigated.

Methods: Concentrations of BDNF and NGF were measured via ELISA in human milk samples collected from 12 mothers with a confirmed COVID-19 PCR, 13 mothers with viral symptoms suggestive of COVID-19, and 22 unexposed mothers (pre-pandemic Ctl-2018).

Behavioral arrest and a characteristic slow waveform are hallmark responses to selective 5-HT receptor activation.

Perception, emotion, and mood are powerfully modulated by serotonin receptor (5-HTR) agonists including hallucinogens. The 5-HTR subtype has been shown to be central to hallucinogen action, yet the precise mechanisms mediating the response to 5-HTR activation remain unclear. Hallucinogens induce the head twitch response (HTR) in rodents, which is the most commonly used behavioral readout of hallucinogen pharmacology.

Regulation of GABA Receptor Subunit Expression in Substance Use Disorders.

The modulation of neuronal cell firing is mediated by the release of the neurotransmitter GABA (γ-aminobuytric acid), which binds to two major families of receptors. The ionotropic GABAA receptors (GABARs) are composed of five distinct subunits that vary in expression by brain region and cell type. The action of GABA on GABARs is modulated by a variety of clinically and pharmacologically important drugs such as benzodiazepines and alcohol.

Administration of Micronized Caffeine Using a Novel Oral Delivery Film Results in Rapid Absorption and Electroencephalogram Suppression.

Route of administration is well-known to impact factors ranging from absorption and distribution, up through the subjective effects of active ingredients. Different routes of administration confer specific advantages, such as more rapid absorption resulting from intravenous injection, or increased convenience with oral administration, but a combination of both rapid and convenient delivery is highly desirable. QuickStrip™ was designed as a rapidly dissolving thin film matrix that contains active ingredients, which may be promising for rapid and convenient delivery the oral mucosa.

Identification of a Core Amino Acid Motif within the α Subunit of GABARs that Promotes Inhibitory Synaptogenesis and Resilience to Seizures.

The fidelity of inhibitory neurotransmission is dependent on the accumulation of γ-aminobutyric acid type A receptors (GABARs) at the appropriate synaptic sites. Synaptic GABARs are constructed from α(1-3), β(1-3), and γ2 subunits, and neurons can target these subtypes to specific synapses. Here, we identify a 15-amino acid inhibitory synapse targeting motif (ISTM) within the α2 subunit that promotes the association between GABARs and the inhibitory scaffold proteins collybistin and gephyrin.

Molecular Specialization of GABAergic Synapses on the Soma and Axon in Cortical and Hippocampal Circuit Function and Dysfunction.

The diversity of inhibitory interneurons allows for the coordination and modulation of excitatory principal cell firing. Interneurons that release GABA (γ-aminobutyric acid) onto the soma and axon exert powerful control by virtue of proximity to the site of action potential generation at the axon initial segment (AIS). Here, we review and examine the cellular and molecular regulation of soma and axon targeting GABAergic synapses in the cortex and hippocampus.

Developmental seizures and mortality result from reducing GABA receptor α2-subunit interaction with collybistin.

Fast inhibitory synaptic transmission is mediated by γ-aminobutyric acid type A receptors (GABARs) that are enriched at functionally diverse synapses via mechanisms that remain unclear. Using isothermal titration calorimetry and complementary methods we demonstrate an exclusive low micromolar binding of collybistin to the α2-subunit of GABARs. To explore the biological relevance of collybistin-α2-subunit selectivity, we generate mice with a mutation in the α2-subunit-collybistin binding region (Gabra2-1).

Common Ribs of Inhibitory Synaptic Dysfunction in the Umbrella of Neurodevelopmental Disorders.

The term neurodevelopmental disorder (NDD) is an umbrella term used to group together a heterogeneous class of disorders characterized by disruption in cognition, emotion, and behavior, early in the developmental timescale. These disorders are heterogeneous, yet they share common behavioral symptomatology as well as overlapping genetic contributors, including proteins involved in the formation, specialization, and function of synaptic connections. Advances may arise from bridging the current knowledge on synapse related factors indicated from both human studies in NDD populations, and in animal models.

TSPO regulation in reactive gliotic diseases.

The brain is the most metabolically active organ in the body. This high metabolic demand is apparent in that 60% of the brain is comprised of mitochondria-enriched cells. A disruption of the brain's ability to meet this immense metabolic demand is central to the pathogenesis of a multitude of neurological disorders, which range from depression to Alzheimer's disease.

KCC2 activity is critical in limiting the onset and severity of status epilepticus.

The K(+)/Cl(-) cotransporter (KCC2) allows adult neurons to maintain low intracellular Cl(-) levels, which are a prerequisite for efficient synaptic inhibition upon activation of γ-aminobutyric acid receptors. Deficits in KCC2 activity are implicated in epileptogenesis, but how increased neuronal activity leads to transporter inactivation is ill defined. In vitro, the activity of KCC2 is potentiated via phosphorylation of serine 940 (S940).

Neural basis of benzodiazepine reward: requirement for α2 containing GABAA receptors in the nucleus accumbens.

Despite long-standing concerns regarding the abuse liability of benzodiazepines, the mechanisms underlying properties of benzodiazepines that may be relevant to abuse are still poorly understood. Earlier studies showed that compounds selective for α1-containing GABAA receptors (α1GABAARs) are abused by humans and self-administered by animals, and that these receptors may underlie a preference for benzodiazepines as well as neuroplastic changes observed in the ventral tegmental area following benzodiazepine administration. There is some evidence, however, that even L-838, 417, a compound with antagonistic properties at α1GABAARs and agonistic properties at the other three benzodiazepine-sensitive GABAA receptor subtypes, is self-administered, and that the α2GABAARs may have a role in benzodiazepine-induced reward enhancement.

The ability of BDNF to modify neurogenesis and depressive-like behaviors is dependent upon phosphorylation of tyrosine residues 365/367 in the GABA(A)-receptor γ2 subunit.

Brain-derived neurotrophic factor (BDNF) is a potent regulator of neuronal activity, neurogenesis, and depressive-like behaviors; however, downstream effectors by which BDNF exerts these varying actions remain to be determined. Here we reveal that BDNF induces long-lasting enhancements in the efficacy of synaptic inhibition by stabilizing γ2 subunit-containing GABA(A) receptors (GABA(A)Rs) at the cell surface, leading to persistent reductions in neuronal excitability. This effect is dependent upon enhanced phosphorylation of tyrosines 365 and 367 (Y365/7) in the GABA(A)R γ2 subunit as revealed using mice in which these residues have been mutated to phenyalanines (Y365/7F).

Disrupting the clustering of GABAA receptor α2 subunits in the frontal cortex leads to reduced γ-power and cognitive deficits.

In schizophrenia, cognitive dysfunction is highly predictive of poor patient outcomes and is not responsive to current medications. Postmortem studies have suggested that cognitive deficits in schizophrenia are correlated with modifications in the number and size of inhibitory synapses. To test if these modifications lead to cognitive deficits, we have created a dominant-negative virus [adeno-associated (AAV)-DN1] that disrupts the clustering of γ-aminobutyric acid type A receptors (GABA(A)Rs) at postsynaptic inhibitory specializations.

Enhanced tonic inhibition influences the hypnotic and amnestic actions of the intravenous anesthetics etomidate and propofol.

Intravenous anesthetics exert a component of their actions via potentiating inhibitory neurotransmission mediated by γ-aminobutyric type-A receptors (GABAARs). Phasic and tonic inhibition is mediated by distinct populations of GABAARs, with the majority of phasic inhibition by subtypes composed of α1-3βγ2 subunits, whereas tonic inhibition is dependent on subtypes assembled from α4-6βδ subunits. To explore the contribution that these distinct forms of inhibition play in mediating intravenous anesthesia, we have used mice in which tyrosine residues 365/7 within the γ2 subunit are mutated to phenyalanines (Y365/7F).

Prevention of LPS-induced microglia activation, cytokine production and sickness behavior with TLR4 receptor interfering peptides.

The innate immune receptor Toll-like 4 (TLR4) is the receptor activated by lipopolysaccharide (LPS), and TLR4-LPS interaction is well known to induce an innate immune response, triggering sickness behavior. Within the brain, TLR4 is highly expressed in brain microglia, and excessive inflammation resulting from activation of this pathway in the brain has been implicated in depressive disorders and neurodegenerative pathologies. We hypothesized that blocking LPS-induced activation of TLR4 would prevent downstream immune signaling in the brain and suppress the induction of sickness behavior.

Functional regulation of GABAA receptors in nervous system pathologies.

Inhibitory neurotransmission is primarily governed by γ-aminobutyric acid (GABA) type A receptors (GABAARs). GABAARs are heteropentameric ligand-gated channels formed by the combination of 19 possible subunits. GABAAR subunits are subject to multiple types of regulation, impacting the localization, properties, and function of assembled receptors.

Early increase in extrasynaptic NMDA receptor signaling and expression contributes to phenotype onset in Huntington's disease mice.

N-methyl-D-aspartate receptor (NMDAR) excitotoxicity is implicated in the pathogenesis of Huntington's disease (HD), a late-onset neurodegenerative disorder. However, NMDARs are poor therapeutic targets, due to their essential physiological role. Recent studies demonstrate that synaptic NMDAR transmission drives neuroprotective gene transcription, whereas extrasynaptic NMDAR activation promotes cell death.

Golgi-specific DHHC zinc finger protein GODZ mediates membrane Ca2+ transport.

The Golgi-specific zinc finger protein GODZ (palmitoyl acyltransferase/DHHC-3) mediates the palmitoylation and post-translational modification of many protein substrates that regulate membrane-protein interactions. Here, we show that GODZ also mediates Ca(2+) transport in expressing Xenopus laevis oocytes. Two-electrode voltage-clamp, fluorescence, and (45)Ca(2+) isotopic uptake determinations demonstrated voltage- and concentration-dependent, saturable, and substrate-inhibitable Ca(2+) transport in oocytes expressing GODZ cRNA but not in oocytes injected with water alone.

Overexpression of the cell adhesion protein neuroligin-1 induces learning deficits and impairs synaptic plasticity by altering the ratio of excitation to inhibition in the hippocampus.

Trans-synaptic cell-adhesion molecules have been implicated in regulating CNS synaptogenesis. Among these, the Neuroligin (NL) family (NLs 1-4) of postsynaptic adhesion proteins has been shown to promote the development and specification of excitatory versus inhibitory synapses. NLs form a heterophilic complex with the presynaptic transmembrane protein Neurexin (NRX).

Microglia processes block the spread of damage in the brain and require functional chloride channels.

Microglia cells exhibit two forms of motility, constant movement of filopodia probing surrounding brain tissue, and outgrowth of larger processes in response to nearby damage. The mechanisms and functions of filopodia sensing and process outgrowth are not well characterized but are likely critical for normal immune function in the brain. Using two photon laser scanning microscopy we investigated microglia process outgrowth in response to damage, and explored the relationship between process outgrowth and filopodia movement.

Huntingtin-interacting proteins, HIP14 and HIP14L, mediate dual functions, palmitoyl acyltransferase and Mg2+ transport.

Polyglutamine expansions of huntingtin protein are responsible for the Huntington neurological disorder. HIP14 protein has been shown to interact with huntingtin. HIP14 and a HIP14-like protein, HIP14L, with a 69% similarity reside in the Golgi and possess palmitoyl acyltransferase activity through innate cysteine-rich domains, DHHC.

Functional characterization of NIPA2, a selective Mg2+ transporter.

We used microarray analysis to identify renal cell transcripts that were upregulated with low magnesium. One transcript, identified as NIPA2 (nonimprinted in Prader-Willi/Angelman syndrome) subtype 2, was increased over twofold relative to cells cultured in normal magnesium. The deduced sequence comprises 129 amino acids with 8 predicted transmembrane regions.