Complex IV subunit isoform COX6A2 protects fast-spiking interneurons from oxidative stress and supports their function.
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ABSTRACT:
SUBMITTER: Sanz-Morello B
PROVIDER: S-EPMC7507454 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:A hallmark of schizophrenia pathophysiology is the dysfunction of cortical inhibitory GABA neurons expressing parvalbumin, which are essential for coordinating neuronal synchrony during various sensory and cognitive tasks. The high metabolic requirements of these fast-spiking cells may render them susceptible to redox dysregulation and oxidative stress. Using mice carrying a genetic redox imbalance, we demonstrate that extracellular perineuronal nets, which constitute a specialized polyanionic matrix enwrapping most of these interneurons as they mature, play a critical role in the protection against oxidative stress. These nets limit the effect of genetically impaired antioxidant systems and/or excessive reactive oxygen species produced by severe environmental insults. We observe an inverse relationship between the robustness of the perineuronal nets around parvalbumin cells and the degree of intracellular oxidative stress they display. Enzymatic degradation of the perineuronal nets renders mature parvalbumin cells and fast rhythmic neuronal synchrony more susceptible to oxidative stress. In parallel, parvalbumin cells enwrapped with mature perineuronal nets are better protected than immature parvalbumin cells surrounded by less-condensed perineuronal nets. Although the perineuronal nets act as a protective shield, they are also themselves sensitive to excess oxidative stress. The protection might therefore reflect a balance between the oxidative burden on perineuronal net degradation and the capacity of the system to maintain the nets. Abnormal perineuronal nets, as observed in the postmortem patient brain, may thus underlie the vulnerability and functional impairment of pivotal inhibitory circuits in schizophrenia.
| S-EPMC3670388 | biostudies-other
Project description:Fast-spiking (FS) interneurons are important elements of neocortical circuitry that constitute the primary source of synaptic inhibition in adult cortex and impart temporal organization on ongoing cortical activity. The highly specialized intrinsic membrane and firing properties that allow cortical FS interneurons to perform these functions are attributable to equally specialized gene expression, which is ultimately coordinated by cell-type-specific transcriptional regulation. Although embryonic transcriptional events govern the initial steps of cell-type specification in most cortical interneurons, including FS cells, the electrophysiological properties that distinguish adult cortical cell types emerge relatively late in postnatal development, and the transcriptional events that drive this maturational process are not known. To address this, we used mouse whole-genome microarrays and whole-cell patch clamp to characterize the transcriptional and electrophysiological maturation of cortical FS interneurons between postnatal day 7 (P7) and P40. We found that the intrinsic and synaptic physiology of FS cells undergoes profound regulation over the first 4 postnatal weeks and that these changes are correlated with primarily monotonic but bidirectional transcriptional regulation of thousands of genes belonging to multiple functional classes. Using our microarray screen as a guide, we discovered that upregulation of two-pore K leak channels between P10 and P25 contributes to one of the major differences between the intrinsic membrane properties of immature and adult FS cells and found a number of other candidate genes that likely confer cell-type specificity on mature FS cells. Experiment Overall Design: We characterized the transcriptional maturation of genetically labeled FS interneurons in mouse S1 cortex using whole-genome microarrays.mRNA was harvested from manually sorted GFPexpressing neurons dissociated from acutely prepared brain slices at a range of developmental time points (P7, P10, P15, P25, and P40) and subsequently reverse transcribed, amplified, labeled, and hybridized to Affymetrix 430 2.0 whole-genome microarrays (three microarrays from three different animals per condition). We used the G42 transgenic mice described by Chattopadhyaya et al. (2004) for all experiments.
2009-09-17 | E-GEOD-17806 | biostudies-arrayexpress
Project description:Fast-spiking (FS) interneurons are important elements of neocortical circuitry that constitute the primary source of synaptic inhibition in adult cortex and impart temporal organization on ongoing cortical activity. The highly specialized intrinsic membrane and firing properties that allow cortical FS interneurons to perform these functions are attributable to equally specialized gene expression, which is ultimately coordinated by cell-type-specific transcriptional regulation. Although embryonic transcriptional events govern the initial steps of cell-type specification in most cortical interneurons, including FS cells, the electrophysiological properties that distinguish adult cortical cell types emerge relatively late in postnatal development, and the transcriptional events that drive this maturational process are not known. To address this, we used mouse whole-genome microarrays and whole-cell patch clamp to characterize the transcriptional and electrophysiological maturation of cortical FS interneurons between postnatal day 7 (P7) and P40. We found that the intrinsic and synaptic physiology of FS cells undergoes profound regulation over the first 4 postnatal weeks and that these changes are correlated with primarily monotonic but bidirectional transcriptional regulation of thousands of genes belonging to multiple functional classes. Using our microarray screen as a guide, we discovered that upregulation of two-pore K leak channels between P10 and P25 contributes to one of the major differences between the intrinsic membrane properties of immature and adult FS cells and found a number of other candidate genes that likely confer cell-type specificity on mature FS cells.
2009-09-05 | GSE17806 | GEO
Project description:Striatal fast-spiking interneurons (FSIs) fire in variable-length runs of action potentials at 20-200 spikes/s separated by pauses. In vivo, or with fluctuating applied current, both runs and pauses become briefer and more variable. During runs, spikes are entrained specifically to gamma-frequency components of the input fluctuations. We stimulated parvalbumin-expressing striatal FSIs in mouse brain slices with broadband noise currents added to direct current steps and measured spike entrainment across all frequencies. As the constant current level was increased, FSIs produced longer runs and showed sharper frequency tuning, with best entrainment at the stimulus frequency matching their intrarun firing rate. We separated the contributions of previous spikes from that of the fluctuating stimulus, revealing a strong contribution of previous action potentials to gamma-frequency entrainment. In contrast, after subtraction of the effect inherited from the previous spike, the remaining stimulus contribution to spike generation was less sharply tuned, showing a larger contribution of lower frequencies. The frequency specificity of entrainment within a run was reproduced with a phase resetting model based on experimentally measured phase resetting curves of the same FSIs. In the model, broadly tuned phase entrainment for the first spike in a run evolved into sharply tuned gamma entrainment over the next few spikes. The data and modeling results indicate that for FSIs firing in brief runs and pauses firing within runs is entrained by gamma-frequency components of the input, whereas the onset timing of runs may be sensitive to a wider range of stimulus frequency components.NEW & NOTEWORTHY Specific types of neurons entrain their spikes to particular oscillation frequencies in their synaptic input. This entrainment is commonly understood in terms of the subthreshold voltage response, but how this translates to spiking is not clear. We show that in striatal fast-spiking interneurons, entrainment to gamma-frequency input depends on rhythmic spike runs and is explained by the phase resetting curve, whereas run initiation can be triggered by a broad range of input frequencies.
| S-EPMC6766739 | biostudies-literature
Project description:BackgroundThe nucleus accumbens (NAc) controls multiple facets of impulsivity but is a heterogeneous brain region with diverse microcircuitry. Prior literature links impulsive behavior in rodents to gamma-aminobutyric acid signaling in the NAc. Here, we studied the regulation of impulsive behavior by fast-spiking interneurons (FSIs), a strong source of gamma-aminobutyric acid-mediated synaptic inhibition in the NAc.MethodsMale and female transgenic mice expressing Cre recombinase in FSIs allowed us to identify these sparsely distributed cells in the NAc. We used a 5-choice serial reaction time task to measure both impulsive action and sustained attention. During the 5-choice serial reaction time task, we monitored FSI activity with fiber photometry calcium imaging and manipulated FSI activity with chemogenetic and optogenetic methodology. We used electrophysiology, optogenetics, and fluorescent in situ hybridization to confirm these methods were robust and specific to FSIs.ResultsIn mice performing the 5-choice serial reaction time task, NAc FSIs showed sustained activity on trials ending with correct responses, but FSI activity declined over time on trials ending with premature responses. The number of premature responses increased significantly after sustained chemogenetic inhibition or temporally delimited optogenetic inhibition of NAc FSIs, without any changes in response latencies or general locomotor activity.ConclusionsThese experiments provide strong evidence that NAc FSIs constrain impulsive actions, most likely through gamma-aminobutyric acid-mediated synaptic inhibition of medium spiny projection neurons. Our findings may provide insight into the pathophysiology of disorders associated with impulsivity and may inform the development of circuit-based therapeutic interventions.
| S-EPMC6823148 | biostudies-literature
Project description:Cortical fast-spiking (FS) interneurons display highly variable electrophysiological properties. Their spike responses to step currents occur almost immediately following the step onset or after a substantial delay, during which subthreshold oscillations are frequently observed. Their firing patterns include high-frequency tonic firing and rhythmic or irregular bursting (stuttering). What is the origin of this variability? In the present paper, we hypothesize that it emerges naturally if one assumes a continuous distribution of properties in a small set of active channels. To test this hypothesis, we construct a minimal, single-compartment conductance-based model of FS cells that includes transient Na(+), delayed-rectifier K(+), and slowly inactivating d-type K(+) conductances. The model is analyzed using nonlinear dynamical system theory. For small Na(+) window current, the neuron exhibits high-frequency tonic firing. At current threshold, the spike response is almost instantaneous for small d-current conductance, gd, and it is delayed for larger gd. As gd further increases, the neuron stutters. Noise substantially reduces the delay duration and induces subthreshold oscillations. In contrast, when the Na(+) window current is large, the neuron always fires tonically. Near threshold, the firing rates are low, and the delay to firing is only weakly sensitive to noise; subthreshold oscillations are not observed. We propose that the variability in the response of cortical FS neurons is a consequence of heterogeneities in their gd and in the strength of their Na(+) window current. We predict the existence of two types of firing patterns in FS neurons, differing in the sensitivity of the delay duration to noise, in the minimal firing rate of the tonic discharge, and in the existence of subthreshold oscillations. We report experimental results from intracellular recordings supporting this prediction.
| S-EPMC1941757 | biostudies-literature
Project description:Gap junctions form electrical synapses that modulate neuronal activity by synchronizing action potential (AP) firing of cortical interneurons (INs). Gap junctions are thought to form predominantly within cortical INs of the same functional class and are therefore considered to act within discrete neuronal populations. Here, we challenge that view and show that the probability of electrical coupling is the same within and between regular-spiking (RS) and fast-spiking (FS) cortical INs in 16-21 days old mice. Firing properties of these two populations were distinct from other INs types including neurogliaform and low-threshold spiking (LTS) cells. We also demonstrate that pre-junctional APs can depolarize post-junctional neurons and increase the probability of firing. Our findings of frequent gap junction coupling between functionally distinct IN subtypes suggest that cortical IN networks are much more extensive and heterogeneous than previously thought. This may have implications on mechanisms ranging from cognitive functions to modulation of pathological states in epilepsy and other neurological disorders.
| S-EPMC5511827 | biostudies-literature
Project description:Fast-spiking (FS) interneurons are important elements of neocortical circuitry that constitute the primary source of synaptic inhibition in adult cortex and impart temporal organization on ongoing cortical activity. The highly specialized intrinsic membrane and firing properties that allow cortical FS interneurons to perform these functions are attributable to equally specialized gene expression, which is ultimately coordinated by cell-type-specific transcriptional regulation. Although embryonic transcriptional events govern the initial steps of cell-type specification in most cortical interneurons, including FS cells, the electrophysiological properties that distinguish adult cortical cell types emerge relatively late in postnatal development, and the transcriptional events that drive this maturational process are not known. To address this, we used mouse whole-genome microarrays and whole-cell patch clamp to characterize the transcriptional and electrophysiological maturation of cortical FS interneurons between postnatal day 7 (P7) and P40. We found that the intrinsic and synaptic physiology of FS cells undergoes profound regulation over the first 4 postnatal weeks and that these changes are correlated with primarily monotonic but bidirectional transcriptional regulation of thousands of genes belonging to multiple functional classes. Using our microarray screen as a guide, we discovered that upregulation of two-pore K(+) leak channels between P10 and P25 contributes to one of the major differences between the intrinsic membrane properties of immature and adult FS cells and found a number of other candidate genes that likely confer cell-type specificity on mature FS cells.
| S-EPMC2749660 | biostudies-literature
Project description:Neuromodulatory control by oxytocin is essential to a wide range of social, parental and stress-related behaviours. Autism spectrum disorders (ASD) are associated with deficiencies in oxytocin levels and with genetic alterations of the oxytocin receptor (OXTR). Thirty years ago, Mühlethaler et al. found that oxytocin increases the firing of inhibitory hippocampal neurons, but it remains unclear how elevated inhibition could account for the ability of oxytocin to improve information processing in the brain. Here we describe in mammalian hippocampus a simple yet powerful mechanism by which oxytocin enhances cortical information transfer while simultaneously lowering background activity, thus greatly improving the signal-to-noise ratio. Increased fast-spiking interneuron activity not only suppresses spontaneous pyramidal cell firing, but also enhances the fidelity of spike transmission and sharpens spike timing. Use-dependent depression at the fast-spiking interneuron-pyramidal cell synapse is both necessary and sufficient for the enhanced spike throughput. We show the generality of this novel circuit mechanism by activation of fast-spiking interneurons with cholecystokinin or channelrhodopsin-2. This provides insight into how a diffusely delivered neuromodulator can improve the performance of neural circuitry that requires synapse specificity and millisecond precision.
| S-EPMC5283693 | biostudies-literature
Project description:Basal ganglia circuits are essential for the organization and execution of voluntary actions. Within the striatum, fast-spiking interneurons (FSIs) are thought to tightly regulate the activity of medium-spiny projection neurons (MSNs) through feed-forward inhibition, yet few studies have investigated the functional contributions of FSIs in behaving animals. We recorded presumed MSNs and FSIs together with motor cortex and globus pallidus (GP) neurons, in rats performing a simple choice task. MSN activity was widely distributed across the task sequence, especially near reward receipt. By contrast, FSIs showed a coordinated pulse of increased activity as chosen actions were initiated, in conjunction with a sharp decrease in GP activity. Both MSNs and FSIs were direction selective, but neighboring MSNs and FSIs showed opposite selectivity. Our findings suggest that individual FSIs participate in local striatal information processing, but more global disinhibition of FSIs by GP is important for initiating chosen actions while suppressing unwanted alternatives.
| S-EPMC2920892 | biostudies-literature