Lee S, Lee E, Kim R, Kim J, Lee S, Park H, Yang E, Kim H, Kim E.
PMID: 29970987 | DOI: 10.3389/fnmol.2018.00209
Shank2 is an abundant postsynaptic scaffolding protein implicated in neurodevelopmental and psychiatric disorders, including autism spectrum disorders (ASD). Deletion of Shank2 in mice has been shown to induce social deficits, repetitive behaviors, and hyperactivity, but the identity of the cell types that contribute to these phenotypes has remained unclear. Here, we report a conditional mouse line with a Shank2 deletion restricted to parvalbumin (PV)-positive neurons (Pv-Cre;Shank2fl/fl mice). These mice display moderate hyperactivity in both novel and familiar environments and enhanced self-grooming in novel, but not familiar, environments. In contrast, they showed normal levels of social interaction, anxiety-like behavior, and learning and memory. Basal brain rhythms in Pv-Cre;Shank2fl/fl mice, measured by electroencephalography, were normal, but susceptibility to pentylenetetrazole (PTZ)-induced seizures was decreased. These results suggest that Shank2 deletion in PV-positive neurons leads to hyperactivity, enhanced self-grooming and suppressed brain excitation.
Qiu, H;Miraucourt, LS;Petitjean, H;Theriault, C;
Spinal cord dorsal horn (DH) inhibition is critical to the processing of sensory inputs, and its impairment leads to mechanical allodynia. How this decreased inhibition occurs and whether its restoration alleviates allodynic pain is poorly understood. Here, we show that the calcium (Ca2+)-binding protein, parvalbumin (PV), controls the activity of inhibitory PV-expressing neurons (PVNs) by enabling them to sustain high-frequency tonic firing patterns. Upon nerve injury, PVNs transition to adaptive firing and decrease their PV expression. Interestingly, decreased PV is necessary and sufficient to the development of mechanical allodynia and the transition of PVNs to adaptive firing. This transition of firing pattern is due to the recruitment of calcium-activated potassium (SK) channels and blocking them during chronic pain restores normal tonic firing. Our findings indicate that PV is essential to the firing activity of PVNs and in preventing allodynia, these observations may lead to novel strategies for chronic pain relief.
Singh, M;Sapkota, K;Sakimura, K;Kano, M;Cowell, RM;Overstreet-Wadiche, L;Hablitz, JJ;Nakazawa, K;
PMID: 36682446 | DOI: 10.1016/j.neuroscience.2023.01.007
N-methyl-D-aspartate receptor (NMDAR) hypofunction during brain development is likely to contribute to the manifestation of schizophrenia (SCZ) in young adulthood. The cellular targets of NMDAR hypofunction appear to be at least in part corticolimbic fast-spiking (FS) interneurons. However, functional alterations in parvalbumin (PV)-positive FS interneurons following NMDAR hypofunction are poorly understood. Paired patch-clamp recordings from murine cortical PV interneurons and pyramidal neurons revealed that genetic deletion of NMDAR subunit Grin1 in prospective PV interneurons before the second postnatal week impaired evoked- and synchronized-GABA release. Whereas intrinsic excitability and spiking characteristics were also disturbed by Grin1 deletion, neither restoring their excitability by K+ channel blockade nor increasing extracellular Ca2+ rescued the GABA release. GABA release was also insensitive to the Cav2.1 channel antagonist ω-agatoxin IVA. Heterozygous deletion of Cacna1a gene (encoding Cav2.1) in PV interneurons produced a similar GABA release phenotype as the Grin1 mutants. Treatment with the Cav2.1/2.2 channel agonist GV-58 augmented somatic Ca2+ currents and GABA release in Cacna1a-haploinsufficient PV interneurons, but failed to enhance GABA release in the Grin1-deleted PV interneurons. Taken together, our results suggest that Grin1 deletion in prospective PV interneurons impairs proper maturation of membrane excitability and Cav2.1-recruited evoked GABA release. This may increase synaptic excitatory/inhibitory ratio in principal neurons, contributing to the emergence of SCZ-like phenotypes.
Molecular Neuropsychiatry
Hu X,. Rocco BR, Fee C, Sibille E.
PMID: - | DOI: 10.1159/000495840
Converging evidence suggests that deficits in somatostatin (SST)-expressing neuron signaling contributes to major depressive disorder. Preclinical studies show that enhancing this signaling, specifically at α5 subunit-containing γ-aminobutyric acid subtype A receptors (α5-GABAARs), provides a potential means to overcome low SST neuron function. The cortical microcircuit comprises multiple subtypes of inhibitory γ-aminobutyric acid (GABA) neurons and excitatory pyramidal cells (PYCs). In this study, multilabel fluorescence in situ hybridization was used to characterize α5-GABAAR gene expression in PYCs and three GABAergic neuron subgroups – vasoactive intestinal peptide (VIP)-, SST-, and parvalbumin (PV)-expressing cells – in the human and mouse frontal cortex. Across species, we found the majority of gene expression in PYCs (human: 39.7%; mouse: 54.14%), less abundant expression in PV neurons (human: 20%; mouse: 16.33%), and no expression in VIP neurons (0%). Only human SST cells expressed GABRA5, albeit at low levels (human: 8.3%; mouse: 0%). Together, this localization suggests potential roles for α5-GABAARs within the cortical microcircuit: (1) regulators of PYCs, (2) regulators of PV cell activity across species, and (3) sparse regulators of SST cell inhibition in humans. These results will advance our ability to predict the effects of pharmacological agents targeting α5-GABAARs, which have shown therapeutic potential in preclinical animal models.
Frezel, N;Ranucci, M;Foster, E;Wende, H;Pelczar, P;Mendes, R;Ganley, RP;Werynska, K;d'Aquin, S;Beccarini, C;Birchmeier, C;Zeilhofer, HU;Wildner, H;
PMID: 36947543 | DOI: 10.1016/j.celrep.2023.112295
Corticospinal tract (CST) neurons innervate the deep spinal dorsal horn to sustain chronic neuropathic pain. The majority of neurons targeted by the CST are interneurons expressing the transcription factor c-Maf. Here, we used intersectional genetics to decipher the function of these neurons in dorsal horn sensory circuits. We find that excitatory c-Maf (c-MafEX) neurons receive sensory input mainly from myelinated fibers and target deep dorsal horn parabrachial projection neurons and superficial dorsal horn neurons, thereby connecting non-nociceptive input to nociceptive output structures. Silencing c-MafEX neurons has little effect in healthy mice but alleviates mechanical hypersensitivity in neuropathic mice. c-MafEX neurons also receive input from inhibitory c-Maf and parvalbumin neurons, and compromising inhibition by these neurons caused mechanical hypersensitivity and spontaneous aversive behaviors reminiscent of c-MafEX neuron activation. Our study identifies c-MafEX neurons as normally silent second-order nociceptors that become engaged in pathological pain signaling upon loss of inhibitory control.
Englund, J;Haikonen, J;Shteinikov, V;Amarilla, SP;Atanasova, T;Shintyapina, A;Ryazantseva, M;Partanen, J;Voikar, V;Lauri, SE;
PMID: 34663781 | DOI: 10.1038/s41398-021-01654-7
Early life stress (ELS) is a well-characterized risk factor for mood and anxiety disorders. GABAergic microcircuits in the amygdala are critically implicated in anxiety; however, whether their function is altered after ELS is not known. Here we identify a novel mechanism by which kainate receptors (KARs) modulate feedforward inhibition in the lateral amygdala (LA) and show that this mechanism is downregulated after ELS induced by maternal separation (MS). Specifically, we show that in control rats but not after MS, endogenous activity of GluK1 subunit containing KARs disinhibit LA principal neurons during activation of cortical afferents. GluK1 antagonism attenuated excitability of parvalbumin (PV)-expressing interneurons, resulting in loss of PV-dependent inhibitory control and an increase in firing of somatostatin-expressing interneurons. Inactivation of Grik1 expression locally in the adult amygdala reduced ongoing GABAergic transmission and was sufficient to produce a mild anxiety-like behavioral phenotype. Interestingly, MS and GluK1-dependent phenotypes showed similar gender specificity, being detectable in male but not female rodents. Our data identify a novel KAR-dependent mechanism for cell-type and projection-specific functional modulation of the LA GABAergic microcircuit and suggest that the loss of GluK1 KAR function contributes to anxiogenesis after ELS.
Parvalbumin interneuron inhibition onto anterior insula neurons projecting to the basolateral amygdala drives aversive taste memory retrieval
Yiannakas, A;Kolatt Chandran, S;Kayyal, H;Gould, N;Khamaisy, M;Rosenblum, K;
PMID: 33930301 | DOI: 10.1016/j.cub.2021.04.010
Memory retrieval refers to the fundamental ability of organisms to make use of acquired, sometimes inconsistent, information about the world. Although memory acquisition has been studied extensively, the neurobiological mechanisms underlying memory retrieval remain largely unknown. Conditioned taste aversion (CTA) is a robust associative paradigm, through which animals can be trained to express aversion toward innately appetitive tastants. The anterior insula (aIC) is indispensable in the ability of mammals to retrieve associative information regarding tastants that have been previously linked with gastric malaise. Here, we show that CTA memory retrieval promotes cell-type-specific activation in the aIC. Using chemogenetic tools in the aIC, we found that CTA memory acquisition requires activation of excitatory neurons and inhibition of inhibitory neurons, whereas retrieval necessitates activation of both excitatory and inhibitory aIC circuits. CTA memory retrieval at the aIC activates parvalbumin (PV) interneurons and increases synaptic inhibition onto activated pyramidal neurons projecting to the basolateral amygdala (aIC-BLA). Unlike innately appetitive taste memory retrieval, CTA retrieval increases synaptic inhibition onto aIC-BLA-projecting neurons that is dependent on activity in aIC PV interneurons. PV aIC interneurons coordinate CTA memory retrieval and are necessary for its dominance when conflicting internal representations are encountered over time. The reinstatement of CTA memories following extinction is also dependent on activation of aIC PV interneurons, which increase the frequency of inhibition onto aIC-BLA-projecting neurons. This newly described interaction of PV and a subset of excitatory neurons can explain the coherency of aversive memory retrieval, an evolutionary pre-requisite for animal survival.
Shukla R, Prevot TD, French L, Isserlin R, Rocco BR, Banasr M, Bader GD, Sibille E.
PMID: - | DOI: 10.1016/j.celrep.2018.09.034
Background Aging is accompanied by altered thinking (cognition) and feeling (mood), functions that depend on information processing by brain cortical cell microcircuits. We hypothesized that age-associated long-term functional and biological changes are mediated by gene transcriptomic changes within neuronal cell-types forming cortical microcircuits, namely excitatory pyramidal cells (PYC) and inhibitory GABAergic neurons expressing vasoactive intestinal peptide (Vip), somatostatin (Sst) and parvalbumin (Pvalb). Methods To test this hypothesis, we assessed locomotor, anxiety-like and cognitive behavioral changes between young (2 months, n=9) and old (22 months, n=12) male C57BL/6 mice, and performed frontal cortex cell-type specific molecular profiling, using laser-capture microscopy and RNA sequencing. Results were analyzed by neuroinformatics and validated by fluorescent in situ hybridization. Results Old-mice displayed increased anxiety and reduced working memory. The four cell-types displayed distinct age-related transcriptomes and biological pathway profiles, affecting metabolic and cell signaling pathways, and selective markers of neuronal vulnerability (Ryr3), resilience (Oxr1), and mitochondrial dynamics (Opa1), suggesting high age-related vulnerability of PYCs, and variable degree of adaptation in GABAergic neurons. Correlations between gene expression and behaviors suggest that changes in cognition and anxiety associated with age are partly mediated by normal age-related cell changes, and that additional age-independent decreases in synaptic and signaling pathways, notably in PYC and SST-neurons further contribute to behavioral changes. Conclusions Our study demonstrates cell-dependent differential vulnerability and coordinated cell-specific cortical microcircuit molecular changes with age. Collectively, the results suggest intrinsic molecular links between aging, cognition and mood-related behaviors with SST-neurons contributing evenly to both behavioral conditions.
European neuropsychopharmacology : the journal of the European College of Neuropsychopharmacology
Begni, V;Pisano, I;Marizzoni, M;Marchisella, F;Creutzberg, KC;De Rosa, F;Cattaneo, A;Gruca, P;Litwa, E;Papp, M;Riva, MA;
PMID: 35830759 | DOI: 10.1016/j.euroneuro.2022.06.005
Chronic stress represents a major contributor for the development of mental illness. This study aimed to investigate how animals exposed to chronic mild stress (CMS) responded to an acute stress (AS), as a vulnerability's challenge, and to establish the potential effects of the antipsychotic drug lurasidone on such mechanisms. Adult male Wistar rats were exposed or not (controls) to a CMS paradigm for 7 weeks. Starting from the end of week 2, animals were randomized to receive vehicle or lurasidone for 5 weeks. Sucrose intake was used to measure anhedonia. At the end, half of the animals were exposed to an acute stress before sacrifice. Exposure to CMS produced a significant reduction in sucrose consumption, whereas lurasidone progressively normalized such alteration. We found that exposure to AS produced an upregulation of Brain derived neurotrophic factor (Bdnf) in the prefrontal cortex of controls animals. This response was impaired in CMS rats and restored by lurasidone treatment. While in control animals, AS-induced increase of Bdnf mRNA levels was specific for Parvalbumin cells, CMS rats treated with lurasidone show a significant upregulation of Bdnf in pyramidal cells. Furthermore, when investigating the activation of different brain regions, CMS rats showed an impairment in the global response to the acute stressor, that was largely restored by lurasidone treatment. Our results suggest that lurasidone treatment in CMS rats may regulate specific circuits and mechanisms, which will ultimately contribute to boost resilience under stressful challenges.
Erythropoietin Stimulates GABAergic Maturation in the Mouse Hippocampus
Khalid, K;Frei, J;Aboouf, MA;Koester-Hegmann, C;Gassmann, M;Fritschy, JM;Schneider Gasser, EM;
PMID: 33495244 | DOI: 10.1523/ENEURO.0006-21.2021
Several neurodevelopmental disabilities are strongly associated with alterations in GABAergic transmission, and therapies to stimulate its normal development are lacking. Erythropoietin (EPO) is clinically used in neonatology to mitigate acute brain injury, and to stimulate neuronal maturation. Yet it remains unclear whether EPO can stimulate maturation of the GABAergic system. Here, with the use of a transgenic mouse line that constitutively overexpresses neuronal EPO (Tg21), we show that EPO stimulates postnatal GABAergic maturation in the hippocampus. We show an increase in hippocampal GABA-immunoreactive neurons, and postnatal elevation of interneurons expressing parvalbumin (PV), somatostatin (SST) and neuropeptide Y (NPY). Analysis of perineuronal net formation and innervation of glutamatergic terminals onto PV+ cells, shows to be enhanced early in postnatal development. Additionally, an increase in GABAAergic synapse density and inhibitory postsynaptic currents (IPSCs) in CA1 pyramidal cells from Tg21 mice is observed. Detection of erythropoietin receptor (EPOR) mRNA was observed to be restricted to glutamatergic pyramidal cells and increased in Tg21 mice at postnatal day 7, along with reduced apoptosis. Our findings show that EPO can stimulate postnatal GABAergic maturation in the hippocampus, by increasing neuronal survival, modulating critical plasticity periods, and increasing synaptic transmission. Our data supports EPO's clinical use to balance GABAergic dysfunction.Significance Statement Using a mouse model that overexpresses recombinant human EPO in the CNS, we observed stimulation of the postnatal maturation of GABAergic transmission in the hippocampus, notably accelerated maturation of PV+ interneurons, enhanced glutamatergic inputs onto these interneurons, and enhanced inhibitory postsynaptic currents (IPSCs) onto pyramidal cells. We show that EPORs are expressed on pyramidal cells, therefore the impact of EPO on GABAergic maturation is likely to be indirect. Our data show that EPO can modulate hippocampal network maturation and support ongoing trials of the use of EPO in clinical neonatology to stimulate neuronal maturation after perinatal brain injury.
Haidar M, Tin K, Zhang C, Nategh M, Covita J, Wykes AD, Rogers J and Gundlach AL
PMID: 30906254 | DOI: 10.3389/fnana.2019.00030
Relaxin-3 is a highly conserved neuropeptide abundantly expressed in neurons of the nucleus incertus (NI), which project to nodes of the septohippocampal system (SHS) including the medial septum/diagonal band of Broca (MS/DB) and dorsal hippocampus, as well as to limbic circuits. High densities of the Gi/o-protein-coupled receptor for relaxin-3, known as relaxin-family peptide-3 receptor (RXFP3) are expressed throughout the SHS, further suggesting a role for relaxin-3/RXFP3 signaling in modulating learning and memory processes that occur within these networks. Therefore, this study sought to gain further anatomical and functional insights into relaxin-3/RXFP3 signaling in the mouse MS/DB. Using Cre/LoxP recombination methods, we assessed locomotion, exploratory behavior, and spatial learning and long-term reference memory in adult C57BL/6J Rxfp3 (loxP/loxP) mice with targeted depletion of Rxfp3 in the MS/DB. Following prior injection of an AAV((1/2))-Cre-IRES-eGFP vector into the MS/DB to delete/deplete Rxfp3 mRNA/RXFP3 protein, mice tested in a Morris water maze (MWM) displayed an impairment in allocentric spatial learning during acquisition, as well as an impairment in long-term reference memory on probe day. However, RXFP3-depleted and control mice displayed similar motor activity in a locomotor cell and exploratory behavior in a large open-field (LOF) test. A quantitative characterization using multiplex, fluorescent in situ hybridization (ISH) identified a high level of co-localization of Rxfp3 mRNA and vesicular GABA transporter (vGAT) mRNA in MS and DB neurons (~87% and ~95% co-expression, respectively). Rxfp3 mRNA was also detected, to a correspondingly lesser extent, in vesicular glutamate transporter 2 (vGlut2) mRNA-containing neurons in MS and DB (~13% and ~5% co-expression, respectively). Similarly, a qualitative assessment of the MS/DB region, identified Rxfp3 mRNA in neurons that expressed parvalbumin (PV) mRNA (reflecting hippocampally-projecting GABA neurons), whereas choline acetyltransferase mRNA-positive (acetylcholine) neurons lacked Rxfp3 mRNA. These data are consistent with a qualitative immunohistochemical analysis that revealed relaxin-3-immunoreactive nerve fibers in close apposition with PV-immunoreactive neurons in the MS/DB. Together these studies suggest relaxin-3/RXFP3 signaling in the MS/DB plays a role in modulating specific learning and long-term memory associated behaviors in adult mice via effects on GABAergic neuron populations known for their involvement in modulating hippocampal theta rhythm and associated cognitive processes.
Khatamsaz, E;Stoller, F;Zach, S;Kätzel, D;Hengerer, B;
| DOI: 10.1016/j.nsa.2022.100659
Background: The Psychiatric Ratings using Intermediate Stratified Markers (PRISM) project focuses on understanding the biological background behind social deficits, specifically social withdrawal irrespective of diagnosis. Reduced connectional integrity in fiber tracts such as Forceps minor has been indicated in low social individuals as a part of the PRISM 1 project. These fiber tracts are also involved in the Default Mode Network (DMN) and the Social network and they share a common region, the Orbitofrontal Cortex (OFC).This study aims to back-translate the clinical data to preclinical studies and associate social dysfunction in rodents with DMN and particularly OFC. Parvalbumin interneurons are targeted based on their fundamental role in maintaining Excitatory Inhibitory (E/I) balance in brain circuits. Numerous studies indicate behavioral impairment in rodents by increasing excitability of PV+ interneurons. Methods: As an initial step, we characterized the population of projection neurons within OFCs by combining Cholera Toxin subunit B (CTB) as a retrograde tracer and In situ hybridization (ISH) technique (RNAscope). We identified the expression of mRNAs marking glutamatergic (vesicular glutamate transporter [VGLUT]) and GABAergic (vesicular GABA transporter [VGAT]) by using Slc17a7 and Slc32a1 probes. CTB was injected unilaterally in the left OFC (AP=2.68, ML=-0.8, DV=2.2). after 10 days mice were perfused and RNAscope assay was performed using RNAscope™ Multiplex Fluorescent kit (ACDBio™).For inducing hypoactivation of OFC, we introduced an excitatory DREADD (designer receptors exclusively activated by designer drugs) to PV+ interneurons by using a PV-Cre mouse line. Mice were injected either AAV-hSyn-DIO-hM3D(Gq)-mCherry virus (n=12) or AAV-hSyn-DIO-mCherry (n=12) as control virus. As a novel behavioral tool, Radiofrequency identification (RFID)-assisted SocialScan combined with video tracking has been used, which provides a long-term observation of social behaviors. Monitoring the behavior in groups of four was performed for 7 days in total. After two pre-application days, Clozapine-N-oxide (CNO) was injected three times on consecutive days intraperitoneally (5mg/kg) as an activator of hM3D. application days were followed by two post-application days. Mice were perfused and RNAscope was performed to visualize c-fos mRNA expression as neuronal activity marker, and PV expression to validate our virus and mouse line efficacy. Results: ISH results indicated VGLUT1 has the highest expression within projection neurons (81%). 6% are VGAT+ and only 3% are both VGLUT1/VGAT positive neurons. Despite demonstrating the GABAergic projection neurons as a minority, their crucial role as local interneurons to moderate the excitatory neurons is indisputable.In in vivo study, CNO administration induced social dysregulation in DREAAD mice, demonstrated by a reduction in different social parameters (approach, fight, etc.) in terms of duration. During post-application days, DREAAD mice showed significantly higher social interaction in all definedparameters (Social Approach: p=0.0009, unpaired T-test) and locomotion as a non-social parameter (p= 0.0207).Results from ISH support our hypothesis that DREADD activation of PV+ interneurons is followed by high expression of neuronal activity markers in these targeted interneurons. Conclusion: This study indicates that manipulation of PV+ interneurons using artificially engineered activating protein receptors, generates in effect activation of these interneurons, and this manipulation particularly in OFC could cause social dysfunction in mice.
