Paliarin, F;Duplantis, C;Jones, AF;Cucinello-Ragland, J;Basavanhalli, S;Blaze, E;Doré, E;Neel, AI;Sun, H;Chen, R;Edwards, S;Gilpin, NW;Messing, RO;Maiya, R;
PMID: 37364995 | DOI: 10.1523/ENEURO.0043-23.2023
Here we describe the generation and characterization of a Cre knockin mouse line which harbors a Cre insertion in the 3'UTR of the kappa opioid receptor gene (Oprk1) locus and provides genetic access to populations of kappa opioid receptor (KOR)-expressing neurons throughout the brain. Using a combination of techniques including RNA in situ hybridization and immunohistochemistry, we report that Cre is expressed with high fidelity in KOR-expressing cells throughout the brain in this mouse line. We also provide evidence that Cre insertion does not alter basal KOR function. Baseline anxiety-like behaviors and nociceptive thresholds are unaltered in Oprk1-Cre mice. Chemogenetic activation of KOR-expressing cells in the basolateral amygdala (BLAKOR cells) resulted in several sex-specific effects on anxiety-like and aversive behaviors. Activation led to decreased anxiety-like behavior on the elevated plus maze and increased sociability in female but not in male Oprk1-Cre mice. Activation of BLAKOR cells also attenuated KOR-agonist induced conditioned place aversion (CPA) in male Oprk1-Cre mice. Overall, these results suggest a potential role for BLAKOR cells in regulating anxiety-like behaviors and KOR-agonist mediated CPA. In summary, these results provide evidence for the utility of the newly generated Oprk1-Cre mice in assessing localization, anatomy, and function of KOR circuits throughout the brain.Significance statementHere we report the generation and characterization of a Oprk1-Cre mouse line that harbors Cre insertion in the 3'UTR of the Oprk1 locus. There is high fidelity of Cre expression to KOR expressing cells throughout the brain in this mouse line and Cre insertion does not impair KOR function. Chemogenettic activation of BLAKORs led to sex-specific effects on anxiety-like behaviors and attenuated KOR-agonist induced conditioned place aversion (CPA). These results provide evidence for the utility of the newly generated Oprk1-Cre mice to interrogate KOR function in discreet circuits.
Lotun, A;Li, D;Xu, H;Su, Q;Tuncer, S;Sanmiguel, J;Mooney, M;Baer, CE;Ulbrich, R;Eyles, SJ;Strittmatter, L;Hayward, LJ;Gessler, DJ;Gao, G;
PMID: 37149081 | DOI: 10.1016/j.pneurobio.2023.102460
Myelinating oligodendrocytes are essential for neuronal communication and homeostasis of the central nervous system (CNS). One of the most abundant molecules in the mammalian CNS is N-acetylaspartate (NAA), which is catabolized into L-aspartate and acetate by the enzyme aspartoacylase (ASPA) in oligodendrocytes. The resulting acetate moiety is thought to contribute to myelin lipid synthesis. In addition, affected NAA metabolism has been implicated in several neurological disorders, including leukodystrophies and demyelinating diseases such as multiple sclerosis. Genetic disruption of ASPA function causes Canavan disease, which is hallmarked by increased NAA levels, myelin and neuronal loss, large vacuole formation in the CNS, and early death in childhood. Although NAA's direct role in the CNS is inconclusive, in peripheral adipose tissue, NAA-derived acetate has been found to modify histones, a mechanism known to be involved in epigenetic regulation of cell differentiation. We hypothesize that a lack of cellular differentiation in the brain contributes to the disruption of myelination and neurodegeneration in diseases with altered NAA metabolism, such as Canavan disease. Our study demonstrates that loss of functional Aspa in mice disrupts myelination and shifts the transcriptional expression of neuronal and oligodendrocyte markers towards less differentiated stages in a spatiotemporal manner. Upon re-expression of ASPA, these oligodendrocyte and neuronal lineage markers are either improved or normalized, suggesting that NAA breakdown by Aspa plays an essential role in the maturation of neurons and oligodendrocytes. Also, this effect of ASPA re-expression is blunted in old mice, potentially due to limited ability of neuronal, rather than oligodendrocyte, recovery.
Molecular Metabolism (2019)
Pan W, Allison MB, Sabatini P, Rupp A, Adams J, Patterson C, Jones JC, Olson DP, Myers MG.
| DOI: doi:10.1016/j.molmet.2019.01.007
Abstract Objectives Leptin acts via its receptor LepRb on specialized neurons in the brain to modulate food intake, energy expenditure, and body weight. LepRb activates signal transducers and activators of transcription (STATs, including STAT1, STAT3, and STAT5) to control gene expression. Methods Because STAT3 is crucial for physiologic leptin action, we used TRAP-seq to examine gene expression in LepRb neurons of mice ablated for Stat3 in LepRb neurons (Stat3LepRbKO mice), revealing the STAT3-dependent transcriptional targets of leptin. To understand roles for STAT proteins in leptin action, we also ablated STAT1 or STAT5 from LepRb neurons and expressed a constitutively-active STAT3 (CASTAT3) in LepRb neurons. Results While we also found increased Stat1 expression and STAT1-mediated transcription of leptin-regulated genes in Stat3LepRbKO mice, ablating Stat1 in LepRb neurons failed to alter energy balance (even on the Stat3LepRbKO background); ablating Stat5 in LepRb neurons also failed to alter energy balance. Importantly, expression of a constitutively-active STAT3 (CASTAT3) in LepRb neurons decreased food intake and body weight and improved metabolic parameters in leptin-deficient (ob/ob) mice, as well as in wild-type animals. Conclusions Thus, STAT3 represents the unique STAT protein required for leptin action and STAT3 suffices to mediate important components of leptin action in the absence of other LepRb signals.
Samineni VK, Grajales-Reyes JG, Copits BA, O’Brien DE, Trigg SL, Gomez AM, Bruchas MR, Gereau RW.
PMID: - | DOI: 10.1523/ENEURO.0129-16.2017
The ventrolateral periaqueductal gray (vlPAG) constitutes a major descending pain modulatory system and is a crucial site for opioid-induced analgesia. A number of previous studies have demonstrated that glutamate and GABA play critical opposing roles in nociceptive processing in the vlPAG. It has been suggested that glutamatergic neurotransmission exerts antinociceptive effects, whereas GABAergic neurotransmission exert pro-nociceptive effects on pain transmission, through descending pathways. The inability to exclusively manipulate subpopulations of neurons in the PAG has prevented direct testing of this hypothesis. Here we demonstrate the different contributions of genetically-defined glutamatergic and GABAergic vlPAG neurons in nociceptive processing by employing cell type-specific chemogenetic approaches in mice. Global chemogenetic manipulation of vlPAG neuronal activity suggests that vlPAG neural circuits exert tonic suppression of nociception, consistent with previous pharmacological and electrophysiological studies. However, selective modulation of GABAergic or glutamatergic neurons demonstrates an inverse regulation of nociceptive behaviors by these cell populations. Selective chemogenetic activation of glutamatergic neurons, or inhibition of GABAergic neurons, in vlPAG suppresses nociception. In contrast, inhibition of glutamatergic neurons, or activation of GABAergic neurons, in vlPAG facilitates nociception. Our findings provide direct experimental support for a model in which excitatory and inhibitory neurons in the PAG bidirectionally modulate nociception.
Significance Statement The PAG is a midbrain region critical for the modulation of pain. However, the roles played by the distinct cell types within the PAG in nociceptive processing are poorly understood. This work addresses the divergent roles of glutamatergic and GABAergic PAG neuronal subpopulations in nociceptive processing. We demonstrate that activation of glutamatergic neurons or inhibition of GABAergic neurons suppresses nociception. Whereas inhibition of glutamatergic neuronal activity or activation of GABAergic neuronal activity potentiates nociception. This report identifies distinct roles for these neuronal populations in modulating nociceptive processing.
Parekh PK, Logan RW, Ketchesin KD, Becker-Krail D, Shelton MA, Hildebrand MA, Barko K, Huang YH, McClung CA.
PMID: 30962277 | DOI: 10.1523/JNEUROSCI.2233-18.2019
The circadian transcription factor neuronal PAS domain 2 (NPAS2) is linked to psychiatric disorders associated with altered reward sensitivity. The expression of Npas2 is preferentially enriched in the mammalian forebrain, including the nucleus accumbens (NAc), a major neural substrate of motivated and reward behavior. Previously, we demonstrated that down-regulation of NPAS2 in the NAc reduces the conditioned behavioral response to cocaine in mice. We also showed that Npas2 is preferentially enriched in dopamine receptor 1 containing medium spiny neurons (D1R-MSNs) of the striatum. To extend these studies, we investigated the impact of NPAS2 disruption on accumbal excitatory synaptic transmission and strength, along with the behavioral sensitivity to cocaine reward in a cell-type specific manner. Viral-mediated knockdown of Npas2 in the NAc of male and female C57BL/6J mice increased the excitatory drive onto MSNs. Using Drd1a-tdTomato mice in combination with viral knockdown, we determined these synaptic adaptations were specific to D1R-MSNs relative to non-D1R-MSNs. Interestingly, NAc-specific knockdown of Npas2 blocked cocaine-induced enhancement of synaptic strength and glutamatergic transmission specifically onto D1R-MSNs. Lastly, we designed, validated, and employed a novel Cre-inducible short-hairpin RNA virus for MSN-subtype specific knockdown of Npas2 Cell-type specific Npas2 knockdown in D1R-MSNs, but not D2R-MSNs, in the NAc reduced cocaine conditioned place preference. Together, our results demonstrate that NPAS2 regulates excitatory synapses of D1R-MSNs in the NAc and cocaine reward-related behavior.SIGNIFICANCE STATEMENTDrug addiction is a widespread public health concern often comorbid with other psychiatric disorders. Disruptions of the circadian clock can predispose or exacerbate substance abuse in vulnerable individuals. We demonstrate a role for the core circadian protein, NPAS2, in mediating glutamatergic neurotransmission at medium spiny neurons (MSNs) in the nucleus accumbens (NAc), a region critical for reward processing. We find that NPAS2 negatively regulates functional excitatory synaptic plasticity in the NAc and is necessary for cocaine-induced plastic changes in MSNs expressing the dopamine 1 receptor (D1R). We further demonstrate disruption of NPAS2 in D1R-MSNs produces augmented cocaine preference. These findings highlight the significance of cell-type specificity in mechanisms underlying reward regulation by NPAS2 and extend our knowledge of its function.
Nikitin, P;Musina, G;Pekov, S;Kuzin, A;Popov, I;Belyaev, A;Kobyakov, G;Usachev, D;Nikolaev, V;Mikhailov, V;
| DOI: 10.3390/cancers15010145
Diffuse gliomas continue to be an important problem in neuro-oncology. To solve it, studies have considered the issues of molecular pathogenesis from the intratumoral heterogeneity point. Here, we carried out a comparative dynamic analysis of the different cell populations’ content in diffuse gliomas of different molecular profiles and grades, considering the cell populations’ functional properties and the relationship with patient survival, using flow cytometry, immunofluorescence, multiparametric fluorescent in situ hybridization, polymerase chain reaction, and cultural methods. It was shown that an increase in the IDH-mutant astrocytomas and oligodendrogliomas malignancy is accompanied by an increase in stem cells’ proportion and mesenchymal cell populations’ appearance arising from oligodendrocyte-progenitor-like cells with cell plasticity and cells’ hypoxia response programs’ activation. In glioblastomas, malignancy increase is accompanied by an increase in both stem and definitive cells with mesenchymal differentiation, while proneuronal glioma stem cells are the most likely the source of mesenchymal glioma stem cells, which, in hypoxic conditions, further give rise to mesenchymal-like cells. Clinical confirmation was a mesenchymal-like cell and mesenchymal glioma stem cell number, and the hypoxic and plastic molecular programs’ activation degree had a significant effect on relapse-free and overall survival. In general, we built a multi-vector model of diffuse gliomas’ pathogenetic tracing up to the practical plane.
Physiol Behav. 2014 Apr 2. pii: S0031-9384(14)00173-5.
Smith JA, Wang L, Hiller H, Taylor CT, de Kloet AD, Krause EG.
PMID: 24704193 | DOI: 10.1016/j.physbeh.2014.03.027.
Previous investigation by our laboratory found that acute hypernatremia potentiates an oxytocinergic tone that inhibits parvocellular neurosecretory neurons in the paraventricular nucleus of the hypothalamus (PVN), attenuates restraint-induced surges in corticosterone (CORT), and reduces anxiety-like behavior in male rats. To investigate the neural mechanisms mediating these effects and extend our findings to a more versatile species, we repeated our studies using laboratory mice. In response to 2.0M NaCl injections, mice had increased plasma sodium concentrations which were associated with a blunted rise in CORT subsequent to restraint challenge relative to 0.15M NaCl injected controls. Immunofluorescent identification of the immediate early gene product Fos found that 2.0M NaCl treatment increased the number of activated neurons producing oxytocin in the PVN. To evaluate the effect of acute hypernatremia on PVN neurons producing corticotropin-releasing hormone (CRH), we used the Cre-lox system to generate mice that produced the red fluorescent protein, tdTomato, in cells that had Cre-recombinase activity driven by CRH gene expression. Analysis of brain tissue from these CRH-reporter mice revealed that 2.0M NaCl treatment caused a dramatic reduction in Fos-positive nuclei specifically in CRH-producing PVN neurons. This altered pattern of activity was predictive of alleviated anxiety-like behavior as mice administered 2.0M NaCl spent more time exploring the open arms of an elevated-plus maze than 0.15M NaCl treated controls. Taken together, these results further implicate an oxytocin-dependent inhibition of CRH neurons in the PVN and demonstrate the impact that slight elevations in plasma sodium have on the hypothalamic-pituitary-adrenocortical axis output and anxiety-like behavior.
Variation in phenotypes from a Bmp-Gata3 genetic pathway is modulated by Shh signaling
Swartz, ME;Lovely, CB;Eberhart, JK;
PMID: 34033651 | DOI: 10.1371/journal.pgen.1009579
We sought to understand how perturbation of signaling pathways and their targets generates variable phenotypes. In humans, GATA3 associates with highly variable defects, such as HDR syndrome, microsomia and choanal atresia. We previously characterized a zebrafish point mutation in gata3 with highly variable craniofacial defects to the posterior palate. This variability could be due to residual Gata3 function, however, we observe the same phenotypic variability in gata3 null mutants. Using hsp:GATA3-GFP transgenics, we demonstrate that Gata3 function is required between 24 and 30 hpf. At this time maxillary neural crest cells fated to generate the palate express gata3. Transplantation experiments show that neural crest cells require Gata3 function for palatal development. Via a candidate approach, we determined if Bmp signaling was upstream of gata3 and if this pathway explained the mutant's phenotypic variation. Using BRE:d2EGFP transgenics, we demonstrate that maxillary neural crest cells are Bmp responsive by 24 hpf. We find that gata3 expression in maxillary neural crest requires Bmp signaling and that blocking Bmp signaling, in hsp:DN-Bmpr1a-GFP embryos, can phenocopy gata3 mutants. Palatal defects are rescued in hsp:DN-Bmpr1a-GFP;hsp:GATA3-GFP double transgenic embryos, collectively demonstrating that gata3 is downstream of Bmp signaling. However, Bmp attenuation does not alter phenotypic variability in gata3 loss-of-function embryos, implicating a different pathway. Due to phenotypes observed in hypomorphic shha mutants, the Sonic Hedgehog (Shh) pathway was a promising candidate for this pathway. Small molecule activators and inhibitors of the Shh pathway lessen and exacerbate, respectively, the phenotypic severity of gata3 mutants. Importantly, inhibition of Shh can cause gata3 haploinsufficiency, as observed in humans. We find that gata3 mutants in a less expressive genetic background have a compensatory upregulation of Shh signaling. These results demonstrate that the level of Shh signaling can modulate the phenotypes observed in gata3 mutants.
The Journal of comparative neurology
Biancardi, V;Yang, X;Ding, X;Passi, D;Funk, GD;Pagliardini, S;
PMID: 37211631 | DOI: 10.1002/cne.25497
Rhythmic inspiratory activity is generated in the preBötzinger complex (preBötC), a neuronal network located bilaterally in the ventrolateral medulla. Cholinergic neurotransmission affects respiratory rhythmogenic neurons and inhibitory glycinergic neurons in the preBötC. Acetylcholine has been extensively investigated given that cholinergic fibers and receptors are present and functional in the preBötC, are important in sleep/wake cycling, and modulate inspiratory frequency through its action on preBötC neurons. Despite its role in modulating inspiratory rhythm, the source of acetylcholine input to the preBötC is not known. In the present study, we used retrograde and anterograde viral tracing approaches in transgenic mice expressing Cre-recombinase driven by the choline acetyltransferase promoter to identify the source of cholinergic inputs to the preBötC. Surprisingly, we observed very few, if any, cholinergic projections originating from the laterodorsal and pedunculopontine tegmental nuclei (LDT/PPT), two main cholinergic, state-dependent systems long hypothesized as the main source of cholinergic inputs to the preBötC. On the contrary, we identified glutamatergic and GABAergic/glycinergic neurons in the PPT/LDT that send projections to the preBötC. Although these neurons contribute minimally to the direct cholinergic modulation of preBötC neurons, they could be involved in state-dependent regulation of breathing. Our data also suggest that the source of cholinergic inputs to the preBötC appears to originate from cholinergic neurons in neighboring regions of the medulla, the intermediate reticular formation, the lateral paragigantocellularis, and the nucleus of the solitary tract.
Voronova A, Yuzwa SA, Wang BS, Zahr S, Syal C, Wang J, Kaplan DR, Miller FD.
PMID: 28472653 | DOI: 10.1016/j.neuron.2017.04.018
During development, newborn interneurons migrate throughout the embryonic brain. Here, we provide evidence that these interneurons act in a paracrine fashion to regulate developmental oligodendrocyte formation. Specifically, we show that medial ganglionic eminence (MGE) interneurons secrete factors that promote genesis of oligodendrocytes from glially biased cortical precursors in culture. Moreover, when MGE interneurons are genetically ablated in vivo prior to their migration, this causes a deficit in cortical oligodendrogenesis. Modeling of the interneuron-precursor paracrine interaction using transcriptome data identifies the cytokine fractalkine as responsible for the pro-oligodendrocyte effect in culture. This paracrine interaction is important in vivo, since knockdown of the fractalkine receptor CX3CR1 in embryonic cortical precursors, or constitutive knockout of CX3CR1, causes decreased numbers of oligodendrocyte progenitor cells (OPCs) and oligodendrocytes in the postnatal cortex. Thus, in addition to their role in regulating neuronal excitability, interneurons act in a paracrine fashion to promote the developmental genesis of oligodendrocytes.
Maynard KR, Kardian A, Hill JL, Mai Y, Barry B, Hallock HL, Jaffe AE, Martinowich K
PMID: 31941661 | DOI: 10.1523/ENEURO.0310-19.2019
Brain-derived neurotrophic factor (BDNF) signals through its cognate receptor tropomyosin receptor kinase B (TrkB) to promote the function of several classes of inhibitory interneurons. We previously reported that loss of BDNF-TrkB signaling in cortistatin (Cort)-expressing interneurons leads to behavioral hyperactivity and spontaneous seizures in mice. We performed bulk RNA sequencing (RNA-seq) from the cortex of mice with disruption of BDNF-TrkB signaling in cortistatin interneurons, and identified differential expression of genes important for excitatory neuron function. Using translating ribosome affinity purification and RNA-seq, we define a molecular profile for Cort-expressing inhibitory neurons and subsequently compare the translatome of normal and TrkB-depleted Cort neurons, revealing alterations in calcium signaling and axon development. Several of the genes enriched in Cort neurons and differentially expressed in TrkB-depleted neurons are also implicated in autism and epilepsy. Our findings highlight TrkB-dependent molecular pathways as critical for the maturation of inhibitory interneurons and support the hypothesis that loss of BDNF signaling in Cort interneurons leads to altered excitatory/inhibitory balance
Iwasaki, M;Lefevre, A;Althammer, F;Clauss Creusot, E;Łąpieś, O;Petitjean, H;Hilfiger, L;Kerspern, D;Melchior, M;Küppers, S;Krabichler, Q;Patwell, R;Kania, A;Gruber, T;Kirchner, MK;Wimmer, M;Fröhlich, H;Dötsch, L;Schimmer, J;Herpertz, SC;Ditzen, B;Schaaf, CP;Schönig, K;Bartsch, D;Gugula, A;Trenk, A;Blasiak, A;Stern, JE;Darbon, P;Grinevich, V;Charlet, A;
PMID: 36828816 | DOI: 10.1038/s41467-023-36641-7
The hypothalamic neuropeptide oxytocin (OT) exerts prominent analgesic effects via central and peripheral action. However, the precise analgesic pathways recruited by OT are largely elusive. Here we discovered a subset of OT neurons whose projections preferentially terminate on OT receptor (OTR)-expressing neurons in the ventrolateral periaqueductal gray (vlPAG). Using a newly generated line of transgenic rats (OTR-IRES-Cre), we determined that most of the vlPAG OTR expressing cells targeted by OT projections are GABAergic. Ex vivo stimulation of parvocellular OT axons in the vlPAG induced local OT release, as measured with OT sensor GRAB. In vivo, optogenetically-evoked axonal OT release in the vlPAG of as well as chemogenetic activation of OTR vlPAG neurons resulted in a long-lasting increase of vlPAG neuronal activity. This lead to an indirect suppression of sensory neuron activity in the spinal cord and strong analgesia in both female and male rats. Altogether, we describe an OT-vlPAG-spinal cord circuit that is critical for analgesia in both inflammatory and neuropathic pain models.
