Barbara Morley - Academia.edu (original) (raw)

Papers by Barbara Morley

Research paper thumbnail of Distinctive Roles for α7*- and α9*-Nicotinic Acetylcholine Receptors in Inflammatory and Autoimmune Responses in the Murine Experimental Autoimmune Encephalomyelitis Model of Multiple Sclerosis

Frontiers in Cellular Neuroscience, Sep 22, 2017

(2017) Distinctive Roles for α7 *-and α9 *-Nicotinic Acetylcholine Receptors in Inflammatory and ... more (2017) Distinctive Roles for α7 *-and α9 *-Nicotinic Acetylcholine Receptors in Inflammatory and Autoimmune Responses in the Murine Experimental Autoimmune Encephalomyelitis Model of Multiple Sclerosis.

Research paper thumbnail of Comparison of the Anti-inflammatory Properties of Two Nicotinic Acetylcholine Receptor Ligands, Phosphocholine and pCF3-diEPP

Frontiers in Cellular Neuroscience

Activation of nicotinic acetylcholine receptors (nAChRs) expressed by innate immune cells can att... more Activation of nicotinic acetylcholine receptors (nAChRs) expressed by innate immune cells can attenuate pro-inflammatory responses. Silent nAChR agonists, which down-modulate inflammation but have little or no ionotropic activity, are of outstanding clinical interest for the prevention and therapy of numerous inflammatory diseases. Here, we compare two silent nAChR agonists, phosphocholine, which is known to interact with nAChR subunits α7, α9, and α10, and pCF3-N,N-diethyl-N′-phenyl-piperazine (pCF3-diEPP), a previously identified α7 nAChR silent agonist, regarding their anti-inflammatory properties and their effects on ionotropic nAChR functions. The lipopolysaccharide (LPS)-induced release of interleukin (IL)-6 by primary murine macrophages was inhibited by pCF3-diEPP, while phosphocholine was ineffective presumably because of instability. In human whole blood cultures pCF3-diEPP inhibited the LPS-induced secretion of IL-6, TNF-α and IL-1β. The ATP-mediated release of IL-1β by LP...

Research paper thumbnail of Attenuation in Nicotinic Acetylcholine Receptor α9 and α10 Subunit Double Knock-Out Mice of Experimental Autoimmune Encephalomyelitis

Biomolecules, 2019

Experimental autoimmune encephalomyelitis (EAE) is attenuated in nicotinic acetylcholine receptor... more Experimental autoimmune encephalomyelitis (EAE) is attenuated in nicotinic acetylcholine receptor (nAChR) α9 subunit knock-out (α9 KO) mice. However, protection is incomplete, raising questions about roles for related, nAChR α10 subunits in ionotropic or recently-revealed metabotropic contributions to effects. Here, we demonstrate reduced EAE severity and delayed onset of disease signs in nAChR α9/α10 subunit double knock-out (DKO) animals relative to effects in wild-type (WT) control mice. These effects are indistinguishable from contemporaneously-observed effects in nicotine-treated WT or in α9 KO mice. Immune cell infiltration into the spinal cord and brain, reactive oxygen species levels in vivo, and demyelination, mostly in the spinal cord, are reduced in DKO mice. Disease severity is not altered relative to WT controls in mice harboring a gain-of-function mutation in α9 subunits. These findings minimize the likelihood that additional deletion of nAChR α10 subunits impacts dise...

Research paper thumbnail of Distinctive Roles for α7*- and α9*-Nicotinic Acetylcholine Receptors in Inflammatory and Autoimmune Responses in the Murine Experimental Autoimmune Encephalomyelitis Model of Multiple Sclerosis

Frontiers in Cellular Neuroscience, 2017

(2017) Distinctive Roles for α7 *-and α9 *-Nicotinic Acetylcholine Receptors in Inflammatory and ... more (2017) Distinctive Roles for α7 *-and α9 *-Nicotinic Acetylcholine Receptors in Inflammatory and Autoimmune Responses in the Murine Experimental Autoimmune Encephalomyelitis Model of Multiple Sclerosis.

Research paper thumbnail of Nicotinic Acetylcholine Receptors Modulate Bone Marrow-Derived Pro-Inflammatory Monocyte Production and Survival

PloS one, 2016

It is increasingly clear that nicotinic acetylcholine receptors (nAChRs) are involved in immune r... more It is increasingly clear that nicotinic acetylcholine receptors (nAChRs) are involved in immune regulation, and that their activation can protect against inflammatory diseases. Previous data have shown that nicotine diminishes the numbers of peripheral monocytes and macrophages, especially those of the pro-inflammatory phenotype. The goal of the present study was to determine if nicotine modulates the production of bone marrow -derived monocytes/macrophages. In this study, we first found that murine bone marrow cells express multiple nAChR subunits, and that the α7 and α9 nAChRs most predominant subtypes found in immune cells and their precursors. Using primary cultures of murine bone marrow cells, we then determined the effect of nicotine on monocyte colony-stimulating factor and interferon gamma (IFNγ)-induced monocyte production. We found that nicotine lowered the overall number of monocytes, and more specifically, inhibited the IFNγ-induced increase in pro-inflammatory monocytes...

Research paper thumbnail of Differential modulation of EAE by α9*‐ and β2*‐nicotinic acetylcholine receptors

Immunology & Cell Biology, 2013

Nicotine is a potent inhibitor of the immune response and is protective against experimental auto... more Nicotine is a potent inhibitor of the immune response and is protective against experimental autoimmune encephalomyelitis (EAE). Initial studies suggested that the cholinergic system modulates inflammation via the α7‐nicotinic acetylcholine receptor (nAChR) subtype. We recently have shown that effector T cells and myeloid cells constitutively express mRNAs encoding nAChR α9 and β2 subunits and found evidence for immune system roles for non‐α7‐nAChRs. In the present study, we assessed the effects of nAChR α9 or β2 subunit gene deletion on EAE onset and severity, with or without nicotine treatment. We report again that disease onset is delayed and severity is attenuated in nicotine‐treated, wild‐type mice, an effect that also is observed in α9 subunit knock‐out (KO) mice irrespective of nicotine treatment. On the other hand, β2 KO mice fail to recover from peak measures of disease severity regardless of nicotine treatment, despite retaining sensitivity to nicotine's attenuation of...

Research paper thumbnail of Ganglionic nAChRs and high‐affinity nicotinic binding sites are not equivalent

FEBS Letters, 1986

High‐affinity (K d ⋍ 10 nM) binding sites for nicotine and acetylcholine (ACh) have recently been... more High‐affinity (K d ⋍ 10 nM) binding sites for nicotine and acetylcholine (ACh) have recently been identified in vertebrate brain. It has been suggested that these sites are desensitized ganglionic (C6) nicotinic acetylcholine receptors (nAChRs). We have tested the pheochromocytoma cell line PC 12, which is known to contain well‐expressed C6 nAChRs, to determine if these nAChRs are associated with high‐affinity [3H]ACh‐binding sites. We found that the high‐affinity nicotinic [3H]ACh‐binding site is absent in PC 12 cells. We also found that the concentration of nicotine or ACh necessary to desensitize carbamylcholine‐stimulated Na+ flux was at least two orders of magnitude greater than the concentrations used in binding experiments. We conclude that high‐affinity nicotinic binding sites are not equivalent to C6 ganglionic receptors.

Research paper thumbnail of Purification and characterization of the α-bungarotoxin binding protein from rat brain

Brain Research, 1985

The a-bungarotoxin (BGT) binding protein from rat brain has been purified and its polypeptide cha... more The a-bungarotoxin (BGT) binding protein from rat brain has been purified and its polypeptide chain composition has been examined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Polypeptide chains with Mrs of 55,000, 53,500 and 49,000 have been identified as constituents of the protein. The affinity ligand [3H]maleimidobenzyl trimethylammonium bromide ([3H]MBTA), used to identify the ligand binding site on neuromuscular junction acetylcholine receptors (NMJ AChRs), binds to the 55,000 dalton polypeptide chain. Using a technique where ligands are bound to the protein while the protein is immobilized on a-cobratoxin-Sepharose 4B, it was established that the brain BGT binding protein, like NMJ AChRs, possesses two binding sites for BGT. These experiments reinforce previous evidence that the brain BGT binding protein is closely related but not identical to NMJ AChRs.

Research paper thumbnail of Generation and Characterization of α9 and α10 Nicotinic Acetylcholine Receptor Subunit Knockout Mice on a C57BL/6J Background

Frontiers in Neuroscience, 2017

We generated constitutive knockout mouse models for the α9 and α10 nicotinic acetylcholine recept... more We generated constitutive knockout mouse models for the α9 and α10 nicotinic acetylcholine receptor (nAChR) subunits by derivation from conditional knockouts by breeding with CRE deleter mice. We then backcrossed them onto a C57BL/6J genetic background. In this manuscript, we report the generation of the strains and an auditory phenotypic characterization of the constitutive α9 and α10 knockouts and a double α9α10 constitutive knockout. Although the α9 and α10 nAChR subunits are relevant to a number of physiological measures, we chose to characterize the mouse with auditory studies to compare them to existing but different α9 and α10 nAChR knockouts (KOs). Auditory brainstem response (ABR) measurements and distortion product otoacoustic emissions (DPOAEs) showed that all constitutive mouse strains had normal hearing. DPOAEs with contralateral noise (efferent adaptation measurements), however, showed that efferent strength was significantly reduced after deletion of both the α9 and α10 subunits, in comparison to wildtype controls. Animals tested were 3-8 weeks of age and efferent strength was not correlated with age. Confocal studies of single and double constitutive KOs showed that all KOs had abnormal efferent innervation of cochlear hair cells. The morphological results are similar to those obtained in other strains using constitutive deletion of exon 4 of α9 or α10 nAChR. The results of our physiological studies, however, differ from previous auditory studies using a α9 KO generated by deletion of the exon 4 region and backcrossed onto a mixed CBA/CaJ X 129Sv background.

Research paper thumbnail of Nicotinic acetylcholine receptors regulate vestibular afferent gain and activation timing

Journal of Comparative Neurology, 2016

Little is known about the function of the cholinergic efferents innervating peripheral vestibular... more Little is known about the function of the cholinergic efferents innervating peripheral vestibular hair cells. We measured vestibular sensory evoked potentials (VsEPs) in α9 knockout (KO) mice, α10 KO mice, α7 KO mice, α9/10 and α7/9 double KO mice, and wild-type (WT) controls. We also studied the morphology and ultra-structure of efferent terminals on vestibular hair cells in α9, α10, and α9/10 KOs. Both type I and type II vestibular hair cells express the α9 and α10 subunits.

Research paper thumbnail of Efferent feedback controls bilateral auditory spontaneous activity

Nature Communications, 2021

In the developing auditory system, spontaneous activity generated in the cochleae propagates into... more In the developing auditory system, spontaneous activity generated in the cochleae propagates into the central nervous system to promote circuit formation. The effects of peripheral firing patterns on spontaneous activity in the central auditory system are not well understood. Here, we describe wide-spread bilateral coupling of spontaneous activity that coincides with the period of transient efferent modulation of inner hair cells from the brainstem medial olivocochlear system. Knocking out α9/α10 nicotinic acetylcholine receptors, a requisite part of the efferent pathway, profoundly reduces bilateral correlations. Pharmacological and chemogenetic experiments confirm that the efferent system is necessary for normal bilateral coupling. Moreover, auditory sensitivity at hearing onset is reduced in the absence of pre-hearing efferent modulation. Together, these results demonstrate how afferent and efferent pathways collectively shape spontaneous activity patterns and reveal the importan...

Research paper thumbnail of Efferent feedback enforces bilateral coupling of spontaneous activity in the developing auditory system

SummaryIn the developing auditory system, spontaneous activity generated in the cochleae propagat... more SummaryIn the developing auditory system, spontaneous activity generated in the cochleae propagates into the central nervous system to promote circuit formation before hearing onset. Effects of the evolving peripheral firing pattern on spontaneous activity in the central auditory system are not well understood. Here, we describe the wide-spread bilateral coupling of spontaneous activity that coincides with the period of transient efferent modulation of inner hair cells from the medial olivochlear (MOC) system. Knocking out the α9/α10 nicotinic acetylcholine receptor, a requisite part of the efferent cholinergic pathway, abolishes these bilateral correlations. Pharmacological and chemogenetic experiments confirm that the MOC system is necessary and sufficient to produce the bilateral coupling. Moreover, auditory sensitivity at hearing onset is reduced in the absence of pre-hearing efferent modulation. Together, our results demonstrate how ascending and descending pathways collectivel...

Research paper thumbnail of Essential role of GluD1 in dendritic spine development and GluN2B to GluN2A NMDAR subunit switch in the cortex and hippocampus reveals ability of GluN2B inhibition in correcting hyperconnectivity

Neuropharmacology, Jan 24, 2015

The glutamate delta-1 (GluD1) receptor is highly expressed in the forebrain. We have previously s... more The glutamate delta-1 (GluD1) receptor is highly expressed in the forebrain. We have previously shown that loss of GluD1 leads to social and cognitive deficits in mice, however, its role in synaptic development and neurotransmission remains poorly understood. Here we report that GluD1 is enriched in the medial prefrontal cortex (mPFC) and GluD1 knockout mice exhibit a higher dendritic spine number, greater excitatory neurotransmission as well as higher number of synapses in mPFC. In addition abnormalities in the LIMK1-cofilin signaling, which regulates spine dynamics, and a lower ratio of GluN2A/GluN2B expression was observed in the mPFC in GluD1 knockout mice. Analysis of the GluD1 knockout CA1 hippocampus similarly indicated the presence of higher spine number and synapses and altered LIMK1-cofilin signaling. We found that systemic administration of an N-methyl-d-aspartate (NMDA) receptor partial agonist d-cycloserine (DCS) at a high-dose, but not at a low-dose, and a GluN2B-selec...

Research paper thumbnail of Glutamate delta-1 receptor regulates dendritic spine morphology and density in cortico-limbic circuit

Research paper thumbnail of Nicotinic Acetylcholine Receptor α9 and α10 Subunits Are Expressed in the Brain of Mice

Frontiers in Cellular Neuroscience, 2017

The α9 and α10 nicotinic acetylcholine receptor (nAChR) subunits are likely to be the evolutionar... more The α9 and α10 nicotinic acetylcholine receptor (nAChR) subunits are likely to be the evolutionary precursors to the entire cys-loop superfamily of ligand-gated ion channels, which includes acetylcholine, GABA, glycine and serotonin ionotropic receptors. nAChRs containing α9 and α10 subunits are found in the inner ear, dorsal root ganglia and many non-excitable tissues, but their expression in the central nervous system has not been definitely demonstrated. Here we show the presence of both α9 and α10 nAChR subunits in the mouse brain by RT-PCR and immunochemical approaches with a range of nAChR subunit-selective antibodies, which selectivity was demonstrated in the brain preparations of α7−/−, α9−/− and α10−/− mice. The α9 and α10 RNA transcripts were found in medulla oblongata (MO), cerebellum, midbrain (MB), thalamus and putamen (TP), somatosensory cortex (SC), frontal cortex (FC) and hippocampus. High α9-selective signal in ELISA was observed in the FC, SC, MO, TP and hippocampus and α10-selective signal was the highest in MO and FC. The α9 and α10 proteins were found in the brain mitochondria, while their presence on the plasma membrane has not been definitely confirmed The α7-, α9and α10-selective antibodies stained mainly neurons and hypertrophied astrocytes, but not microglia. The α9and α10-positive cells formed ordered structures or zones in cerebellum and superior olive (SO) and were randomly distributed among α7-positive cells in the FC; they were found in CA1, CA3 and CA4, but not in CA2 region of the hippocampus. The α9 and α10 subunits were up-regulated in α7−/− mice and both α7 and α9 subunits were down-regulated in α10−/− mice. We conclude that α9 and α10 nAChR subunits are expressed in distinct neurons of the mouse brain and in the brain mitochondria and are compensatory up-regulated in the absence of α7 subunits.

Research paper thumbnail of Distinctive Roles for α7*- and α9*-Nicotinic Acetylcholine Receptors in Inflammatory and Autoimmune Responses in the Murine Experimental Autoimmune Encephalomyelitis Model of Multiple Sclerosis

Frontiers in Cellular Neuroscience, Sep 22, 2017

(2017) Distinctive Roles for α7 *-and α9 *-Nicotinic Acetylcholine Receptors in Inflammatory and ... more (2017) Distinctive Roles for α7 *-and α9 *-Nicotinic Acetylcholine Receptors in Inflammatory and Autoimmune Responses in the Murine Experimental Autoimmune Encephalomyelitis Model of Multiple Sclerosis.

Research paper thumbnail of Comparison of the Anti-inflammatory Properties of Two Nicotinic Acetylcholine Receptor Ligands, Phosphocholine and pCF3-diEPP

Frontiers in Cellular Neuroscience

Activation of nicotinic acetylcholine receptors (nAChRs) expressed by innate immune cells can att... more Activation of nicotinic acetylcholine receptors (nAChRs) expressed by innate immune cells can attenuate pro-inflammatory responses. Silent nAChR agonists, which down-modulate inflammation but have little or no ionotropic activity, are of outstanding clinical interest for the prevention and therapy of numerous inflammatory diseases. Here, we compare two silent nAChR agonists, phosphocholine, which is known to interact with nAChR subunits α7, α9, and α10, and pCF3-N,N-diethyl-N′-phenyl-piperazine (pCF3-diEPP), a previously identified α7 nAChR silent agonist, regarding their anti-inflammatory properties and their effects on ionotropic nAChR functions. The lipopolysaccharide (LPS)-induced release of interleukin (IL)-6 by primary murine macrophages was inhibited by pCF3-diEPP, while phosphocholine was ineffective presumably because of instability. In human whole blood cultures pCF3-diEPP inhibited the LPS-induced secretion of IL-6, TNF-α and IL-1β. The ATP-mediated release of IL-1β by LP...

Research paper thumbnail of Attenuation in Nicotinic Acetylcholine Receptor α9 and α10 Subunit Double Knock-Out Mice of Experimental Autoimmune Encephalomyelitis

Biomolecules, 2019

Experimental autoimmune encephalomyelitis (EAE) is attenuated in nicotinic acetylcholine receptor... more Experimental autoimmune encephalomyelitis (EAE) is attenuated in nicotinic acetylcholine receptor (nAChR) α9 subunit knock-out (α9 KO) mice. However, protection is incomplete, raising questions about roles for related, nAChR α10 subunits in ionotropic or recently-revealed metabotropic contributions to effects. Here, we demonstrate reduced EAE severity and delayed onset of disease signs in nAChR α9/α10 subunit double knock-out (DKO) animals relative to effects in wild-type (WT) control mice. These effects are indistinguishable from contemporaneously-observed effects in nicotine-treated WT or in α9 KO mice. Immune cell infiltration into the spinal cord and brain, reactive oxygen species levels in vivo, and demyelination, mostly in the spinal cord, are reduced in DKO mice. Disease severity is not altered relative to WT controls in mice harboring a gain-of-function mutation in α9 subunits. These findings minimize the likelihood that additional deletion of nAChR α10 subunits impacts dise...

Research paper thumbnail of Distinctive Roles for α7*- and α9*-Nicotinic Acetylcholine Receptors in Inflammatory and Autoimmune Responses in the Murine Experimental Autoimmune Encephalomyelitis Model of Multiple Sclerosis

Frontiers in Cellular Neuroscience, 2017

(2017) Distinctive Roles for α7 *-and α9 *-Nicotinic Acetylcholine Receptors in Inflammatory and ... more (2017) Distinctive Roles for α7 *-and α9 *-Nicotinic Acetylcholine Receptors in Inflammatory and Autoimmune Responses in the Murine Experimental Autoimmune Encephalomyelitis Model of Multiple Sclerosis.

Research paper thumbnail of Nicotinic Acetylcholine Receptors Modulate Bone Marrow-Derived Pro-Inflammatory Monocyte Production and Survival

PloS one, 2016

It is increasingly clear that nicotinic acetylcholine receptors (nAChRs) are involved in immune r... more It is increasingly clear that nicotinic acetylcholine receptors (nAChRs) are involved in immune regulation, and that their activation can protect against inflammatory diseases. Previous data have shown that nicotine diminishes the numbers of peripheral monocytes and macrophages, especially those of the pro-inflammatory phenotype. The goal of the present study was to determine if nicotine modulates the production of bone marrow -derived monocytes/macrophages. In this study, we first found that murine bone marrow cells express multiple nAChR subunits, and that the α7 and α9 nAChRs most predominant subtypes found in immune cells and their precursors. Using primary cultures of murine bone marrow cells, we then determined the effect of nicotine on monocyte colony-stimulating factor and interferon gamma (IFNγ)-induced monocyte production. We found that nicotine lowered the overall number of monocytes, and more specifically, inhibited the IFNγ-induced increase in pro-inflammatory monocytes...

Research paper thumbnail of Differential modulation of EAE by α9*‐ and β2*‐nicotinic acetylcholine receptors

Immunology & Cell Biology, 2013

Nicotine is a potent inhibitor of the immune response and is protective against experimental auto... more Nicotine is a potent inhibitor of the immune response and is protective against experimental autoimmune encephalomyelitis (EAE). Initial studies suggested that the cholinergic system modulates inflammation via the α7‐nicotinic acetylcholine receptor (nAChR) subtype. We recently have shown that effector T cells and myeloid cells constitutively express mRNAs encoding nAChR α9 and β2 subunits and found evidence for immune system roles for non‐α7‐nAChRs. In the present study, we assessed the effects of nAChR α9 or β2 subunit gene deletion on EAE onset and severity, with or without nicotine treatment. We report again that disease onset is delayed and severity is attenuated in nicotine‐treated, wild‐type mice, an effect that also is observed in α9 subunit knock‐out (KO) mice irrespective of nicotine treatment. On the other hand, β2 KO mice fail to recover from peak measures of disease severity regardless of nicotine treatment, despite retaining sensitivity to nicotine's attenuation of...

Research paper thumbnail of Ganglionic nAChRs and high‐affinity nicotinic binding sites are not equivalent

FEBS Letters, 1986

High‐affinity (K d ⋍ 10 nM) binding sites for nicotine and acetylcholine (ACh) have recently been... more High‐affinity (K d ⋍ 10 nM) binding sites for nicotine and acetylcholine (ACh) have recently been identified in vertebrate brain. It has been suggested that these sites are desensitized ganglionic (C6) nicotinic acetylcholine receptors (nAChRs). We have tested the pheochromocytoma cell line PC 12, which is known to contain well‐expressed C6 nAChRs, to determine if these nAChRs are associated with high‐affinity [3H]ACh‐binding sites. We found that the high‐affinity nicotinic [3H]ACh‐binding site is absent in PC 12 cells. We also found that the concentration of nicotine or ACh necessary to desensitize carbamylcholine‐stimulated Na+ flux was at least two orders of magnitude greater than the concentrations used in binding experiments. We conclude that high‐affinity nicotinic binding sites are not equivalent to C6 ganglionic receptors.

Research paper thumbnail of Purification and characterization of the α-bungarotoxin binding protein from rat brain

Brain Research, 1985

The a-bungarotoxin (BGT) binding protein from rat brain has been purified and its polypeptide cha... more The a-bungarotoxin (BGT) binding protein from rat brain has been purified and its polypeptide chain composition has been examined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Polypeptide chains with Mrs of 55,000, 53,500 and 49,000 have been identified as constituents of the protein. The affinity ligand [3H]maleimidobenzyl trimethylammonium bromide ([3H]MBTA), used to identify the ligand binding site on neuromuscular junction acetylcholine receptors (NMJ AChRs), binds to the 55,000 dalton polypeptide chain. Using a technique where ligands are bound to the protein while the protein is immobilized on a-cobratoxin-Sepharose 4B, it was established that the brain BGT binding protein, like NMJ AChRs, possesses two binding sites for BGT. These experiments reinforce previous evidence that the brain BGT binding protein is closely related but not identical to NMJ AChRs.

Research paper thumbnail of Generation and Characterization of α9 and α10 Nicotinic Acetylcholine Receptor Subunit Knockout Mice on a C57BL/6J Background

Frontiers in Neuroscience, 2017

We generated constitutive knockout mouse models for the α9 and α10 nicotinic acetylcholine recept... more We generated constitutive knockout mouse models for the α9 and α10 nicotinic acetylcholine receptor (nAChR) subunits by derivation from conditional knockouts by breeding with CRE deleter mice. We then backcrossed them onto a C57BL/6J genetic background. In this manuscript, we report the generation of the strains and an auditory phenotypic characterization of the constitutive α9 and α10 knockouts and a double α9α10 constitutive knockout. Although the α9 and α10 nAChR subunits are relevant to a number of physiological measures, we chose to characterize the mouse with auditory studies to compare them to existing but different α9 and α10 nAChR knockouts (KOs). Auditory brainstem response (ABR) measurements and distortion product otoacoustic emissions (DPOAEs) showed that all constitutive mouse strains had normal hearing. DPOAEs with contralateral noise (efferent adaptation measurements), however, showed that efferent strength was significantly reduced after deletion of both the α9 and α10 subunits, in comparison to wildtype controls. Animals tested were 3-8 weeks of age and efferent strength was not correlated with age. Confocal studies of single and double constitutive KOs showed that all KOs had abnormal efferent innervation of cochlear hair cells. The morphological results are similar to those obtained in other strains using constitutive deletion of exon 4 of α9 or α10 nAChR. The results of our physiological studies, however, differ from previous auditory studies using a α9 KO generated by deletion of the exon 4 region and backcrossed onto a mixed CBA/CaJ X 129Sv background.

Research paper thumbnail of Nicotinic acetylcholine receptors regulate vestibular afferent gain and activation timing

Journal of Comparative Neurology, 2016

Little is known about the function of the cholinergic efferents innervating peripheral vestibular... more Little is known about the function of the cholinergic efferents innervating peripheral vestibular hair cells. We measured vestibular sensory evoked potentials (VsEPs) in α9 knockout (KO) mice, α10 KO mice, α7 KO mice, α9/10 and α7/9 double KO mice, and wild-type (WT) controls. We also studied the morphology and ultra-structure of efferent terminals on vestibular hair cells in α9, α10, and α9/10 KOs. Both type I and type II vestibular hair cells express the α9 and α10 subunits.

Research paper thumbnail of Efferent feedback controls bilateral auditory spontaneous activity

Nature Communications, 2021

In the developing auditory system, spontaneous activity generated in the cochleae propagates into... more In the developing auditory system, spontaneous activity generated in the cochleae propagates into the central nervous system to promote circuit formation. The effects of peripheral firing patterns on spontaneous activity in the central auditory system are not well understood. Here, we describe wide-spread bilateral coupling of spontaneous activity that coincides with the period of transient efferent modulation of inner hair cells from the brainstem medial olivocochlear system. Knocking out α9/α10 nicotinic acetylcholine receptors, a requisite part of the efferent pathway, profoundly reduces bilateral correlations. Pharmacological and chemogenetic experiments confirm that the efferent system is necessary for normal bilateral coupling. Moreover, auditory sensitivity at hearing onset is reduced in the absence of pre-hearing efferent modulation. Together, these results demonstrate how afferent and efferent pathways collectively shape spontaneous activity patterns and reveal the importan...

Research paper thumbnail of Efferent feedback enforces bilateral coupling of spontaneous activity in the developing auditory system

SummaryIn the developing auditory system, spontaneous activity generated in the cochleae propagat... more SummaryIn the developing auditory system, spontaneous activity generated in the cochleae propagates into the central nervous system to promote circuit formation before hearing onset. Effects of the evolving peripheral firing pattern on spontaneous activity in the central auditory system are not well understood. Here, we describe the wide-spread bilateral coupling of spontaneous activity that coincides with the period of transient efferent modulation of inner hair cells from the medial olivochlear (MOC) system. Knocking out the α9/α10 nicotinic acetylcholine receptor, a requisite part of the efferent cholinergic pathway, abolishes these bilateral correlations. Pharmacological and chemogenetic experiments confirm that the MOC system is necessary and sufficient to produce the bilateral coupling. Moreover, auditory sensitivity at hearing onset is reduced in the absence of pre-hearing efferent modulation. Together, our results demonstrate how ascending and descending pathways collectivel...

Research paper thumbnail of Essential role of GluD1 in dendritic spine development and GluN2B to GluN2A NMDAR subunit switch in the cortex and hippocampus reveals ability of GluN2B inhibition in correcting hyperconnectivity

Neuropharmacology, Jan 24, 2015

The glutamate delta-1 (GluD1) receptor is highly expressed in the forebrain. We have previously s... more The glutamate delta-1 (GluD1) receptor is highly expressed in the forebrain. We have previously shown that loss of GluD1 leads to social and cognitive deficits in mice, however, its role in synaptic development and neurotransmission remains poorly understood. Here we report that GluD1 is enriched in the medial prefrontal cortex (mPFC) and GluD1 knockout mice exhibit a higher dendritic spine number, greater excitatory neurotransmission as well as higher number of synapses in mPFC. In addition abnormalities in the LIMK1-cofilin signaling, which regulates spine dynamics, and a lower ratio of GluN2A/GluN2B expression was observed in the mPFC in GluD1 knockout mice. Analysis of the GluD1 knockout CA1 hippocampus similarly indicated the presence of higher spine number and synapses and altered LIMK1-cofilin signaling. We found that systemic administration of an N-methyl-d-aspartate (NMDA) receptor partial agonist d-cycloserine (DCS) at a high-dose, but not at a low-dose, and a GluN2B-selec...

Research paper thumbnail of Glutamate delta-1 receptor regulates dendritic spine morphology and density in cortico-limbic circuit

Research paper thumbnail of Nicotinic Acetylcholine Receptor α9 and α10 Subunits Are Expressed in the Brain of Mice

Frontiers in Cellular Neuroscience, 2017

The α9 and α10 nicotinic acetylcholine receptor (nAChR) subunits are likely to be the evolutionar... more The α9 and α10 nicotinic acetylcholine receptor (nAChR) subunits are likely to be the evolutionary precursors to the entire cys-loop superfamily of ligand-gated ion channels, which includes acetylcholine, GABA, glycine and serotonin ionotropic receptors. nAChRs containing α9 and α10 subunits are found in the inner ear, dorsal root ganglia and many non-excitable tissues, but their expression in the central nervous system has not been definitely demonstrated. Here we show the presence of both α9 and α10 nAChR subunits in the mouse brain by RT-PCR and immunochemical approaches with a range of nAChR subunit-selective antibodies, which selectivity was demonstrated in the brain preparations of α7−/−, α9−/− and α10−/− mice. The α9 and α10 RNA transcripts were found in medulla oblongata (MO), cerebellum, midbrain (MB), thalamus and putamen (TP), somatosensory cortex (SC), frontal cortex (FC) and hippocampus. High α9-selective signal in ELISA was observed in the FC, SC, MO, TP and hippocampus and α10-selective signal was the highest in MO and FC. The α9 and α10 proteins were found in the brain mitochondria, while their presence on the plasma membrane has not been definitely confirmed The α7-, α9and α10-selective antibodies stained mainly neurons and hypertrophied astrocytes, but not microglia. The α9and α10-positive cells formed ordered structures or zones in cerebellum and superior olive (SO) and were randomly distributed among α7-positive cells in the FC; they were found in CA1, CA3 and CA4, but not in CA2 region of the hippocampus. The α9 and α10 subunits were up-regulated in α7−/− mice and both α7 and α9 subunits were down-regulated in α10−/− mice. We conclude that α9 and α10 nAChR subunits are expressed in distinct neurons of the mouse brain and in the brain mitochondria and are compensatory up-regulated in the absence of α7 subunits.