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  • Society for Neuroscience  (10)
  • Biodiversity Research  (10)
  • 1
    In: The Journal of Neuroscience, Society for Neuroscience, Vol. 28, No. 2 ( 2008-01-09), p. 548-561
    Abstract: Little is known about molecular changes occurring within retinal ganglion cells (RGCs) before their death in glaucoma. Taking advantage of the fact that γ-synuclein (Sncg) mRNA is expressed specifically and highly in adult mouse RGCs, we show in the DBA/2J mouse model of glaucoma that there is not only a loss of cells expressing this gene, but also a downregulation of gene expression of Sncg and many other genes within large numbers of RGCs. This downregulation of gene expression within RGCs occurs together with reductions in FluoroGold (FG) retrograde transport. Surprisingly, there are also large numbers of Sncg-expressing cells without any FG labeling, and among these many that have a marker previously associated with disconnected RGCs, accumulation of phosphorylated neurofilaments in their somas. These same diseased retinas also have large numbers of RGCs that maintain the intraocular portion while losing the optic nerve portion of their axons, and these disconnected axons terminate within the optic nerve head. Our data support the view that RGC degeneration in glaucoma has two separable stages: the first involves atrophy of RGCs, whereas the second involves an insult to axons, which causes the degeneration of axon portions distal to the optic nerve head but does not cause the immediate degeneration of intraretinal portions of axons or the immediate death of RGCs.
    Type of Medium: Online Resource
    ISSN: 0270-6474 , 1529-2401
    Language: English
    Publisher: Society for Neuroscience
    Publication Date: 2008
    detail.hit.zdb_id: 1475274-8
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  • 2
    In: The Journal of Neuroscience, Society for Neuroscience, Vol. 33, No. 42 ( 2013-10-16), p. 16627-16641
    Abstract: Topically applied camphor elicits a sensation of cool, but nothing is known about how it affects cold temperature sensing. We found that camphor sensitizes a subpopulation of menthol-sensitive native cutaneous nociceptors in the mouse to cold, but desensitizes and partially blocks heterologously expressed TRPM8 (transient receptor potential cation channel subfamily M member 8). In contrast, camphor reduces potassium outward currents in cultured sensory neurons and, in cold nociceptors, the cold-sensitizing effects of camphor and menthol are additive. Using a membrane potential dye-based screening assay and heterologously expressed potassium channels, we found that the effects of camphor are mediated by inhibition of K v 7.2/3 channels subtypes that generate the M-current in neurons. In line with this finding, the specific M-current blocker XE991 reproduced the cold-sensitizing effect of camphor in nociceptors. However, the M-channel blocking effects of XE991 and camphor are not sufficient to initiate cold transduction but require a cold-activated inward current generated by TRPM8. The cold-sensitizing effects of XE991 and camphor are largest in high-threshold cold nociceptors. Low-threshold corneal cold thermoreceptors that express high levels of TRPM8 and lack potassium channels are not affected by camphor. We also found that menthol—like camphor—potently inhibits K v 7.2/3 channels. The apparent functional synergism arising from TRPM8 activation and M-current block can improve the effectiveness of topical coolants and cooling lotions, and may also enhance TRPM8-mediated analgesia.
    Type of Medium: Online Resource
    ISSN: 0270-6474 , 1529-2401
    Language: English
    Publisher: Society for Neuroscience
    Publication Date: 2013
    detail.hit.zdb_id: 1475274-8
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  • 3
    Online Resource
    Online Resource
    Society for Neuroscience ; 2019
    In:  The Journal of Neuroscience Vol. 39, No. 11 ( 2019-03-13), p. 2025-2040
    In: The Journal of Neuroscience, Society for Neuroscience, Vol. 39, No. 11 ( 2019-03-13), p. 2025-2040
    Abstract: Microglia play important roles in shaping the developing CNS, and at early stages they have been proposed to regulate progenitor proliferation, differentiation, and neuronal survival. However, these studies reveal contradictory outcomes, highlighting the complexity of these cell–cell interactions. Here, we investigate microglia function during embryonic mouse retina development, where only microglia, progenitors, and neurons are present. In both sexes, we determine that microglia primarily interact with retinal neurons and find that depletion of microglia via conditional KO of the Csf1 receptor results in increased density of retinal ganglion cells (RGCs). Pharmacological inhibition of microglia also results in an increase in RGCs, with no effect on retinal progenitor proliferation, RGC genesis, or apoptosis. We show that microglia in the embryonic retina are enriched for phagocytic markers and observe engulfment of nonapoptotic Brn3-labeled RGCs. We investigate the molecular pathways that can mediate cell engulfment by microglia and find selective downregulation of complement pathway components with microglia inhibition, and further show that C1q protein marks a subset of RGCs in the embryonic retina. KO of complement receptor 3 ( CR3; Itgam ), which is only expressed by microglia, results in increased RGC density, similar to what we observed after depletion or inhibition of microglia. Thus, our data suggest that microglia regulate neuron elimination in the embryonic mouse retina by complement-mediated phagocytosis of non-apoptotic newborn RGCs. SIGNIFICANCE STATEMENT Microglia are emerging as active and important participants in regulating neuron number in development, during adult neurogenesis, and following stem cell therapies. However, their role in these contexts and the mechanisms involved are not fully defined. Using a well-characterized in vivo system, we provide evidence that microglia regulate neuronal elimination by complement-mediated engulfment of nonapoptotic neurons. This work provides a significant advancement of the field by defining in vivo molecular mechanisms for microglia-mediated cell elimination. Our data add to a growing body of evidence that microglia are essential for proper nervous system development. In addition, we elucidate microglia function in the developing retina, which may shed light on microglia involvement in the context of retinal injury and disease.
    Type of Medium: Online Resource
    ISSN: 0270-6474 , 1529-2401
    Language: English
    Publisher: Society for Neuroscience
    Publication Date: 2019
    detail.hit.zdb_id: 1475274-8
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  • 4
    In: The Journal of Neuroscience, Society for Neuroscience, Vol. 43, No. 25 ( 2023-06-21), p. 4738-4749
    Abstract: The impact of tau pathology on sleep microarchitecture features, including slow oscillations, spindles, and their coupling, has been understudied, despite the proposed importance of these electrophysiological features toward learning and memory. Dual orexin receptor antagonists (DORAs) are known to promote sleep, but whether and how they affect sleep microarchitecture in the setting of tauopathy is unknown. In the PS19 mouse model of tauopathy MAPT (microtubule-associated protein tau) P301S (both male and female), young PS19 mice 2–3 months old show a sleep electrophysiology signature with markedly reduced spindle duration and power and elevated slow oscillation (SO) density compared with littermate controls, although there is no significant tau hyperphosphorylation, tangle formation, or neurodegeneration at this age. With aging, there is evidence for sleep disruption in PS19 mice, characterized by reduced REM duration, increased non-REM and REM fragmentation, and more frequent brief arousals at the macrolevel and reduced spindle density, SO density, and spindle-SO coupling at the microlevel. In ∼33% of aged PS19 mice, we unexpectedly observed abnormal goal-directed behaviors in REM, including mastication, paw grasp, and forelimb/hindlimb extension, seemingly consistent with REM behavior disorder (RBD). Oral administration of DORA-12 in aged PS19 mice increased non-REM and REM duration, albeit with shorter bout lengths, and increased spindle density, spindle duration, and SO density without change to spindle–SO coupling, power in either the SO or spindle bands, or the arousal index. We observed a significant effect of DORA-12 on objective measures of RBD, thereby encouraging future exploration of DORA effects on sleep-mediated cognition and RBD treatment. SIGNIFICANCE STATEMENT The specific effect of tauopathy on sleep macroarchitecture and microarchitecture throughout aging remains unknown. Our key findings include the following: (1) the identification of a sleep EEG signature constituting an early biomarker of impending tauopathy; (2) sleep physiology deteriorates with aging that are also markers of off-line cognitive processing; (3) the novel observation that dream enactment behaviors reminiscent of RBD occur, likely the first such observation in a tauopathy model; and (4) a dual orexin receptor antagonist is capable of restoring several of the sleep macroarchitecture and microarchitecture abnormalities.
    Type of Medium: Online Resource
    ISSN: 0270-6474 , 1529-2401
    Language: English
    Publisher: Society for Neuroscience
    Publication Date: 2023
    detail.hit.zdb_id: 1475274-8
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  • 5
    Online Resource
    Online Resource
    Society for Neuroscience ; 2023
    In:  The Journal of Neuroscience
    In: The Journal of Neuroscience, Society for Neuroscience
    Abstract: Motor actions, such as reaching or grasping, can be decoded from fMRI activity of early visual cortex in sighted humans. This effect can depend on vision or visual imagery, or alternatively, could be driven by mechanisms independent of visual experience. Here, we show that the actions of reaching in different directions can be reliably decoded from fMRI activity of early visual cortex in congenitally blind humans (both sexes). Thus, neither visual experience nor visual imagery is necessary for early visual cortex to represent action-related information. We also demonstrate that, within early visual cortex of blind humans, the accuracy of reach direction decoding is highest in areas typically representing foveal vision and gradually decreases in areas typically representing peripheral vision. We propose that this might indicate the existence of a predictive, hard-wired mechanism of aligning action and visual spaces. This mechanism might send action-related information primarily to the high-resolution foveal visual areas, which are critical for guiding and online correction of motor actions. Finally, we show that, beyond early visual cortex, the decoding of reach direction in blind humans is most accurate in dorsal stream areas known to be critical for visuo-spatial and visuo-motor integration in the sighted. Thus, these areas can develop space and action representations even in the lifelong absence of vision. Overall, our findings in congenitally blind humans match previous research on the action system in the sighted, and suggest that the development of action representations in the human brain might be largely independent of visual experience. Significance Statement Early visual cortex (EVC) was traditionally thought to process only visual signals from the retina. Recent studies proved this account incomplete, and showed EVC involvement in many activities not directly related to incoming visual information, such as memory, sound, or action processing. Is EVC involved in these activities because of visual imagery? Here, we show robust reach direction representation in EVC of humans born blind. This demonstrates that EVC can represent actions independently of vision and visual imagery. Beyond EVC, we found that reach direction representation in blind humans is strongest in dorsal brain areas, critical for action processing in the sighted. This suggests that the development of action representations in the human brain is largely independent of visual experience.
    Type of Medium: Online Resource
    ISSN: 0270-6474 , 1529-2401
    Language: English
    Publisher: Society for Neuroscience
    Publication Date: 2023
    detail.hit.zdb_id: 1475274-8
    SSG: 12
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  • 6
    Online Resource
    Online Resource
    Society for Neuroscience ; 2016
    In:  The Journal of Neuroscience Vol. 36, No. 45 ( 2016-11-09), p. 11435-11439
    In: The Journal of Neuroscience, Society for Neuroscience, Vol. 36, No. 45 ( 2016-11-09), p. 11435-11439
    Abstract: Cold temperature detection involves the process of sensory transduction in cutaneous primary sensory nerve terminals, which converts thermal stimuli into depolarizations of the membrane. This transformation into electrical signals is followed by the subsequent propagation of action potentials in cold-sensitive afferent nerve fibers. A large array of ion channels shapes this process; however, the precise contribution of specific ion channel subtypes to cold perception and cold pain remains elusive. This review aims at giving an update on our current understanding of the role played by TRPs, leak K + and voltage-gated Na + and K + channels in the transduction of cold by nociceptors and in cold-induced pain.
    Type of Medium: Online Resource
    ISSN: 0270-6474 , 1529-2401
    Language: English
    Publisher: Society for Neuroscience
    Publication Date: 2016
    detail.hit.zdb_id: 1475274-8
    SSG: 12
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  • 7
    Online Resource
    Online Resource
    Society for Neuroscience ; 2004
    In:  The Journal of Neuroscience Vol. 24, No. 36 ( 2004-09-08), p. 7814-7820
    In: The Journal of Neuroscience, Society for Neuroscience, Vol. 24, No. 36 ( 2004-09-08), p. 7814-7820
    Abstract: In the mature cochlea, inner hair cells (IHCs) transduce acoustic signals into receptor potentials, communicating to the brain by synaptic contacts with afferent fibers. Before the onset of hearing, a transient efferent innervation is found on IHCs, mediated by a nicotinic cholinergic receptor that may contain both α9 and α10 subunits. Calcium influx through that receptor activates calcium-dependent (SK2-containing) potassium channels. This inhibitory synapse is thought to disappear after the onset of hearing [after postnatal day 12 (P12)]. We documented this developmental transition using whole-cell recordings from IHCs in apical turns of the rat organ of Corti. Acetylcholine elicited ionic currents in 88-100% of IHCs between P3 and P14, but in only 1 of 11 IHCs at P16-P22. Potassium depolarization of efferent terminals caused IPSCs in 67% of IHCs at P3, in 100% at P7-P9, in 93% at P10-P12, but in only 40% at P13-P14 and in none of the IHCs tested between P16 and P22. Earlier work had shown by in situ hybridization that α9 mRNA is expressed in adult IHCs but thatα10 mRNA disappears after the onset of hearing. In the present study, antibodies toα10 and to the associated calcium-dependent (SK2) potassium channel showed a similar developmental loss. The correlated expression of these gene products with functional innervation suggests that Alpha10 and SK2 , but not Alpha9, are regulated by synaptic activity. Furthermore, this developmental knock-out of α10, but not α9, supports the hypothesis that functional nicotinic acetylcholine receptors in hair cells are heteromers containing both these subunits.
    Type of Medium: Online Resource
    ISSN: 0270-6474 , 1529-2401
    Language: English
    Publisher: Society for Neuroscience
    Publication Date: 2004
    detail.hit.zdb_id: 1475274-8
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  • 8
    In: The Journal of Neuroscience, Society for Neuroscience, Vol. 28, No. 11 ( 2008-03-12), p. 2735-2744
    Abstract: Glaucoma is characterized by retinal ganglion cell (RGC) pathology and a progressive loss of vision. Previous studies suggest RGC death is responsible for vision loss in glaucoma, yet evidence from other neurodegenerative diseases suggests axonal degeneration, in the absence of neuronal loss, can significantly affect neuronal function. To characterize RGC degeneration in the DBA/2 mouse model of glaucoma, we quantified RGCs in mice of various ages using neuronal-specific nuclear protein (NeuN) immunolabeling, retrograde labeling, and optic nerve axon counts. Surprisingly, the number of NeuN-labeled RGCs did not decline significantly until 18 months of age, at which time a significant decrease in RGC somal size was also observed. Axon dysfunction and degeneration occurred before loss of NeuN-positive RGCs, because significant declines in RGC number assayed by retrograde tracers and axon counts were observed at 13 months. To examine whether axonal dysfunction/degeneration affected gene expression in RGC axons or somas, NeuN and neurofilament-heavy (NF-H) immunolabeling was performed along with quantitative reverse transcription-PCR for RGC-specific genes in retinas of aged DBA/2 mice. Although these mice had similar numbers of NeuN-positive RGCs, the expression of neurofilament light, Brn-3b, and Sncg mRNA varied; this variation in RGC-specific gene expression was correlated with the appearance of NF-H immunoreactive RGC axons. Together, these data support a progression of RGC degeneration in this model of glaucoma, beginning with loss of retrograde label, where axon dysfunction and degeneration precede neuronal loss. This progression of degeneration suggests a need to examine the RGC axon as a locus of pathology in glaucoma.
    Type of Medium: Online Resource
    ISSN: 0270-6474 , 1529-2401
    Language: English
    Publisher: Society for Neuroscience
    Publication Date: 2008
    detail.hit.zdb_id: 1475274-8
    SSG: 12
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  • 9
    In: The Journal of Neuroscience, Society for Neuroscience, Vol. 30, No. 19 ( 2010-05-12), p. 6751-6762
    Abstract: Acetylcholine is the major neurotransmitter of the olivocochlear efferent system, which provides feedback to cochlear hair cells and sensory neurons. To study the role of cochlear muscarinic receptors, we studied receptor localization with immunohistochemistry and reverse transcription-PCR and measured olivocochlear function, cochlear responses, and histopathology in mice with targeted deletion of each of the five receptor subtypes. M 2 , M 4 , and M 5 were detected in microdissected immature (postnatal days 10–13) inner hair cells and spiral ganglion cells but not outer hair cells. In the adult (6 weeks), the same transcripts were found in microdissected organ of Corti and spiral ganglion samples. M 2 protein was found, by immunohistochemistry, in olivocochlear fibers in both outer and inner hair cell areas. M 3 mRNA was amplified only from whole cochleas, and M 1 message was never seen in wild-type ears. Auditory brainstem responses (ABRs) and distortion product otoacoustic emissions (DPOAEs) were unaffected by loss of G q -coupled receptors (M 1 , M 3 , or M 5 ), as were shock-evoked olivocochlear effects and vulnerability to acoustic injury. In contrast, loss of G i -coupled receptors (M 2 and/or M 4 ) decreased neural responses without affecting DPOAEs (at low frequencies). This phenotype and the expression pattern are consistent with excitatory muscarinic signaling in cochlear sensory neurons. At high frequencies, both ABRs and DPOAEs were attenuated by loss of M 2 and/or M 4 , and the vulnerability to acoustic injury was dramatically decreased. This aspect of the phenotype and the expression pattern are consistent with a presynaptic role for muscarinic autoreceptors in decreasing ACh release from olivocochlear terminals during high-level acoustic stimulation and suggest that muscarinic antagonists could enhance the resistance of the inner ear to noise-induced hearing loss.
    Type of Medium: Online Resource
    ISSN: 0270-6474 , 1529-2401
    Language: English
    Publisher: Society for Neuroscience
    Publication Date: 2010
    detail.hit.zdb_id: 1475274-8
    SSG: 12
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  • 10
    In: The Journal of Neuroscience, Society for Neuroscience, Vol. 31, No. 4 ( 2011-01-26), p. 1267-1278
    Abstract: Cells of the inner ear face constant metabolic and structural stress. Exposure to intense sound or certain drugs destroys cochlea hair cells, which in mammals do not regenerate. Thus, an endogenous stress response system may exist within the cochlea to protect it from everyday stressors. We recently described the existence of corticotropin-releasing factor (CRF) in the mouse cochlea. The CRF receptor type 1 (CRFR1) is considered the primary and canonical target of CRF signaling, and systemically it plays an essential role in coordinating the body-wide stress response via activation of the hypothalamic-pituitary-adrenal (HPA) axis. Here, we describe an essential role for CRFR1 in auditory system development and function, and offer the first description of a complete HPA equivalent signaling system resident within the cochlea. To reveal the role of CRFR1 activation in the cochlea, we have used mice carrying a null ablation of the CRFR1 gene. CRFR1 −/− mice exhibited elevated auditory thresholds at all frequencies tested, indicating reduced sensitivity. Furthermore, our results suggest that CRFR1 has a developmental role affecting inner hair cell morphology and afferent and efferent synapse distribution. Given the role of HPA signaling in maintaining local homeostasis in other tissues, the presence of a cochlear HPA signaling system suggests important roles for CRFR1 activity in setting cochlear sensitivity, perhaps both neural and non-neural mechanisms. These data highlight the complex pleiotropic mechanisms modulated by CRFR1 signaling in the cochlea.
    Type of Medium: Online Resource
    ISSN: 0270-6474 , 1529-2401
    Language: English
    Publisher: Society for Neuroscience
    Publication Date: 2011
    detail.hit.zdb_id: 1475274-8
    SSG: 12
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