Navegando por Autor "Borges, Thawann Malfatti"

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Decreasing dorsal cochlear nucleus activity ameliorates noise-induced tinnitus perception in mice
(Springer Science and Business Media LLC, 2022-05-12) Borges, Thawann Malfatti; Boerner, Barbara Ciralli; Hilscher, Markus M.; Leao, Richardson Naves; Leão, Emelie Katarina Svahn
Background: The dorsal cochlear nucleus (DCN) is a region known to integrate somatosensory and auditory inputs and is identified as a potential key structure in the generation of phantom sound perception, especially noise-induced tinnitus. Yet, how altered homeostatic plasticity of the DCN induces and maintains the sensation of tinnitus is not clear. Here, we chemogenetically decrease activity of a subgroup of DCN neurons, Ca2+/Calmodulin kinase 2 α (CaMKII α)-positive DCN neurons, using Gi-coupled human M4 Designer Receptors Exclusively Activated by Designer Drugs (hM4Di DREADDs), to investigate their role in noise-induced tinnitus. Results: Mice were exposed to loud noise (9–11kHz, 90dBSPL, 1h, followed by 2h of silence), and auditory brainstem responses (ABRs) and gap prepulse inhibition of acoustic startle (GPIAS) were recorded 2 days before and 2 weeks after noise exposure to identify animals with a significantly decreased inhibition of startle, indicating tinnitus but without permanent hearing loss. Neuronal activity of CaMKII α+ neurons expressing hM4Di in the DCN was lowered by administration of clozapine-N-oxide (CNO). We found that acutely decreasing firing rate of CaMKII α+ DCN units decrease tinnitus-like responses (p = 3e −3, n = 11 mice), compared to the control group that showed no improvement in GPIAS (control virus; CaMKII α-YFP + CNO, p = 0.696, n = 7 mice). Extracellular recordings confirmed CNO to decrease unit firing frequency of CaMKII α-hM4Di+ mice and alter best frequency and tuning width of response to sound. However, these effects were not seen if CNO had been previously administered during the noise exposure (n = 6 experimental and 6 control mice). Conclusion: We found that lowering DCN activity in mice displaying tinnitus-related behavior reduces tinnitus, but lowering DCN activity during noise exposure does not prevent noise-induced tinnitus. Our results suggest that CaMKII α-positive cells in the DCN are not crucial for tinnitus induction but play a significant role in maintaining tinnitus perception in mice
Loud noise-exposure changes the firing frequency of subtypes of layer 5 pyramidal neurons and Martinotti cells in the mouse auditory cortex
(Frontiers Media SA, 2023-05) Sousa, Íngrid Nogueira; Lima, Thiago Zaqueu de; Borges, Thawann Malfatti; Leão, Emelie Katarina Svahn
Introduction: Loud noise-exposure can generate noise-induced tinnitus in both humans and animals. Imaging and in vivo studies show that noise exposure affects the auditory cortex; however, cellular mechanisms of tinnitus generation are unclear. Methods: Here we compare membrane properties of layer 5 (L5) pyramidal cells (PCs) and Martinotti cells expressing the cholinergic receptor nicotinic alpha 2 subunit gene (Chrna2) of the primary auditory cortex (A1) from control and noise-exposed (4–18 kHz, 90 dB, 1.5 h, followed by 1.5 h silence) 5–8 week old mice. PCs were furthermore classified in type A or type B based on electrophysiological membrane properties, and a logistic regression model predicting that afterhyperpolarization (AHP) and afterdepolarization (ADP) are sufficient to predict cell type, and these features are preserved after noise trauma. Results: One week after a loud noise-exposure no passive membrane properties of type A or B PCs were altered but principal component analysis showed greater separation between type A PCs from control and noise-exposed mice. When comparing individual firing properties, noise exposure differentially affected type A and B PC firing frequency in response to depolarizing current steps. Specifically, type A PCs decreased initial firing frequency in response to +200 pA steps (p = 0.020) as well as decreased steady state firing frequency (p = 0.050) while type B PCs, on the contrary, significantly increased steady state firing frequency (p = 0.048) in response to a + 150 pA step 1 week after noise exposure. In addition, L5 Martinotti cells showed a more hyperpolarized resting membrane potential (p = 0.04), higher rheobase (p = 0.008) and an increased initial (p = 8.5 × 10–5) and steady state firing frequency (p = 6.3 × 10–5) in slices from noise-exposed mice compared to control. Discussion: These results show that loud noise can cause distinct effects on type A and B L5 PCs and inhibitory Martinotti cells of the primary auditory cortex 1 week following noise exposure. As the L5 comprises PCs that send feedback to other areas, loud noise exposure appears to alter levels of activity of the descending and contralateral auditory system
The role of activity of the dorsal cochlear nucleus in tinnitus perception in mice
(Universidade Federal do Rio Grande do Norte, 2020-03-27) Borges, Thawann Malfatti; Leão, Emelie Katarina Svahn; ; ; Rosa, Marine Raquel Diniz da; ; Vasconcelos, Nivaldo Antonio Portela de; ; Leão, Richardson Naves; ; Pereira, Rodrigo Neves Romcy; ; Maciel, Sérgio Túlio Neuenschwander;
Tinnitus induzido por ru´ıdo ´e a percep¸c˜ao aguda ou crˆonica de um som fantasma, sem fonte f´ısica, causada pela exposi¸c˜ao excessiva ao ru´ıdo intenso. Os pacientes com tinnitus que relatam incˆomodo causado pelo tinnitus frequentemente sofrem de aumento de ansiedade, estresse, falta de concentra¸c˜ao, insˆonia e depress˜ao, condi¸c˜oes que podem diminuir severamente a qualidade de vida. Ainda n˜ao h´a cura ou uma op¸c˜ao de tratamento confi´avel para o tinnitus, destacando que mais estudos dos mecanismos celulares por tr´as da gera¸c˜ao e manuten¸c˜ao do tinnitus s˜ao necess´arios. O n´ucleo coclear dorsal (DCN), uma regi˜ao do tronco encef´alico conhecida por integrar inputs somatosensoriais e auditivos, foi identificado como uma potencial estrutura chave na gera¸c˜ao do tinnitus. No entanto, ainda faltam estudos investigando o efeito da manipula¸c˜ao de subgrupos de neurˆonios do DCN no tinnitus in vivo. Aqui, mostramos primeiro como a estimula¸c˜ao optogen´etica de c´elulas do DCN expressando prote´ınas para ativar (CaMKIIα-ChR2) ou inibir (CaMKIIα-eArch3.0) neurˆonios expressando o promotor gen´etico calcium/calmodulin-dependent protein kinase type II α pode modular diferentes respostas de unidades do DCN a sons simples. Nossos resultados mostram que esses neurˆonios s˜ao altamente interessantes para modular o processamento do som do tronco encef´alico auditivo. Em seguida, em camundongos com tinnitus induzido por ru´ıdo, mostramos que nossa exposi¸c˜ao ao ru´ıdo n˜ao leva `a perda auditiva, mas muda a percep¸c˜ao de uma lacuna de silˆencio no ru´ıdo de fundo antes de um sobressalto ac´ustico. Isto indica que os camundongos tˆem tinnitus em uma freq¨uˆencia espec´ıfica que ´e igualada pelo som de fundo testado. A seguir mostramos que a inibi¸c˜ao quimiogen´etica das c´elulas do DCN expressando CaMKIIα-hM4Di, uma prote´ına sint´etica que diminui a excitabilidade de neurˆonios, pode diminuir significativamente o tinnitus (p = 0.038, n = 11 camundongos) em compara¸c˜ao com os camundongos controle, que n˜ao mostraram melhora no tinnitus (v´ırus controle; CaMKIIα-eYFP, p = 0.696, n = 7 camundongos). Os registros de unidades confirmaram inibi¸c˜ao quimiogen´etica da atividade de c´elulas do DCN expressando CaMKIIα-hM4Di. Especificamente, a diminui¸c˜ao da excitabilidade das unidades do DCN usando receptores quimiogen´eticos de prote´ına g ativados por baixas doses de clozapina-N-´oxido diminuiu a freq¨uˆencia de disparo, modulou a melhor freq¨uˆencia e largura da curva de resposta por frequˆencia de unidades do DCN que respondem a som. Em seguida, para examinar se esta popula¸c˜ao ´e necess´aria para gerar tinnitus induzido pelo ru´ıdo, os neurˆonios do DCN expressando CaMKIIα-hM4Di foram inibidos quimiogeneticamente durante a indu¸c˜ao do tinnitus (n = 6 camundongos experimentais e 6 camundongos controle), mas tal manipula¸c˜ao n˜ao impediu o surgimento do tinnitus, nem a inibi¸c˜ao quimiogenetica 2 semanas depois diminuiu a percep¸c˜ao do tinnitus. Nossos resultados sugerem que as c´elulas do DCN expressando CaMKIIα-hM4Di n˜ao s˜ao cruciais para a indu¸c˜ao do tinnitus, mas desempenham um papel significativo na manuten¸c˜ao do tinnitus em camundongos. Este estudo acrescenta a compreens˜ao do papel de um subgrupo de c´elulas do DCN no tinnitus, apontando para um alvo potencial para interven¸c˜oes de tinnitus.
Unraveling the role of Slc10a4 in auditory processing and sensory motor gating: Implications for neuropsychiatric disorders?
(Elsevier BV, 2023-12) Boerner, Barbara Ciralli; Borges, Thawann Malfatti; Hilscher, Markus M; Leao, Richardson Naves; Cederroth, Christopher R; Leão, Emelie Katarina Svahn; Kullander, Klas
Background: Psychiatric disorders, such as schizophrenia, are complex and challenging to study, partly due to the lack of suitable animal models. However, the absence of the Slc10a4 gene, which codes for a monoaminergic and cholinergic associated vesicular transporter protein, in knockout mice (Slc10a4-/-), leads to the accumulation of extracellular dopamine. A major challenge for studying schizophrenia is the lack of suitable animal models that accurately represent the disorder. We sought to overcome this challenge by using Slc10a4-/- mice as a potential model, considering their altered dopamine levels. This makes them a potential animal model for schizophrenia, a disorder known to be associated with altered dopamine signaling in the brain. Methods: The locomotion, auditory sensory filtering and prepulse inhibition (PPI) of Slc10a4-/- mice were quantified and compared to wildtype (WT) littermates. Intrahippocampal electrodes were used to record auditory event-related potentials (aERPs) for quantifying sensory filtering in response to paired-clicks. The channel above aERPs phase reversal was chosen for reliably comparing results between animals, and aERPs amplitude and latency of click responses were quantified. WT and Slc10a4-/- mice were also administered subanesthetic doses of ketamine to provoke psychomimetic behavior. Results: Baseline locomotion during auditory stimulation was similar between Slc10a4-/- mice and WT littermates. In WT animals, normal auditory gating was observed after i.p saline injections, and it was maintained under the influence of 5 mg/kg ketamine, but disrupted by 20 mg/kg ketamine. On the other hand, Slc10a4-/- mice did not show significant differences between N40 S1 and S2 amplitude responses in saline or low dose ketamine treatment. Auditory gating was considered preserved since the second N40 peak was consistently suppressed, but with increased latency. The P80 component showed higher amplitude, with shorter S2 latency under saline and 5 mg/kg ketamine treatment in Slc10a4-/- mice, which was not observed in WT littermates. Prepulse inhibition was also decreased in Slc10a4-/- mice when the longer interstimulus interval of 100 ms was applied, compared to WT littermates. Conclusion: The Slc10a4-/- mice responses indicate that cholinergic and monoaminergic systems participate in the PPI magnitude, in the temporal coding (response latency) of the auditory sensory gating component N40, and in the amplitude of aERPs P80 component. These results suggest that Slc10a4-/- mice can be considered as potential models for neuropsychiatric conditions
Using cortical neuron markers to target cells in the dorsal cochlear nucleus
(Society for Neuroscience, 2021-02-09) Borges, Thawann Malfatti; Boerner, Barbara Ciralli; Hilscher, Markus M; Edwards, Steven J.; Kullander, Klas; Leão, Richardson Naves; Leão, Emelie Katarina Svahn
The dorsal cochlear nucleus (DCN) is a region of particular interest for auditory and tinnitus research. Yet, lack of useful genetic markers for in vivo manipulations hinders elucidation of the DCN contribution to tinnitus pathophysiology. This work assesses whether adeno-associated viral vectors (AAV) containing the calcium/calmodulin-dependent protein kinase 2 alpha (CaMKIIα) promoter and a mouse line of nicotinic acetylcholine receptor alpha 2 subunit (Chrna2)-Cre can target specific DCN populations. We found that CaMKIIα cannot be used to target excitatory fusiform DCN neurons as labelled cells showed diverse morphology indicating they belong to different classes of DCN neurons. Light stimulation after driving Channelrhodopsin2 by the CaMKIIα promoter generated spikes in some units but firing rate decreased when light stimulation coincided with sound. Expression and activation of CaMKIIα-eArchaerhodopsin3.0 in the DCN produced inhibition in some units but sound-driven spikes were delayed by concomitant light stimulation. We explored the existence of Cre+ cells in the DCN of Chrna2-Cre mice by hydrogel embedding technique (CLARITY). There were almost no Cre+ cell bodies in the DCN; however, we identified profuse projections arising from the ventral cochlear nucleus (VCN). Anterograde labeling in the VCN revealed projections to the ipsilateral superior olive and contralateral medial nucleus of the trapezoid body (bushy cells); and a second bundle terminating in the DCN, suggesting the latter to be excitatory Chrna2+ T-stellate cells. Exciting Chrna2+ cells increased DCN firing. This work shows that cortical molecular tools may be useful for manipulating the DCN especially for tinnitus studies
Validation of optogenetic protein expression in the Dorsal cochlear nucleus: molecular basis for in vitro and in vivo investigation of tinnitus in mice
(Universidade Federal do Rio Grande do Norte, 2015-06-26) Borges, Thawann Malfatti; Leão, Emelie Katarina Svahn; ; http://lattes.cnpq.br/1279823352935722; ; http://lattes.cnpq.br/1262934391596208; Leão, Ricardo Maurício Xavier; ; http://lattes.cnpq.br/8125613125649746; Leão, Richardson Naves; ; http://lattes.cnpq.br/0683942077872227
Tinnitus is the perception of a sound in the absence of a corresponding physical stimulus. It is not clear yet what mechanisms are involved in tinnitus and how it starts and/or becomes chronic. Due to the relationship between tinnitus and somatosensory trauma/stimuli, the dorsal cochlear nucleus (DCN), a region known to integrate somatosensory and auditory pathways, has been identified as a potential key structure in the generation of phantom sound perception. Here, we target specific neuronal populations in the DCN to allow further investigation on how this region may contribute to the generation of tinnitus signals that spread to other auditory areas. We examined the expression of optogenetic proteins (Channelrhodopsin 2 - ChR2; and enhanced Archaerhodopsin 3.0 - eArch3.0), targeting neurons expressing Calmoduline Kinase II alpha (CaMKIIa) promoter in wild-type C57/Bl6 mice and neurons expressing nicotinic acetylcholine receptor subunit alpha-2 promoter (ChRNA2) in ChRNA2- Cre transgenic C57/Bl6 mice, using local virus injection, verified by fluorescence microscopy. Unit responses were differentiated based on their electrophysiological response to sound. We then investigated if firing of neurons expressing optogenetic tools can be controlled in vivo and if the same neurons also fire action potentials in response to precisely timed sound stimulation. Both in vivo and preliminary in vitro data shows that neurons expressing ChR2 do respond to sound, and that they furthermore also can respond to light stimulation with a stable and similar waveform. Moreover, in vivo data shows that neurons expressing eArch3.0, responding to sound, will decrease their firing rate when exposed to green light. Thereby showing that optogenetic tools can be used functionally in the DCN, it is possible to further test tinnitus theories by, for example, producing an increased firing rate in the DCN, trying to mimic tinnitus; or inhibiting increased spontaneous firing rate in the DCN of animals with noise-induced or salycilate-induced tinnitus.

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Navegando por Autor "Borges, Thawann Malfatti"