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1.
J Physiol Sci ; 69(6): 903-917, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31435871

RESUMO

The vestibular system contributes to not only eye movement and posture but also the sympathetic response. Plastic alteration of the vestibulo-sympathetic reflex is induced by hypergravity load; however, the mechanism remains unknown. Here, we examined 2 g-induced changing in responsiveness of CAMK2-expressing neurons in the vestibular nucleus complex using optogenetic tools. The excitatory photostimulation of the CAMK2-expressing neurons in the unilateral vestibular nuclear complex induced body tilt to the contralateral side, while inhibitory photostimulation showed the opposite response. Photoactivation of either cell body or the axonal terminal in the rostral ventrolateral medulla showed sympathoexcitation followed by the pressor response. Furthermore, this response was significantly attenuated (49.8 ± 4%) after the 1st day of 2 g loading, and this value was further reduced by the 5th day (22.4 ± 3%), suggesting that 2 g-induced attenuation of the vestibulo-sympathetic reflex involves at least decrease in responsiveness of CAMK2-expressing neurons in the vestibular nuclear complex.


Assuntos
Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/metabolismo , Hipergravidade , Plasticidade Neuronal/fisiologia , Reflexo/fisiologia , Núcleos Vestibulares/fisiologia , Animais , Pressão Sanguínea , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/genética , Feminino , Regulação da Expressão Gênica/efeitos da radiação , Frequência Cardíaca , Masculino , Neurônios/metabolismo , Ratos , Estilbamidinas
2.
J Neuroinflammation ; 16(1): 67, 2019 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-30927920

RESUMO

BACKGROUND: Patients diagnosed with chronic fatigue syndrome (CFS) or fibromyalgia experience chronic pain. Concomitantly, the rat model of CFS exhibits microglial activation in the lumbar spinal cord and pain behavior without peripheral tissue damage and/or inflammation. The present study addressed the mechanism underlying the association between pain and chronic stress using this rat model. METHODS: Chronic or continuous stress-loading (CS) model rats, housed in a cage with a thin level of water (1.5 cm in depth), were used. The von Frey test and pressure pain test were employed to measure pain behavior. The neuronal and microglial activations were immunohistochemically demonstrated with antibodies against ATF3 and Iba1. Electromyography was used to evaluate muscle activity. RESULTS: The expression of ATF3, a marker of neuronal hyperactivity or injury, was first observed in the lumbar dorsal root ganglion (DRG) neurons 2 days after CS initiation. More than 50% of ATF3-positive neurons simultaneously expressed the proprioceptor markers TrkC or VGluT1, whereas the co-expression rates for TrkA, TrkB, IB4, and CGRP were lower than 20%. Retrograde labeling using fluorogold showed that ATF3-positive proprioceptive DRG neurons mainly projected to the soleus. Substantial microglial accumulation was observed in the medial part of the dorsal horn on the fifth CS day. Microglial accumulation was observed around a subset of motor neurons in the dorsal part of the ventral horn on the sixth CS day. The motor neurons surrounded by microglia were ATF3-positive and mainly projected to the soleus. Electromyographic activity in the soleus was two to three times higher in the CS group than in the control group. These results suggest that chronic proprioceptor activation induces the sequential activation of neurons along the spinal reflex arc, and the neuronal activation further activates microglia along the arc. Proprioceptor suppression by ankle joint immobilization significantly suppressed the accumulation of microglia in the spinal cord, as well as the pain behavior. CONCLUSION: Our results indicate that proprioceptor-induced microglial activation may be a key player in the initiation and maintenance of abnormal pain in patients with CFS.


Assuntos
Citocinas/metabolismo , Síndrome de Fadiga Crônica/complicações , Microglia/patologia , Dor/etiologia , Dor/patologia , Distúrbios Somatossensoriais/etiologia , Fator 3 Ativador da Transcrição/genética , Fator 3 Ativador da Transcrição/metabolismo , Animais , Peptídeo Relacionado com Gene de Calcitonina/metabolismo , Proteínas de Ligação ao Cálcio/metabolismo , Gânglios Espinais/patologia , Regulação da Expressão Gênica/efeitos dos fármacos , Masculino , Proteínas dos Microfilamentos/metabolismo , Microglia/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Neurônios/metabolismo , Medição da Dor , Ratos , Ratos Sprague-Dawley , Receptores de Fator de Crescimento Neural/genética , Receptores de Fator de Crescimento Neural/metabolismo , Distúrbios Somatossensoriais/patologia , Estilbamidinas/metabolismo , Proteína Vesicular 1 de Transporte de Glutamato/metabolismo
3.
Brain Struct Funct ; 224(3): 1067-1095, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30610368

RESUMO

The central extended amygdala (EAc) is a forebrain macrosystem which has been widely implicated in reward, fear, anxiety, and pain. Its two key structures, the lateral bed nucleus of the stria terminalis (BSTL) and the central nucleus of the amygdala (CeA), share similar mesoscale connectivity. However, it is not known whether they also share similar cell-specific neuronal circuits. We addressed this question using tract-tracing and immunofluorescence to reveal the EAc microcircuits involving two neuronal populations expressing either protein kinase C delta (PKCδ) or somatostatin (SOM). PKCδ and SOM are expressed predominantly in the dorsal BSTL (BSTLD) and in the lateral/capsular parts of CeA (CeL/C). We found that, in both BSTLD and CeL/C, PKCδ+ cells are the main recipient of extra-EAc inputs from the lateral parabrachial nucleus (LPB), while SOM+ cells constitute the main source of long-range projections to extra-EAc targets, including LPB and periaqueductal gray. PKCδ+ cells can also integrate inputs from the basolateral nucleus of the amygdala or insular cortex. Within EAc, PKCδ+, but not SOM+ neurons, serve as the major source of inputs to the ventral BSTL and to the medial part of CeA. However, both cell types can be involved in mutual connections between BSTLD and CeL/C. These results unveil the pivotal positions of PKCδ+ and SOM+ neurons in organizing parallel cell-specific neuronal circuits within CeA and BSTL, but also between them, which further reinforce the notion of EAc as a structural and functional macrosystem.


Assuntos
Núcleo Central da Amígdala/citologia , Neurônios/classificação , Neurônios/metabolismo , Núcleos Septais/citologia , Animais , Biotina/análogos & derivados , Biotina/metabolismo , Peptídeo Relacionado com Gene de Calcitonina/metabolismo , Toxina da Cólera/metabolismo , Dextranos/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Vias Neurais , Neurônios/fisiologia , Proteína Quinase C-delta/metabolismo , Somatostatina/metabolismo , Estilbamidinas/metabolismo
4.
Pain ; 160(1): 269-278, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30211781

RESUMO

Joint neuropathic pain occurs in a subset of arthritis patients, and lysophosphatidic acid (LPA) has been implicated as a mediator of joint neuropathy. The mechanism by which LPA promotes neuropathic pain is unknown but may be related to altered signalling of the voltage-gated sodium channel Nav1.8 located on nociceptors. Because arthritis and neuropathic pain are more prevalent in females, this study aimed to explore potential sex differences in the development of LPA-induced joint neuropathy and whether Nav1.8 played a role in the associated neuropathic pain. Joint neuropathy was induced in male and female Wistar rats (179-284 g) by intra-articular injection of 50-µg LPA. Pain behaviour was assessed over 21 days using von Frey hair algesiometry. On day 21, electrophysiological recordings of joint primary afferents were conducted to measure peripheral sensitisation. Saphenous nerve morphology and expression of the nerve-damage marker ATF3 and Nav1.8 in ipsilateral dorsal root ganglions were compared on the basis of sex. The analgesic properties of the selective Nav1.8 antagonist A-803467 was determined in pain behaviour and electrophysiology experiments. Females developed more severe mechanical allodynia than males after LPA treatment. Lysophosphatidic acid caused more pronounced demyelination of the saphenous nerve in females, but no sex differences were observed in the expression of ATF3 or Nav1.8 in dorsal root ganglion neurones. Blockade of Nav1.8 channels with A-803467 resulted in a decrease in joint mechanosensitivity and secondary allodynia with females exhibiting a greater response. These findings suggest that LPA has sex-specific effects on joint neuropathy and Nav1.8 gating, which should be considered when treating neuropathic arthritis patients.


Assuntos
Artralgia/induzido quimicamente , Articulação do Joelho/patologia , Lisofosfolipídeos/toxicidade , Canal de Sódio Disparado por Voltagem NAV1.8/metabolismo , Caracteres Sexuais , Fator 3 Ativador da Transcrição/genética , Fator 3 Ativador da Transcrição/metabolismo , Compostos de Anilina/farmacologia , Animais , Modelos Animais de Doenças , Comportamento Exploratório , Feminino , Furanos/farmacologia , Hiperalgesia/induzido quimicamente , Masculino , Canal de Sódio Disparado por Voltagem NAV1.8/genética , Medição da Dor , Ratos , Ratos Wistar , Estilbamidinas/metabolismo
5.
PLoS One ; 13(10): e0205133, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30289890

RESUMO

Cholera toxin subunit B (CTB) and Fluorogold(FG) are two widely utilized retrograde tracers to assess the number and function of retinal ganglion cells (RGCs). However, the relative advantages and disadvantages of these tracers remain unclear, which may lead to their inappropriate application. In this study, we compared these tracers by separately injecting the tracer into the superior Colliculi (SC) in rats, one or 2 weeks later, the rats were sacrificed, and their retinas, brains, and optic nerves were collected. From the first to second week, FG displayed a greater number of labeled RGCs and a larger diffusion area in the SC than CTB; The number of CTB labeled RGCs and the diffusion area of CTB in the SC increased significantly, but there was no distinction between FG; Furthermore, CTB exhibited more labeled RGC neurites and longer neurites than FG, but no difference was evident between the same trace; The optic nerves labeled using CTB were much clearer than those labeled using FG. In conclusion, both CTB and FG can be used for the retrograde labeling of RGCs in rats at 1 or 2 weeks. FG achieves retrograde labeling of a greater number of RGCs than CTB, whereas CTB better delineates the morphology of RGCs. Furthermore, CTB seems more suitable for retrograde labeling of some small, non-image forming nuclei in the brain to which certain RGC subtypes project their axons.


Assuntos
Toxina da Cólera , Corantes Fluorescentes , Técnicas de Rastreamento Neuroanatômico , Marcadores do Trato Nervoso , Células Ganglionares da Retina/citologia , Estilbamidinas , Animais , Feminino , Microscopia de Fluorescência , Neuritos , Nervo Óptico/citologia , Ratos Sprague-Dawley , Colículos Superiores/citologia , Vias Visuais/citologia
6.
Epilepsia ; 59(11): 2019-2034, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30338519

RESUMO

OBJECTIVE: To determine when spontaneous granule cell epileptiform discharges first occur after hippocampal injury, and to identify the postinjury "latent" period as either a "silent" gestational state of epileptogenesis or a subtle epileptic state in gradual transition to a more obvious epileptic state. METHODS: Nonconvulsive status epilepticus evoked by perforant path stimulation in urethane-sedated rats produced selective and extensive hippocampal injury and a "latent" period that preceded the onset of the first clinically obvious epileptic seizures. Continuous granule cell layer depth recording and video monitoring assessed the time course of granule cell hyperexcitability and the onset/offset times of spontaneous epileptiform discharges and behavioral seizures. RESULTS: One day postinjury, granule cells in awake rats were hyperexcitable to afferent input, and continuously generated spontaneous population spikes. During the ~2-4 week "latent" period, granule cell epileptiform discharges lasting ~30 seconds caused subtle focal seizures characterized by immobilization and facial automatisms that were undetected by behavioral assessment alone but identified post hoc. Granule cell layer epileptiform discharge duration eventually tripled, which caused the first clinically obvious seizure, ending the "latent" period. Behavioral seizure duration was linked tightly to spontaneous granule cell layer events. Granule cell epileptiform discharges preceded all behavioral seizure onsets, and clonic behaviors ended abruptly within seconds of the termination of each granule cell epileptiform discharge. Noninjurious hippocampal excitation produced no evidence of granule cell hyperexcitability or epileptogenesis. SIGNIFICANCE: The latent period in this model is a subtle epileptic state in transition to a more clinically obvious epileptic state, not a seizure-free "gestational" state when an unidentified epileptogenic mechanism gradually develops. Based on the onset/offset times of electrographic and behavioral events, granule cell behavior may be the prime determinant of seizure onset, phenotype, duration, and offset in this model of hippocampal-onset epilepsy. Extensive hippocampal neuron loss could be the primary epileptogenic mechanism.


Assuntos
Epilepsia do Lobo Temporal/complicações , Hipocampo/patologia , Neurônios/fisiologia , Tempo de Reação/fisiologia , Potenciais de Ação/fisiologia , Animais , Modelos Animais de Doenças , Estimulação Elétrica/efeitos adversos , Hipocampo/lesões , Masculino , Via Perfurante/fisiopatologia , Ratos , Ratos Sprague-Dawley , Esclerose/complicações , Estilbamidinas/metabolismo , Fatores de Tempo
7.
Exp Neurol ; 309: 107-118, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30110606

RESUMO

Parkinson's disease (PD) is a neurodegenerative disorder characterized by loss of dopaminergic neurons in the substantia nigra compacta (SNpc) and the only risk factor is aging. We showed that in 6-hydroxydopamine (6-OHDA)-model of PD there is a reduction in the neuronal profile within the brainstem ventral respiratory column with a decrease in the hypercapnic ventilatory response. Here we tested the involvement of orexin cells from the lateral hypothalamus/perifornical area (LH/PeF) on breathing in a 6-OHDA PD model. In this model of PD, there is a reduction in the total number of orexinergic neurons and in the number of orexinergic neurons that project to the RTN, without changing the number of CO2-activated orexinergic neurons during the dark phase. The ventilation at rest and in response to hypercapnia (7% CO2) was assessed in animals that received 6-OHDA or vehicle injections into the striatum and saporin anti-Orexin-B or IgG saporin into the LH/PeF during the sleep and awake states. The experiments showed a reduction of respiratory frequency (fR) at rest during the light phase in PD animals only during sleep. During the dark phase, there was an impaired fR response to hypercapnia in PD animals with depletion of orexinergic neurons in awake and sleeping rats. In conclusion, the degeneration of orexinergic neurons in this model of PD can be related to impaired chemoreceptor function in the dark phase.


Assuntos
Hipotálamo/patologia , Neurônios/metabolismo , Orexinas/metabolismo , Doença de Parkinson/patologia , Doença de Parkinson/fisiopatologia , Respiração , Animais , Escuridão , Modelos Animais de Doenças , Eletroencefalografia , Eletromiografia , Potenciais Evocados/efeitos dos fármacos , Potenciais Evocados/fisiologia , Regulação da Expressão Gênica/efeitos dos fármacos , Masculino , Neurônios/efeitos dos fármacos , Oxidopamina/toxicidade , Doença de Parkinson/etiologia , Ventilação Pulmonar/fisiologia , Ratos , Ratos Wistar , Saporinas/farmacologia , Estilbamidinas/metabolismo , Simpatolíticos/toxicidade
8.
J Neurosci Methods ; 308: 142-150, 2018 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-30056087

RESUMO

BACKGROUND: Intrasciatic nerve injection of the Ricinus communis agglutinin (RCA or ricin) causes degeneration of motor neurons (MNs) with functional deficits, such as those that occur in amyotrophic lateral sclerosis (ALS). The objective of this study was to develop a new comprehensive platform for quantitative evaluation of MN loss, muscular atrophy and behavioral deficits using different ricin injection regimens. NEW METHOD: Fluorogold (FG)-guided stereological quantification of MNs, in vivo magnetic resonance imaging (MRI) of muscular atrophy, and CatWalk behavioral testing were used to evaluate the outcome of rats treated with different ricin regimens (RCA60 0.5 µg, RCA60 3 µg, and RCA120 6 µg) as animal models of MN degeneration. RESULTS: FG-guided stereological counting of MNs enabled identification, dissection and robust quantification of ricin-induced MN loss. The RCA60 0.5 µg and RCA120 6 µg regimens were found to be best suited as preclinical MN depletion models, with a low mortality and a reproducible MN loss, accompanied by muscle atrophy and functional deficits evaluated by MRI and the CatWalk method, respectively. COMPARISON WITH EXISTING METHODS: 1) Fluorogold neuronal tracing provides a robust and straightforward means for quantifying MN loss in the spinal cord; 2) MRI is well-suited to non-invasively assess muscle atrophy; and 3) The CatWalk method is more flexible than rotarod test for studying motor deficits. CONCLUSION: Intrasciatic injection of RCA60 or RCA120 induces nerve injury and muscle atrophy, which can be properly evaluated by a comprehensive platform using FG-guided quantitative 3D topographic histological analysis, MRI and the CatWalk behavioral test.


Assuntos
Esclerose Amiotrófica Lateral/patologia , Contagem de Células/métodos , Modelos Animais de Doenças , Neurônios Motores/patologia , Atrofia Muscular/induzido quimicamente , Traumatismos dos Nervos Periféricos/induzido quimicamente , Ricina/administração & dosagem , Animais , Feminino , Imageamento Tridimensional , Locomoção , Imagem por Ressonância Magnética , Neurônios Motores/efeitos dos fármacos , Atrofia Muscular/diagnóstico por imagem , Atrofia Muscular/patologia , Traumatismos dos Nervos Periféricos/diagnóstico por imagem , Traumatismos dos Nervos Periféricos/patologia , Ratos Sprague-Dawley , Nervo Isquiático/diagnóstico por imagem , Nervo Isquiático/efeitos dos fármacos , Nervo Isquiático/patologia , Estilbamidinas/administração & dosagem
9.
J Integr Neurosci ; 17(3-4): 609-618, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30056432

RESUMO

The role of cerebellum in coordination of somatic motor activity has been studied in detailed in various species. However, experimental and clinical studies have shown the involvement of the cerebellum with various visceral and cognitive functions via its vast connections with the central nervous system. The present study aims to define the cortical and subcortical and brain stem connections of the cerebellum via the superior (SCP) and middle (MCP) cerebellar peduncle using biotinylated dextran amine (BDA) and Fluoro-Gold (FG) tracer in Wistar albino rats. 14 male albino rats received 20-50-nl pressure injections of either FG or BDA tracer into the SCP and MCP. Following 7-10 days of survival period, the animals were processed according to the related protocol for two tracers. Labelled cells and axons were documented using light and fluorescence microscope. The SCP connects cerebellum to the insular and infralimbic cortices whereas, MCP addition to the insular cortex, it also connects cerebellum to the rhinal, primary sensory, piriform and auditory cortices. Both SCP and MCP connected the cerebellum to the ventral, lateral, posterior and central, thalamic nuclei. Additionally, SCP also connects parafasicular thalamic nucleus to the cerebellum. The SCP connects cerebellum to basal ganglia (ventral pallidum and clastrum) and limbic structures (amygdaloidal nuclei and bed nucleus of stria terminalis), however, the MCP have no connections with basal ganglia or limbic structures. Both the SCP and MCP densely connects cerebellum to various brainstem structures. Attaining the knowledge of the connections of the SCP and MCP is important for the diagnosis of lesions in the MCP and SCP and would deepen current understanding of the neuronal circuit of various diseases or lesions involving the SCP and MCP.


Assuntos
Tronco Encefálico/anatomia & histologia , Cerebelo/anatomia & histologia , Córtex Cerebral/anatomia & histologia , Animais , Biotina/análogos & derivados , Dextranos , Corantes Fluorescentes , Masculino , Vias Neurais/anatomia & histologia , Técnicas de Rastreamento Neuroanatômico , Ratos Wistar , Estilbamidinas
10.
Acta Neuropathol Commun ; 6(1): 66, 2018 07 23.
Artigo em Inglês | MEDLINE | ID: mdl-30037353

RESUMO

Using mice expressing green fluorescent protein (GFP) from a transgenic CD11c promoter we found that a controlled optic nerve crush (ONC) injury attracted GFPhi retinal myeloid cells to the dying retinal ganglion cells and their axons. However, the origin of these retinal myeloid cells was uncertain. In this study we use transgenic mice in conjunction with ONC, partial and full optic nerve transection (ONT), and parabiosis to determine the origin of injury induced retinal myeloid cells. Analysis of parabiotic mice and fate mapping showed that responding retinal myeloid cells were not derived from circulating macrophages and that GFPhi myeloid cells could be derived from GFPlo microglia. Comparison of optic nerve to retina following an ONC showed a much greater concentration of GFPhi cells and GFPlo microglia in the optic nerve. Optic nerve injury also induced Ki67+ cells in the optic nerve but not in the retina. Comparison of the retinal myeloid cell response after full versus partial ONT revealed fewer GFPhi cells and GFPlo microglia in the retina following a full ONT despite it being a more severe injury, suggesting that full transection of the optic nerve can block the migration of responding myeloid cells to the retina. Our results suggest that the optic nerve can be a reservoir for activated microglia and other retinal myeloid cells in the retina following optic nerve injury.


Assuntos
Neuroglia/patologia , Traumatismos do Nervo Óptico/patologia , Nervo Óptico/metabolismo , Nervo Óptico/patologia , Retina/patologia , Animais , Antígeno CD11c/genética , Antígeno CD11c/metabolismo , Receptor 1 de Quimiocina CX3C/genética , Receptor 1 de Quimiocina CX3C/metabolismo , Modelos Animais de Doenças , Antígeno Ki-67/metabolismo , Antígenos Comuns de Leucócito/metabolismo , Proteínas Luminescentes/genética , Proteínas Luminescentes/metabolismo , Macrófagos/patologia , Camundongos , Camundongos Transgênicos , Células Mieloides , Quiasma Óptico/patologia , Parabiose , Retina/metabolismo , Estilbamidinas/metabolismo , Fatores de Tempo
11.
Brain Struct Funct ; 223(7): 3297-3316, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29869133

RESUMO

The periaqueductal gray (PAG) is a mesencephalic brain structure organised in subdivisions with specific anatomical connections with the rest of the brain. These connections support the different PAG functions and especially its role in emotion. Mainly described in territorial and predatory mammals, examination of the PAG connections suggests an opposite role of the ventral and the dorsal/lateral PAG in passive and active coping style, respectively. In mammals, the organisation of PAG connections may reflect the coping style of each species. Based on this hypothesis, we investigated the anatomical connections of the PAG in sheep, a gregarious and prey species. Since emotional responses expressed by sheep are typical of active coping style, we focused our interest on the dorsal and lateral parts of the PAG. After injection of fluorogold and fluororuby, the most numerous connections occurred with the anterior cingulate gyrus, the anterior hypothalamic region, the ventromedial hypothalamic nucleus and the PAG itself. Our observations show that the sheep PAG belongs to the neuronal circuit of emotion and has specific parts as in other mammals. However, unlike other mammals, we observed very few connections between PAG and either the thalamic or the amygdalar nuclei. Interestingly, when comparing across species, the PAG connections of sheep were noticeably more like those previously described in other social species, rabbits and squirrel monkeys, than those in territorial species, rats or cats.


Assuntos
Comportamento Animal , Emoções , Neurônios/fisiologia , Substância Cinzenta Periaquedutal/fisiologia , Animais , Dextranos/administração & dosagem , Feminino , Corantes Fluorescentes/administração & dosagem , Vias Neurais/fisiologia , Técnicas de Rastreamento Neuroanatômico , Marcadores do Trato Nervoso/administração & dosagem , Substância Cinzenta Periaquedutal/citologia , Rodaminas/administração & dosagem , Carneiro Doméstico , Comportamento Social , Especificidade da Espécie , Estilbamidinas/administração & dosagem
12.
Cerebellum ; 17(5): 517-524, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29637507

RESUMO

The connections between the cerebellum and the hypothalamus have been well documented. However, the specific cerebellar peduncle through which the hypothalamo-cerebellar and cerebello-hypothalamic connections pass has not been demonstrated. The present study aims to define the specific cerebellar peduncle through which connects the cerebellum to specific hypothalamic nuclei. Seventeen male albino rats received 20-50-nl pressure injections of either Fluoro-Gold (FG) or biotinylated dextran amine (BDA) tracer into the superior (SCP), middle (MCP), and inferior (ICP) cerebellar peduncle. Following 7-10 days of survival period, the animals were processed according to the appropriate protocol for the two tracers used. Labeled cells and axons were documented using light or fluorescence microscopy. The present study showed connections between the hypothalamus and the cerebellum via both the SCP and the MCP but not the ICP. The hypothalamo-cerebellar connections via the SCP were from the lateral, dorsomedial, paraventricular, and posterior hypothalamic nuclei, and cerebello-hypothalamic connections were to the preoptic and lateral hypothalamic nuclei. The hypothalamo-cerebellar connections via the MCP were from the lateral, dorsomedial, ventromedial, and mammillary hypothalamic nuclei; and cerebello-hypothalamic connections were to the posterior, arcuate, and ventromedial hypothalamic nuclei. The hypothlamo-cerebellar connections were denser compared to the cerebello-hypothlamic connections via both the SCP and the MCP. The connection between the cerebellum and the hypothalamus was more prominent via the SCP than MCP. Both the hypothlamo-cerebellar and cerebello-hypothalamic connections were bilateral, with ipsilateral preponderance. Reciprocal connections were with the lateral hypothalamic nucleus via the SCP and the ventromedial nucleus via the MCP were observed. Cerebellum takes part in the higher order brain functions via its extensive connections. The knowledge of hypothalamo-cerebellar and cerebello-hypothalamic connections conveyed within the SCP and MCP can be important for the lesions involving the MCP and SCP. These connections can also change the conceptual architecture of the cerebellar circuitry and deepen current understanding.


Assuntos
Cerebelo/anatomia & histologia , Hipotálamo/anatomia & histologia , Pedúnculo Cerebelar Médio/anatomia & histologia , Animais , Biotina/análogos & derivados , Contagem de Células , Dextranos , Masculino , Microscopia de Fluorescência , Vias Neurais/anatomia & histologia , Técnicas de Rastreamento Neuroanatômico , Neurônios/citologia , Ratos Wistar , Estilbamidinas
13.
Pain ; 159(5): 907-918, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29672451

RESUMO

Chronic pain can be initiated by one or more acute stimulations to sensitize neurons into the primed state. In the primed state, the basal nociceptive thresholds of the animal are normal, but, in response to another hyperalgesic stimulus, the animal develops enhanced and prolonged hyperalgesia. The exact mechanism of how primed state is formed is not completely understood. Here, we showed that spinal protein kinase C (PKC)/extracellular signal-regulated kinase (ERK) signal pathway is required for neuronal plasticity change, hyperalgesic priming formation, and the development of chronic hyperalgesia using acid-induced muscle pain model in mice. We discovered that phosphorylated extracellular signal-regulated kinase-positive neurons in the amygdala, spinal cord, and dorsal root ganglion were significantly increased after first acid injection. Inhibition of the phosphorylated extracellular signal-regulated kinase activity intrathecally, but not intracerebroventricularly or intramuscularly before first acid injection, prevented the development of chronic pain induced by second acid injection, which suggests that hyperalgesic priming signal is stored at spinal cord level. Furthermore, intrathecal injection of PKC but not protein kinase A blocker prevented the development of chronic pain, and PKC agonist was sufficient to induce prolonged hyperalgesia response after acid injection. We also found that mammalian target of rapamycin-dependent protein synthesis was required for the priming establishment. To test whether hyperalgesic priming leads to synaptic plasticity change, we recorded field excitatory postsynaptic potentials from spinal cord slices and found enhanced long-term potentiation in mice that received one acid injection. This long-term potentiation enhancement was prevented by inhibition of extracellular signal-regulated kinase. These findings show that the activation of PKC/ERK signal pathway and downstream protein synthesis is required for hyperalgesic priming and the consolidation of pain singling.


Assuntos
MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Hiperalgesia/metabolismo , Mialgia/fisiopatologia , Proteínas Quinases/metabolismo , Ácidos/toxicidade , Animais , Modelos Animais de Doenças , Inibidores Enzimáticos/farmacologia , Potenciais Pós-Sinápticos Excitadores/efeitos dos fármacos , Potenciais Pós-Sinápticos Excitadores/fisiologia , Feminino , Gânglios Espinais/metabolismo , Gânglios Espinais/patologia , Camundongos , Camundongos Endogâmicos C57BL , Mialgia/induzido quimicamente , Mialgia/patologia , Neurônios/efeitos dos fármacos , Neurônios/fisiologia , Medição da Dor , Sirolimo/metabolismo , Medula Espinal/metabolismo , Medula Espinal/patologia , Estilbamidinas/metabolismo
14.
Mol Brain ; 11(1): 22, 2018 04 12.
Artigo em Inglês | MEDLINE | ID: mdl-29650024

RESUMO

The trigemino-thalamic (T-T) and trigemino-parabrachial (T-P) pathways are strongly implicated in the sensory-discriminative and affective/emotional aspects of orofacial pain, respectively. These T-T and T-P projection fibers originate from the spinal trigeminal nucleus (Vsp). We previously determined that many vesicular glutamate transporter (VGLUT1 and/or VGLUT2) mRNA-positive neurons were distributed in the Vsp of the adult rat, and most of these neurons sent their axons to the thalamus or cerebellum. However, whether VGLUT1 or VGLUT2 mRNA-positive projection neurons exist that send their axons to both the thalamus and the parabrachial nucleus (PBN) has not been reported. Thus, in the present study, dual retrograde tract tracing was used in combination with fluorescence in situ hybridization (FISH) for VGLUT1 or VGLUT2 mRNA to identify the existence of VGLUT1 or VGLUT2 mRNA neurons that send collateral projections to both the thalamus and the PBN. Neurons in the Vsp that send collateral projections to both the thalamus and the PBN were mainly VGLUT2 mRNA-positive, with a proportion of 90.3%, 93.0% and 85.4% in the oral (Vo), interpolar (Vi) and caudal (Vc) subnucleus of the Vsp, respectively. Moreover, approximately 34.0% of the collateral projection neurons in the Vc showed Fos immunopositivity after injection of formalin into the lip, and parts of calcitonin gene-related peptide (CGRP)-immunopositive axonal varicosities were in direct contact with the Vc collateral projection neurons. These results indicate that most collateral projection neurons in the Vsp, particularly in the Vc, which express mainly VGLUT2, may relay orofacial nociceptive information directly to the thalamus and PBN via axon collaterals.


Assuntos
Neurônios/metabolismo , Núcleos Parabraquiais/metabolismo , Tálamo/metabolismo , Núcleo Espinal do Trigêmeo/metabolismo , Proteína Vesicular 1 de Transporte de Glutamato/genética , Proteína Vesicular 2 de Transporte de Glutamato/genética , Animais , Axônios/metabolismo , Biotina/administração & dosagem , Biotina/análogos & derivados , Peptídeo Relacionado com Gene de Calcitonina/metabolismo , Dendritos/metabolismo , Dextranos/administração & dosagem , Formaldeído , Hibridização in Situ Fluorescente , Injeções Subcutâneas , Lábio , Masculino , Proteínas Proto-Oncogênicas c-fos/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ratos Sprague-Dawley , Rodaminas/administração & dosagem , Estilbamidinas/administração & dosagem , Sinapses/metabolismo , Proteína Vesicular 1 de Transporte de Glutamato/metabolismo , Proteína Vesicular 2 de Transporte de Glutamato/metabolismo
15.
J Comp Neurol ; 526(9): 1498-1526, 2018 06 15.
Artigo em Inglês | MEDLINE | ID: mdl-29524205

RESUMO

The prefrontal cortex (PFC) is usually defined as the frontal cortical area receiving a mediodorsal thalamic (MD) innervation. Certain areas in the medial wall of the rat frontal area receive a MD innervation. A second frontal area that is the target of MD projections is located dorsal to the rhinal sulcus and often referred to as the orbitofrontal cortex (OFC). Both the medial PFC and OFC are comprised of a large number of cytoarchitectonic regions. We assessed the afferent innervation of the different areas of the OFC, with a focus on projections arising from the mediodorsal thalamic nucleus, the basolateral nucleus of the amygdala, and the midbrain dopamine neurons. Although there are specific inputs to various OFC areas, a simplified organizational scheme could be defined, with the medial areas of the OFC receiving thalamic inputs, the lateral areas of the OFC being the recipient of amygdala afferents, and a central zone that was the target of midbrain dopamine neurons. Anterograde tracer data were consistent with this organization of afferents, and revealed that the OFC inputs from these three subcortical sites were largely spatially segregated. This spatial segregation suggests that the central portion of the OFC (pregenual agranular insular cortex) is the only OFC region that is a prefrontal cortical area, analogous to the prelimbic cortex in the medial prefrontal cortex. These findings highlight the heterogeneity of the OFC, and suggest possible functional attributes of the three different OFC areas.


Assuntos
Vias Aferentes/fisiologia , Complexo Nuclear Basolateral da Amígdala/citologia , Núcleo Mediodorsal do Tálamo/citologia , Mesencéfalo/citologia , Córtex Pré-Frontal/citologia , Animais , Complexo Nuclear Basolateral da Amígdala/metabolismo , Monoaminas Biogênicas/metabolismo , Toxina da Cólera/metabolismo , Células HEK293 , Humanos , Masculino , Núcleo Mediodorsal do Tálamo/metabolismo , Mesencéfalo/metabolismo , Córtex Pré-Frontal/metabolismo , Ratos , Ratos Sprague-Dawley , Estilbamidinas , Transfecção , Tirosina 3-Mono-Oxigenase/genética , Tirosina 3-Mono-Oxigenase/metabolismo
16.
Brain Struct Funct ; 223(6): 2733-2751, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29574585

RESUMO

The acoustic startle reflex (ASR) is a short and intense defensive reaction in response to a loud and unexpected acoustic stimulus. In the rat, a primary startle pathway encompasses three serially connected central structures: the cochlear root neurons, the giant neurons of the nucleus reticularis pontis caudalis (PnC), and the spinal motoneurons. As a sensorimotor interface, the PnC has a central role in the ASR circuitry, especially the integration of different sensory stimuli and brain states into initiation of motor responses. Since the basal ganglia circuits control movement and action selection, we hypothesize that their output via the substantia nigra (SN) may interplay with the ASR primary circuit by providing inputs to PnC. Moreover, the pedunculopontine tegmental nucleus (PPTg) has been proposed as a functional and neural extension of the SN, so it is another goal of this study to describe possible anatomical connections from the PPTg to PnC. Here, we made 6-OHDA neurotoxic lesions of the SN pars compacta (SNc) and submitted the rats to a custom-built ASR measurement session to assess amplitude and latency of motor responses. We found that following lesion of the SNc, ASR amplitude decreased and latency increased compared to those values from the sham-surgery and control groups. The number of dopamine neurons remaining in the SNc after lesion was also estimated using a stereological approach, and it correlated with our behavioral results. Moreover, we employed neural tract-tracing techniques to highlight direct projections from the SN to PnC, and indirect projections through the PPTg. Finally, we also measured levels of excitatory amino acid neurotransmitters in the PnC following lesion of the SN, and found that they change following an ipsi/contralateral pattern. Taken together, our results identify nigrofugal efferents onto the primary ASR circuit that may modulate motor responses.


Assuntos
Vias Auditivas/fisiologia , Movimento/fisiologia , Reflexo de Sobressalto/fisiologia , Formação Reticular/fisiologia , Substância Negra/fisiologia , Estimulação Acústica , Animais , Vias Auditivas/efeitos dos fármacos , Biotina/análogos & derivados , Biotina/metabolismo , Conectoma , Dextranos/metabolismo , Lateralidade Funcional/efeitos dos fármacos , Masculino , NADPH Desidrogenase/metabolismo , Neurotoxinas/toxicidade , Neurotransmissores/metabolismo , Oxidopamina/toxicidade , Ratos , Ratos Wistar , Tempo de Reação/efeitos dos fármacos , Tempo de Reação/fisiologia , Reflexo de Sobressalto/efeitos dos fármacos , Formação Reticular/efeitos dos fármacos , Medula Espinal/citologia , Medula Espinal/efeitos dos fármacos , Estilbamidinas/metabolismo , Substância Negra/lesões , Tirosina 3-Mono-Oxigenase/metabolismo
17.
Exp Neurol ; 303: 12-28, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29337147

RESUMO

Deletion of the phosphatase and tensin (PTEN) gene in neonatal mice leads to enlargement of the cell bodies of cortical motoneurons (CMNs) in adulthood (Gutilla et al., 2016). Here, we assessed whether PTEN deletion in adult mice would trigger growth of mature neurons. PTEN was deleted by injecting AAV-Cre into the sensorimotor cortex of adult transgenic mice with a lox-P flanked exon 5 of the PTEN gene and Cre-dependent reporter gene tdTomato. PTEN-deleted CMN's identified by tdT expression and retrograde labeling with fluorogold (FG) were significantly enlarged four months following PTEN deletion, and continued to increase in size through the latest time intervals examined (12-15 months post-deletion). Sholl analyses of tdT-positive pyramidal neurons revealed increases in dendritic branches at 6 months following adult PTEN deletion, and greater increases at 12 months. 12 months after adult PTEN deletion, axons in the medullary pyramids were significantly larger and G-ratios were higher. Mice with PTEN deletion exhibited no overt neurological symptoms and no seizures. Assessment of motor function on the rotarod and cylinder test revealed slight impairment of coordination with unilateral deletion; however, mice with bilateral PTEN deletion in the motor cortex performed better than controls on the rotarod at 8 and 10 months post-deletion. Our findings demonstrate that robust neuronal growth can be induced in fully mature cortical neurons long after the developmental period has ended and that this continuous growth occurs without obvious functional impairments.


Assuntos
Axônios/fisiologia , Córtex Cerebral/citologia , Dendritos/fisiologia , Neurônios/citologia , PTEN Fosfo-Hidrolase/deficiência , Fatores Etários , Animais , Axônios/ultraestrutura , Dendritos/ultraestrutura , Éxons/genética , Comportamento Exploratório/fisiologia , Proteína Glial Fibrilar Ácida/metabolismo , Aprendizagem/fisiologia , Camundongos , Camundongos Transgênicos , Microscopia Eletrônica , Atividade Motora/genética , Bainha de Mielina/metabolismo , Bainha de Mielina/ultraestrutura , Crescimento Neuronal/genética , PTEN Fosfo-Hidrolase/genética , PTEN Fosfo-Hidrolase/metabolismo , Transtornos Psicomotores/genética , Transdução de Sinais/genética , Estilbamidinas/metabolismo
18.
Eur J Neurosci ; 47(8): 959-967, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29359831

RESUMO

The degree of behavioural control that an organism has over a stressor is a potent modulator of the stressor's impact; controllable stressors produce none of the neurochemical and behavioural sequelae that occur if the stressor is uncontrollable. Research demonstrating the importance of control and the neural mechanisms responsible has been conducted almost entirely with male rats. It is unknown if behavioural control is stress blunting in females, and whether or not a similar resilience circuitry is engaged. Female rats were exposed to controllable, yoked uncontrollable or no tailshock. In separate experiments, behavioural (juvenile social exploration, fear and shuttle box escape) and neurochemical (activation of dorsal raphe serotonin and dorsal raphe-projecting prelimbic neurons) outcomes, which are sensitive to the dimension of control in males, were assessed. Despite successful acquisition of the controlling response, behavioural control did not mitigate dorsal raphe serotonergic activation and behavioural outcomes induced by tailshock, as it does in males. Moreover, behavioural control failed to selectively engage prelimbic cells that project to the dorsal raphe as in males. Pharmacological activation of the prelimbic cortex restored the stress-buffering effects of control. Collectively, the data demonstrate stressor controllability phenomena are absent in females and that the protective prelimbic circuitry is present but not engaged. Reduced benefit from coping responses may represent a novel approach for understanding differential sex prevalence in stress-related psychiatric disorders.


Assuntos
Aprendizagem da Esquiva/fisiologia , Núcleo Dorsal da Rafe/metabolismo , Núcleo Dorsal da Rafe/fisiologia , Comportamento Exploratório/fisiologia , Medo/fisiologia , Serotonina/metabolismo , Estresse Psicológico/metabolismo , Animais , Eletrochoque , Feminino , Lobo Límbico/efeitos dos fármacos , Microinjeções , Técnicas de Rastreamento Neuroanatômico , Neurônios/metabolismo , Picrotoxina/farmacologia , Proteínas Proto-Oncogênicas c-fos/metabolismo , Ratos , Estilbamidinas/metabolismo
19.
J Dent Res ; 97(4): 460-466, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29130364

RESUMO

Retrograde fluorescent labeling of dental primary afferent neurons (DPANs) has been described in rats through crystalline fluorescent DiI, while in the mouse, this technique was achieved with only Fluoro-Gold, a neurotoxic fluorescent dye with membrane penetration characteristics superior to the carbocyanine dyes. We reevaluated this technique in the rat with the aim to transfer it to the mouse because comprehensive physiologic studies require access to the mouse as a model organism. Using conventional immunohistochemistry, we assessed in rats and mice the speed of axonal dye transport from the application site to the trigeminal ganglion, the numbers of stained DPANs, and the fluorescence intensity via 1) conventional crystalline DiI and 2) a novel DiI formulation with improved penetration properties and staining efficiency. A 3-dimensional reconstruction of an entire trigeminal ganglion with 2-photon laser scanning fluorescence microscopy permitted visualization of DPANs in all 3 divisions of the trigeminal nerve. We quantified DPANs in mice expressing the farnesylated enhanced green fluorescent protein (EGFPf) from the transient receptor potential cation channel subfamily M member 8 (TRPM8EGFPf/+) locus in the 3 branches. We also evaluated the viability of the labeled DPANs in dissociated trigeminal ganglion cultures using calcium microfluorometry, and we assessed the sensitivity to capsaicin, an agonist of the TRPV1 receptor. Reproducible DiI labeling of DPANs in the mouse is an important tool 1) to investigate the molecular and functional specialization of DPANs within the trigeminal nociceptive system and 2) to recognize exclusive molecular characteristics that differentiate nociception in the trigeminal system from that in the somatic system. A versatile tool to enhance our understanding of the molecular composition and characteristics of DPANs will be essential for the development of mechanism-based therapeutic approaches for dentine hypersensitivity and inflammatory tooth pain.


Assuntos
Polpa Dentária/inervação , Corantes Fluorescentes/farmacocinética , Nociceptores/ultraestrutura , Estilbamidinas/farmacocinética , Animais , Imuno-Histoquímica , Camundongos , Microscopia de Fluorescência , Neurônios Aferentes/ultraestrutura , Ratos , Coloração e Rotulagem , Gânglio Trigeminal/ultraestrutura
20.
Brain Struct Funct ; 223(3): 1165-1190, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29094306

RESUMO

The nervous system integrates information from multiple senses. This multisensory integration already occurs in primary sensory cortices via direct thalamocortical and corticocortical connections across modalities. In humans, sensory loss from birth results in functional recruitment of the deprived cortical territory by the spared senses but the underlying circuit changes are not well known. Using tracer injections into primary auditory, somatosensory, and visual cortex within the first postnatal month of life in a rodent model (Mongolian gerbil) we show that multisensory thalamocortical connections emerge before corticocortical connections but mostly disappear during development. Early auditory, somatosensory, or visual deprivation increases multisensory connections via axonal reorganization processes mediated by non-lemniscal thalamic nuclei and the primary areas themselves. Functional single-photon emission computed tomography of regional cerebral blood flow reveals altered stimulus-induced activity and higher functional connectivity specifically between primary areas in deprived animals. Together, we show that intracortical multisensory connections are formed as a consequence of sensory-driven multisensory thalamocortical activity and that spared senses functionally recruit deprived cortical areas by an altered development of sensory thalamocortical and corticocortical connections. The functional-anatomical changes after early sensory deprivation have translational implications for the therapy of developmental hearing loss, blindness, and sensory paralysis and might also underlie developmental synesthesia.


Assuntos
Mapeamento Encefálico , Rede Nervosa/fisiologia , Vias Neurais/fisiologia , Sensação/fisiologia , Córtex Somatossensorial/fisiologia , Núcleos Talâmicos/fisiologia , Estimulação Acústica , Fatores Etários , Animais , Feminino , Proteína GAP-43/metabolismo , Gerbillinae , Masculino , Proteínas Associadas aos Microtúbulos/metabolismo , Rede Nervosa/diagnóstico por imagem , Vias Neurais/diagnóstico por imagem , Neuropeptídeos/metabolismo , Estimulação Luminosa , Privação Sensorial , Córtex Somatossensorial/diagnóstico por imagem , Estilbamidinas/metabolismo , Tecnécio Tc 99m Exametazima/farmacocinética , Núcleos Talâmicos/diagnóstico por imagem , Tomografia Computadorizada de Emissão de Fóton Único
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