Polymodal Functionality of C. elegans OLL Neurons in Mechanosensation and Thermosensation / 神经科学通报·英文版

Sensory modalities are important for survival but the molecular mechanisms remain challenging due to the polymodal functionality of sensory neurons. Here, we report the C. elegans outer labial lateral (OLL) sensilla sensory neurons respond to touch and cold. Mechanosensation of OLL neurons resulted in cell-autonomous mechanically-evoked Ca

Caracterização da expressão de vias de reparo e medida de dano ao DNA em epitélio olfatório de camundongos / Molecular characterization of DNA repair in mouse olfactory epithelium

As primeiras células responsáveis pela percepção olfatória são os neurônios olfatórios (OSNs) presentes no epitélio olfatório (EO) da cavidade nasal, que reconhecem moléculas voláteis presentes no ar, denominadas odorantes, através de receptores específicos. Diferentemente de neurônios do sistema nervoso central (SNC), que estão relativamente protegidos de genotoxinas exógenas, OSNs estão em constante contato com agentes potencialmente genotóxicos, incluindo o oxigênio atmosférico. Além disto, em contraste com a maioria dos neurônios do SNC, OSNs são periodicamente repostos através de neurogênese adulta, portanto, possuem um tempo de vida menor do que outros neurônios. A função olfatória diminui durante o envelhecimento normal e patológico, através de mecanismos que ainda não estão totalmente claros. Em doenças neurodegenerativas, a perda do olfato é um dos sintomas iniciais e é utilizada como marcador de resposta a alguns tratamentos. Relações causais entre deficiências em reparo de DNA e neurodegeneração já foram demonstradas em vários modelos experimentais. No entanto, ainda não se sabe se alterações nessas vias contribuem para a perda olfatória observada nessas condições, provavelmente porque não há dados disponíveis na literatura sobre vias de reparo de DNA em OSNs. Por isso, o objetivo deste estudo foi caracterizar as vias de reparo de DNA presentes em populações de OSNs maduros e seus precursores. Analisamos dados de expressão de genes de reparo extraídos de dois transcriptomas diferentes, um relacionado à idade e outro, ao estágio de diferenciação destes neurônios. Em seguida, validamos os resultados obtidos da análise in silico através de PCR em tempo real utilizando amostras de EO de camundongos da linhagem C57BL/6J em duas idades (neonatos e com três semanas de idade). Nossos resultados indicam que OSNs são proficientes em todas as vias de reparo de excisão analisadas, apresentando expressão detectável de genes essenciais de cada via. A comparação entre populações enriquecidas em precursores ou em neurônios maduros, nas duas análises, sugere que a atividade de pelo menos quatro vias de reparo de excisão é menor em camundongos jovens, quando comparados aos neonatos, sugerindo, portanto, que há diminuição na expressão durante a diferenciação destas células. Esta observação vai corrobora com dados da literatura que mostraram que a expressão e atividade de proteínas de reparo em células proliferativas é maior do que em célulasterminalmente diferenciadas. Para testar a hipótese de que, por estarem em constante contato com agentes genotóxicos, OSNs acumulam mais lesões em DNA do que células no SNC, comparamos os níveis de lesões em DNA obtido de amostras de EO e de bulbo olfatório (BO), e de córtex temporal (CT), uma região cerebral que não apresenta taxas significativas de neurogênese e não expostas ao ambiente externo. A taxa de lesão foi calculada a partir de dados obtidos por PCR de longa extensão. Resultados obtidos utilizando EO, BO e CT de camundongos com três semanas de idade mostram que a amplificação em amostras de CT é muito menor do que em EO ou BO, sugerindo que neurônios do SNC acumulam mais lesões do que neurônios de regiões que apresentam neurogênese, mesmo que estas estejam constantemente expostas a agentes genotóxicos exógenos. Além disso, a eficiência de amplificação de fragmentos longos de DNA mitocondrial (mtDNA) foi menor em EO do que em BO, sugerindo que a constante exposição ao oxigênio atmosférico contribui para o acúmulo de lesões ao mtDNA, que é mais suscetível do que o DNA nuclear. Esse trabalho demonstra, pela primeira vez, que OSNs expressam proteínas essenciais de vias de reparo de DNA, cuja expressão decresce durante o processo de maturação dos neurônios olfatórios. Esses resultados devem contribuir para o entendimento dos mecanismos de manutenção da integridade genômica nestas células tão únicas

The first cells responsible for olfactory perception are the olfactory sensory neurons (OSNs), located in the olfactory epitelhium (OE) in the nasal cavity, which recognize volatile molecules in the air, called odorants, through olfactory receptors. Unlike neurons located in the central nervous system (CNS), which are relatively protected from exogenous toxins, OSNs are in constant contact with genotoxic agents, including atmospheric oxygen. Moreover, in contrast with most neurons in CNS, OSNs are periodically replaced through adult neurogenesis, therefore, having shorter lifespan than most neurons. Olfactory function decreases during normal and pathological aging, through mechanisms that are still not fully understood. In neurodegenerative diseases, olfactory loss is an early symptom and, in some cases, is used as a treatment response marker. DNA repair defects have been causally linked with neurodegeneration in different experimental models. However, it still unclear whether DNA repair alterations contribute to olfactory loss in these conditions, probably because there are no data available on DNA repair dynamic in OSNs. Therefore, our goal was to characterize the DNA repair pathways present in precursor and mature OSNs populations. We analyzed gene expression data from age-related and differentiation stage-related transcriptomes of these neurons, and validated the results by real time PCR using mouse OE samples from C57BL/6J lineage in two different ages (newborns and three weeks old). Our results indicate that OSNs are proficient in all DNA repair pathways investigated, showing detectable expression of essential genes from each pathway. When comparing populations enriched for mature OSNs or its precursors, our results suggest that the activities of at least four repair pathways are lower in young mice than in newborns, suggesting that DNA repair expression decreases during OSNs differentiation. This observation is consistent with published data showing that the expression and activities of repair proteins is lower in terminally differentiated than in proliferative cells . To test the hypothesis that OSNs would accumulate more DNA damage than CNS neurons, since they are in constant contact wtih genotoxic agents, we compared DNA damage levels in nuclear and mitochondrial DNA from OE, olfactory bulb (OB), and temporal cortex (TC) samples. We chose to use the TC region and a non-olfactory related control as it does not show significant adult neurogenesis and it is not exposed to external environment. Lesion rate wascalculated from data obtained by long extension PCR. Results from 3 weeks old mice OE, OB and TC samples showed that the amplification in TC samples is much lower than OE or OB samples, suggesting that neurons in CNS accumulate more damage than neurons that undergo neurogenesis. Besides, lesion frequency was higher in OE mitochondrial DNA (mtDNA) than in OB, suggesting that the constant exposure to atmospheric oxygen may contribute to accumulation of mtDNA lesions. This work demonstrates, for the first time, that OSNs are proficient in at least four DNA repair pathways, and that expression of key genes in these pathways decreases with differentiation. These results will contribute to better our understanding of the mechanisms involved in genomic stability in such unique cell types

Lysosomal Hydrolase Cathepsin D Non-proteolytically Modulates Dendritic Morphology in Drosophila / 神经科学通报·英文版

The main lysosomal protease cathepsin D (cathD) is essential for maintaining tissue homeostasis via its degradative function, and its loss leads to ceroid accumulation in the mammalian nervous system, which results in progressive neurodegeneration. Increasing evidence implies non-proteolytic roles of cathD in regulating various biological processes such as apoptosis, cell proliferation, and migration. Along these lines, we here showed that cathD is required for modulating dendritic architecture in the nervous system independent of its traditional degradative function. Upon cathD depletion, class I and class III arborization (da) neurons in Drosophila larvae exhibited aberrant dendritic morphology, including over-branching, aberrant turning, and elongation defects. Re-introduction of wild-type cathD or its proteolytically-inactive mutant dramatically abolished these morphological defects. Moreover, cathD knockdown also led to dendritic defects in the adult mushroom bodies, suggesting that cathD-mediated processes are required in both the peripheral and central nervous systems. Taken together, our results demonstrate a critical role of cathD in shaping dendritic architecture independent of its proteolytic function.

Neuronal Correlation Between Acupoint BL 23 and the Adrenal Gland in Rats / 针刺研究

OBJECTIVE: To explore the neuroanatomical basis of acupoint-visceral correlation by studying the distribution of the neurons associated with acupoint "Shenshu" (BL 23) area and adrenal gland in rats. METHODS: AF 488-CTB and AF 594-CTB were injected into the left side of BL 23 area and adrenal gland in the same rat respectively. Three days after injection, the dorsal root ganglions (DRG), sympathetic chain, and spinal cord were dissected out from the perfused rats. The neuronal labeling with AF 488/594-CTB was directly observed on the sections under a fluorescent microscope or a laser scanning confocal microscope. RESULTS: All neural labeling was observed in the injection side. The sensory neurons associated with both acupoint BL 23 and adrenal gland distributed from thoracic (T) 10 to lumbar (L) 2 DRG with high concentration in T 12-T 13 and T 11-T 12, respectively, in which some of them were simultaneously labeled with both AF 488/594-CTB and located in T 12-L 1 DRG. For the sympathetic innervation, the postganglionic neurons correlated with BL 23 and adrenal gland were labeled with AF 488/594-CTB separately in the sympathetic chain at the lumbar segments, while the labeled preganglionic neurons were only observed at the lateral horn of T 11-T 13 spinal segments in the cases of adrenal gland. In addition, the labeled motor neurons were mainly detected in the spinal ventral horn at cervical (C) 7-C 8 and T 11-L 1 segments. CONCLUSION: These results indicate that there are segmental correlation between BL 23 and adrenal gland on the sensory and sympathetic innervations, and this correlation might be a neural pathway for modulating the function role of adrenal gland through BL 23 needling.

Interplay of Signaling Molecules in Olfactory Sensory Neuron toward Signal Amplification / 한양의대학술지

Over the last decades, piles of data have been accumulated to understand the olfactory sensation in every aspect, ranging from the intracellular signaling to cognitive perception. This review focuses on the ion conduction through multiple ion channels expressed in olfactory sensory neurons (OSNs) to describe how odorant binding to olfactory receptors is transduced into an electrical signal. Olfactory signal transduction and the generation of the depolarizing receptor current occur in the cilia, where the unique extraciliary environment of the nasal mucosa assists in the neuronal activation. Upon contacting with odorants, OSNs dissociate G protein-coupled receptors, initiating a signal transduction pathway that leads to firing of action potential. This signaling pathway has a unique, two step organization: a cAMP-gated Ca2+ (CNG) channel and a Ca2+-activated Cl- channel (CACC), both of which contribute to signal amplification. This transduction mechanism requires an outward-directed driving force of Cl- established by active accumulation of Cl- within the lumen of the sensory cilia. To permit Cl- accumulation, OSNs avoid the expression of the 'Chloride Sensor: WNK3', that functions as the main Cl- exclusion co-transporter in neurons of the central nervous system (CNS). Cl- accumulation provides OSNs with the driving force for the depolarization, increasing the excitatory response magnitude. This is an interesting adaptation because of the fact that the olfactory cilia reside in the mucus, outside the body, where the concentrations of ions are not as well regulated as they are in normal interstitial compartments.

Cerebellar atrophy is frequently associated with non-paraneoplastic sensory neuronopathy / Atrofia cerebelar não é um achado frequente em pacientes com neuronopatia sensitiva não paraneoplasica

Sensory neuronopathies (SN) are peripheral nervous system disorders associated with degeneration of dorsal root ganglion neurons. Despite the evidence of a defective proprioceptive sensory input in SN,the prominent gait and truncal ataxia raises the question of a concomitant involvement of the cerebellum. OBJECTIVE: To evaluate cerebellar atrophy in SN. METHOD: We analyzed MRI-based volumetry of anterior lobe (paleocerebellum) and total cerebellum in patients with non-paraneoplastic chronic SN and compared to age- and gender-matched controls. RESULTS: Cerebellum and anterior lobe MRI volumetry were performed in 20 patients and nine controls. Mean anterior lobe and cerebellar volume were not statistically different. Three patients (15 percent), however, had an abnormal anterior lobe and cerebellar volume index (values outside 2.5 standard deviations). One of them also had a specific atrophy of the anterior lobe. All these patients had infectious or dysimmune associated SN. CONCLUSION: Cerebellar atrophy is infrequently associated with SN, but can be found in some patients with SN related to infectious or immune mediated conditions. It can be more prominent in the anterior lobe and may contribute to the ataxia seen in these patients.

Neuronopatias sensitivas (NS) são distúrbios do sistema nervoso periférico associados com a degeneração dos neurônios do gânglio da raiz dorsal. Apesar da evidência de um defeito das aferências proprioceptivas, a ataxia proeminente da marcha e do tronco levanta a questão de uma participação concomitante do cerebelo. OBJETIVO: Avaliar a atrofia cerebelar nas NS. MÉTODO: Foi analisada volumetria pela ressonância magnética do cerebelo total e do lobo anterior (paleocerebelo) em pacientes com NS crônica não-paraneoplásica e comparada a controles com idades e sexos correspondentes. RESULTADOS: A volumetria do cerebelo e lobo anterior foi realizada em 20 pacientes e nove controles. As médias do volume cerebelar e do lobo anterior não foram estatisticamente diferentes. Três pacientes, entretanto, tiveram um valor anormal do índice de volume cerebelar e do lobo anterior (valores fora de 2,5 desvios-padrão). Um deles tinha inclusive uma atrofia específica do lobo anterior. Todos esses pacientes tinham NS associada a doenças infecciosas ou disimunes. CONCLUSÃO: Atrofia cerebelar é raramente associada com SN, mas pode ser encontrada em alguns pacientes com NS relacionada com doenças infecciosas ou imunológicas. Esta atrofia pode ser mais proeminente no lobo anterior e pode contribuir para a ataxia observada nestes pacientes.

Morphological Changes of the Sensory Neurons in the Peripheral Neuropathy of Rat Tibial Nerve Using WGA-HRP Tracing Method / 체질인류학회지

Neuropathy is a general term referring to disorders of nerves, and produces when the nerves are damaged. It is characterized by spontaneous pain, allodynia and hyperalgesia. The purpose of present study is to observe the number of WGA-HRP (wheat germ agglutinin-horseradish peroxidase) labelded sensory neurons of DRG (dorsal root ganglia), and distributions according to cell size of sensory neuron in tibial nerve ligation model (NLM). The tibial nerve ligation was performed with 3-0 silk by the application of three tight ligatures at the mid-thigh level. In the neuropathy model of rat tibial nerve ligation, morphological changes of sensory neurons in DRG were observed using WGA-HRP. Rats of NLM showed the neuropathic behaviors. Rats were shown guarding affected limb and limping. Their toes and ankle joint of operated limb were hyperflexed. Under light microscopy, tibial nerve showed degeneration of axons in NLM. In control and NLM, labeled sensory neurons of tibial nerve distributed L4 and L5 DRG. In control group, the labeled sensory neurons were round or oval in shape. They were large and small cells, and mixed pattern. Total number of labeled sensory neurons in NLM decreased significantly from control group. The number of labeled sensory neurons in L4 and L5 DRG decreased significantly from control group. Labeled large and small cells decreased significantly from control group. Present study may serve as the basic information about the changes of DRG sensory neurons in NLM.

Substance P inhibits GABA-activated currents in bullfrog primary sensory neurons by protein kinase C / 新乡医学院学报

Objective To research the mechanism or pathway through which Substance P(SP) inhibits r-aminobutyric acid(GABA) activated currents in bullfrog dorsal root ganglion(DRG) neurons.Method The experiment was conducted on freshly isolated bullfrog dorsal root ganglion neurons using a whole-cell patch-clamp technique.Results SP could caused a slow inward current when SP was applied to DRG neurons;SP could inhibits GABA-activated currents;The inhibition could be reduced largely when protein kinase C(PKC) inhibiter,1-(5-isoquinolinesulphorry)-2-methylpiperazine(H-7), was dialyzed in cell body.Conclusion The SP ton inhibit GABA-activated currents through protein kinase C.

Retrograde tracing study on neurons labeled by injecting rear-thigh muscles with DiI in mice / 第三军医大学学报

Objective To explore the fluorescent distribution, and the relation between fluorescent intensity and time after injecting rear-thigh muscles with DiI. Methods Sixty-five new born mice were equally and randomly divided into 13 groups. Fluorescent distribution and intensity were investigated at 2, 4, 6, 8, 12, 24 h, and 2, 4, 7, 14, 28 d and 2, 3 months after injecting the left posterior limb rear thigh muscles with 1.5 ?l 4 mg/ml DiI for one mouse. Results The labeling neurons were scattered from L2 level to S2 level and associated dorsal root ganglion (DRG), but the most were located at L4 to L6 section. The faint red fluorescence neurons were observed at dorsal root ganglion and cornu anterius medullae spinalis 6 h post-injection. The labeling neurons increased up to the 4th day. The fluorescent intensity enhanced gradually from 6 h to 24 h, then kept the intensity for 3 months. Conclusion It is a quick, precise, persistent method to trance and label the dorsal root ganglions sensory neuron and spinal motoneuron by injecting rear-thigh muscles with DiI, and the rate of labeling neurons can be improved by prolonging the tracing time properly. It is also provide basic data for clinical or experimental neuron label and location.

SIMULTANEOUS INNERVATION OF HEART AND STOMACH BY DICHOTOMIZING BRANCH OF PERIPHERAL PROCESS OF CGRP IMMUNOREACTIVE DORSAL ROOT GANGLION NEURONS——A TRIPLE LABELLING STUDY / 解剖学报

Propedium iodide (PI) and bisbenzimide (Bb) were injected into anterior wall of the cardiac ventricle and lesser curvature of the stomach in the rat respectively. We have found that PI labelled cells are distributed in C_4-T_(12), Bb labelled cells in T_4-L_1, PI-Bb double labelled cells in T_6-T_(11) dorsal root ganglia. This result indicate that dichotomizing branches of peripheral process from some of dorsal root ganglionic neuron projecte to two visceral organs simultaneously. By means of immunocytochemistry (PAP method), some of double fluorescence cells are CGRP positive. The significance of the viscero-visceral sensory converging to same primary sensory neuron was discussed.

A STUDY OF SEGMENTAL DISTRIBUTION OF PRIMARY SENSORY NEURONS OF RABBIT UTERUS BY RETROGRADE HORSERADISH PEROXIDASE (HRP) METHOD / 解剖学报

The distribution of the primary sonsory neurons from the uterus was studied in 20 female rabbits by the HRP method. The results were as follows:The HRP-labeled cells were found in all the spinal ganglia from T_9 to Co_1,but they were highly concentrated in two groups, namely L_(2～5) and S_(3～4). There were more labeled cells in the lumbar group than in the sacral group with the highest freguency in L_4 and S_3 ganglion in each group respectively. There were only a few labeled cells in L_(6～7) and S_1 spinal ganglia. The ratio of labeled cells in the thoracic and lumbar ganglia to those in the sacral and coccygeal was about 5:1.The number of labeled cells was largest following injection of HRP in the uterine cervix, smallest in the middle of the body and intermidiate in the upper and lower rogions of the uterine body. There is no difference in the distribution of labeled cell from different regions of the uterus.The majority of labeled cells were small, only a few were large ones.