Diss. (sammanfattning) Umeå : Univ., 2007. / Härtill 4 uppsatser.

Orientador: Fabio Papes / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-24T14:16:00Z (GMT). No. of bitstreams: 1 Tolentino_FelipeThadeu_M.pdf: 9244448 bytes, checksum: deea9f7963e05d8a997d9b5a554f9708 (MD5) Previous issue date: 2014 / Resumo: O Sistema Sensorial Olfativo de mamíferos é composto por vários subsistemas na cavidade nasal. Dentre estes, destacam-se o sistema olfativo principal e o sistema olfativo acessório ou vomeronasal. O primeiro realiza a detecção geral de odores e parece participar também da detecção de algumas substâncias que levam a respostas comportamentais instintivas (feromônios), enquanto o último é especializado na detecção desta classe de semioquímicos. A detecção dos estímulos sensoriais olfativos resulta em informações importantes que dependem de vias complexas para sua interpretação e para a geração de respostas apropriadas por parte do sistema nervoso central. Existem vários pontos ainda desconhecidos sobre o funcionamento do sistema olfativo, tanto no que diz respeito aos mecanismos moleculares subjacentes à escolha dos receptores a serem expressos por um dado neurônio sensorial ¿ sendo que cada neurônio olfativo expressa apenas um receptor dentro de uma grande família multi-gênica ¿ quanto em relação ao processamento da informação sensorial em centros cerebrais superiores. Neurônios sensoriais olfativos cultivados eficientemente in vitro seriam extremamente úteis, pois poderiam ser utilizados como ferramenta para o estudo destes problemas, como a investigação da atividade das células sensoriais olfativas, possibilitando, por exemplo, uma melhor compreensão dos mecanismos genéticos e moleculares por trás da expressão dos receptores olfativos e de suas propriedades de detecção. Neste trabalho foram desenvolvidas ferramentas baseadas em vetores retrovirais com o objetivo de induzir a diferenciação celular de neurônios olfativos in vitro, utilizando uma combinação de fatores de transcrição, por meio de transdução viral em células-alvo (fibroblastos murinos). Os retrovírus produzidos foram testados e algumas combinações de fatores de transcrição foram preliminarmente testadas, sendo capazes de induzir mudanças moleculares em fibroblastos acompanhadas da expressão de marcadores de neurônios sensoriais olfativos / Abstract: The mammalian Olfactory System enables the vast majority of animal species to identify the presence and quality of food, predators, competitors, conspecifics and potential mates in the environment. Olfactory stimuli detected by sensory neurons are interpreted by brain processing pathways to generate appropriate behavioral and endocrine responses. Despite its central importance in mammalian physiology, several aspects about the biology of this sensory system remain uncharacterized. For example, it is known that each olfactory sensory neuron (OSN) in the nasal cavity expresses only one gene out of a large multi-gene family coding for receptors involved in odorant and pheromone detection. However, the molecular mechanisms behind this process of olfactory receptor gene choice are not fully understood. The study of this and many other aspects of olfaction has been made difficult by the lack of appropriate in vitro cellular models. An efficient way to obtain cultured OSNs would thus be extremely useful, enabling researchers to investigate the sensory neuron¿s activity in a controllable environment, avoiding obstacles imposed by the cellular heterogeneity found in sensory organs in vivo. In this study, we aimed at obtaining OSNs directly differentiated from mouse embryonic fibroblasts (MEF) using the forced expression of specific transcription factors via retroviral vectors. We therefore developed tools based on retroviral vectors with the objective of differentiating olfactory sensory neurons in vitro, using viral transduction in target cells (murine fibroblasts) with combinations of select transcription factors. Retroviruses were tested and some combinations of transcription factors were tested on a preliminary basis, which were capable of inducing molecular alterations on fibroblasts followed by the expression of olfactory sensory neuron markers / Mestrado / Genetica Animal e Evolução / Mestre em Genética e Biologia Molecular

Chez les abeilles domestiques, les neurones à récepteurs olfactifs hébergés dans les antennes sont des neurones sensoriels primaires responsables de la détection des odeurs et des phéromones. L'information olfactive est ensuite acheminée par les nerfs antennaires jusqu'aux lobes antennaires qui constituent le premier étage d'intégration de l'information olfactive. Les abeilles butineuses sont exposées aux insecticides, notamment ceux de la classe des pyréthrinoïdes, qui sont utilisés pour la protection des plantes et la lutte contre les insectes considérés comme étant nuisibles.Nous avons caractérisé l'effet des pyréthrinoïdes sur les canaux sodiques activés par le potentiel (responsables des potentiels d'action) dans les deux premiers étages du système olfactif de l'abeille. Nos enregistrements électrophysiologiques en mode potentiel imposé dans les neurones à récepteurs olfactifs mis en culture révèlent que l'effet des pyréthrinoïdes de type I et II (notamment la tétraméthrine et la deltaméthrine) est amplifié par une intensification de l'activité électrique neuronale. Cette amplification survient notamment via le démasquage de canaux sodiques silencieux que nous avons également mis en évidence avec la toxine d'anémone de mer ATX-II. Le niveau maximal de canaux sodiques modifiés est atteint en quelques centaines de millisecondes. Dans les neurones centraux des lobes antennaires, cette amplification apparait très limitée voire absente avec les pyréthrinoïdes mais elle peut toutefois survenir en présence de l'alcaloïde végétal vératridine. Par ailleurs, dans ces neurones centraux, les pyréthrinoïdes semblent être à l’origine d’une accélération de l'inactivation lente des canaux sodiques auparavant décrite en présence de certains anesthésiques locaux. Les modifications différentielles observées dans les neurones périphériques et centraux pourraient être responsables des effets délétères des pyréthrinoïdes sur les capacités de perception, d'orientation et d'apprentissage de l'abeille domestique. / In domestic honeybees, the olfactory receptor neurons localized in the antennae are primary sensory neurons responsible for the detection of odor and pheromone compounds. The olfactory information is further conveyed to the antennal lobes by the antennal nerves. The antennal lobes are the first stage of integration of the olfactory information. Forager bees are exposed to insecticides, especially pyrethroids that are used for plant protection and eradication of pests.In the honeybee olfactory pathway, we investigated the effects of pyrethroids on the voltage-gated sodium channels (which underlie action potentials). Our patch-clamp recordings in the antennal olfactory receptor neurons maintained in cell culture reveal that the effects of type I and type II pyrethroids (e.g. tetramethrin and deltamethrin) are increased by an augmentation of neuronal electrical activity. The amplification of the effects of pyrethroids occurs as a result of the unmasking of silent sodium channels that we have also shown evidence for, with sea anemone toxin ATX-II. The maximal sodium channels modification takes place within few hundreds of milliseconds. In the central antennal lobe neurons, that amplification is rather limited or absent with pyrethroids but the plant alkaloid veratridine is able to induce such an amplification. Furthermore, in the latter cell type, pyrethroids cause an acceleration of the sodium channels slow inactivation. Such an effect has been previously reported for some local anesthetics. The differential actions of pyrethroids that we have observed in the peripheral and central neurons may be responsible for the impairment of learning performance, perception and disorientation exhibited by pyrethroid-exposed honeybees.

No description available.

Background: Patients with Panic Disorder (PD) direct their attention towards potential threat, followed by panic attacks, and increased sweat production. Onés own anxiety sweat odor influences the attentional focus, and discrimination of threat or non-threat. Since olfactory projection areas overlap with neuronal areas of a panic-specific fear network, the present study investigated the neuronal processing of odors in general and of stress-related sweat odors in particular in patients with PD. Methods: A sample of 13 patients with PD with/ without agoraphobia and 13 age- and gender-matched healthy controls underwent an fMRI investigation during olfactory stimulation with their stress-related sweat odors (TSST, ergometry) as well as artificial odors (peach, artificial sweat) as non-fearful non-body odors. Principal Findings: The two groups did not differ with respect to their olfactory identification ability. Independent of the kind of odor, the patients with PD showed activations in fronto-cortical areas in contrast to the healthy controls who showed activations in olfaction-related areas such as the amygdalae and the hippocampus. For artificial odors, the patients with PD showed a decreased neuronal activation of the thalamus, the posterior cingulate cortex and the anterior cingulate cortex. Under the presentation of sweat odor caused by ergometric exercise, the patients with PD showed an increased activation in the superior temporal gyrus, the supramarginal gyrus, and the cingulate cortex which was positively correlated with the severity of the psychopathology. For the sweat odor from the anxiety condition, the patients with PD showed an increased activation in the gyrus frontalis inferior, which was positively correlated with the severity of the psychopathology. Conclusions: The results suggest altered neuronal processing of olfactory stimuli in PD. Both artificial odors and stress-related body odors activate specific parts of a fear-network which is associated with an increased severity of the psychopathology.

Objective: Decrease of olfactory function in Parkinson's disease (PD) is a well-investigated fact. Studies indicate that pharmacological treatment of PD fails to restore olfactory function in PD patients. The aim of this investigation was whether patients with PD would benefit from “training” with odors in terms of an improvement of their general olfactory function. It has been hypothesized that olfactory training should produce both an improved sensitivity towards the odors used in the training process and an overall increase of olfactory function. Methods: We recruited 70 subjects with PD and olfactory loss into this single-center, prospective, controlled non-blinded study. Thirty-five patients were assigned to the olfactory training group and 35 subjects to the control group (no training). Olfactory training was performed over a period of 12 weeks while patients exposed themselves twice daily to four odors (phenyl ethyl alcohol: rose, eucalyptol: eucalyptus, citronellal: lemon, and eugenol: cloves). Olfactory testing was performed before and after training using the “Sniffin' Sticks” (thresholds for phenyl ethyl alcohol, tests for odor discrimination, and odor identification) in addition to threshold tests for the odors used in the training process. Results: Compared to baseline, trained PD patients experienced a significant increase in their olfactory function, which was observed for the Sniffin' Sticks test score and for thresholds for the odors used in the training process. Olfactory function was unchanged in PD patients who did not perform olfactory training. Conclusion: The present results indicate that olfactory training may increase olfactory sensitivity in PD patients.

Background: Patients with Panic Disorder (PD) direct their attention towards potential threat, followed by panic attacks, and increased sweat production. Onés own anxiety sweat odor influences the attentional focus, and discrimination of threat or non-threat. Since olfactory projection areas overlap with neuronal areas of a panic-specific fear network, the present study investigated the neuronal processing of odors in general and of stress-related sweat odors in particular in patients with PD. Methods: A sample of 13 patients with PD with/ without agoraphobia and 13 age- and gender-matched healthy controls underwent an fMRI investigation during olfactory stimulation with their stress-related sweat odors (TSST, ergometry) as well as artificial odors (peach, artificial sweat) as non-fearful non-body odors. Principal Findings: The two groups did not differ with respect to their olfactory identification ability. Independent of the kind of odor, the patients with PD showed activations in fronto-cortical areas in contrast to the healthy controls who showed activations in olfaction-related areas such as the amygdalae and the hippocampus. For artificial odors, the patients with PD showed a decreased neuronal activation of the thalamus, the posterior cingulate cortex and the anterior cingulate cortex. Under the presentation of sweat odor caused by ergometric exercise, the patients with PD showed an increased activation in the superior temporal gyrus, the supramarginal gyrus, and the cingulate cortex which was positively correlated with the severity of the psychopathology. For the sweat odor from the anxiety condition, the patients with PD showed an increased activation in the gyrus frontalis inferior, which was positively correlated with the severity of the psychopathology. Conclusions: The results suggest altered neuronal processing of olfactory stimuli in PD. Both artificial odors and stress-related body odors activate specific parts of a fear-network which is associated with an increased severity of the psychopathology.

This thesis focuses on several aspects of olfactory processing in Drosophila. In chapter I and II, I will discuss how odorants are encoded in the brain. In both insects and mammals, olfactory receptor neurons (ORNs) expressing the same odorant receptor gene converge onto the same glomerulus. This topographical organization segregates incoming odor information into combinatorial maps. One prominent theory suggests that insects and mammals discriminate odors based on these distinct combinatorial spatial codes. I tested the combinatorial coding hypothesis by engineering flies that have only one class of functional ORNs and therefore cannot support combinatorial maps. These files can be taught to discriminate between two odorants that activate the single functional class of ORN and identify an odorant across a range of concentrations, demonstrating that a combinatorial code is not required to support learned odor discrimination. In addition, these data suggest that odorant identity can be encoded as temporal patterns of ORN activity. Behaviors are influenced by motivational states of the animal. Chapter III of this thesis focuses on understanding how motivational states control behavior. Appetitive memory in Drosophilaprovides an excellent system for such studies because the motivational state of hunger promotes reliance on learned appetitive cues whereas satiety suppresses it. We found that activation of neuropeptide F (dNPF) neurons in fed flies releases appetitive memory performance from satiety-mediated suppression. Through a GAL4 screen, we identified six dopaminergic neurons that are a substrate for dNPF regulation. In satiated flies, these neurons inhibit mushroom body output, thereby suppressing appetitive memory performance. Hunger promotes dNPF release, which blocks the inhibitory dopaminergic neurons. The motivational drive of hunger thus affects behavior through a hierarchical inhibitory control mechanism: satiety inhibits memory performance through a subset of dopaminergic neurons, and hunger promotes appetitive memory retrieval via dNPF-mediated disinhibition of these neurons. The aforementioned studies utilize sophisticated genetic tools for Drosophila. In chapter IV, I will talk about two new genetic tools. We developed a new technique to restrict gene expression to different subsets of mushroom body neurons with unprecedented precision. We also adapted the light-activated adenylyl cyclase (PAC) from Euglena gracilis as a light-inducable cAMP system for Drosophila. This system can be used to induce cAMP synthesis in targeted neurons in live, behaving preparations.