Low doses of a neonicotinoid insecticide modify pheromone response thresholds of central but not peripheral olfactory neurons in a pest insect

International audience

慢性阿片类物质滥用对空间认知功能的影响及嗅觉系统与吗啡成瘾的相互作用

中文摘要 　 Ⅰ　慢性阿片类物质滥用对空间认知功能的影响本章首先对成瘾的神经生物学机制进行综述，然后介绍我的实验研究内容，实验目的是探讨海马在阿片类成瘾中的作用，及阿片类物质滥用对空间认知功能的影响。实验1采用单细胞记录技术，记录自由活动大鼠在慢性吗啡给予后戒断期间海马CA1区神经元发放频率，比较其在吗啡相关环境（阳性环境）及无关环境（阴性环境）中神经元发放频率的变化，且比较神经元发放变化率在各组间的差异。实验2检测了在海洛因戒断初期海洛因依赖者的地图/图标跟随及地图/图标工作记忆的能力。实验3采用Y迷宫行为范式检测在戒断不同时期，慢性吗啡给予对小鼠Y迷宫空间识别能力的影响。实验结果如下：实验1：吗啡戒断后，大鼠海马CA1区部分神经元在阳性环境及阴性环境中的发放率有显著性差异，这些神经元分为两类：Ⅰ类神经元在阳性环境中发放频率高于在阴性环境，Ⅱ类神经元在阳性环境中发放频率低于在阴性环境，其中吗啡组的Ⅱ类神经元发放变化率与盐水组相比存在显著性差异。实验2：海洛因依赖者，尤其女性海洛因依赖者，在地图跟随及地图/图标工作记忆中的成绩明显低于正常被试。实验3：在吗啡戒断第2天、第9天、第19天，小鼠Y迷宫空间识别记忆能力均受到损伤。以上实验结果表明，海马神经元在吗啡相关环境与无关环境中发放频率不同，从而编码了环境刺激与药物经历相关的记忆，在阿片类药物成瘾中起到一定作用；以及阿片类物质滥用损伤了大脑空间认知功能。 Ⅱ　嗅觉系统与吗啡成瘾的相互作用本章首先对嗅觉系统的功能及脑疾病引起嗅觉功能异常进行了综述，然后介绍我的实验研究内容，实验目的是探讨嗅觉系统在吗啡成瘾过程中的作用，及慢性吗啡给予对嗅觉功能的影响。实验1：利用条件化位置偏好模型（CPP），研究气味线索对吗啡依赖及渴求的影响。结果发现，单一嗅觉刺激使小鼠建立条件化位置偏好，形成吗啡依赖。当改变外界环境，动物进入完全新异的环境，依然寻求与吗啡相关的气味线索，说明吗啡相关气味线索能有效诱发小鼠对吗啡的渴求。实验2：研究短期及长期吗啡给予后小鼠嗅觉功能的变化。结果发现， 4天或21天的吗啡给予导致小鼠嗅觉敏感度降低（嗅觉阈值升高），而嗅觉辨别能力没有显著影响。小鼠嗅觉记忆能力受到损伤，随着吗啡给予时间的延长，这种记忆损伤更加明显。我们的实验表明嗅觉系统在吗啡依赖及渴求过程起到非常重要的作用，吗啡成瘾导致部分嗅觉功能的损伤。与药物相关的环境线索是诱发渴求及复吸的原因之一，因此，至少在啮齿类动物模型上，用嗅觉刺激作为药物相关的环境线索来研究渴求及复吸的机制，可能是较好的研究方法。

Functional evolution of mammalian odorant receptors.

The mammalian odorant receptor (OR) repertoire is an attractive model to study evolution, because ORs have been subjected to rapid evolution between species, presumably caused by changes of the olfactory system to adapt to the environment. However, functional assessment of ORs in related species remains largely untested. Here we investigated the functional properties of primate and rodent ORs to determine how well evolutionary distance predicts functional characteristics. Using human and mouse ORs with previously identified ligands, we cloned 18 OR orthologs from chimpanzee and rhesus macaque and 17 mouse-rat orthologous pairs that are broadly representative of the OR repertoire. We functionally characterized the in vitro responses of ORs to a wide panel of odors and found similar ligand selectivity but dramatic differences in response magnitude. 87% of human-primate orthologs and 94% of mouse-rat orthologs showed differences in receptor potency (EC50) and/or efficacy (dynamic range) to an individual ligand. Notably dN/dS ratio, an indication of selective pressure during evolution, does not predict functional similarities between orthologs. Additionally, we found that orthologs responded to a common ligand 82% of the time, while human OR paralogs of the same subfamily responded to the common ligand only 33% of the time. Our results suggest that, while OR orthologs tend to show conserved ligand selectivity, their potency and/or efficacy dynamically change during evolution, even in closely related species. These functional changes in orthologs provide a platform for examining how the evolution of ORs can meet species-specific demands.

Les habiletés olfactives des aveugles de naissance : organisation anatomo-fonctionnelle et aspects comportementaux

La littérature décrit certains phénomènes de réorganisation physiologique et fonctionnelle dans le cerveau des aveugles de naissance, notamment en ce qui a trait au traitement de l’information tactile et auditive. Cependant, le système olfactif des aveugles n’a reçu que très peu d’attention de la part des chercheurs. Le but de cette étude est donc de comprendre comment les aveugles traitent l’information olfactive au niveau comportemental et d’investiguer les substrats neuronaux impliqués dans ce processus. Puisque, en règle générale, les aveugles utilisent leurs sens résiduels de façon compensatoire et que le système olfactif est extrêmement plastique, des changements au niveau de l’organisation anatomo-fonctionnelle pourraient en résulter. Par le biais de méthodes psychophysiques et d’imagerie cérébrale (Imagerie par Résonance Magnétique fonctionnelle-IRMf), nous avons investigué les substrats anatomo-fonctionnels sollicités par des stimuli olfactifs. Nous avons trouvé que les aveugles ont un seuil de détection plus bas que les voyants, mais que leur capacité à discriminer et identifier des odeurs est similaire au groupe contrôle. Ils ont aussi plus conscience de l’environnement olfactif. Les résultats d’imagerie révèlent un signal BOLD plus intense dans le cortex orbitofrontal droit, le thalamus, l’hippocampe droit et le cortex occipital lors de l’exécution d’une tâche de détection d’odeur. Nous concluons que les individus aveugles se fient d’avantage à leur sens de l’odorat que les voyants afin d’évoluer dans leur environnement physique et social. Cette étude démontre pour la première fois que le cortex visuel des aveugles peut être recruté par des stimuli olfactifs, ce qui prouve que cette région assume des fonctions multimodales.

Work performance, productivity and indoor air

Temperature, relative humidity, and air quality all affect the sensory system via thermo receptors in the skin and the olfactory system. Air quality is mainly defined by the contaminants in the air. However, the most persistent memory of any space is often its odor. Strong, emotional, and past experiences are awakened by the olfactory sense. Odors can also influence cognitive processes that affect creative task performance, as well as personal memories and moods. Besides nitrogen and oxygen, the air contains particles and many chemicals that affect the efficiency of the oxygenation process in the blood, and ultimately the air breathed affects thinking and concentration. It is important to show clients the value of spending more capital on high-quality buildings that promote good ventilation. The process of achieving indoor-air quality is a continual one throughout the design, construction, commissioning, and facilities management processes. This paper reviews the evidence.

The interaction between the physical environments and people

Buildings affect people in various ways. They can help us to work more effectively; they also present a wide range of stimuli for our senses to react to. Intelligent buildings are designed to be aesthetic in sensory terms not just visually appealing but ones in which occupants experience delight, freshness, airiness, daylight, views out and social ambience. All these factors contribute to a general aesthetic which gives pleasure and affects one’s mood. If there is to be a common vision, it is essential for architects, engineers and clients to work closely together throughout the planning, design, construction and operational stages which represent the conception, birth and life of the building. There has to be an understanding of how patterns of work are best suited to a particular building form served by appropriate environmental systems. A host of technologies are emerging that help these processes, but in the end it is how we think about achieving responsive buildings that matters. Intelligent buildings should cope with social and technological changes and also be adaptable to short-term and long-term human needs. We live through our senses. They rely on stimulation from the tasks we are focused on; people around us but also the physical environment. We breathe air and its quality affects the olfactory system; temperature is felt by thermoreceptors in the skin; sound enters our ears; the visual scene is beheld by our eyes. All these stimuli are transmitted along the sensory nervous system to the brain for processing from which physiological and psychological reactions and judgments are formed depending on perception, expectancies and past experiences. It is clear that the environmental setting plays a role in this sensory process. This is the essence of sensory design. Space plays its part as well. The flow of communication is partly electronic but also largely by people meeting face to face. Our sense of space wants different things at different times. Sometimes privacy but other times social needs have to be satisfied besides the organizational requirement to have effective human communications throughout the building. In general if the senses are satisfied people feel better and work better.

Contribution to the chemoreception capacity of juvenile Loggerhead sea turtles (Caretta caretta, L.)

Loggerhead sea turtle juveniles (Caretta caretta), pelagic stage, are found in waters of Madeira archipelago. Pelagic turtles are in the main growth phase of their life cycle and consequently higher energy needs. However, knowledge about the ecology of pelagic loggerhead sea turtles is still quite rudimentary, mainly about the mechanisms that lead them to find food in the vast ocean. Studies with other pelagic species, such as procellariiform birds, revealed that the olfactory system play an important role for the detection of feeding areas, through the detection of concentration peaks of DMS (dimethylsulfide), a scent compound that naturally exists in the marine environment and it is related to areas of high productivity. Based on the assumption that loggerhead sea turtles use a similar mechanism, behavioural experiments were conducted in order to analyze the chemoreception capacity to DMS (airborne chemoreception - theoretically responsible for the long distance detection of areas with food patches; and aquatic chemoreception - theoretically responsible for the short distance detection of preys). The first step was to observe if pelagic loggerheads demonstrate sensitivity to DMS and the second was to verify if they really use the DMS, in natural conditions, as an airborne cue to find areas where food patches might be available. Four juveniles of loggerhead sea turtles were tested in captivity and three wild turtles in the open ocean. The results of airborne chemoreception experiments in captivity revealed that one turtle clearly demonstrated sensitivity to DMS and the sea experiments confirmed this result. However, the experiments were not conclusive on the question whether the pelagic turtles actually use the DMS as an airborne cue to detect long distance food patches. In aquatic chemoreception experiments was not observed sensitivity to DMS by the three sea turtles tested. In the classical conditioning experiment, where DMS and food were given nearly at the same time revealed that after a certain period of time, the sea turtle tested did not associated the DMS stimulus with a possible food reward. The main cause of mortality of loggerhead sea turtles in Madeira waters is due to the accidental capture (bycatch) by deep pelagic longlines fishery which the target species is the black-scabbard (Aphanopus carbo) fish. Chub mackerel (Scomber japonicus) is one of the baits used in this fishery. Aquatic chemoreception experiments were conducted in order to evaluate the attractiveness of the chub mackerel for sea turtles. For the three sea turtles tested, the results showed that in 90% of the cases the sea turtles were extremely attracted by the underwater smell of this fish.

Avaliação das atividades ansiolítica e antidepressiva dos óleos essenciais de Mentha piperita L. e Cananga odorata (Lam.) Hook. f. & Thomson em camundongos, por via inalatória

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

GnRH/GnIH e seus receptores no sistema olfato-retinal de zebrafish

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Permanent anosmia and ageusia after resection of a left temporoinsular low-grade glioma: anatomofunctional considerations

Five percent of the general population has olfactory or gustatory disorders, although most do not complain about it. However, in some cases, these symptoms can be disabling and may affect quality of life. Anosmia was reported as a possible complication following head injury and neurosurgical procedures, particularly after the resection of tumors located in the anterior fossa and the treatment of aneurysms in the anterior circulation. Nonetheless, in all of these situations, olfactory dysfunction could be explained by damage to the peripheral olfactory system. Here, the authors report a case of complete anosmia associated with ageusia following awake resection of a low-grade glioma involving the left temporoinsular region, with no recovery during a follow-up of 3 years. The frontal lobe was not retracted, and the olfactory tract was not visualized during surgery; therefore, postoperative anosmia and ageusia are likely explained by damage to the cortex and central pathways responsible for these senses. The authors suggest that the patient might have had a subclinical right hemianosmia before surgery, which is a common condition. After resection of the central structures critical for smell and taste processing in the left hemisphere, the patient could have finally had bilateral and complete olfactory and gustatory loss. This is the first known report of permanent anosmia and ageusia following glioma surgery. Because these symptoms might have been underestimated, more attention should be devoted to olfaction and taste, especially with regard to possible subclinical preoperative deficit. (http://thejns.org/doi/abs/10.3171/2012.2.JNS111982)

A GFP-equipped bidirectional expression module well suited for monitoring tetracycline-regulated gene expression in mouse

Doxycycline (Dox)-sensitive co-regulation of two transcriptionally coupled transgenes was investigated in the mouse. For this, we generated four independent mouse lines carrying coding regions for green fluorescent protein (GFP) and β-galactosidase in a bicistronic, bidirectional module. In all four lines the expression module was silent but was activated when transcription factor tTA was provided by the α-CaMKII-tTA transgene. In vivo analysis of GFP fluorescence, β-galactosidase and immunochemical stainings revealed differences in GFP and β-galactosidase levels between the lines, but comparable patterns of expression. Strong signals were found in neurons of the olfactory system, neocortical, limbic lobe and basal ganglia structures. Weaker expression was limited to thalamic, pontine and medullary structures, the spinal cord, the eye and to some Purkinje cells in the cerebellum. Strong GFP signals were always accompanied by intense β-galactosidase activity, both of which could be co-regulated by Dox. We conclude that the tTA-sensitive bidirectional expression module is well suited to express genes of interest in a regulated manner and that GFP can be used to track transcriptional activity of the module in the living mouse.

Novel antennal lobe substructures revealed in the small hive beetle Aethina tumida

The small hive beetle, Aethina tumida, is an emerging pest of social bee colonies. A. tumida shows a specialized life style for which olfaction seems to play a crucial role. To better understand the olfactory system of the beetle, we used immunohistochemistry and 3-D reconstruction to analyze brain structures, especially the paired antennal lobes (AL), which represent the first integration centers for odor information in the insect brain. The basic neuroarchitecture of the A. tumida brain compares well to the typical beetle and insect brain. In comparison to other insects, the AL are relatively large in relationship to other brain areas, suggesting that olfaction is of major importance for the beetle. The AL of both sexes contain about 70 olfactory glomeruli with no obvious size differences of the glomeruli between sexes. Similar to all other insects including beetles, immunostaining with an antiserum against serotonin revealed a large cell that projects from one AL to the contralateral AL to densely innervate all glomeruli. Immunostaining with an antiserum against tachykinin-related peptides (TKRP) revealed hitherto unknown structures in the AL. Small TKRP-immunoreactive spherical substructures are in both sexes evenly distributed within all glomeruli. The source for these immunoreactive islets is very likely a group of about 80 local AL interneurons. We offer two hypotheses on the function of such structures.

Distinct types of glial cells populate the Drosophila antenna

Background: The development of nervous systems involves reciprocal interactions between neurons and glia. In the Drosophila olfactory system, peripheral glial cells arise from sensory lineages specified by the basic helix- loop- helix transcription factor, Atonal. These glia wrap around the developing olfactory axons early during development and pattern the three distinct fascicles as they exit the antenna. In the moth Manduca sexta, an additional set of central glia migrate to the base of the antennal nerve where axons sort to their glomerular targets. In this work, we have investigated whether similar types of cells exist in the Drosophila antenna. Results: We have used different P( Gal4) lines to drive Green Fluorescent Protein ( GFP) in distinct populations of cells within the Drosophila antenna. Mz317:: GFP, a marker for cell body and perineural glia, labels the majority of peripheral glia. An additional similar to 30 glial cells detected by GH146:: GFP do not derive from any of the sensory lineages and appear to migrate into the antenna from the brain. Their appearance in the third antennal segment is regulated by normal function of the Epidermal Growth Factor receptor and small GTPases. We denote these distinct populations of cells as Mz317- glia and GH146- glia respectively. In the adult, processes of GH146- glial cells ensheath the olfactory receptor neurons directly, while those of the Mz317- glia form a peripheral layer. Ablation of GH146- glia does not result in any significant effects on the patterning of the olfactory receptor axons. Conclusion: We have demonstrated the presence of at least two distinct populations of glial cells within the Drosophila antenna. GH146- glial cells originate in the brain and migrate to the antenna along the newly formed olfactory axons. The number of cells populating the third segment of the antenna is regulated by signaling through the Epidermal Growth Factor receptor. These glia share several features of the sorting zone cells described in Manduca.

Plasticity in Insect Olfaction: To Smell or Not to Smell?

International audience

Immunolocalization of Arthropsin in the Onychophoran Euperipatoides rowelli (Peripatopsidae)

Opsins are light-sensitive proteins that play a key role in animal vision and are related to the ancient photoreceptive molecule rhodopsin found in unicellular organisms. In general, opsins involved in vision comprise two major groups: the rhabdomeric (r-opsins) and the ciliary opsins (c-opsins). The functionality of opsins, which is dependent on their protein structure, may have changed during evolution. In arthropods, typically r-opsins are responsible for vision, whereas in vertebrates c-opsins are components of visual photoreceptors. Recently, an enigmatic r-opsin-like protein called arthropsin has been identified in various bilaterian taxa, including arthropods, lophotrochozoans, and chordates, by performing transcriptomic and genomic analyses. Since the role of arthropsin and its distribution within the body are unknown, we immunolocalized this protein in a representative of Onychophora – Euperipatoides rowelli – an ecdysozoan taxon which is regarded as one of the closest relatives of Arthropoda. Our data show that arthropsin is expressed in the central nervous system of E. rowelli, including the brain and the ventral nerve cords, but not in the eyes. These findings are consistent with previous results based on reverse transcription PCR in a closely related onychophoran species and suggest that arthropsin is a non-visual protein. Based on its distribution in the central brain region and the mushroom bodies, we speculate that the onychophoran arthropsin might be either a photosensitive molecule playing a role in the circadian clock, or a non-photosensitive protein involved in olfactory pathways, or both.