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Olfactory System (olfactory + system)
Kinds of Olfactory System Selected AbstractsDistribution Pattern of Neuropeptide Y in the Brain, Pituitary and Olfactory System during the Larval Development of the Toad Rhinella arenarum (Amphibia: Anura)ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 2 2009T. Heer Summary The first NPY-immunoreactivity (ir) in the central nervous system of Rhinella arenarum was obtained just after hatching in the pre-optic area, ventral thalamus and rostral rhombencephalon. During pre-metamorphosis, new NPY-ir cells were observed in other brain areas such as pallium, septum and striatum, infundibulum and pars intermedia of the pituitary. Further maturation continued through pro-metamorphosis with the appearance of cell groups in the diagonal band, amygdala, pre-optic nucleus, dorsal nucleus of the habenula, anterior ventral and dorsal thalamus, suprachiasmatic nucleus, tuberculum posterior, tectum, torus semicircularis, inter-peduncular nucleus and median eminence. During the metamorphic climax and soon after, the relative abundance of NPY-ir fibres decreased in all hypothalamic areas and the staining intensity and number of NPY-ir cells in the pallium also decreased, whereas no cells were found in the striatum, dorsal nucleus of the habenula and tectum. In the olfactory epithelium, nerve or bulb, neither cells nor NPY-ir fibres were found during the stages of development analysed. The ontogeny pattern of the NPY-ir neuronal system in the brain of Rh. arenarum is more similar to the spatiotemporal appearance reported for Rana esculenta than to that reported for Xenopus laevis. Many NPY-ir fibres were found in the median eminence and in the pars intermedia of the pituitary, supporting the idea that this neuropeptide may play a role in the modulation of hypophyseal secretion during development. [source] Spatially and temporally regulated expression of specific heparan sulfate epitopes in the developing mouse olfactory systemDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 2 2010Jun Takatoh Heparan sulfate (HS) comprises a structurally diverse group of glycosaminoglycans present ubiquitously on cell surfaces and in the extracellular matrix. The spatially and temporally regulated expression of specific HS structures is essential for various developmental processes in the nervous system but their distributions in the mouse olfactory system have not been explored. Here, we examined the spatiotemporal distribution of particular HS species in the developing mouse olfactory system using three structure-specific monoclonal antibodies (HepSS-1, JM403 and NAH46). The major findings were as follows. (i) During olfactory bulb morphogenesis, the HepSS-1 epitope was strongly expressed in anterior telencephalic cells and coexpressed with fibroblast growth factor receptor 1. (ii) In early postnatal glomeruli, the JM403 epitope was expressed at different levels among individual glomeruli. The expression pattern and levels of the JM403 epitope were both associated with those of ephrin-A3. (iii) In the vomeronasal system, the JM403 epitope was expressed in all vomeronasal axons but became increasingly restricted to vomeronasal axons terminating in the anterior region of the accessory olfactory bulb by 3 weeks of age. Our results demonstrate that each HS epitope exhibits a unique expression pattern during the development of the mouse olfactory system. Thus, each HS epitope is closely associated with particular developmental processes of the olfactory system and might have a particular role in developmental events. [source] Cloning and expression of three zebrafish roundabout homologs suggest roles in axon guidance and cell migrationDEVELOPMENTAL DYNAMICS, Issue 2 2001Jeong-Soo Lee Abstract We report the cloning and expression patterns of three novel zebrafish Roundabout homologs. The Roundabout (robo) gene encodes a transmembrane receptor that is essential for axon guidance in Drosophila and Robo family members have been implicated in cell migration. Analysis of extracellular domains and conserved cytoplasmic motifs shows that zebrafish Robo1 and Robo2 are orthologs of mammalian Robo1 and Robo2, respectively, while zebrafish Robo3 is likely to be an ortholog of mouse Rig-1. The three zebrafish robos are expressed in distinct but overlapping patterns during embryogenesis. They are highly expressed in the developing nervous system, including the olfactory system, visual system, hindbrain, cranial ganglia, spinal cord, and posterior lateral line primordium. They are also expressed in several nonneuronal tissues, including somites and fin buds. The timing and patterns of expression suggest roles for zebrafish robos in axon guidance and cell migration. Wiley-Liss, Inc. © 2001 Wiley-Liss, Inc. [source] Phenotypic plasticity in number of glomeruli and sensory innervation of the antennal lobe in leaf-cutting ant workers (A. vollenweideri)DEVELOPMENTAL NEUROBIOLOGY, Issue 4 2010Christina Kelber Abstract In the leaf-cutting ant Atta vollenweideri, the worker caste exhibits a pronounced size-polymorphism, and division of labor is dependent on worker size (alloethism). Behavior is largely guided by olfaction, and the olfactory system is highly developed. In a recent study, two different phenotypes of the antennal lobe of Atta vollenweideri workers were found: MG- and RG-phenotype (with/without a macroglomerulus). Here we ask whether the glomerular numbers are related to worker size. We found that the antennal lobes of small workers contain ,390 glomeruli (low-number; LN-phenotype), and in large workers we found a substantially higher number of ,440 glomeruli (high-number; HN-phenotype). All LN-phenotype workers and some small HN-phenotype workers do not possess an MG (LN-RG-phenotype and HN-RG-phenotype), and the remaining majority of HN-phenotype workers do possess an MG (HN-MG-phenotype). Using mass-staining of antennal olfactory receptor neurons we found that the sensory tracts divide the antennal lobe into six clusters of glomeruli (T1,T6). In LN-phenotype workers, ,50 glomeruli are missing in the T4-cluster. Selective staining of single sensilla and their associated receptor neurons revealed that T4-glomeruli are innervated by receptor neurons from the main type of olfactory sensilla, the Sensilla trichodea curvata. The other type of olfactory sensilla (Sensilla basiconica) exclusively innervates T6-glomeruli. Quantitative analyses of differently sized workers revealed that the volume of T6 glomeruli scales with the power of 2.54 to the number of Sensilla basiconica. The results suggest that developmental plasticity leading to antennal-lobe phenotypes promotes differences in olfactory-guided behavior and may underlie task specialization within ant colonies. © 2009 Wiley Periodicals, Inc. Develop Neurobiol 70: 222,234, 2010. [source] The molecular receptive range of an olfactory receptor in vivo (Drosophila melanogaster Or22a)DEVELOPMENTAL NEUROBIOLOGY, Issue 14 2006Daniela Pelz Abstract Understanding how odors are coded within an olfactory system requires knowledge about its input. This is constituted by the molecular receptive ranges (MRR) of olfactory sensory neurons that converge in the glomeruli of the olfactory bulb (vertebrates) or the antennal lobe (AL, insects). Aiming at a comprehensive characterization of MRRs in Drosophila melanogaster we measured odor-evoked calcium responses in olfactory sensory neurons that express the olfactory receptor Or22a. We used an automated stimulus application system to screen [Ca2+] responses to 104 odors both in the antenna (sensory transduction) and in the AL (neuronal transmission). At 10,2 (vol/vol) dilution, 39 odors elicited at least a half-maximal response. For these odorants we established dose-response relationships over their entire dynamic range. We tested 15 additional chemicals that are structurally related to the most efficient odors. Ethyl hexanoate and methyl hexanoate were the best stimuli, eliciting consistent responses at dilutions as low as 10,9. Two substances led to calcium decrease, suggesting that Or22a might be constitutively active, and that these substances might act as inverse agonists, reminiscent of G-protein coupled receptors. There was no difference between the antennal and the AL MRR. Furthermore we show that Or22a has a broad yet selective MRR, and must be functionally described both as a specialist and a generalist. Both these descriptions are ecologically relevant. Given that adult Drosophila use approximately 43 ORs, a complete description of all MRRs appears now in reach. © 2006 Wiley Periodicals, Inc. J Neurobiol, 2006 [source] Cell surface glycoconjugates in the olfactory system of lungfish Protopterus annectens OwenACTA ZOOLOGICA, Issue 2 2000Valeria Franceschini Abstract Franceschini, V. Lazzari, M. and Ciani, F. 2000. Cell surface glycoconjugates in the olfactory system of lungfish Protopterus annectens Owen. ,Acta Zoologica (Stockholm) 81: 131,137 Lectin binding was performed on the olfactory system of lungfish Protopterus annectens to identify specific glycoconjugates on the cell surface of olfactory receptor cells. The lectin histochemical patterns and the Western blot analysis indicate that the receptor cells of the olfactory mucosa are characterized by high density of ,-N-acetyl- d -galactosamine residues on the saccharidic chains of the surface glycoproteins. Other lectins display a regional pattern between the regions of the olfactory bulbs. This different histochemical lectin pattern might be due to a different regional segregation of the olfactory projections. On the other hand it could allow the identification of an area corresponding to the accessory olfactory bulb of terrestrial vertebrates in the ventrolateral region of Protopterus olfactory bulb. The presence in the dipnoan olfactory system of a vomeronasal organ homologous to the organ in amphibians is discussed. Moreover, the selective lectin binding on the surface of primary olfactory neurones suggests that specific cell surface glycoproteins may have a role in the axonal growth due to the continuous cycle of proliferation and the death of olfactory receptor cells. [source] A direct main olfactory bulb projection to the ,vomeronasal' amygdala in female mice selectively responds to volatile pheromones from malesEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 3 2009Ningdong Kang Abstract The main olfactory system, like the accessory olfactory system, responds to pheromones involved in social communication. Whereas pheromones detected by the accessory system are transmitted to the hypothalamus via the medial (,vomeronasal') amygdala, the pathway by which pheromones are detected and transmitted by the main system is not well understood. We examined in female mice whether a direct projection from mitral/tufted (M/T) cells in the main olfactory bulb (MOB) to the medial amygdala exists, and whether medial amygdala-projecting M/T cells are activated by volatile urinary odors from conspecifics or a predator (cat). Simultaneous anterograde tracing using Phaseolus vulgaris leucoagglutinin and Fluoro-Ruby placed in the MOB and accessory olfactory bulb (AOB), respectively, revealed that axons of MOB M/T cells projected to superficial laminae of layer Ia in anterior and posterodorsal subdivisions of the medial amygdala, whereas projection neurons from the AOB sent axons to non-overlapping, deeper layer Ia laminae of the same subdivisions. Placement of the retrograde tracer cholera toxin B into the medial amygdala labeled M/T cells that were concentrated in the ventral MOB. Urinary volatiles from male mice, but not from female conspecifics or cat, induced Fos in medial amygdala-projecting MOB M/T cells of female subjects, suggesting that information about male odors is transmitted directly from the MOB to the ,vomeronasal' amygdala. The presence of a direct MOB-to-medial amygdala pathway in mice and other mammals could enable volatile, opposite-sex pheromones to gain privileged access to diencephalic structures that control mate recognition and reproduction. [source] The vomeronasal organ is required for the expression of lordosis behaviour, but not sex discrimination in female miceEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 2 2006Matthieu Keller Abstract The role of the vomeronasal organ (VNO) in mediating neuroendocrine responses in female mice is well known; however, whether the VNO is equally important for sex discrimination is more controversial as evidence exists for a role of the main olfactory system in mate recognition. Therefore, we studied the effect of VNO removal (VNOx) on the ability of female mice to discriminate between volatile and non-volatile odours of conspecifics of the two sexes and in different endocrine states using Y-maze tests. VNOx female mice were able to reliably distinguish between male and female or male and gonadectomized (gdx) male volatile odours. However, when subjects had to discriminate between male and female or gdx male non-volatile odours, VNOx females were no longer able to discriminate between sex or different endocrine status. These results thus show that the VNO is primarily involved in the detection and processing of non-volatile odours, and that female mice can use volatile odours detected and processed by the main olfactory system for mate recognition. However, VNO inputs are needed to promote contact with the male, including facilitation of lordosis responses to his mounts. A single subcutaneous injection with gonadotropin-releasing hormone (GnRH) partially reversed the deficit in lordosis behaviour observed in VNOx females suggesting that VNO inputs may reach hypothalamic GnRH neurons to influence the display of sexual behaviour. [source] Single olfactory sensory neurons simultaneously integrate the components of an odour mixtureEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 10 2003Patricia Duchamp-Viret Abstract Most odours are complex mixtures. However, the capacities of olfactory sensory neurons (OSNs) to process complex odour stimuli have never been explored in air-breathing vertebrates. To face this issue, the present study compares the electrical responses of single OSNs to two odour molecules, delivered singly and mixed together, in rats in vivo. This work is the first aimed at demonstrating that single OSNs simultaneously integrate several chemical signals and which, furthermore, attempts to describe such processes for the whole concentration range over which single OSNs can work. The results stress that complex interactions occur between components in odour mixtures and that OSN responses to such mixtures are not simply predictable from the responses to their components. Three types of interactions are described. They are termed suppression, hypoadditivity and synergy, in accord with psychophysical terminology. This allows us to draw links between peripheral odour reception and central odour coding. Indeed, events occurring in single OSNs may account for the dominating or even the masking effects of odour molecules in complex mixtures, i.e. for the prevailing action of a minor component in the final qualitative perception of a mixture. We conclude that our observations with binary mixtures anticipate the complexity of processes which may rise at the level of a single OSN in physiological conditions. Following this hypothesis, a natural odour would induce a multi-chemical integration at the level of single OSNs which may result in refining their individual odour-coding properties, leading them to play a crucial role in the final performance of the olfactory system. [source] A novel brain receptor is expressed in a distinct population of olfactory sensory neuronsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2000Sidonie Conzelmann Abstract Three novel G-protein-coupled receptor genes related to the previously described RA1c gene have been isolated from the mouse genome. Expression of these genes has been detected in distinct areas of the brain and also in the olfactory epithelium of the nose. Developmental studies revealed a differential onset of expression: in the brain at embryonic stage 17, in the olfactory system at stage E12. In order to determine which cell type in the olfactory epithelium expresses this unique receptor type, a transgenic approach was employed which allowed a coexpression of histological markers together with the receptor and thus visualization of the appropriate cell population. It was found that the receptor-expressing cells were located very close to the basal membrane of the epithelium; however, the cells extended a dendritic process to the epithelial surface and their axons projected into the main olfactory bulb where they converged onto two or three glomeruli in the dorsal and posterior region of the bulb. Thus, these data provide evidence that this unique type of receptor is expressed in mature olfactory neurons and suggests that it may be involved in the detection of special odour molecules. [source] Calponin is expressed by fibroblasts and meningeal cells but not olfactory ensheathing cells in the adult peripheral olfactory systemGLIA, Issue 2 2007Chrystelle Ibanez Abstract Olfactory ensheathing cells (OECs), the principal glial cells of the peripheral olfactory system, have many phenotypic similarities with Schwann cells of the peripheral nervous system. This makes reliably distinguishing these two cells types difficult, especially following transplantation into areas of injury in the central nervous system. In an attempt to identify markers by which these two cells types can be distinguished, a recent proteomic analysis of fetal OECs and adult Schwann cells identified the actin-binding protein calponin as a potential marker expressed by OECs but not Schwann cells. Since many studies designed with the translational goal of autologous transplantation in mind have used adult OECs, this study examined the expression of calponin by adult OECs, both in vivo within the peripheral olfactory system and in vitro. Calponin colocalized with strongly fibronectin positive fibroblasts in the olfactory mucosa (OM) and meningeal cells in the olfactory bulb (OB) but not with S100, or neuropeptide-Y positive OECs. In tissue culture, calponin was strongly expressed by fibronectin-expressing fibroblasts from OM, sciatic nerve and skin and by meningeal cells from the OB, but not by p75NTR - and S100,-expressing OECs. These data, supported by Western blotting, indicate that calponin can not be used to distinguish adult OECs and Schwann cells. © 2006 Wiley-Liss, Inc. [source] New method of purification for establishing primary cultures of ensheathing cells from the adult olfactory bulb,GLIA, Issue 2 2001Holly H. Nash Abstract Ensheathing cells exclusively enfold olfactory axons. The ability of olfactory axons to reinnervate the adult mammalian olfactory bulb throughout the lifetime of an organism is believed to result from the presence of this unique glial cell in the olfactory system. This theory has been substantiated by research demonstrating the ability of transplanted ensheathing cells to promote axonal regrowth in areas of the central nervous system that are normally nonpermissive. A simple method for purifying ensheathing cells resulting in a large yield of cells is therefore invaluable for transplantation studies. We have developed such a method based on the differing rates of attachment of the various harvested cell types. The greatest percentage of cells (70.4%) that attached during the first step of the separation was determined to be fibroblasts. The remainder of the cells were classified as astrocytes (20.8%) and ensheathing cells (6.8%). The percentage of attached astrocytes (67.6%) was greatly increased during the second purification step while the percentage of fibroblasts decreased greatly (27.9%) and the percentage of ensheathing cells (5.3%) slightly decreased. In the final cultures, 93.2 % of the attached cells were ensheathing cells, while astrocytes (5.9%) and fibroblasts (1.4%) were only minor components. This simple, inexpensive method of purifying ensheathing cells will facilitate their use in central nervous system regeneration research. GLIA 34:81,87, 2001. © 2001 Wiley-Liss, Inc. [source] Subicular and CA1 hippocampal projections to the accessory olfactory bulbHIPPOCAMPUS, Issue 2 2009C. de la Rosa-Prieto Abstract The hippocampal formation is anatomically and functionally related to the olfactory structures especially in rodents. The entorhinal cortex (EC) receives afferent projections from the main olfactory bulb; this constitutes an olfactory pathway to the hippocampus. In addition to the olfactory system, most mammals possess an accessory olfactory (or vomeronasal) system. The relationships between the hippocampal formation and the vomeronasal system are virtually unexplored. Recently, a centrifugal projection from CA1 to the accessory olfactory bulb has been identified using anterograde tracers. In the study reported herein, experiments using anterograde tracers confirm this projection, and injections of retrograde tracers show the distribution and morphology of a population of CA1 and ventral subicular neurons projecting to the accessory olfactory bulb of rats. These results extend previous descriptions of hippocampal projections to the accessory olfactory bulb by including the ventral subiculum and characterizing the morphology, neurochemistry (double labeling with somatostatin), and distribution of such neurons. These data suggest feedback hippocampal control of chemosensory stimuli in the accessory olfactory bulb. Whether this projection processes spatial information on conspecifics or is involved in learning and memory processes associated with chemical stimuli remains to be elucidated. © 2008 Wiley-Liss, Inc. [source] Olfactory receptors: G protein-coupled receptors and beyondJOURNAL OF NEUROCHEMISTRY, Issue 6 2009Marc Spehr Abstract Sensing the chemical environment is critical for all organisms. Diverse animals from insects to mammals utilize highly organized olfactory system to detect, encode, and process chemostimuli that may carry important information critical for health, survival, social interactions and reproduction. Therefore, for animals to properly interpret and react to their environment it is imperative that the olfactory system recognizes chemical stimuli with appropriate selectivity and sensitivity. Because olfactory receptor proteins play such an essential role in the specific recognition of diverse stimuli, understanding how they interact with and transduce their cognate ligands is a high priority. In the nearly two decades since the discovery that the mammalian odorant receptor gene family constitutes the largest group of G protein-coupled receptor (GPCR) genes, much attention has been focused on the roles of GPCRs in vertebrate and invertebrate olfaction. However, is has become clear that the ,family' of olfactory receptors is highly diverse, with roles for enzymes and ligand-gated ion channels as well as GPCRs in the primary detection of olfactory stimuli. [source] Cell and molecular biology of human olfactionMICROSCOPY RESEARCH AND TECHNIQUE, Issue 3 2002Nancy E. Rawson Abstract Progress in our understanding of olfactory receptor physiology has progressed greatly over the past 10 years. It has become clear that many anatomical and molecular features of the peripheral aspect of the olfactory system have remained highly conserved across diverse species. Yet, this structure is responsible for conveying a wide variety of information about the environment that is necessary to the successful location of food, mates, and avoidance of danger, and it is thus not surprising that specializations have also evolved to suit the differing needs of different species. While the basic anatomical features reflect those of other mammals, functional studies of human olfactory receptor neurons have revealed physiological features both similar to and differing from those of other mammalian species. This review presents an overview of both the anatomical and physiological data describing the cell and molecular biology of the peripheral human olfactory system and how it functions in health and disease. Microsc. Res. Tech. 58:142,151, 2002. © 2002 Wiley-Liss, Inc. [source] Wnt/frizzled family members mediate olfactory sensory neuron axon extensionTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 3 2008Diego J. Rodriguez-Gil Abstract A comprehensive model has yet to emerge, but it seems likely that numerous mechanisms contribute to the specificity of olfactory sensory neuron (OSN) axon innervation of the olfactory bulb. Elsewhere in the nervous system the Wnt/Fz family has been implicated in patterning of anterior-posterior axes, cell type specification, cell proliferation, and axon guidance. Because of our work describing cadherin-catenin family member expression in the primary olfactory pathway, and because mechanisms of Wnt-Fz interactions can depend in part on catenins, we were encouraged to explore Wnt-Fz expression and function in OSN axon extension. Here, we show that OSNs express Fz-1, Fz-3, and Wnt-5a, whereas olfactory ensheathing cells (OECs) express Wnt-4. Fz-7 is also expressed in the olfactory nerve by cells that delineate large axon fascicles, but are negative for OEC markers. Fz-1 showed a developmental downregulation. However, in adults it is expressed at different levels across the olfactory epithelium and in restricted glomeruli across the olfactory bulb, suggesting an important role in the formation and maintenance of OSN connections to the olfactory bulb. Reporter TOPGAL mice demonstrated that some OECs located in the inner olfactory nerve layer can respond to Wnt ligands. Of further interest, we show here with in vitro assays that Wnt-5a increases OSN axon outgrowth and alters growth cone morphology. Our data point to a key role for Wnt/Fz molecules in the development of the mouse olfactory system, providing complementary mechanisms required for OSN axon extension and coalescence. J. Comp. Neurol. 511:301,317, 2008. © 2008 Wiley-Liss, Inc. [source] Editor's remarks: Chemotopic odorant coding in a mammalian olfactory system, Johnson et al., J Comp Neurol 503:1,34,THE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 1 2007Thomas E. Finger Associate Editor No abstract is available for this article. [source] Chemotopic odorant coding in a mammalian olfactory system,THE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 1 2007Brett A. Johnson Abstract Systematic mapping studies involving 365 odorant chemicals have shown that glomerular responses in the rat olfactory bulb are organized spatially in patterns that are related to the chemistry of the odorant stimuli. This organization involves the spatial clustering of principal responses to numerous odorants that share key aspects of chemistry such as functional groups, hydrocarbon structural elements, and/or overall molecular properties related to water solubility. In several of the clusters, responses shift progressively in position according to odorant carbon chain length. These response domains appear to be constructed from orderly projections of sensory neurons in the olfactory epithelium and may also involve chromatography across the nasal mucosa. The spatial clustering of glomerular responses may serve to "tune" the principal responses of bulbar projection neurons by way of inhibitory interneuronal networks, allowing the projection neurons to respond to a narrower range of stimuli than their associated sensory neurons. When glomerular activity patterns are viewed relative to the overall level of glomerular activation, the patterns accurately predict the perception of odor quality, thereby supporting the notion that spatial patterns of activity are the key factors underlying that aspect of the olfactory code. A critical analysis suggests that alternative coding mechanisms for odor quality, such as those based on temporal patterns of responses, enjoy little experimental support. J. Comp. Neurol. 503:1,34, 2007. © 2007 Wiley-Liss, Inc. [source] Differential responses to branched and unsaturated aliphatic hydrocarbons in the rat olfactory systemTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 4 2006Sabrina L. Ho Abstract In an effort to understand mammalian olfactory processing, we have been describing the responses to systematically different odorants in the glomerular layer of the main olfactory bulb of rats. Previously, we demonstrated chemotopically organized and distinct olfactory responses to a homologous series of straight-chained alkanes that consisted of purely hydrocarbon structures, indicating that hydrocarbon chains could serve as molecular features in the combinatorial coding of odorant information. To better understand the processing of hydrocarbon odorants, we now have examined responses to other types of chemical changes in these kinds of molecules, namely, branching and carbon,carbon bond saturation. To this end, we used the [14C]2-deoxyglucose method to determine glomerular responses to a group of eight-carbon branched alkane isomers, unsaturated octenes (double-bonded), and octynes (triple-bonded). In contrast to the differential responses we observed previously for straight-chained alkanes of differing carbon number, the rat olfactory system was not particularly sensitive to these variations in branching and bond saturation. This result was unexpected, given the distinct molecular conformations and property profiles of the odorants. The similarity in activity patterns was paralleled by a similarity in spontaneous perceptual responses measured using a habituation assay. These results demonstrate again the functional relationship between bulbar activity patterns and odor perception. The results further suggest that the olfactory system does not respond equally to all aspects of odorant chemistry, functioning as a specific, rather than a general, chemical analysis system. J. Comp. Neurol. 499:519,532, 2006. © 2006 Wiley-Liss, Inc. [source] Frequency and Localization of the Putative Vomeronasal Organ in Humans in Relation to Age and Gender,THE LARYNGOSCOPE, Issue 3 2001Michael Knecht MD Abstract Objectives/Hypotheses In many species the vomeronasal organ (VNO) serves as a chemosensory organ in addition to the olfactory system. The present investigation was undertaken to study 1) the frequency of monolateral or bilateral detection of the putative VNO (pVNO) in humans, 2) its localization in humans, and 3) whether detectability of the pVNO varies with age or gender. Study Design Prospective. Methods A total of 173 subjects participated in this study (88 women and 85 men; age range, 2,91 y). Inspection of the nose was performed with a speculum and a 30° endoscope. The exact localization of the VNO was measured with custom-built rulers. Results The study revealed the following major results: 1) A pVNO is detectable in approximately two-thirds of the population and bilateral pVNOs are present in approximately 40% of investigated subjects, 2) its localization on the left and right nasal septum is almost symmetrical, and 3) and detectability of the pVNO is not related to age or gender. Conclusions The present data indicated that the pVNO is present in approximately two-thirds of the population. This value may be biased by methodological or biological factors; nevertheless, it indicates that the pVNO is not observed in all humans regardless of age and gender. Thus, considering its variability in shape and immunohistochemical characteristics and the missing nerval connections between the peripheral "organ" and the central nervous system, the present results are not suited to argue for a functional significance of the pVNO in humans. [source] Lectin Histochemical Analysis of the Olfactory Bulbs in the Barfin Flounder (Verasper moseri)ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 1 2010N. Nakamuta Summary Several lines of evidence have shown that the olfactory system of the fish contains the main and accessory olfactory systems. However, morphological data indicate that the accessory olfactory bulb, the primary centre for the accessory olfactory system, will not differentiate in the fish. Therefore, the fish olfactory bulb is supposed to engage in both main and accessory olfactory systems. To examine this possibility, we investigated the olfactory bulb of the barfin flounder (Verasper moseri) by histochemical examination using lectins. The olfactory bulb of the barfin flounder showed a laminar structure with four layers, and diffuse glomerular architecture was observed in the glomerular layer. Based on the expression patterns of sugar residues, the glomerular layer of the barfin olfactory bulb was largely divided into three portions. Heterogeneity in the lectin-binding pattern among olfactory glomeruli was clearly demonstrated by the fluorescent double-lectin staining. The results of this study suggest that the fish olfactory bulb contains both regions equivalent to the main and accessory olfactory bulbs, and they are subdivided into small subsets with different functions. [source] Olfactory epithelium amyloid-, and paired helical filament-tau pathology in Alzheimer diseaseANNALS OF NEUROLOGY, Issue 4 2010Steven E. Arnold MD Objective Olfactory dysfunction is common in Alzheimer disease (AD) and other neurodegenerative diseases. Paired helical filament (PHF)-tau, ,-synuclein, and amyloid-, lesions occur early and severely in cerebral regions of the olfactory system, and they have also been observed in olfactory epithelium (OE). However, their frequency, abundance, and disease specificity, and the relationships of OE pathology to brain pathology have not been established. Methods We investigated the pathological expression of amyloid-,, PHFtau, ,-synuclein, and TDP-43 in postmortem OE of 79 cases with AD, 63 cases with various other neurodegenerative diseases, and 45 neuropathologically normal cases. Results Amyloid-, was present as punctate and small patchy aggregates in 71% of AD cases, compared with 22% of normal cases and 14% of cases with other diseases, and in greater amounts in AD than in either of the other 2 diagnostic categories. PHFtau was evident in dystrophic neurites in 55% of cases with AD, 34% with normal brains, and 39% with other neurodegenerative diseases, also at higher densities in AD. ,-Synuclein was present in dystrophic neurites in 7 cases, 6 of which also had cerebral Lewy bodies. Pathological TDP-43 inclusions were not observed in the OE in any cases. Amyloid-, and to a lesser degree, PHFtau ratings in OE significantly correlated with cortical A, and PHFtau lesion ratings in the brain. Interpretation These data demonstrate that AD pathology in the OE is present in the majority of cases with pathologically verified AD and correlates with brain pathology. Future work may assess the utility of amyloid-, and PHFtau measurement in OE as a biomarker for AD. ANN NEUROL 2010;67:462,469 [source] Structure of rat odorant-binding protein OBP1 at 1.6,Å resolutionACTA CRYSTALLOGRAPHICA SECTION D, Issue 5 2009Scott A. White The nasal mucosa is a specialist interfacial region sandwiched between the olfactory system and the gaseous chemical milieu. In mammals and insects, this region is rich in odorant-binding proteins that are thought to aid olfaction by assisting mass transfer of the many different organoleptic compounds that make up the olfactory landscape. However, in mammals at least, our grasp on the exact function of odorant-binding proteins is tentative and better insight into the role of these proteins is warranted, not least because of their apparent significance in the olfactory systems of insects. Here, the crystal structure of rat odorant-binding protein 1 is reported at 1.6,Å resolution. This protein is one of the best-characterized mammalian odorant-binding proteins and only the third such protein structure to be solved at high resolution. The protein was crystallized in the holo form and contains an unidentifiable ligand that is probably an artefact from the Pichia pastoris expression system. Comparisons are made between this structure and a modelled OBP1 structure produced using the crystal structure of aphrodisin as a template. Comparisons are also made between OBP1 and the other two rat OBP subtypes, for which crystallographic data are unavailable. Interestingly, we also show that OBP1 is monomeric, which is in contrast to its previous assignment. [source] GABAergic modulation of primary gustatory afferent synaptic efficacyDEVELOPMENTAL NEUROBIOLOGY, Issue 2 2002Andrew A. Sharp Abstract Modulation of synaptic transmission at the primary sensory afferent synapse is well documented for the somatosensory and olfactory systems. The present study was undertaken to test whether GABA impacts on transmission of gustatory information at the primary afferent synapse. In goldfish, the vagal gustatory input terminates in a laminated structure, the vagal lobes, whose sensory layers are homologous to the mammalian nucleus of the solitary tract. We relied on immunoreactivity for the GABA-transporter, GAT-1, to determine the distribution of GABAergic synapses in the vagal lobe. Immunocytochemistry showed dense, punctate GAT-1 immunoreactivity coincident with the layers of termination of primary afferent fibers. The laminar nature and polarized dendritic structure of the vagal lobe make it amenable to an in vitro slice preparation to study early synaptic events in the transmission of gustatory input. Electrical stimulation of the gustatory nerves in vitro produces synaptic field potentials (fEPSPs) predominantly mediated by ionotropic glutamate receptors. Bath application of either the GABAA receptor agonist muscimol or the GABAB receptor agonist baclofen caused a nearly complete suppression of the primary fEPSP. Coapplication of the appropriate GABAA or GABAB receptor antagonist bicuculline or CGP-55845 significantly reversed the effects of the agonists. These data indicate that GABAergic terminals situated in proximity to primary gustatory afferent terminals can modulate primary afferent input via both GABAA and GABAB receptors. The mechanism of action of GABAB receptors suggests a presynaptic locus of action for that receptor. © 2002 Wiley Periodicals, Inc. J Neurobiol 52: 133,143, 2002 [source] A novel Takeout-like protein expressed in the taste and olfactory organs of the blowfly, Phormia reginaFEBS JOURNAL, Issue 18 2006Kazuyo Fujikawa In insects, the functional molecules responsible for the taste system are still obscure. The gene for a 28.5 kDa protein purified from taste sensilla of the blowfly Phormia regina belongs to a gene family that includes takeout of Drosophila melanogaster. Molecular phylogenetic analysis revealed that the Phormia Takeout-like protein is most similar to the protein encoded by a member of the Drosophila takeout gene family, CG14661, whose expression and function have not been identified yet. Western blot analyses revealed that Phormia Takeout-like protein was exclusively expressed in antennae and labellum of the adult blowfly in both sexes. Immunohistochemical experiments demonstrated that Takeout-like protein was localized around the lamella structure of the auxiliary cells and in the sensillar lymph of the labellar taste sensillum. In antennae, Takeout-like protein was distributed at the base of the olfactory sensilla as well. No significant differences in Takeout-like protein expression were found between the sexes. Our results suggest that Phormia Takeout-like protein is involved in some early events concerned with chemoreception in both the taste and olfactory systems. [source] Evolution of the amygdaloid complex in vertebrates, with special reference to the anamnio-amniotic transitionJOURNAL OF ANATOMY, Issue 2 2007Nerea Moreno Abstract Numerous studies over the last few years have demonstrated that the amygdaloid complex in amniotes shares basic developmental, hodological and neurochemical features. Furthermore, homologous territories of all the main amygdaloid subdivisions have been recognized among amniotes, primarily highlighted by the common expression patterns for numerous developmental genes. Thus, derivatives from the lateral pallium, ventral pallium and subpallium constitute the fundamental parts of the amygdaloid complex. With the development of new technical approaches, study of the precise neuroanatomy of the telencephalon of the anuran amphibians (anamniotes) has been possible. Current embryological, hodological and immunohistochemical evidence strongly suggests that most of the structures present in amniotes are recognizable in these anamniotes. These investigations have yielded enough results to support the notion that the organization of the anuran amygdaloid complex includes subdivisions with their origin in ventral pallial and subpallial territories; a strong relationship with the vomeronasal and olfactory systems; abundant intra-amygdaloid connections; a main output centre involved in the autonomic system; recognizable amygdaloid fibre systems; and distinct chemoarchitecture. Therefore, the new ideas regarding the amygdaloid evolution based on the recent findings in anamniotes, and especially in anurans, strongly support the notion that basic amygdaloid structures were present at least in the brain of ancestral tetrapods organized following a basic plan shared by tetrapods. [source] Importance of the olfactory sense to migratory sea lampreys Petromyzon marinus seeking riverine spawning habitatJOURNAL OF FISH BIOLOGY, Issue 4 2010L. A. Vrieze This study tested the hypothesis that the sea lamprey Petromyzon marinus, a diadromous species of fish, relies on innately discerned odours, including pheromones, to locate riverine spawning habitat. Migratory, sexually immature P. marinus were captured as they entered streams flowing into the Great Lakes, and their olfactory systems were occluded or not by injecting either innocuous dental impression material or a saline control into their nasopores. Animals were then released back into lakes or streams and their recapture rates in stream traps noted. When released into Lake Huron, P. marinus with intact (functional) olfactory systems were very successful in locating rivers (recapture rates ranged up to 65%), while animals with occluded nasopores were virtually unable to do so and had recapture rates five to 20 times lower than intact animals. With few exceptions, intact fish entered the stream closest to their release point within a few days, irrespective of where they had been originally captured; their ability to locate streams is apparently innate and well developed. In contrast, when released within streams, both intact and occluded P. marinus successfully swam upstream to traps for several days although the ability of the former exceeded that of the latter after this period. Migratory P. marinus rely heavily on olfactory cues, of which a larval pheromone is presumably one, to locate river mouths and to a lesser extent to promote upstream movement within rivers. [source] Neurotransmitters and neuropeptides in the brain of the locustMICROSCOPY RESEARCH AND TECHNIQUE, Issue 3 2002Uwe Homberg Abstract As part of continuous research on the neurobiology of the locust, the distribution and functions of neurotransmitter candidates in the nervous system have been analyzed particularly well. In the locust brain, acetylcholine, glutamate, ,-aminobutyric acid (GABA), and the biogenic amines serotonin, dopamine, octopamine, and histamine most likely serve a transmitter function. Increasing evidence, furthermore, supports a signalling function for the gaseous molecule nitric oxide, but a role for neuroptides is so far suggested only by immunocytochemistry. Acetylcholine, glutamate, and GABA appear to be present in large numbers of interneurons. As in other insects, antennal sensory afferents might be cholinergic, while glutamate is the transmitter candidate of antennal motoneurons. GABA is regarded as the principle inhibitory transmitter of the brain, which is supported by physiological studies in the antennal lobe. The cellular distribution of biogenic amines has been analyzed particularly well, in some cases down to physiologically characterized neurons. Amines are present in small numbers of interneurons, often with large branching patterns, suggesting neuromodulatory roles. Histamine, furthermore, is the transmitter of photoreceptor neurons. In addition to these "classical transmitter substances," more than 60 neuropeptides were identified in the locust. Many antisera against locust neuropeptides label characteristic patterns of neurosecretory neurons and interneurons, suggesting that these peptides have neuroactive functions in addition to hormonal roles. Physiological studies supporting a neuroactive role, however, are still lacking. Nitric oxide, the latest addition to the list of neurotransmitter candidates, appears to be involved in early stages of sensory processing in the visual and olfactory systems. Microsc. Res. Tech. 56:189,209, 2002. © 2002 Wiley-Liss, Inc. [source] Lectin Histochemical Analysis of the Olfactory Bulbs in the Barfin Flounder (Verasper moseri)ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 1 2010N. Nakamuta Summary Several lines of evidence have shown that the olfactory system of the fish contains the main and accessory olfactory systems. However, morphological data indicate that the accessory olfactory bulb, the primary centre for the accessory olfactory system, will not differentiate in the fish. Therefore, the fish olfactory bulb is supposed to engage in both main and accessory olfactory systems. To examine this possibility, we investigated the olfactory bulb of the barfin flounder (Verasper moseri) by histochemical examination using lectins. The olfactory bulb of the barfin flounder showed a laminar structure with four layers, and diffuse glomerular architecture was observed in the glomerular layer. Based on the expression patterns of sugar residues, the glomerular layer of the barfin olfactory bulb was largely divided into three portions. Heterogeneity in the lectin-binding pattern among olfactory glomeruli was clearly demonstrated by the fluorescent double-lectin staining. The results of this study suggest that the fish olfactory bulb contains both regions equivalent to the main and accessory olfactory bulbs, and they are subdivided into small subsets with different functions. [source] Structure of rat odorant-binding protein OBP1 at 1.6,Å resolutionACTA CRYSTALLOGRAPHICA SECTION D, Issue 5 2009Scott A. White The nasal mucosa is a specialist interfacial region sandwiched between the olfactory system and the gaseous chemical milieu. In mammals and insects, this region is rich in odorant-binding proteins that are thought to aid olfaction by assisting mass transfer of the many different organoleptic compounds that make up the olfactory landscape. However, in mammals at least, our grasp on the exact function of odorant-binding proteins is tentative and better insight into the role of these proteins is warranted, not least because of their apparent significance in the olfactory systems of insects. Here, the crystal structure of rat odorant-binding protein 1 is reported at 1.6,Å resolution. This protein is one of the best-characterized mammalian odorant-binding proteins and only the third such protein structure to be solved at high resolution. The protein was crystallized in the holo form and contains an unidentifiable ligand that is probably an artefact from the Pichia pastoris expression system. Comparisons are made between this structure and a modelled OBP1 structure produced using the crystal structure of aphrodisin as a template. Comparisons are also made between OBP1 and the other two rat OBP subtypes, for which crystallographic data are unavailable. Interestingly, we also show that OBP1 is monomeric, which is in contrast to its previous assignment. [source] | ||||||||||||||||||||||||||||