Odor information processing along an OR-specific neuronal pathway
Final Report Abstract
Olfactory system of mammals relies on large set of sensory neurons expressing odorant receptors (ORs). A unique OR37 subfamily is exclusive for mammals and are highly conserved across species. We performed anatomical comparative assessment of the interneuronal composition of OR37 glomeruli in contrast to other odorant-receptor types. In a collaborative approach we addressed the question whether a reduced demand for periglomerular interneurons in the MOB has an impact on neurogenesis. We further tested functional correlates of the OR37 system activation using IEG-based and immunohistochemical assessment. The mouse OR37 receptor subtypes were shown to be activated by the long-chain aliphatic aldehydes and their biological source of these compounds was shown to be bodily secretions from conspecifics. Physiologically OR37 activation by conspecific secretions or ligands down-modulated hypothalamic PVN corticotropin-releasing hormone neurons activity in the stress-inducing novelty conditions, suggesting their role in social buffering. Finally, we investigated the system of another specific OR subtype, Olfr78 family, expressed both in the MOE and in the intestinal tissue and activated by the nutrient-derived short-chain fatty acids and identified their functional role in the colon. Due to technical problems we deviated from our original goal of dissection of OR37-specific dynamics and we focused, instead, on investigating the functional role of respiratory dynamics in behaving freely-moving animals. We identified a generic quiescent-state modulation imposed by the respiratory 4 Hz rhythmic dynamics on large range of limbic circuits and performed comprehensive characterization of this phenomenon. We identified a functional link between fear behaviour and limbic 4 Hz rhythm in mice. We developed high resolution 3D behaviour analysis methodology and identified orofacial behaviours associated with distinct sniffing modes providing putatively different exploratory regimes. We further demonstrated that alternation between distinct exploratory postural and sniffing modes resulted in rate remapping of hippocampal spatial representation, suggesting that identified modes are consistent with alternating active sampling of distinct sensory modalities. We developed a novel virtual reality system and demonstrated that rats engage in spontaneous exploration of purely virtual entities in a similar fashion to their real counterparts, exhibiting comparable postural and sniffing exploratory modes.
Publications
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(2015) Activation of the mouse odorant receptor 37 subsystem coincides with a reduction of novel environment-induced activity within the paraventricular nucleus of the hypothalamus. Eur J Neurosci. 41(6):793-801
Klein B, Bautze V, Maier AM, Deussing J, Breer H, Strotmann J
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(2015) Expression of odorant receptor Olfr78 in enteroendocrine cells of the colon. Cell Tissue Res. 361(3):697-710
Fleischer J, Bumbalo R, Bautze V, Strotmann J, Breer H
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(2015) Simultaneous measurement of cholinergic tone and neuronal network dynamics in vivo in the rat brain using a novel choline oxidase based electrochemical biosensor. Biosensors and Bioelectronics, 69:83–94
Santos R, Laranjinha J, Barbosa RM, Sirota A
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(2016) 4-Hz oscillations synchronize prefrontal–amygdala circuits during fear behaviour. Nat Neurosci. 19(4):605-12
Karalis N, Dejean C, Chaudun F, Khoder S, Rozeske R, Wurtz H, Bagur S, Benchenane K, Sirota A, Courtin J, Herry C
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(2016) Decreased demand for olfactory periglomerular cells impacts on neural precursor cell viability in the rostral migratory stream. Sci Rep. 6:32203
Langenfurth A, Gu S, Bautze V, Zhang C, Neumann JE, Schüller U, Stock K, Wolf SA, Maier AM, Mastrella G, Pak A, Cheng H, Kälin RE, Holmbeck K, Strotmann J, Kettenmann H, Glass R
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Structural features of an OR37 glomerulus: A comparative study. Front. Neuroanat.
Maier AM, Breer H, Strotmann J
