Olfactory Receptors in Non-Chemosensory Organs: The Nervous System in Health and Disease

Olfactory receptors (ORs) and down-stream functional signaling molecules adenylyl cyclase 3 (AC3), olfactory G protein \u3b1 subunit (G\u3b1olf), OR transporters receptor transporter proteins 1 and 2 (RTP1 and RTP2), receptor expression enhancing protein 1 (REEP1), and UDP-glucuronosyltransferases (UGTs) are expressed in neurons of the human and murine central nervous system (CNS). In vitro studies have shown that these receptors react to external stimuli and therefore are equipped to be functional. However, ORs are not directly related to the detection of odors. Several molecules delivered from the blood, cerebrospinal fluid, neighboring local neurons and glial cells, distant cells through the extracellular space, and the cells' own self-regulating internal homeostasis can be postulated as possible ligands. Moreover, a single neuron outside the olfactory epithelium expresses more than one receptor, and the mechanism of transcriptional regulation may be different in olfactory epithelia and brain neurons. OR gene expression is altered in several neurodegenerative diseases including Parkinson's disease (PD), Alzheimer's disease (AD), progressive supranuclear palsy (PSP) and sporadic Creutzfeldt-Jakob disease (sCJD) subtypes MM1 and VV2 with disease-, region- and subtype-specific patterns. Altered gene expression is also observed in the prefrontal cortex in schizophrenia with a major but not total influence of chlorpromazine treatment. Preliminary parallel observations have also shown the presence of taste receptors (TASRs), mainly of the bitter taste family, in the mammalian brain, whose function is not related to taste. TASRs in brain are also abnormally regulated in neurodegenerative diseases. These seminal observations point to the need for further studies on ORs and TASRs chemoreceptors in the mammalian brain

Functional characterization of olfactory binding proteins for appeasing compounds and molecular cloning in the vomeronasal organ of pre-pubertal pigs.

International audienceThe appeasing behaviour of pre-pubertal pigs appears to result from the perception of maternal odours (fatty acids) and of steroids coming from the male. We have used a ligand-oriented approach to functionally characterize olfactory binding proteins involved in the detection of appeasing compounds in the nasal mucosa (NM) and the vomeronasal organ (VNO) of pre-pubertal pigs. Several proteins were identified, combining binding assay, immunodetection and protein sequencing. Their sites of expression in nasal and vomeronasal tissues were studied by reverse transcription polymerase chain reaction (RT-PCR). The proteins belong to the lipocalin superfamily: Alpha-1-acid glycoprotein (AGP), odorant-binding protein (OBP), salivary lipocalin (SAL) and Von Ebner's gland protein (VEG), and displayed different binding capacities for the appeasing compounds. RT-PCR experiments showed that OBP and VEG are expressed not only in the NM, but also in the VNO and that SAL is only expressed in the VNO. This is the first report of the expression of these lipocalins in the VNO. Different binding affinities between lipocalins and appeasing compounds, together with their different localizations in the olfactory systems, suggest multiple possibilities for the peripheral coding of appeasing signals

Expression of polysialyltransferases (STX and PST) in adult rat ă olfactory bulb after an olfactory associative discrimination task

International audienceNeuronal plasticity and neurogenesis occur in the adult hippocampus and ă in other brain structures such as the olfactory bulb and often involve ă the neural cell adhesion molecule NCAM. During an olfactory associative ă discrimination learning task, NCAM polysialylation triggers neuronal ă plasticity in the adult hippocampus. The PST enzyme likely modulates ă this polysialylation, but not STX, a second sialyltransferase. How the ă two polysialyltransferases are involved in the adult olfactory bulb ă remains unknown. We addressed this question by investigating the effect ă of olfactory associative learning on plasticity and neurogenesis. After ă a hippocampo-dependent olfactory associative task learning, we measured ă the expression of both PST and STX polysialyltransferases in the ă olfactory bulbs of adult rats using quantitative PCR. In parallel, ă immunohistochemistry was used to evaluate both NCAM polysialylation ă level and newly-born cells, with or without learning. After learning, no ă changes were observed neither in the expression level of PST and NCAM ă polysialylation, nor in STX gene expression level and newly-born cells ă number in the olfactory bulb. (C) 2016 Elsevier Inc. All rights ă reserved

Expression of the Cerebral Olfactory Receptors Olfr110/111 and Olfr544 Is Altered During Aging and in Alzheimer’s Disease-Like Mice

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Increase in polysialyltransferase gene expression following LTP in adult rat dentate gyrus

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