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1. Divergent bitter and sweet taste perception intensity in chronic rhinosinusitis patients

   https://doi.org/10.1002/alr.22686  

   Lin, Cailu ; Civantos, Alyssa M. ; Arnold, Monique ; Stevens, Elizabeth M. ; Cowart, Beverly J. ; Colquitt, Lauren R. ; Mansfield, Corrine ; Kennedy, David W. ; Brooks, Steven G. ; Workman, Alan D. ; et al ( August 2020 , International Forum of Allergy & Rhinology)

   Bitter and sweet taste receptors are present in the human upper airway, where they have roles in innate immunity. Previous studies have shown that 1 of the 25 bitter receptors,TAS2R38, responds to specific bacterial signaling molecules and evokes 1 type of a defense response in the upper airway, whereas ligands of sweet receptors suppress other types of defense responses.

   We examined whether other bitter taste receptors might also be involved in innate immunity by using sensory responses to bitter compounds that are not ligands ofTAS2R38(quinine and denatonium benzoate) to assess the sensitivity of other bitter receptors in chronic rhinosinusitis (CRS) patients. CRS patients with (n = 426) and without (n = 226) nasal polyps and controls (n = 356) rated the intensity of quinine, denatonium benzoate, phenylthiocarbamide (PTC; a ligand forTAS2R38), sucrose, and salt.

   CRS patients rated the bitter compounds denatonium benzoate and quinine as less intense and sucrose as more intense than did controls (false discovery rate [FDR] <0.05) and CRS patients and controls did not differ in their ratings of salt (FDR >0.05). PTC bitter taste intensity differed between patient and control groups but were less marked than those previously reported. Though differences were statistically significant, overall effect sizes were small.

   CRS patients report bitter stimuli as less intense but sweet stimuli as more intense than do control subjects. We speculate that taste responses may reflect the competence of sinonasal innate immunity mediated by taste receptor function, and thus a taste test may have potential for clinical utility in CRS patients.

    

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2. Differential Effects of Diet and Weight on Taste Responses in Diet‐Induced Obese Mice

   https://doi.org/10.1002/oby.22684  

   Ahart, Zachary C. ; Martin, Laura E. ; Kemp, Bailey R. ; Dutta Banik, Debarghya ; Roberts, Stefan G. E. ; Torregrossa, Ann‐Marie ; Medler, Kathryn F. ( December 2019 , Obesity)

   Previous studies have reported that individuals with obesity have reduced taste perception, but the relationship between obesity and taste is poorly understood. Earlier work has demonstrated that diet‐induced obesity directly impairs taste. Currently, it is not clear whether these changes to taste are due to obesity or to the high‐fat diet exposure. The goal of the current study was to determine whether diet or excess weight is responsible for the taste deficits induced by diet‐induced obesity.

   C57BL/6 mice were placed on either high‐fat or standard chow in the presence or absence of captopril. Mice on captopril did not gain weight when exposed to a high‐fat diet. Changes in the responses to different taste stimuli were evaluated using live cell imaging, brief‐access licking, immunohistochemistry, and real‐time polymerase chain reaction.

   Diet and weight gain each affected taste responses, but their effects varied by stimulus. Two key signaling proteins, α‐gustducin and phospholipase Cβ2, were significantly reduced in the mice on the high‐fat diet with and without weight gain, identifying a potential mechanism for the reduced taste responsiveness to some stimuli.

   Our data indicate that, for some stimuli, diet alone can cause taste deficits, even without the onset of obesity.

    

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3. TRPM4 and PLCβ3 contribute to normal behavioral responses to an array of sweeteners and carbohydrates but PLCβ3 is not needed for taste-driven licking for glucose

   https://doi.org/10.1093/chemse/bjae001  

   Ascencio Gutierrez, Verenice ; Martin, Laura E. ; Simental-Ramos, Aracely ; James, Kimberly F. ; Medler, Kathryn F. ; Schier, Lindsey A. ; Torregrossa, Ann-Marie ( January 2024 , Chemical Senses)

   The peripheral taste system is more complex than previously thought. The novel taste-signaling proteins TRPM4 and PLCβ3 appear to function in normal taste responding as part of Type II taste cell signaling or as part of a broadly responsive (BR) taste cell that can respond to some or all classes of tastants. This work begins to disentangle the roles of intracellular components found in Type II taste cells (TRPM5, TRPM4, and IP3R3) or the BR taste cells (PLCβ3 and TRPM4) in driving behavioral responses to various saccharides and other sweeteners in brief-access taste tests. We found that TRPM4, TRPM5, TRPM4/5, and IP3R3 knockout (KO) mice show blunted or abolished responding to all stimuli compared with wild-type. IP3R3 KO mice did, however, lick more for glucose than fructose following extensive experience with the 2 sugars. PLCβ3 KO mice were largely unresponsive to all stimuli except they showed normal concentration-dependent responding to glucose. The results show that key intracellular signaling proteins associated with Type II and BR taste cells are mutually required for taste-driven responses to a wide range of sweet and carbohydrate stimuli, except glucose. This confirms and extends a previous finding demonstrating that Type II and BR cells are both necessary for taste-driven licking to sucrose. Glucose appears to engage unique intracellular taste-signaling mechanisms, which remain to be fully elucidated.

    

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4. Satb2 neurons in the parabrachial nucleus mediate taste perception

   https://doi.org/10.1038/s41467-020-20100-8  

   Jarvie, Brooke C. ; Chen, Jane Y. ; King, Hunter O. ; Palmiter, Richard D. ( January 2021 , Nature Communications)

   The neural circuitry mediating taste has been mapped out from the periphery to the cortex, but genetic identity of taste-responsive neurons has remained elusive. Here, we describe a population of neurons in the gustatory region of the parabrachial nucleus that express the transcription factor Satb2 and project to taste-associated regions, including the gustatory thalamus and insular cortex. Using calcium imaging in awake, freely licking mice, we show that Satb2 neurons respond to the five basic taste modalities. Optogenetic activation of these neurons enhances taste preferences, whereas chronic inactivation decreases the magnitude of taste preferences in both brief- and long-access taste tests. Simultaneous inactivation of Satb2 and calcitonin gene-related peptide neurons in the PBN abolishes responses to aversive tastes. These data suggest that taste information in the parabrachial nucleus is conveyed by multiple populations of neurons, including both Satb2 and calcitonin gene-related peptide neurons.

    

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5. Discovery of a bone‐like blood particle in the peripheral circulation of humans and rodents

   https://doi.org/10.1111/micc.12579  

   Prisby, Rhonda ; Ross, Jean ; Opdenaker, Lynn ; McLane, Mary Ann ; Lee, Seungyong ; Sun, Xiangle ; Guderian, Sophie ( July 2019 , Microcirculation)

   To characterize ossified bone marrow blood vessels and confirm the presence of ossified particles (OSP) in humans and rodents.

   Human bone marrow blood vessels were processed for scanning and transmission electron microscopy. Whole blood samples were collected from younger (26‐39 years; n = 6) and older (55‐63 years; n = 6) volunteers and male Fischer‐344 rats (1 month, n = 7; 6 months, n = 7; 12 months, n = 7; 18‐months, n = 6; 24 months, n = 8).OSPin the whole blood samples were sorted and imaged with microscopy to determine diameter, circularity, and solidity. Additionally, the chemical composition ofOSPwas determined via elemental analysis.

   SEMrevealed two types of ossified bone marrow blood vessels: that is, “transitioning” and “ossified.”OSPwere adhered to the surface of transitioning vessels and theoretically gain access to and circulate within the blood. The majority ofOSPwere ≤15 μm in diameter, but many were of sufficient size to serve as emboli (ie, >15 μm).OSPwere predominately oblong in shape and several had jagged tips and edges.

   We introduce a novel, bone‐like blood particle that may be diagnostic of bone marrow blood vessel ossification. Further,OSPmay associate with several disease states (eg, atherosclerosis).

    

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