scholarly journals Acetic acid modulates spike rate and spike latency to salt in peripheral gustatory neurons of rats

2012 ◽  
Vol 108 (9) ◽  
pp. 2405-2418 ◽  
Author(s):  
Joseph M. Breza ◽  
Robert J. Contreras
Keyword(s):  
Acetic Acid ◽  
Artificial Saliva ◽  
Type I ◽  
Dependent Manner ◽  
Chorda Tympani ◽  
Gustatory System ◽  
Chorda Tympani Nerve ◽  
Concentration Dependent Manner ◽  
Lingual Epithelium ◽  
Taste Cells

Sour and salt taste interactions are not well understood in the peripheral gustatory system. Therefore, we investigated the interaction of acetic acid and NaCl on taste processing by rat chorda tympani neurons. We recorded multi-unit responses from the severed chorda tympani nerve (CT) and single-cell responses from intact narrowly tuned and broadly tuned salt-sensitive neurons in the geniculate ganglion simultaneously with stimulus-evoked summated potentials to signal when the stimulus contacted the lingual epithelium. Artificial saliva served as the rinse and solvent for all stimuli [0.3 M NH4Cl, 0.5 M sucrose, 0.1 M NaCl, 0.01 M citric acid, 0.02 M quinine hydrochloride (QHCl), 0.1 M KCl, 0.003–0.1 M acetic acid, and 0.003–0.1 M acetic acid mixed with 0.1 M NaCl]. We used benzamil to assess NaCl responses mediated by the epithelial sodium channel (ENaC). The CT nerve responses to acetic acid/NaCl mixtures were less than those predicted by summing the component responses. Single-unit analyses revealed that acetic acid activated acid-generalist neurons exclusively in a concentration-dependent manner: increasing acid concentration increased response frequency and decreased response latency in a parallel fashion. Acetic acid suppressed NaCl responses in ENaC-dependent NaCl-specialist neurons, whereas acetic acid-NaCl mixtures were additive in acid-generalist neurons. These data suggest that acetic acid attenuates sodium responses in ENaC-expressing-taste cells in contact with NaCl-specialist neurons, whereas acetic acid-NaCl mixtures activate distinct receptor/cellular mechanisms on taste cells in contact with acid-generalist neurons. We speculate that NaCl-specialist neurons are in contact with type I cells, whereas acid-generalist neurons are in contact with type III cells in fungiform taste buds.

Differential temperature dependence of taste nerve responses to various taste stimuli in dogs and rats

1991 ◽  
Vol 261 (6) ◽  
pp. R1402-R1408 ◽  
Author(s):  
M. Nakamura ◽  
K. Kurihara
Keyword(s):  
Acetic Acid ◽  
Temperature Dependence ◽  
Temperature Change ◽  
Dose Response ◽  
Monosodium Glutamate ◽  
Taste Receptor ◽  
Chorda Tympani ◽  
Chorda Tympani Nerve ◽  
Response Curves ◽  
Tonic Response

The temperature dependence of the canine and rat chorda tympani nerve responses to various taste stimuli was examined. The temperature dependence greatly varied with species of stimuli. In the dog, the tonic responses to fructose, sucrose, acetic acid, and guanosine 5'-monophosphate (GMP) and the response induced by the synergism between monosodium glutamate (MSG) and GMP showed peaks at approximately 30 degrees C, whereas those to NaCl, NH4Cl, and MSG showed peaks between 10 and 20 degrees C. In the rat, the tonic response to NH4Cl increased with an increase in temperature up to 45 degrees C, whereas the responses to other stimuli examined showed peaks at approximately 30 degrees C. The responses to glycine, sucrose, and quinine showed sharp temperature dependence, and the responses to acids (HCl and acetic acid) and salts (NaCl and KCl) showed relatively flat dependence. The effects of the temperature change on dose-response curves for fructose, NH4Cl, and GMP were examined using dogs. The temperature change did not practically affect the thresholds for these stimuli and affected the magnitude of the responses to higher concentrations of stimuli. The origins of the temperature dependence were discussed in terms of taste receptor mechanisms.

scholarly journals Optogenetic Activation of Type III Taste Cells Modulates Taste Responses

2020 ◽  
Vol 45 (7) ◽  
pp. 533-539
Author(s):  
Aurelie Vandenbeuch ◽  
Courtney E Wilson ◽  
Sue C Kinnamon
Keyword(s):  
Light Response ◽  
Sensory Nerves ◽  
Taste Bud ◽  
Chorda Tympani ◽  
Chorda Tympani Nerve ◽  
Type Iii ◽  
Nonspecific Effects ◽  
Taste Cells ◽  
Specific Stimulation ◽  
The Brain

Abstract Studies have suggested that communication between taste cells shapes the gustatory signal before transmission to the brain. To further explore the possibility of intragemmal signal modulation, we adopted an optogenetic approach to stimulate sour-sensitive (Type III) taste cells using mice expressing Cre recombinase under a specific Type III cell promoter, Pkd2l1 (polycystic kidney disease-2-like 1), crossed with mice expressing Cre-dependent channelrhodopsin (ChR2). The application of blue light onto the tongue allowed for the specific stimulation of Type III cells and circumvented the nonspecific effects of chemical stimulation. To understand whether taste modality information is preprocessed in the taste bud before transmission to the sensory nerves, we recorded chorda tympani nerve activity during light and/or chemical tastant application to the tongue. To assess intragemmal modulation, we compared nerve responses to various tastants with or without concurrent light-induced activation of the Type III cells. Our results show that light significantly decreased taste responses to sweet, bitter, salty, and acidic stimuli. On the contrary, the light response was not consistently affected by sweet or bitter stimuli, suggesting that activation of Type II cells does not affect nerve responses to stimuli that activate Type III cells.

Sweet Taste Responses of Mouse Chorda Tympani Neurons: Existence of Gurmarin-Sensitive and -Insensitive Receptor Components

1999 ◽  
Vol 81 (6) ◽  
pp. 3087-3091 ◽  
Author(s):  
Yuzo Ninomiya ◽  
Toshiaki Imoto ◽  
Tadataka Sugimura
Keyword(s):  
Sweet Taste ◽  
The Other ◽  
Chorda Tympani ◽  
Chorda Tympani Nerve ◽  
Inhibitory Effects ◽  
Single Fibers ◽  
Taste Cells ◽  
C57bl Mice ◽  
Mouse Taste

Sweet taste responses of mouse chorda tympani neurons: existence of gurmarin-sensitive and -insensitive receptor components. Inhibitory effects of gurmarin (gur) on responses to sucrose and other sweeteners of single fibers of the chorda tympani nerve in C57BL mice were examined. Of 30 single fibers that strongly responded to 0.5 M sucrose but were not or to lesser extent responsive to 0.1 M NaCl, 0.01 M HCl, and 0.02 M quinine HCl (sucrose-best fibers), 16 fibers showed large suppression of responses to sucrose and other sweeteners by lingual treatment with 4.8 μM (∼20 μg/ml) gur (suppressed to 4–52% of control: gur-sensitive fibers), whereas the remaining 14 fibers showed no such gur inhibition (77–106% of control: gur-insensitive fibers). In gur-sensitive fibers, responses to sucrose inhibited by gur recovered to ∼70% of control responses after rinsing the tongue with 15 mM β-cyclodextrin and were almost abolished by further treatment with 2% pronase. In gur-insensitive fibers, sucrose responses were not inhibited by gur, but were largely suppressed by pronase. These results suggest existence of two different receptor components for sweeteners with different susceptibilities to gur in mouse taste cells, one gur sensitive and the other gur insensitive. Taste cells possessing each component may be specifically innervated by a particular type of chorda tympani neurons.

scholarly journals Characterization of Human Iodothyronine Sulfotransferases1

1999 ◽  
Vol 84 (4) ◽  
pp. 1357-1364 ◽  
Author(s):  
Monique H. A. Kester ◽  
Ellen Kaptein ◽  
Thirza J. Roest ◽  
Caren H. van Dijk ◽  
Dick Tibboel ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Human Liver ◽  
Type I ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Iodothyronine Deiodinase ◽  
Liver Cytosol ◽  
Thyroid Hormone Metabolism ◽  
Liver And Kidney ◽  
Phenol Sulfotransferase

Sulfation is an important pathway of thyroid hormone metabolism that facilitates the degradation of the hormone by the type I iodothyronine deiodinase, but little is known about which human sulfotransferase isoenzymes are involved. We have investigated the sulfation of the prohormone T4, the active hormone T3, and the metabolites rT3 and 3,3′-diiodothyronine (3,3′-T2) by human liver and kidney cytosol as well as by recombinant human SULT1A1 and SULT1A3, previously known as phenol-preferring and monoamine-preferring phenol sulfotransferase, respectively. In all cases, the substrate preference was 3,3′-T2 >> rT3 > T3 > T4. The apparent Km values of 3,3′-T2 and T3 [at 50 μmol/L 3′-phosphoadenosine-5′-phosphosulfate (PAPS)] were 1.02 and 54.9μ mol/L for liver cytosol, 0.64 and 27.8 μmol/L for kidney cytosol, 0.14 and 29.1 μmol/L for SULT1A1, and 33 and 112 μmol/L for SULT1A3, respectively. The apparent Km of PAPS (at 0.1μ mol/L 3,3′-T2) was 6.0 μmol/L for liver cytosol, 9.0μ mol/L for kidney cytosol, 0.65 μmol/L for SULT1A1, and 2.7μ mol/L for SULT1A3. The sulfation of 3,3′-T2 was inhibited by the other iodothyronines in a concentration-dependent manner. The inhibition profiles of the 3,3′-T2 sulfotransferase activities of liver and kidney cytosol obtained by addition of 10 μmol/L of the various analogs were better correlated with the inhibition profile of SULT1A1 than with that of SULT1A3. These results indicate similar substrate specificities for iodothyronine sulfation by native human liver and kidney sulfotransferases and recombinant SULT1A1 and SULT1A3. Of the latter, SULT1A1 clearly shows the highest affinity for both iodothyronines and PAPS, but it remains to be established whether it is the prominent isoenzyme for sulfation of thyroid hormone in human liver and kidney.

scholarly journals Effects of voltage perturbation of the lingual receptive field on chorda tympani responses to Na+ and K+ salts in the rat: implications for gustatory transduction.

1994 ◽  
Vol 104 (5) ◽  
pp. 885-907 ◽  
Author(s):  
Q Ye ◽  
G L Heck ◽  
J A DeSimone
Keyword(s):  
Receptive Field ◽  
Voltage Clamp ◽  
Maximal Response ◽  
Chorda Tympani ◽  
Chorda Tympani Nerve ◽  
Salt Taste ◽  
Negative Voltage ◽  
Voltage Clamp Condition ◽  
Taste Cells ◽  
Clamp Condition

Taste sensory responses from the chorda tympani nerve of the rat were recorded with the lingual receptive field under current or voltage clamp. Consistent with previous results (Ye, Q., G. L. Heck, and J. A. DeSimone. 1993. Journal of Neurophysiology. 70:167-178), responses to NaCl were highly sensitive to lingual voltage clamp condition. This can be attributed to changes in the electrochemical driving force for Na+ ions through apical membrane transducer channels in taste cells. In contrast, responses to KCl over the concentration range 50-500 mM were insensitive to the voltage clamp condition of the receptive field. These results indicate the absence of K+ conductances comparable to those for Na+ in the apical membranes of taste cells. This was supported by the strong anion dependence of K salt responses. At zero current clamp, the potassium gluconate (KGlu) threshold was > 250 mM, and onset kinetics were slow (12 s to reach half-maximal response). Faster onset kinetics and larger responses to KGlu occurred at negative voltage clamp (-50 mV). This indicates that when K+ ion is transported as a current, and thereby uncoupled from gluconate mobility, its rate of delivery to the K+ taste transducer increases. Analysis of conductances shows that the paracellular pathway in the lingual epithelium is 28 times more permeable to KCl than to KGlu. Responses to KGlu under negative voltage clamp were not affected by agents that are K+ channel blockers in other systems. The results indicate that K salt taste transduction is under paracellular diffusion control, which limits chemoreception efficiency. We conclude that rat K salt taste occurs by means of a subtight junctional transducer for K+ ions with access limited by anion mobility. The data suggest that this transducer is not cation selective which also accounts for the voltage and amiloride insensitive part of the response to NaCl.

scholarly journals A Newly Identified Leptospiral Adhesin Mediates Attachment to Laminin

2006 ◽  
Vol 74 (11) ◽  
pp. 6356-6364 ◽  
Author(s):  
Angela S. Barbosa ◽  
Patricia A. E. Abreu ◽  
Fernanda O. Neves ◽  
Marina V. Atzingen ◽  
Mônica M. Watanabe ◽  
...  
Keyword(s):  
Type I Collagen ◽  
Collagen Type ◽  
Outer Membrane Proteins ◽  
Collagen Type I ◽  
Surface Proteins ◽  
Collagen Type Iv ◽  
Type I ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Sodium Metaperiodate

ABSTRACT Pathogenic leptospires have the ability to survive and disseminate to multiple organs after penetrating the host. Several pathogens, including spirochetes, have been shown to express surface proteins that interact with the extracellular matrix (ECM). This adhesin-mediated binding process seems to be a crucial step in the colonization of host tissues. This study examined the interaction of putative leptospiral outer membrane proteins with laminin, collagen type I, collagen type IV, cellular fibronectin, and plasma fibronectin. Six predicted coding sequences selected from the Leptospira interrogans serovar Copenhageni genome were cloned, and proteins were expressed, purified by metal affinity chromatography, and characterized by circular dichroism spectroscopy. Their capacity to mediate attachment to ECM components was evaluated by binding assays. We have identified a leptospiral protein encoded by LIC12906, named Lsa24 (leptospiral surface adhesin; 24 kDa) that binds strongly to laminin. Attachment of Lsa24 to laminin was specific, dose dependent, and saturable. Laminin oxidation by sodium metaperiodate reduced the protein-laminin interaction in a concentration-dependent manner, indicating that laminin sugar moieties are crucial for this interaction. Triton X-114-solubilized extract of L. interrogans and phase partitioning showed that Lsa24 was exclusively in the detergent phase, indicating that it is a component of the leptospiral membrane. Moreover, Lsa24 partially inhibited leptospiral adherence to immobilized laminin. This newly identified membrane protein may play a role in mediating adhesion of L. interrogans to the host. To our knowledge, this is the first leptospiral adhesin with laminin-binding properties reported to date.

scholarly journals GAD65Cre drives reporter expression in multiple taste cell types

2021 ◽  
Author(s):  
Eric D. Larson ◽  
Aurelie Vandenbeuch ◽  
Catherine B. Anderson ◽  
Sue C. Kinnamon
Keyword(s):  
Cell Function ◽  
Cell Types ◽  
Taste Cell ◽  
Taste Buds ◽  
Specific Marker ◽  
Type I ◽  
Chorda Tympani ◽  
Type I Cells ◽  
Taste Cells ◽  
I Cells

ABSTRACTIn taste buds, Type I cells represent the majority of cells (50-60%) and primarily have a glial-like function in taste buds. However, recent studies suggest that they have additional sensory and signaling functions including amiloride-sensitive salt transduction, oxytocin modulation of taste, and substance P mediated GABA release. Nonetheless, the overall function of Type I cells in transduction and signaling remains unclear, primarily because of the lack of a reliable reporter for this cell type. GAD65 expression is specific to Type I taste cells and GAD65 has been used as a Cre driver to study Type I cells in salt taste transduction. To test the specificity of transgene-driven expression, we crossed GAD65Cre mice with floxed tdTomato and Channelrhodopsin (ChR2) lines and examined the progeny with immunochemistry, chorda tympani recording, and calcium imaging. We report that while many tdTomato+ taste cells express NTPDase2, a specific marker of Type I cells, we see expression of tdTomato in both Gustducin and SNAP25 positive taste cells. We also see ChR2 in cells just outside the fungiform taste buds. Chorda tympani recordings in the GAD65Cre/ChR2 mice show large responses to blue light, larger than any response to standard taste stimuli. Further, several isolated tdTomato positive taste cells responded to KCl depolarization with increases in intracellular calcium, indicating the presence of voltage-gated calcium channels. Taken together, these data suggest that GAD65Cre mice drive expression in multiple taste cell types and thus cannot be considered a reliable reporter of Type I cell function.

scholarly journals Toxicity Effects of Methylene Blue on Rat Intervertebral Disc Annulus Fibrosus Cells

2019 ◽  
Vol 2 (22.2) ◽  
pp. 155-164
Author(s):  
Liang Zhang
Keyword(s):  
Methylene Blue ◽  
Cell Apoptosis ◽  
Annulus Fibrosus ◽  
Caspase 3 ◽  
In Vitro Study ◽  
Collagen Type I ◽  
Type I ◽  
Dependent Manner ◽  
Concentration Dependent Manner

Background: There is an increasing local application of methylene blue (MB) in the treatment of discogenic low back pain (LBP) and percutaneous transforaminal endoscopic discectomy (PTED) procedures. MB could generate DNA damage and induce apoptosis in different cell types; however, the effects of MB on intervertebral disc (IVD) annulus fibrosus (AF) cells are not clearly understood. Objective: The objective of this study was to investigate the effects of different concentrations of MB on rat AF cells in vitro. Study Design: This study used an experimental design. Setting: This research was conducted at the Orthopaedic Institute of the Clinical Medical College of Yangzhou University. Methods: AF cells were isolated and cultured with different concentrations of MB (0, 2, 20, and 200 μg/mL) and assessed to determine the possible cytotoxic effects of MB. The cell proliferation was detected by Cell Counting Kit-8 (CCK-8) assay. The inverted phase-contrast microscopy was used to perform morphological observation of apoptotic cells, and flow cytometry was used to measure the incidence of cell apoptosis. The mRNA and protein expression levels of apoptosis-associated genes (caspase-3, Bcl-2, and Bax) and other related genes (collagen type I, transforming growth factor β1 [TGF-β1], fibroblast growth factor [bFGF], and tissue inhibitor of metalloproteinase-1 [TIMP-1]) were analyzed by quantitative real-time PCR (RT-PCR) and Western blotting. Results: Our results indicated that MB reduced cell viability in a concentration- and timedependent manner. MB also induced marked AF cell apoptosis in a concentration-dependent manner observed by inverted phase-contrast microscopy, flow cytometry, and indicated by the increased expression of caspase-3. Both RT-PCR and Western blotting revealed significant upregulation of Bax and caspase-3 expression levels accompanied by decreased expression of Bcl2 in a concentration-dependent manner. Moreover, collagen type I, TGF-β1, bFGF, and TIMP-1 mRNA and protein levels were also found to be decreased by MB in a concentration-dependent manner. Limitations: Limitations of this study were the in vitro study design and lack of in vivo validation of the observed effects of MB on human IVD cells. Conclusions: Our results indicate that a high concentration of MB can not only inhibit proliferation and paracrine function of AF cells, but can also induce cell apoptosis in a concentration-dependent manner, suggesting that it is necessary to choose low concentrations of MB in practical application and limit the use of MB in the treatment of discogenic LBP to research protocols. Key words: Methylene blue, annulus fibrosus cell, proliferation, apoptosis, paracrine

scholarly journals Involvement of BMP-15 in Glucocorticoid Actions on Ovarian Steroidogenesis by Rat Granulosa Cells

2021 ◽  
Vol 5 (Supplement_1) ◽  
pp. A767-A768
Author(s):  
Chiaki Kashino ◽  
Toru Hasegawa ◽  
Yasuhiro Nakano ◽  
Nahoko Iwata ◽  
Koichiro Yamamoto ◽  
...  
Keyword(s):  
Bone Morphogenetic Proteins ◽  
Granulosa Cells ◽  
Type I ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Ovarian Steroidogenesis ◽  
Cell Functions ◽  
Camp Synthesis ◽  
Bmp Receptors

Abstract Glucocorticoid receptor (GR) are known to be expressed in the ovary and glucocorticoids are shown to exert direct effects on granulosa cell functions. In the clinical setting, menstrual abnormality, amenorrhea and hypermenorrhea can be shown in patients with glucocorticoid excess. On the other hand, glucocorticoids can also be used for the treatment of PCOS with hyperandrogenism. However, the effects of glucocorticoids on the reproductive system have not been fully elucidated. In the present study, we investigated the influence of glucocorticoids on follicular steroidogenesis using primary culture of rat granulosa cells, by focusing on the ovarian bone morphogenetic proteins (BMPs) acting as a luteinizing inhibitor. Granulosa cells isolated from female immature rats were treated with follicle-stimulating hormone (FSH) in the presence of dexamethasone (Dex) in serum-free conditions. After treatment with Dex for 48 h, the changes of estradiol (E2) and progesterone (P4) production and cAMP synthesis induced by FSH treatments were measured by ELISA. Total RNAs of granulosa cells treated with FSH, Dex and BMPs were extracted and mRNA levels of steroidogenetic factors and enzymes, BMP receptors and Id-1 were quantified by real-time RT-PCR. Phosphorylation of Smad1/5/9 induced by BMPs was evaluated by Western blotting using cell lysates in the presence or absence of Dex. As a result, it was revealed that Dex treatment decreased FSH-induced E2 production by granulosa cells. In accordance with the steroid results, Dex suppressed FSH-induced P450arom mRNA expression as well as FSH-induced cAMP synthesis by granulosa cells. By contrast, Dex treatment augmented FSH-induced P4 production by granulosa cells in a concentration-dependent manner. Dex treatment was found to enhance basal and FSH-induced mRNA levels of P4-synthetic enzymes including P450scc and 3βHSD. Of note, Dex treatment activated the BMP target gene Id-1 transcription and Smad1/5/9 phosphorylation, in particular, induced by BMP-15 among various BMP ligands including BMP-2, -4, -6, -7, -9 and -15. It was also revealed that Dex treatment increased mRNA levels of ALK-6, a type-I receptor for BMP-15, and that BMP-15 treatment in turn upregulated GR mRNA levels expressed by granulosa cells. Given that BMP-15 acts as an inhibitor for P4 production by suppressing FSH-receptor actions, it was suggested that glucocorticoid is functionally linked to the enhancement of endogenous BMP-15, leading to the negative feedback toward the P4 overproduction induced by FSH and Dex in granulosa cells. Collectively, it was revealed that glucocorticoids elicit differential effects on the ovarian steroidogenesis of E2 and P4, in which GR and BMP-15 actions are mutually enhanced in granulosa cells.

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