Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Taste Buds”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,765 records · Page 98Linked to original sources
PubMed1993

Loss and recovery of sodium-salt taste following bilateral chorda tympani nerve crush.

The ability of the gustatory system to recover following peripheral nerve injury was investigated in adult hamsters. A conditioned taste aversion paradigm was utilized to test sodium salt-taste function after bilateral crush of the chorda tympani nerve and after nerve regeneration. Bilateral chorda tympani crush abolished expression of a previously learned conditioned taste aversion to 0.1 M NaCl. At 10 to 16 weeks following surgery, the hamsters were reconditioned three times to 0.1 M NaCl. The hamsters were able to relearn the conditioned taste aversion and by 16 weeks, the crush and sham groups showed equally strong and specific aversions to 0.1 M NaCl. A second surgery to cut the regenerated chorda tympani nerves resulted, again, in the loss of expression of the conditioned taste aversion. Thus, regenerated chorda tympani nerves are capable of carrying the information needed to form a conditioned taste aversion specific for sodium salts in the adult hamster.

Animals↗
PubMed1993

In utero release from a single transient hypoxic episode: a positive reinforcer?

In this experiment, fetal rats, Rattus norvegicus, were subjected to a single transient hypoxic episode before an injection of orange essence or isotonic saline through the uterine and amniotic membranes into the amniotic fluid within 5 s of the release from hypoxia. Other animals experienced either orange essence or isotonic saline alone following no hypoxic episode. At 120 days after birth, adult rats were given a two-choice preference test between orange and water. Only those animals who experienced the orange following release from hypoxia showed a preference for the orange. These results suggest that the acquired preference is not a result of simple exposure but is suggestive of a role for reoxygenation as a positive reinforcer.

Animals↗
PubMed1994

Learned olfactory discrimination versus innate taste responses to amino acids in channel catfish (Ictalurus punctatus).

Intact channel catfish conditioned to the L-amino acids, proline, arginine, alanine, and lysine, discriminated these stimuli from all other amino acids tested. Behavioral structure-activity tests indicated that L-pipecolate was the only effective agonist of the L-proline conditioned response. For channel catfish in which one of the paired olfactory organs was surgically removed, the number of turns to the conditioned stimulus was 40% fewer than those of intact catfish; however, these semiosmic channel catfish discriminated the conditioned from nonconditioned stimuli, as evidenced by their responding to the conditioned amino acid, with a two- to threefold greater number of turns than to the nonconditioned amino acids. Irrespective of the number of conditioning trials attempted, catfish with both olfactory organs removed were unable to discriminate the conditioned from the nonconditioned stimuli.

Amino Acids↗
PubMed1994

Differences in taste responses to Polycose and common sugars in the rat as revealed by behavioral and electrophysiological studies.

Behavioral and electrophysiological experiments were performed to examine the suggestion that rats have two types of carbohydrate taste receptors, one for polysaccharides (e.g., Polycose) and one for common sugars (e.g., sucrose). Qualitative difference between the tastes of Polycose and sugars including sucrose, maltose, glucose, and fructose was surveyed by means of a conditioned taste aversion paradigm in which the number of licks for 20 s to each taste stimulus was measured. Aversive conditioning to Polycose did not generalize to sugars, while aversive conditioning to sucrose generalized to other sugars, but not to Polycose. In the electrophysiological study, taste responses of the whole chorda tympani were recorded. A proteolytic enzyme, pronase E, suppressed nerve responses to both Polycose and sugars to less than 50%. A novel anti-sweet peptide, gurmarin, strongly suppressed responses to sugars, but had essentially no effect on Polycose responses. On the other hand, KHCO3 enhanced responses to sugars to about 300%, but had little effect on Polycose responses. These results have confirmed the notion that rats can differentiate the tastes between Polycose and common sugars and that rats have two types of carbohydrate receptors.

Animals↗
PubMed1994

Receptor mechanisms of bitter substances.

The receptor mechanism of bitter substances was discussed from the following points of views. (a) Both electrostatic and hydrophobic interactions of bitter substances with taste receptor membranes contribute to reception of bitter substances having a positive charge. (b) In the frog, the responses to bitter substances are easily adapted. The presence of Ca ion in the medium prolongs the responses. (c) Bitter substances elicit electrical responses in nongustatory cells such as neuroblastoma cells and olfactory cells, suggesting that bitter substances induce the response by nonreceptor-mediated mechanism. (d) There is also a possibility that receptors for some bitter substances are G-protein coupled. We cloned G-protein coupled receptors from bovine taste tissues. (e) A specific inhibitor of bitter taste has been desired in pharmaceutical and food sciences, but it has not been available. We found that a lipoprotein made of phosphatidic acid and beta-lactoglobulin selectively inhibits the responses to bitter substances in the frog and humans. Binding of the lipoprotein to the receptor sites for bitter substances leads to suppression of the response.

Amino Acid Sequence↗
PubMed1994

Receptor potential of the frog taste cell in response to bitter stimuli.

Molecular mechanisms of generation of the receptor potential in the bullfrog taste cell for bitter stimuli were investigated with an intracellular recording technique. During generation of the receptor potential in response to bitter stimuli, the input resistance of the taste cell increased slightly. We could not find the reversal potential for the depolarizing receptor potential induced by quinine-HCl(Q-HCl). The Q-HCl-induced response was increased with decreasing Cl- concentration in the superficial fluid. The Q-HCl response was greatly reduced by interstitial furosemide, as a blocker of Na+/Cl- cotransport, indicating that a Na+/Cl- cotransport occurs through the basolateral membrane of Q-HCl sensitive taste cells. Therefore it is concluded that the receptor potential for Q-HCl stimulation is produced by an active secretion of intracellularly accumulated Cl- through Cl- pumps of the apical receptive membrane.

Animals↗
PubMed1994

Molecular cloning of G proteins and phosphodiesterases from rat taste cells.

To identify and characterize those proteins involved in taste transduction, we cloned G proteins and phosphodiesterases from rat taste tissue. Using degenerate primers corresponding to conserved regions of G protein alpha subunits, the polymerase chain reaction was used to amplify and clone eight distinct cDNAs: alpha i-2, alpha i-3, alpha 12, alpha 14, a(s), alpha t-rod, alpha t-cone and alpha gustducin. alpha i-3, alpha 14, alpha s, and alpha t-rod are more highly expressed in taste tissue than in the surrounding nonsensory tissue. alpha gustducin is only expressed in taste cells. Rod transducin had previously been found only in the rod cells of the retina, where it converts light stimulation of rhodopsin into activation of cGMP phosphodiesterase. The primary sequence of alpha gustducin shows striking similarities to rod transducin in the receptor interaction domain and the phosphodiesterase activation site. We propose that gustducin and transducin regulate phosphodiesterase activity in taste cells and that this may promote bitter transduction and inhibit sweet transduction. Consistent with this proposal, we cloned two types of cAMP PDE from taste tissue: dnc-1 and PDE-3.

Amino Acid Sequence↗
PubMed1994

Denatonium bitter tasting among transgenic mice expressing rat von Ebner's gland protein.

Von Ebner's gland protein (VEGP) is a secretory protein, which is abundantly expressed in the small von Ebner's salivary glands of the tongue. VEGP as component of the perireceptor environment around taste papillae might function as transporter of hydrophobic molecules, for example bitter substances. Here we report a new approach to investigate the physiological role of VEGP by expression of the cloned rat VEGP gene in transgenic mice. Taste papillae of mice, in contrast to rats, do not contain VEGP. The founder mouse 4345 and three offspring carry the transgene as shown by PCR analysis and saliva of the transgenic mice contains high amounts of VEGP. In two-bottle preference tests, transgenic and nontransgenic siblings show significantly different capabilities to taste the bitter compound denatonium benzoate at 10 microM. The reduced sensitivity of transgenic mice to denatonium benzoate points to a clearance function of VEGP the specificity of which for taste compounds and other molecules remains to be seen.

Animals↗
PubMed1994

Neural coding of aversive and appetitive gustatory stimuli: interactions in the hamster brain stem.

There is increasing evidence, both electrophysiological and behavioral, that bitter and sweet stimuli drive parallel pathways in the gustatory brainstem. Here we report two lines of investigation that suggest significant interactions among these parallel systems. First, responses recorded from single cells in the hamster's parabrachial nuclei (PbN) show that quinine hydrochloride (QHCl) produces a substantial suppression (> 40%) of the responses of PbN cells to sucrose. Sucrose stimulation has a reciprocal suppressive effect on the response to QHCl. These results imply that aversive and appetitive stimuli produce mutual inhibition in the gustatory system; studies of the chorda tympani nerve response suggest that this inhibition likely arises within the brainstem. A second line of investigation, using both an in vitro brainstem slice preparation and in vivo pharmacological manipulations of cells in the hamster NST, has demonstrated an inhibitory network within the rostral NST that plays a role in the modulation of taste activity. Patch-clamp and extracellular recording studies in vitro show that cells within the rostral central subdivision of the NST are inhibited by gamma-aminobutyric acid (GABA); this mediation is largely through the GABAA receptor subtype. Here we show that responses to taste stimulation recorded extracellularly from NST cells in vivo can be inhibited by local microinjections of GABA; this inhibition is blocked by the GABAA receptor antagonist bicuculline methiodide. Responses to sucrose are significantly more inhibited than those to NaCl or KCl. These combined lines of evidence show that appetitive and aversive stimuli activate mutually inhibitory systems within the brainstem and suggest that the basis for this interaction is a GABAergic inhibitory network within the NST.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Structural basis for bitterness based on Rabdosia diterpenes.

Bitterness of naturally occurring substances seems to be due to a balance between the "bitter unit" and the hydrophobic portions of the molecule. The study based on the Rabdosia diterpenes indicates that the bitter unit consists of a proton donor DH group and a proton acceptor A group. In addition to this DH-A unit, an A-A unit may also be possible. The bitter compounds could enter the molecular structure of the receptor site with the bitter unit oriented into the aqueous phase by hydrogen bonding and the hydrophobic portion aligned into the lipid phase by dispersion forces.

Animals↗
PubMed1979

Unusual association of 'chloride cells' with another cell type in the skin of the glass catfish, Kryptopterus bicirrhis.

A previously undescribed association of typical 'chloride cells' and a second distinct cell type are observed in the skin of the freshwater glass catfish, Kryptopterus bicirrhis. The second cell type is similar to the chloride cell in that it contains abundant smooth endoplasmic reticulum and mitochondria. However, its small size and greater electron density suggest it is a 'resting' or non-functional chloride cell. Together these two cells form a crypt which leads to the skin surface. They may constitute a specialized structure involved in the passage of ions across the skin of these fish.

Animals↗
PubMed1990

A conceptual model of taste receptors.

Of all the senses, that of taste is perhaps the hardest to define and quantify and elucidation of the underlying mechanisms is unrespondingly difficult. This article describes a conceptual model--at the molecular level--for the four basic taste modalities, using apparent specific volume as a fundamental parameter. It also considers possible practical applications.

Humans↗
PubMed1985

The innervation of the primate fungiform papilla--development, distribution and changes following selective ablation.

The development of the terminal parts of the chorda tympani nerve, lingual nerve and cranial sympathetics in the macaque fungiform papillae were studied by light- and electron microscopy. Their respective distributions in the intra- and extragemmal compartments of papillae from adult macaques were examined following selective ablation of each nerve. Prior to midgestation, a single bundle of unmyelinated axons which contained numerous axoaxonic synapses passed through the subepithelial connective tissue and ramified in the single nascent chemosensory corpuscle and surrounding non-gustatory epithelium. Following midgestation, additional chemosensory corpuscles appeared, possibly by division of existing corpuscles, myelination of axons was begun, axoaxonic synapses were eliminated, and nerve terminals appeared in the subepithelial connective tissue as free nerve endings and coiled simple nerve endings. In the perinatal period, coiled simple endings, corpuscular receptors and Meissner corpuscles were present in the papilla core. Large numbers of intra-epithelial nerve endings were present in the extragemmal epithelium throughout development. Tonofilament collars ensheathed intra-epithelial axons and 80-100 nm dense core granules, occupying adjacent epithelial cells, appeared to be sequestered near such axons. Experimental selective ablation indicated that the terminal parts of chorda tympani fibers were present only within chemosensory corpuscles. In contrast, lingual nerve endings were present both in the extragemmal epithelium and chemosensory corpuscles and also were the sole supply of corpuscular receptors. Sympathetics appeared to be sparsely distributed in the papilla core. Intra-epithelial axons degenerated within 24 h following transection, while axons with Schwann or lamellar cell sheaths or myelin persisted for at least 3 days.

Animals↗
PubMed1985

Addition of functional amiloride-sensitive components to the receptor membrane: a possible mechanism for altered taste responses during development.

The developmental increase in response sensitivity of rat peripheral taste afferents to NaCl and LiCl occurs concomitantly with an increase in sensitivity to the sodium ion transport blocker amiloride. Lingual application of amiloride had no effect on chorda tympani nerve taste responses to monochloride salts in early postnatal rats. However, amiloride suppressed NaCl and LiCl responses in proportion to the increased sensitivity to these stimuli during development in postweaning and adult rats without suppressing responses to NH4Cl and KCl.

Age Factors↗
PubMed1996

Ontogeny of regulatory neuropeptides in the bullfrog taste organ.

During metamorphic stages (stages XX-XXV), the first appearance of nerve fibers containing substance P (SP), calcitonin gene-related peptide (CGRP), vasoactive intestinal polypeptide (VIP), galanin (GAL), and neuropeptide Y (NPY) in the bullfrog taste organs was different for each substance. CGRP fibers appeared first in association with the immature taste organs at stage XX. Up to stage XXV, the taste organs, epithelial disks, are close to their adult form, and SP, VIP and GAL fibers appeared within them. Throughout these stages, NPY fibers were absent, and no taste cells had immunoreactivity of the five neuropeptides. The present findings and previous physiological studies suggest that the immature taste organs in metamorphic stages already function as chemical and mechanical receptors and that these sensory mechanisms are under the control of peptidergic innervation.

Animals↗
PubMed1990

Developmental neurobiology of salt taste sensation.

A principal process in the homeostatic control of sodium levels is salt intake, and the sense of taste has a primary role in regulating ingestion. Because ingestion of sodium chloride (NaCl) is essential for life, the taste system for salt sensation might be expected to exhibit mature functional characteristics from very early development. However, major changes in gustatory nerve responses to NaCl take place during development. In sheep and rat, the peripheral nerve responses to NaCl are of low magnitude during early development. Progressively, the taste system acquires an increasing proportion of fibers that respond maximally to NaCl. The sodium responsiveness emerges in the context of shifting peripheral innervation patterns and the apparent addition of functional receptor membrane channels sensitive to the sodium transport blocker, amiloride. These developmental processes can be altered by early manipulation of sodium in the diet.

Action Potentials↗
PubMed1994

Universality of parabrachial mediation of conditioned taste aversion.

Disruption of conditioned taste aversion (CTA) by tetrodotoxin (TTX) blockade of parabrachial nuclei elicited after ingestion of the gustatory CS and before administration of the visceral US is revealed by unchanged CS preference in retrieval test performed two days after acquisition. The universality of the above amnesia was examined in rats. In Experiment 1, parabrachial TTX disrupted CTAs when sodium saccharin (0.1%), quinine hydrochloride (0.0072%), sodium chloride (0.9%) or a garlic extract were used as the CS and i.p. LiCl (0.15 M, 2% body weight) as the US. In Experiment 2, parabrachial TTX disrupted CTAs when 0.9% NaCl was used as the CS and i.p. injection of LiCl (0.15 M, 2% body weight), D-amphetamine (3 mg/kg) or carbachol (0.15 mg/kg) served as the US. Experiment 3 showed that post-drinking parabrachial TTX blocked also CTA induced by LiCl drinking, i.e. under conditions of CS-US identity. Experiments 4 and 5 demonstrated that the amnesia is not confounded by TTX-induced reduction of fluid intake because the CTA disruption was well expressed even when tested after recovery of normal fluid intake 3 days after TTX injection and in animals receiving 12 days of preacquisition adaptation to limited fluid access. It is concluded that parabrachial nuclei represent an important point of convergence for various classes of CTA eliciting stimuli.

Afferent Pathways↗
PubMed1986

Contribution of electrostatic and hydrophobic interactions of bitter substances with taste receptor membranes to generation of receptor potentials.

The effects of changed ionic environments on the frog taste nerve responses to the bitter substances were examined. The responses to quinine and strychnine carrying a positive charge were suppressed by an increase in ionic strength of stimulating solutions. It was concluded that electrostatic interaction of these positive bitter substances with the receptor membranes greatly contributes to the adsorption of the substances on the membranes and that this interaction was suppressed by an increase in ionic strength. The responses to neutral bitter substances (caffeine and theophylline) were unchanged by an increase in salt concentration. The zeta potential of the mouse neuroblastoma (N-18 clone), which was depolarized by various bitter substances similarly to a taste cell, was measured in the presence of the bitter substances. The zeta potential was a little changed by quinine and practically unchanged by strychnine, caffeine and theophylline. The membrane fluidity of the N-18 cell monitored with 2-(9-anthroyloxy)stearic acid was changed in response to the bitter substances, while the fluidity monitored with 12-(9-anthroyloxy)stearic acid or 1,6-diphenyl-1,3,5-hexatriene was unchanged. This suggested that the bitter substances are adsorbed on the hydrophobic region near the surface and induce a conformational change at the region. The depolarization by the bitter substances seems to stem from changes in the "boundary potential" at the region near the surface within the membrane interior.

Adsorption↗