Gustatory information processing begins with taste bud cells, which are activated by sapid molecules via specific taste receptors and transmit their signals to gustatory afferent fibers. Taste bud cells are morphologically classified into 4 groups (Type I — IV cells), two of which are involved in gustatory sig-naling. Type II cells express , , and umami taste receptors and transduction components and respond best to , , or umami stimuli, suggesting that , , and umami tastes are detected by different sets of Type II cells. Type III cells express putative sour taste receptors and respond to sour or multiple taste stimuli, indicating that sour tastes are mediated by Type III cells. These data suggest that each taste quality could be discriminated among taste bud cells. Type II cells do not possess a conventional synaptic structure but they release ATP in response to taste stimuli. Type III cells have a synaptic structure and they release serotonin and norepinephrine but not ATP. Therefore, each taste cell may use distinct mechanisms and transmitters for signal transmission to gustatory nerve fibers.

抄録全体を表示

  I have an opportunity to have co-operative studies with Chinese group of Kunming Institute of Botany. Since then, I have investigated the chemical constituents of a number of Chinese plants of Araliaceae, Umbelliferae, Labiatae, Cucurbitaceae and other families. This review describes the structural elucidation of the cucurbitane, oleanane and dammarane glycosides, and their biological activities under the joint studies on cucurbitaceous plants, Bolbostemma, Hemsleya, Siraitia and Neoalsomitra species. New oleanane glycosides having novel cyclic structure were isolated from Bolbostemma paniculatum. The potent solubilizing effect of these compounds was investigated. A number of cucurbitane glycosides were isolated from Hemsleya carnosiflora, H. panacis-scandens, Siraitia grosvenorii and S. siamensis. Some of these glycosides taste , or tasteless. The structure-taste relationships of the glycosides of a 3-α-hydroxy-cucurbit-5-ene-type triterpene have been discussed. Anti-tumor-promotion effects as well as the ecdysteroid agonist and antagonist activities of these cucurbitane glycosides were investigated. New dammarane glycosides were isolated from Neoalsomitra integrifoliola.

抄録全体を表示

Taste buds contain three types of taste cells. Each type can respond to taste stimulation, and type II and III taste cells are electrically excitable. However, there are differences between the properties of type II and III taste cells. In this study, we found that Fxyd6, an Na,K-ATPase regulator gene, is expressed in type II taste cells in the taste buds of mice. Double-labeled in situ hybridization analysis showed that Fxyd6 was coexpressed with transient receptor potential cation channel, subfamily M, member 5 (Trpm5), a critical component of the , , and umami taste signal transduction pathways and that it was specifically expressed in type II taste cells. We also found that taste cells frequently coexpressed Fxyd6 and Na,K-ATPase β1. These results indicate the presence of an inherent mechanism that regulated transmembrane Na⁺ dynamics in type II taste cells.

抄録全体を表示

Oral fat sensitivity (OFS, the ability to detect fat) may be related to overeating-induced obesity. However, it is largely unknown whether OFS affects taste preference and eating habits. Therefore, we aimed to evaluate (1) the association between body mass index (BMI) and OFS and (2) the relationship of OFS with four types of taste preference (sweet, sour, salty, and bitter) and eating habits using serial concentrations of oleic acid (OA) homogenized in non-fat milk and a self-reported questionnaire. Participants were 25 healthy Japanese individuals (mean age: 27.0 ± 5.6 years), among whom the OA detection threshold was significantly associated with BMI. Participants were divided into two subgroups based on oral sensitivity to 2.8 mM OA: hypersensitive (able to detect 2.8 mM OA, n = 16) and hyposensitive (unable to detect 2.8 mM OA, n = 9). The degree of sweet taste preference of the hypersensitive group was significantly higher than that of the hyposensitive group. Furthermore, there was significantly higher degree of preference for high-fat sweet foods than low-fat sweet foods in the hypersensitive group. There was also a significant inverse correlation between the OA detection threshold and the degree of both spare eating and postprandial satiety. Thus, OFS is associated not only with BMI, but also with the preference for high-fat sweet foods and eating habits. The present study provides novel insights that measuring OFS may be useful for assessing the risk of obesity associated with overeating in countries, including Japan, where BMI is increasing in the population.

抄録全体を表示

Food extracts from spices and teas were examined for the taste altering ability on sweet, umami and bitter tastes by using the taste sensation test. The idea arose based upon the findings that 1) some food extracts from spices and teas act as salt taste enhancers and 2) the enhancing effect is directly proportional to glutamate decarboxylase 67 (GAD67) activity in vitro. Our results indicated that those extracts significantly activated or inhibited GAD67 enzyme activity were able to alter sweet, umami, and bitter tastes. However, there were no relationships between the taste potency of each of the examined extracts and the GAD67 relative activity ratio. While it is unlikely that the extracts have directly activated GAD67 activity and enhanced sweet, umami or bitter tastes, the results do not exclude the idea that GABA may participate in the taste cell-to-cell communications.

抄録全体を表示

We developed a neural network simulator for structure-activity correlation of molecules: Neco. A self-organized network model for high-speed learning was included in Neco, a perceptron type with the three layers. In the hidden layer the neurons is self-organized by using Mahalanobis generalized distance. Using this simulator, hydrophobic parameter, logP, of perillartine derivatives was predicted. We used for inputs the set of six parameters: five STERIMOL (L, Wl, Wu, Wr, and Wd) parameters and the / activity. The 22 sampled data is used for training. Our neural network accurately can predicted hydrophobic parameter, logP. Compared with a normal perceptron network, the learning ability of our network is quite higher and its convergence speed is greatly larger than it.

抄録全体を表示

We developed a neural network simulator for structure-activity correlation of molecules: Neco. A self-organized network model for high-speed learning was included in Neco, a perceptron type with the three layers. In the hidden layer the neurons is self-organized by using Mahalanobis generalized distance. Using this simulator, hydrophobic parameter, logP, of perillartine derivatives was predicted. We used for inputs the set of six parameters: five STERIMOL (L, Wl, Wu, Wr, and Wd) parameters and the / activity. The 22 sampled data is used for training. Our neural network accurately can predicted hydrophobic parameter, logP. Compared with a normal perceptron network, the learning ability of our network is quite higher and its convergence speed is greatly larger than it.

抄録全体を表示

We developed a neural network simulator for structure-activity correlation of molecules: Neco. A self-organized network model for high-speed learning was included in Neco, a perceptron type with the three layers. In the hidden layer the neurons is self-organized by using Mahalanobis generalized distance. Using this simulator, hydrophobic parameter, logP, of perillartine derivatives was predicted. We used for inputs the set of six parameters: five STERIMOL (L, Wl, Wu, Wr, and Wd) parameters and the / activity. The 22 sampled data is used for training. Our neural network accurately can predicted hydrophobic parameter, logP. Compared with a normal perceptron network, the learning ability of our network is quite higher and its convergence speed is greatly larger than it.

抄録全体を表示

学習方法として中間層において自己組織化を行い、全体に教師付学習の両方を行う、自己組織化とパーセプトロンを融合した二ューラルネットワークシミュレータの開発をプラットフォーム非依存性を持つ Java 言語を用いて行った。本シミュレータは、自己組織化と教師付学習の双方の特徴を併せもつため、従来のニューラルネットワークよりも高精度な認識処理を実現し、かつ高速学習が可能となる。
  このシミュレータを用いて、分子構造によって甘味や苦味の性質を示す22種類のペリラルチン類の疎水性パラメータ logP の予測を行った。入力パラメータは分子構造STERIMOLパラメータ5種のパラメータと甘味／苦味の分類値を用いた。出力層のノード数を１つにすることで、 logP の値を連続した数値データとして予測できるようにした。絶対誤差が平均して0.02までの学習を500回程度で行うことができ、また未学習データに対しては平均して0.3程度の絶対誤差、最大でも0.8程度の絶対誤差で予測が可能であった。単純パーセプトロンの予測精度は、平均して0.6程度の絶対誤差であり、また最大の絶対誤差は1.3程度と大きく、本手法がより精度の高い予測を行っていることがわかった。
&nsp; 本手法は学習回数が単純パーセプトロンに比較して1/5 - 1/10程度少なく、高速学習が可能であった。

抄録全体を表示

Gustatory signaling begins with taste receptor cells that express taste receptors. Recent molecular biological studies have identified taste receptors and transduction components for basic tastes (sweet, salty, sour, bitter, and umami). Activation of these receptor systems leads to depolarization and an increase in [Ca²⁺]_i in taste receptor cells. Then transmitters are released from taste cells and activate gustatory nerve fibers. The connection between taste cells and gustatory nerve fibers would be specific because there may be only limited divergence of taste information at the peripheral transmission. Recent studies have demonstrated that sweet taste information can be modulated by hormones or other endogenous factors that could act on their receptors in a specific group of taste cells. These peripheral modulations of taste information may influence preference behavior and food intake. This paper summarizes data on molecular mechanisms for detection and transduction of taste signals in taste bud cells, information transmission from taste cells to gustatory nerve fibers, and modulation of taste signals at peripheral taste organs, in particular for sweet taste, which may play important roles in regulating energy homeostasis.

抄録全体を表示

In Japan, the majority of chicken meat is obtained from fast-growing broiler chickens. Because most Japanese chicken breeds have a low meat yield and egg production, many of these breeds are endangered. Recently, the palatability of meat and eggs of native chickens has been reevaluated in the Japanese market. Jidori, which means chicken from the local, is an indigenous local chicken that is more delicious, firmer in texture, and more expensive than the broiler chickens. Most Japanese consumers recognize that the meat of Jidori chicken is richer in flavor than that of the broiler chicken. However, the reason for this rich flavor of the meat of Jidori chicken has not been elucidated. Recently, we found that arachidonic acid (AA) (C20:4n-6), a polyunsaturated fatty acid, is associated with the rich flavor of the meat and eggs of Jidori chicken. The present paper summarizes the discovery of the involvement of AA in the flavor characteristic of the meat and eggs of chicken, and also the genetic regulation of the AA content in the meat and eggs of Jidori chicken.

抄録全体を表示

The taste molecular biology has suggested that, among the five basic taste, , , and umami tastes are received by G protein-coupled receptors on taste bud cells. Recent studies on the molecular entity of the receptors have disclosed the presence of T 1 R and T 2 R. Our group has investigated the intracellular signalingmechanism following the taste reception has elucidated the involvement of the phosphoinositol turnover passway with phospholipase Cβ2 playing a central role.

抄録全体を表示

Objective Based on the increasing incidence of smell and taste dysfunction among coronavirus disease 2019 (COVID-19) patients, such issues have been considered an early symptom of infection. However, few studies have investigated the type of taste components that are most frequently affected in COVID-19 patients. This study investigated the difference in frequencies of the types of taste component disorders among hospitalized COVID-19 patients.

Methods In this retrospective, single-center, observational study, patients' background characteristics, clinical course, laboratory and radiological findings, and details on taste and/or smell disorders were collected and analyzed from medical records.

Patients A total of 227 COVID-19 patients were enrolled, among whom 92 (40.5%) complained of taste disorders.

Results Multiple types of taste disorders (hypogeusia/ageusia and hypersensitivity, or hypersensitivity and changing tastes) were reported in 10 patients. In particular, 23 patients reported hypersensitivity to at least 1 type of taste, and 2 patients complained of a bitter taste on consuming sweet foods. Impairment of all taste components was found in 48 patients (52.2%). The most frequent taste disorder was salty taste disorder (81 patients, 89.0%). Hypersensitivity to salty taste was most frequently observed (19 patients, 20.9%).

Conclusion Patients with COVID-19 develop multiple types of taste disorders, among which salty taste disorder was the most frequent, with many patients developing hypersensitivity to salty taste. As smell and taste are subjective senses, further studies with the combined use of objective examinations will be required to confirm the findings.

抄録全体を表示

Recognition of the environment causes insensible and conscious responses, and finally it changes our body resulting in a certain output to the world. However, little is known about its process in brain. This paper studied the influence of the gustatory stimulation on brain activity by an auditory oddball task. Subjects were healthy university students (n=6) with healthy sense of taste. Erythritol (60vol%) was used as a sweet taste and turmeric as a bitter one (2.9vol%). The latency of P300 component was shorter in bitter taste than that in sweet one (p< 0.05, paired t-test). We think that the better taste raises the alert level and accelerates the information processing of sound in brain.

抄録全体を表示

本研究では、農業生産現場におけるガチョウの除草利用に向けた基礎的知見を得ることを目的とし、甘味（スクロース）、塩味（塩化ナトリウム）、酸味（クエン酸一水和物）、苦味（塩酸キニーネ）および旨味（グルタミン酸ナトリウム）に対するガチョウの味覚反応を2瓶選択法で明らかにした。これらの味物質を水道水で溶かし、それぞれ11段階の濃度を設け、低濃度から高濃度に向けて上昇法で試験を行った。水道水を対照とした総飲水量に対する味溶液の摂取割合を選好指数とし、χ²検定（5％水準）により選好指数39.7から60.3％を不弁別範囲、60.3％以上を嗜好範囲、39.7％以下を拒絶範囲と定義した。その結果、ガチョウは甘味濃度0.02から20％の溶液に対して嗜好も拒絶も示さなかった。一方、塩味、酸味、苦味および旨味に対してはそれぞれ2.5、0.32、0.04および5％以上で拒絶反応を示した。以上より、ガチョウはどの味物質に対しても嗜好を示さなかったものの、塩味、酸味および旨味に比べて苦味に対してはより低濃度から拒絶を示した。したがって、ガチョウは塩味、酸味および旨味よりも苦味に敏感であり、味覚により飼料を選択採食していることが示唆された。

抄録全体を表示

G-protein coupled receptors (GCR) have been cloned from olfactory, vomeronasal and taste organs. Roles of these receptors in these organs are discussed. Olfactory and gustatory responses are induced via cAMP-dependent pathway, IP₃-dependent pathway and second messenger-independent pathway. A single olfactory cell responds to various species of odorants, although a single olfactory cell has only one type of GCR. The responses of mammalian vomeronasal receptor cells to pheromones are induced via IP₃. A single rat vomeronasal receptor cell responds only to one species of urine which contains pheromones. The receptor mechanisms of , and umami substances are discussed.

抄録全体を表示

In the present study, we examined specific markers for taste bud cells in the mouse and the postnatal development of volatile papilla taste bud cells in ddY mice. We examined the immunoreactivity of 4 types of carbonic anhydrase isoenzymes, CA I, CA II, CA III and CA VI, as specific markers for taste bud cells, and K8.13 cytokeratin antibody as a specific marker for the lingual epithelial cells. Of the carbonic anhydrase isoenzymes, only CA III immunoreactivity was clearly detected in the spindle shaped gustatory cells. CA VI immunoreactivity was detectable in suspentacular cells. CA I and CA II antibodies did not recognize any taste bud cell specifically. K8.13 cytokeratin immunoreactivity was detected in the lingual epithelial cells, but not in taste bud cells. At 7 days after birth, the suckling phase, very small taste buds developed from the anaplastic gustatory cells. At 14 days after birth, the taste buds showed larger size than those at 7 days after birth. At 21 days birth, after the weaning phase, taste bud structure approximated the mature structure. These results demonstrate the specificity of anti-CA III and anti-CA VI for gustatory cells and suspentacular cells, respectively. These markers should be useful for an analysis of taste bud development in mice.

抄録全体を表示

The use of monosodium glutamate (MSG) as a flavor enhancer spans more than 100 y and there are many studies indicating the safety of general use of MSG. Recently, however, Collison et al. (2010) reported a two-generation study with a low dose of MSG that caused abdominal obesity, insulin resistance and dyslipidemia in mice. Due to public health concerns over metabolic syndrome, their report merits careful analysis. The present study attempted to repeat the Collison et al. findings. Groups of male or female C57BL/6J mice were fed a control diet or one supplemented with high-fructose corn syrup (HFCS) at a level of 20%. Drinking water control was provided or treatment groups were given 0.064% MSG solution (w/v). Diets and MSG administration continued throughout mating and during gestation and lactation periods. To further investigate the effects of ingestion of MSG, the offspring were continued on the same dosing conditions until they reached 32 wk of age. MSG administration in mice fed a normal or a HFCS diet throughout gestation and for 32 wk after birth, did not affect growth, girth size, abdominal fat weight or body composition. This study reports that MSG did not trigger insulin resistance, dyslipidemia or hepatic steatosis, regardless of the diet, not reproducing the results of the above-mentioned study (Collison et al., 2010).

抄録全体を表示