A Comparative Study of Whole-Mouth Taste Thresholds between North Korean Refugees and South Koreans / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES@#Since Korea has been divided into two countries over 60 years ago and differences has gradually developed between the two, an influx of North Korean refugees to South Korea have soared over the past 20 years. Their complaints regarding taste intensity, particularly about strong sweetness of foods, are common after entry into South Korea. Because a long-term over-exposure or restriction to some taste stimuli causes profound alterations in corresponding taste sensitivity in humans, we hypothesized that sugar restriction, which remains common in North Korea, has influenced sweet sensitivity of North Koreans.SUBJECTS AND METHOD: To test this hypothesis, we assessed the taste stimuli recognition and detection thresholds of both young adults North refugees and South Koreans using a 1-mL whole-mouth gustatory test applied to a series of sweet, bitter, sour, and salty solutions.@*RESULTS@#As expected, the cumulative curve of the recognition threshold for sucrose shifted to the left and the mean recognition threshold for sucrose was significantly lower (0.5357% vs. 0.7393%, p=0.044) for North refugees than for South participants. On the other hand, the recognition threshold for salt was significantly higher (0.2174% vs. 0.1212%, p=0.027) in North refugees. No differences on the recognition taste sensitivity for quinine hydrochloride and citric acid were observed.@*CONCLUSION@#The findings documented in the present study indicate that a prolonged food deficit seems to have changed the taste sensitivity of healthy North Korean refugees. The altered taste sensitivity was most pronounced for sweet and salty tastes, and lasted up to 3.5 years after the refugees left North Korea.

Comparison of Salt Taste Threshold and Salt Intake between Hypertensive and Normotensive Group / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Salt-taste threshold can influence salt appetite, and is thought to be another marker of sodium intake. Many studies have found an association between sodium intake and blood pressure. The aim of this study was to compare the salt-taste threshold and salt intake between hypertensive and normotensive groups. SUBJECTS AND METHOD: One hundred twenty volunteers (51 men and 69 women) who did not take antihypertensive medications were evaluated. First, a questionnaire, which included questions regarding demographic information and preference of salty taste, was conducted, and 24-hour ambulatory blood pressure was checked. Then salt taste threshold was measured by assessing the ability of the subjects to discern the taste of salt in graded solutions of saline. Lastly, 24-hour urinary sodium was measured in a 24-hour urine collection. RESULTS: The salt taste threshold and taste preference for salt were slightly higher in hypertensive group. There was slightly higher salt intake measured as 24-hour urinary sodium in the hypertensive group, compared with the normotensive group. However, there were no significant differences in salt taste threshold, preference of salty taste, and salt intake between the normotensive and the hypertensive groups. CONCLUSION: The threshold of salt taste was not related to sodium intake and hypertension status. These results suggest that the development of hypertension depends on the complex interaction of factors such as genes and environmental factors rather than sensory factors like taste threshold and taste preference.

Naringenin stimulates cholecystokinin secretion in STC-1 cells

BACKGROUND/OBJECTIVES: Cholecystokinin (CCK), a hormone or neuropeptide, is secreted in response to intraluminal nutrients by enteroendocrine I-cells of the intestine and has important physiological actions related to appetite regulation and satiety. The stimulation on CCK secretion from the intestine is of potential relevance for body weight management. Naringenin (4',5,7-trihydroxyflavanone) and its glycoside naringin (naringenin 7-rhamnoglucoside) have been reported to have many biological functions. In the current study, we investigated the question of whether naringenin and naringin could stimulate CCK secretion and then examined the mechanisms involved in CCK release. MATERIALS/METHODS: STC-1 cells were used as a model of enteroendocrine cells. CCK release and changes in intracellular Ca2+ ([Ca2+]i) were measured after incubation of cells with naringenin and naringin for 1 h. RESULTS: Naringenin caused significant (P < 0.05) stimulation of CCK secretion, but naringin did not. In addition, regarding the secretory mechanisms, naringenin-induced CCK secretion involved increases in [Ca2+]i, influx of extracellular Ca2+, at least in part, and activation of TRP channels, including TRPA1. CONCLUSION: Findings of this study suggest that naringenin could have a role in appetite regulation and satiety.

Differences in Taste Thresholds According to Sex and Age Groups in Korean / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: The aim of the study was to compare the gustatory function between age-matched men and women in Korean subjects. SUBJECTS AND METHOD: Healthy non-smoking volunteers without smell and taste disorders were investigated. Thirty-nine men and women of the same age group were evaluated for gustatory function. Whole mouth taste test was performed with successive solutions of sucrose, sodium chloride, citric acid, and quinine hydrochloride. The electrical taste thresholds were measured using an electrogustometer for four different sites in the oral cavity, i.e., both sides of anterior and posterior tongue. RESULTS: Female subjects had lower mean values of detection and recognition thresholds for all of the four tastes than male subjects, although these results did not reach statistical significance except for the detection threshold for salt and the recognition threshold for quinine. In electrogustometry, thresholds in the posterior tongue of glossopharyngeal nerve area were significantly higher for men than women. CONCLUSION: Men had higher taste threshold than women of the same age category. For additional information on the effects of gender and aging on taste thresholds, further studies including a large number of well-controlled subjects are essential.

Hesperetin Stimulates Cholecystokinin Secretion in Enteroendocrine STC-1 Cells

Hesperetin (3',5,7-trihydroxy 4'-methoxyflavanone) and its glycoside hesperidin (hesperetin 7-rhamnoglucoside) in oranges have been reported to possess pharmacological effects related to anti-obesity. However, hesperetin and hesperidin have not been studied on suppressive effects on appetite. This study examined that hesperetin and hesperidin can stimulate the release of cholecystokinin (CCK), one of appetite-regulating hormones, from the enteroendocrine STC-1 cells, and then examined the mechanisms involved in the CCK release. Hesperetin significantly and dose-dependently stimulated CCK secretion with an EC50 of 0.050 mM and increased the intracellular Ca2+ concentrations ([Ca2+]i) compared to the untreated control. The stimulatory effect by hesperetin was mediated via the entry of extracellular Ca2+ and the activation of TRP channels including TRPA1. These results suggest that hesperetin can be a candidate biomolecule for the suppression of appetite and eventually for the therapeutics of obesity.

The Effect of Aging on Taste Thresholds in Korean / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: The sense of taste is one of the most important human senses and plays a critical role in an individual's food preferences and the nutritional status. Proper gustatory function in older people is important for quality of life and enjoyment of food. The objectives of this study was to investigate the effect of aging on taste thresholds in Korean subjects. SUBJECTS AND METHOD: One hundred sixty normal volunteers without smell and taste disorders were investigated. Each subject was given a questionnaire for age, sex, status of smoking and medication. Then, a whole mouth taste test was performed with successive solutions of sucrose, sodium chloride, citric acid, and quinine hydrochloride. RESULTS: Older subjects (over 50 years) showed worse taste sensitivity compared with younger subjects (age 20-29 years). The detection thresholds of all four basic tastes and the recognition threshold of salty taste of elderly participants were significantly higher than those of young participants. CONCLUSION: Gustatory sensitivity was found to decrease with age. Especially, older subjects appeared to have a reduced perception of salt, which can alter eating habits, such as intake of more salty foods. Our data can provide preliminary normative values for future investigation of chemosensation in the Korean population.

Impact of Lysophosphatidylcholine on the Plasminogen Activator System in Cultured Vascular Smooth Muscle Cells

The balance between tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor type 1 (PAI-1) regulates fibrinolysis. PAI-1 expression increases in atherosclerotic arteries and vascular smooth muscle cells (VSMCs) are one of major constituents of atheroma. We investigated the impact of lysophosphatidylcholine (lysoPC), an active component of oxidized low-density lipoprotein, on the plasminogen activator system of the rat VSMCs. The lysoPC stimulated the protein and gene expressions of PAI-1 but did not affect the protein expression of t-PA. Fibrin overlay zymography revealed that lysoPC increased the activity of PAI-1 in the conditioned media, while concurrently decreasing that of free t-PA. Vitamin E inhibited the lysoPC-induced PAI-1 expression. Further, lysoPC increased the intracellular reactive oxygen species (ROS) formation. Caffeic acid phenethyl ester, an inhibitor of NF-kappaB, blocked this lysoPC effect. Indeed, lysoPC induced the NF-kappaB-mediated transcriptional activity as measured by luciferase reporter assay. In addition, genistein, an inhibitor of protein-tyrosine kinase (PTK), diminished the lysoPC effect, while 7,12-dimethylbenz[a]anthracene, a stimulator of PTK, stimulated PAI-1 production. In conclusion, lysoPC does not affect t-PA expression but induces PAI-1 expression in the VSMC by mediating NF-kappaB and the genistein-sensitive PTK signaling pathways via oxidative stress. Importantly, lysoPC stimulates the enzyme activity of PAI-1 and suppresses that of t-PA.

Effect of Korean Native Cimicifuga Species on Proliferation of Vascular Smooth Muscle Cells / 대한폐경학회지

OBJECTIVES: To examine the effect of extracts of Korean native Cimicifuge species on cell proliferation in vascular smooth muscle cells (VSMC). METHODS: VSMC were isolated from rat aorta. Cell proliferation was assessed by measure of bromodeoxyuridine incorporation into the cells. Differences in Reactive oxygen species (ROS) levels were examined after exposure to the extracts of Korean native Cimicifuge species using the detection reagents dichlorofluorecin diacetate. The rhizomes/roots were air-dried and milled with a commercial food mixer. Milled rhizomes/roots of each Cimicifuga species were separately extracted by 80% ethanol, absolute methanol, and 40% 2-propanol using homogenizer and evaporated under reduced pressure at low temperatures. Effects of extracts dissolved in phosphate-buffered saline (0.3 mg/mL) were examined. RESULTS: Ethanolic, methanolic or propanolic extracts of 4 Korean native Cimicifuge species (Cimicifuga [C] davurica, C. japonica, C. heracleifolia var. bifida Nakai, C. simplex) were screened. The addition of extracts of each Korean native Cimicifuge species to cells in the presence of 10% fetal bovine serum (FBS) potently inhibited cell proliferation. Significant decrease of 23%-30% was observed. Vitamin E, a potent antioxidant, inhibited 10% FBS-stimulated cell proliferation of VSMC. We also demonstrated that extracts of each Korean native Cimicifuge species decreased intracellular ROS generation induced with 10% FBS. The effect of Korean native Cimicifuge species was not species-specific and solvent-specific. CONCLUSION: TExtracts of Korean native Cimicifuge species inhibit VSMC proliferation via inhibition of intracellular ROS. These findings suggest that Cimicifuge species used for reducing menopause symptoms might be cardioprotective in women.

Cytotoxic Effects of Lysophosphatidylcholine on Vascular Smooth Muscle Cells / 대한폐경학회지

OBJECTIVES: To investigate the cytotoxic effects of lysophosphatidylcholine (lysoPC), an active component of oxidized low-density lipoproteins (LDL), on vascular smooth muscle cells (VSMCs). METHODS: VSMCs were derived from rat aorta. Cell death was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay, lactic dehydrogenase (LDH) assay, and DNA fragmentation assay. Apoptosis was quantified by propidium iodide staining and fluorescent activated cell sorting (FACS) analysis, and intracellular free radical production was determined using 2',7'-dichlorofluorescin diacetate (DCF-DA). In addition, the changes in caspases, bcl-2 and bax proteins were evaluated by western blot analysis. RESULTS: LysoPC over 25 microM induced more than 50% of the cell death at 10 hours on MTT assay with no change in the level of LDH. The DNA ladder pattern showed that cell death induced by lysoPC was caused by apoptosis, which was associated with increased free radical production. Vitamin E, a potent antioxidant and caffeic acid phenylethyl ester (CAPE), an inhibitor of nuclear factor-kappaB (NF-kappaB), blocked apoptosis. The casepase-3 precursor decreased and the active form of caspase-8 increased. Total bcl-2 and bax proteins did not change with lysoPC treatment, but translocation of bax from cytosole to the mitochondria membrane was observed. CONCLUSION: LysoPC induces apoptosis in VSMCs via an oxidant mechanism, dependent on NF-kappaB.

The Relationship between Single Nucleotide Polymorphisms of the Carbonic Anhydrase 6 Gene andPhenylthiocarbamide Taste Sensitivity, Taste Disorder / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: The phenylthiocarbamide (PTC) and 6-n-propylthiouracil (PROP) taste sensitivity varies among individuals. Recently, it is reported that PROP taste responsiveness is associated with carbonic anhydrase 6 (CA6) gene polymorphism. The CA6 gene, a zinc metalloprotein in human saliva, is affected in taste function and might be correlated with gustatory diversity. The aim of this study was to examine whether PTC taste sensitivity and taste disorder is associated with the CA6 gene polymorphism rs2274327 (C/T), rs2274328 (A/C), and rs2274333 (A/G). SUBJECTS AND METHOD: A total of 217 healthy normal subjects were recruited as controls, and 50 taste disorder patients were recruited as experimental group. The polymorphisms of CA6 gene were genotyped by polymerase chain reaction-restriction fragment length polymorphism analysis. All statistical analyses were calculated using the statistical package for the social science software. Haplotypes were estimated by Haploveiw and the PHASE programs. RESULTS: The CA6 gene polymorphisms showed association with taste disorder but not with PTC sensitivity (taster/nontaster). The number of control subjects carrying AA genotype of single nucleotide polymorphism rs2274328 (A/C) in the CA6 gene was higher than the number of the subjects with taste disorder (p=0.048). However, there was no association between controls and taste disorder subjects in the haplotype analysis. CONCLUSION: These data suggest that the CA6 gene polymorphism rs2274328 could affect taste function impairment in patients with taste disorder. This observation requires a further functional study of gustin protein to clarify the association of the CA6 gene polymorphisms with the taste disorder and sensitivity.

c-Fos Expression in the Nucleus of the Solitary Tract in Response to Salt Stimulation in Rats

Salt signals in tongue are relayed to the nucleus of the solitary tract (NST). This signaling is very important to determine whether to swallow salt-related nutrition or not and suggests some implications in discrimination of salt concentration. Salt concentration-dependent electrical responses in the chorda tympani and the NST were well reported. But salt concentration-dependency and spatial distribution of c-Fos in the NST were not well established. In the present study, NaCl signaling in the NST was studied in urethane-anesthetized rats. The c-Fos immunoreactivity in the six different NST areas along the rostral-caudal axis and six subregions in each of bilateral NST were compared between applications of distilled water and different concentrations of NaCl to the tongue of experimental animals. From this study, salt stimulation with high concentration (1.0 M NaCl) induced significantly higher c-Fos expression in intermediate NST and dorsal-medial and dorsal-middle subregions of the NST compared to distilled water stimulation. The result represents the specific spatial distribution of salt taste perception in the NST.

Relationship between Taste Genotype and Smoking and Alcohol Intake / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Genetic variations of bitter taste receptors (TAS2R) have shown different responses to bitter taste compounds and the frequencies of these variations were different within and between populations. Recently, single nucleotide polymorphisms (SNPs) in the TAS2R38 and TAS2R16 genes demonstrated a significant association with smoking and alcohol consumption in several studies. The aim of this study was to determine the relationship between bitter taste gene polymorphism and cigarette smoking and alcohol intake in Korean. SUBJECTS AND METHOD: One hundred seventy four healthy normal volunteers were asked to fill in a questionnaire regarding demographic information, smoking history, frequency of alcohol intake. Peripheral blood samples were obtained for DNA extraction and genotyping. Single nucleotide polymorphisms were identified on the TAS2R38 and TAS2R16 genes. RESULTS: Haplotype analyses of the three SNPs inside the TAS2R38 gene allowed identifying of only two haplotypes that were associated with the non-taster phenotype (AVI homozygous) and the taster phenotype (PAV homozygous and PAV/AVI heterozygous). Common SNP within TAS2R16, which results in aminoacid change in the protein (K172N), is not demonstrated in this study. Smokers and frequent drinkers were more prevalent among non-tasters than tasters in male. CONCLUSION: Functional variants in TAS2R38 correlated with cigarette smoking in the Korean male. Our findings suggest that taster status plays a role in governing the development of nicotine dependence.