Previous studies have shown a modulatory influence of limbic forebrain areas, such as the central nucleus of the amygdala and lateral hypothalamus, on the activity of taste-responsive cells in the nucleus of the solitary tract (NST). The bed nucleus of the stria terminalis (BST), which receives gustatory afferent information, also sends descending axons to the NST. The present studies were designed to investigate the role of the BST in the modulation of NST gustatory activity. Extracellular action potentials were recorded from 101 taste-responsive cells in the NST of urethane-anesthetized hamsters and analyzed for a change in excitability following bilateral electrical stimulation of the BST. The response of NST taste cells to stimulation of the BST was predominately inhibitory. Orthodromic inhibitory responses were observed in 29 of 101 (28.7%) NST taste-responsive cells, with four cells inhibited bilaterally. An increase in excitability was observed in seven of the 101 (6.9%) NST taste cells. Of the 34 cells showing these responses, 25 were modulated by the ipsilateral BST and 15 by the contralateral; four were inhibited bilaterally and two inhibited ipsilaterally and excited contralaterally. The duration of inhibitory responses (mean = 177.9 ms) was significantly longer than that of excitatory responses (35.4 ms). Application of subthreshold electrical stimulation to the BST during taste trials inhibited or excited the taste responses of every BST-responsive NST cell tested with this protocol. NST neurons that were most responsive to sucrose, NaCl, citric acid or quinine hydrochloride were all affected by BST stimulation, although citric acid-best cells were significantly more often modulated and NaCl-best less often modulated than expected by chance. These results combine with excitatory and inhibitory modulation of NST neurons by the insular cortex, lateral hypothalamus and central nucleus of the amygdala to demonstrate extensive centrifugal modulation of brainstem gustatory neurons.
PurposeFungi, rhinoviruses (RVs), and eosinophils are associated with upper respiratory diseases. We evaluated the effects of fungal stimulation and eosinophil co-culture on the expression of mucin genes in RV-infected nasal polyp epithelial cells.MethodsNasal polyp epithelial cells were obtained from chronic rhinosinusitis patients. Cultured epithelial cells were stimulated with Alternaria and Aspergillus with or without RV-16 infection. The epithelial cells were co-cultured with eosinophils for 16 h. MUC4, MUC5AC, MUC5B, and MUC8 mRNA expressions in the epithelial cells were quantified using real-time RT-PCR. To determine the underlying mechanism, nuclear factor-κB (NF-κB), activator protein-1 (AP-1), and mitogen-activated protein kinase (MAPK) inhibitors were used to inhibit mucin gene expression.ResultsFungi and RV-16 induced mucin gene expression in nasal polyp epithelial cells. However, there was no synergistic increase in mucin gene expression, with the exception of MUC4 mRNA expression stimulated by 25 µg/mL Aspergillus. When RV-16-infected epithelial cells were stimulated with fungi and then co-cultured with eosinophils, MUC4, MUC5B, and MUC8 mRNA expressions increased. Mucin gene expression was inhibited by NF-κB inhibitors.ConclusionsRV-16, airborne fungi, and eosinophils may exacerbate the inflammatory process in nasal mucosal diseases by enhancing mucin gene expression.
Background and ObjectivesZZThe 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 MethodZZOne 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. ResultsZZOlder 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. ConclusionZZGustatory 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.
Background and Objectives: Olfactory training is an alternative treatment based on modulation of the regeneration process of the olfactory system via repeated exposure to odors. Our study aimed to investigate the impact of olfactory training with intranasal corticosteroid in Korean patients with various causes of olfactory dysfunction. Subjects and Method: Our study population comprised 134 adults with olfactory dysfunction of different etiologies (postviral infection n=85; post-traumatic n=18; and idiopathic n=31). For training, patients exposed themselves to four different odors twice a day. All patients used fluticasone nasal spray (two sprays in each nostril once daily). Olfactory function was evaluated at baseline and again at three months, and results were quantified as patient TDI (threshold, discrimination, and identification) score. Results: Olfactory function improved in 74 of 134 patients (55.2%). Etiology of olfactory disorder, sex, and age had statistically significant influence on the improvement rate of olfactory function, among which etiology of olfactory loss was the most important. However, initial severity and duration of olfactory loss had no statistically significant influence on the improvement rate. The TDI score at three months of olfactory training showed remarkable improvement, primarily because of improvements in the discrimination and identification components. Conclusion: The present study showed that olfactory training with intranasal corticosteroid was beneficial to improve olfactory function in patients with olfactory dysfunction, particularly in postviral infection patients.
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