Chemical Senses最新文献

Cronkhite-Canada syndrome (CCS) is a very rare gastrointestinal disorder with ectodermal abnormalities. Taste abnormalities appear in more than 80% of cases. Our objective was to investigate the characteristics of CCS. Ten patients with taste abnormalities who were diagnosed with CCS were included. A medical interview, examination of the tongue findings, and blood tests were performed, and taste functions were assessed using an electrogustometry (EGM) and a filter paper disc (FPD) before and after treatment. There was nail atrophy in all cases, weight loss in 8 cases, hair loss in 6 cases, skin hyperpigmentation in 5 cases, gastrointestinal symptoms in 4 cases, and atrophy of the lingual papillae in at least 8 cases. Zinc therapy for taste disorders by the previous physicians was ineffective in all cases. The results of the FPD at the first examination showed a severe decrease in taste function of the anterior tongue, whereas taste function tended to be preserved in the posterior tongue (P < 0.01, Wilcoxon). In all cases, subjective symptoms improved within 3 mo after treatment of CCS. Taste function improved significantly after treatment (FPD in anterior tongue, P < 0.05, EGM in posterior tongue, P < 0.01, Wilcoxon). Taste disorder in CCS tended to be severe in the anterior tongue with findings of tongue papillary atrophy, which appears to be an ectodermal abnormality. Their taste function improved along with symptoms after treatment. The taste tests were useful for determining the effect of treatment for CCS.

Gustatory dysfunction is an often overlooked symptom in people with multiple sclerosis (PwMS), potentially leading to poor appetite, malnutrition, weight loss, and decreased quality of life. This systematic review and meta-analysis aimed to assess the pooled prevalence of gustatory dysfunction in PwMS and compare their gustatory test scores with healthy controls. An online database search of PubMed, Embase, Scopus, and Web of Science was conducted on 2024 June 29. Observational studies reporting gustatory dysfunction or gustatory test scores in PwMS were included. Pooled prevalence rates were calculated using a random-effects model, with subgroup analyses based on the type of gustatory test used. Standardized mean differences (SMD) were calculated for comparisons between PwMS and healthy controls. A total of 9 studies encompassing 1385 PwMS were included. The pooled prevalence of gustatory dysfunction among PwMS was 16.4% (95% confidence intervals [95% CI]: 8.7% to 24.1%, I² = 90%, P < 0.01). Subgroup analysis showed a prevalence of 18.8% (95% CI: 10.5% to 27.2%, I² = 0%) in 4 studies using the Taste Strip Test (TST), while 3 non-TST studies using liquid tastants or self-reports reported a prevalence of 20.2% (95% CI: 7.2% to 33.3%, I² = 86%). PwMS had significantly lower gustatory test scores compared to healthy controls (SMD: -0.93, 95% CI: -1.20 to -0.65, I² = 0%, P = 0.48). Gustatory dysfunction affects a notable proportion of PwMS, with prevalence rates varying by assessment method. Future studies should assess the possible causes of gustatory dysfunction in PwMS using validated gustatory assessment scales.

Although animals can reliably locate and recognize odorants embedded in complex environments, the neural circuits for accomplishing these tasks remain incompletely understood. Adaptation is likely to be important as it could allow neurons in a brain area to adjust to the broader sensory environment. Adaptive processes must be flexible enough to allow the brain to make dynamic adjustments, while maintaining sufficient stability so that organisms do not forget important olfactory associations. Processing within the mouse olfactory bulb is likely involved in generating adaptation, although there are conflicting models of how it transforms the glomerular output of the mouse olfactory bulb. Here we performed 2-photon Ca2+ imaging from mitral/tufted glomeruli in awake mice to determine the time course of recovery from adaptation, and whether it acts broadly or selectively across the glomerular population. Individual glomerular responses, as well as the overall population odor representation were similar across imaging sessions. However, odor-concentration pairings presented with interstimulus intervals upwards of 30-s evoked heterogeneous adaptation that was concentration-dependent. We demonstrate that this form of adaptation is unrelated to variations in respiration, and olfactory receptor neuron glomerular measurements indicate that it is unlikely to be inherited from the periphery. Our results indicate that the olfactory bulb output can reliably transmit stable odor representations, but recent odor experiences can selectively shape neural responsiveness for upwards of 30 seconds. We propose that neural circuits that allow for non-uniform adaptation across mitral/tufted glomeruli could be important for making dynamic adjustments in complex odor environments.

Taste buds are commonly studied in rodent models, but some differences exist between mice and humans in terms of gustatory mechanisms and sensitivities. Whether these functional differences are reflected in structural differences between species is unclear. Using immunofluorescent image stacks, we compared morphological and molecular characteristics of mouse and human fungiform taste buds. The results suggest that while the general features of fungiform taste buds are similar between mice and humans, several characteristics differ significantly. Human taste buds are larger and taller than those of mice, yet they contain similar numbers of taste cells. Taste buds in humans are more heavily innervated by gustatory nerve fibers expressing the purinergic receptor P2X3 showing a 40% higher innervation density than in mice. Like Type II cells of mice, a subset (about 30%) of cells in human taste buds is immunoreactive for PLCβ2. These PLCβ2-immunoreactive cells display CALHM1-immunoreactive puncta closely apposed to gustatory nerve fibers suggestive of channel-type synapses in Type II cells in mice. These puncta, used as a measure of synaptic contact, are significantly larger in humans compared to mice suggesting a higher efflux of ATP neurotransmitter in humans. Altogether these findings suggest that while many similarities exist in the organization of murine and human fungiform taste buds, significant differences do exist in taste bud size, innervation density, and size of synaptic contacts that may impact gustatory signal transmission.