Effects of visual and aromatic stimulations on the perception of five fundamental tastes.

Taste perception is affected by various environmental factors. In the present study, we investigated the effects of visual and aromatic stimulations on stress responses and taste perception. Fourteen young healthy participants were assessed for stress levels and taste intensities under 5 different conditions: normal (no stimuli), watching an action scene, watching a forest scene, sniffing a rosemary aroma, and sniffing a lavender aroma. Compared to participants under the action scene condition, participants under the forest scene or under the rosemary aroma condition showed significantly lower stress levels. Furthermore, the forest scene condition significantly increased the saltiness intensity, whereas the rosemary aroma condition significantly increased the bitterness intensity. A positive or negative correlation was observed between the stress level and taste intensity of sourness and saltiness, respectively. These findings indicate that visual image and aroma have the potential to change taste perception as well as modulate stress conditions.

Genistein inhibits chondrogenic differentiation and mineralization of ATDC5 cells.

Isoflavones are phytoestrogens abundant in leguminous crops and are used to prevent a variety of hormonal disorders. In the present study, the effects of genistein and daidzein on the chondrogenic differentiation of ATDC5 cells were investigated. Genistein (10 µM) treatment markedly reduced production of sulfated proteoglycans and collagen fibers in the ATDC5 cells. Genistein suppressed the expression of genes involved in chondrocyte differentiation such as Sox9, Col2a1, Col10a1, Acan, and Tgfb1. Additionally, genistein significantly decreased calcium deposition in ATDC5 cells during chondrogenic differentiation; however, it increased calcification under non-chondrogenic mineralizing conditions. Daidzein exhibited a similar effect of suppressing chondrogenesis in ATDC5 cells, although its efficacy was 10-times lower than that of genistein. These findings suggest that a high concentration of genistein inhibits chondrogenesis and chondrogenic mineralization, whereas it enhances non-chondrogenic mineralization.

N-acetylmannosamine improves object recognition and hippocampal cell proliferation in middle-aged mice.

Sialic acids may modulate cell proliferation and gene expression, particularly in neural cells in vitro. However, the function of sialic acids in the central nervous system has not previously been examined. We examined whether N-acetylmannosamine (ManNAc) could improve object recognition and hippocampal cell proliferations in middle-aged mice. C56BL/6J mice aged 52 weeks were treated with ManNAc for 4 weeks. Their cognitive-ability was assessed with a place and object recognition test. ManNAc, but not N-acetylglucosamine or N-acetylneuraminic acid, improved the index score in the place recognition task at a dosage of 5.0 mg/mL in drinking water. Additionally, ManNAc enhanced the hippocampal cell proliferation, which was evaluated by a bromodeoxyuridine assay and the number of Ki67-immunoreactive cells. We could demonstrate that ManNAc had positive effects on the age-related brain dysfunction. These findings suggest that the use of ManNAc or related compounds may be a new approach for the treatment of human dementia.