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The gut microbiota changes greatly at the onset of disease, and the importance of intestinal bacteria has been highlighted. The gut microbiota also changes greatly with aging. Aging causes skin dryness, but it is not known how changes in the gut microbiota with aging affects the expression of genes that are important for maintaining skin function. In this study, we investigated how age‐related changes in gut microbiota affect the expression of genes that regulate skin function. The gut microbiotas from young mice and aged mice were transplanted into germ‐free mice (fecal microbiota transplantation [FMT]). These recipient mice were designated FMT‐young mice and FMT‐old mice respectively, and the expression levels of genes important for maintaining skin function were analyzed. The dermal water content was significantly lower in old mice than that in young mice, indicating dry skin. The gut microbiota significantly differed between old mice and young mice. The water channel aquaporin‐3 (Aqp3) expression level in the skin of FMT‐old mice was significantly higher than that in FMT‐young mice. In addition, among the genes that play an important role in maintaining skin function, the expression levels of those encoding ceramide‐degrading enzyme, ceramide synthase, hyaluronic acid‐degrading enzyme, and Type I collagen were also significantly higher in FMT‐old mice than in FMT‐young mice. It was revealed that the gut microbiota, which changes with age, regulates the expression levels of genes related to skin function, including AQP3. [ABSTRACT FROM AUTHOR]

Tokishakuyakusan (TSS), a traditional Kampo medicine, can effectively alleviate symptoms unique to women, such as menstrual pain and menopausal symptoms, and this effect is believed to be related to its ability to increase the secretion of female hormones. TSS is also believed to be effective against skin pigmentation. However, no studies have examined the effect of TSS on pigmentation. In this study, we conducted basic research to determine the effects of TSS on pigmentation. Female HRM-2 mice were given free access to a normal diet or a TSS-containing diet for 7 weeks. For 3 weeks starting from the 4th week of treatment, the back of the skin was irradiated with ultraviolet (UV) light, and the melanin level was measured. The expression levels of melanogenesis-related genes and inflammatory markers in the skin were analyzed. The melanin level in the skin of the mice exposed to UV radiation was approximately three times greater than that in the skin of the mice in the non-UV-irradiated group, confirming pigmentation due to UV irradiation. The protein expression levels of tyrosinase (Tyr), tyrosinase-related protein-1 (Tyrp1), and dopachrome tautomerase (Dct), which are important for melanin production, were significantly greater in the UV irradiation group than in the non-UV irradiation group. In contrast, the amount of skin melanin in the mice treated with TSS was significantly lower than that in the UV-irradiated group, and the expression levels of melanogenesis-related enzymes were also lower. Furthermore, TSS significantly decreased the expression of microphthalmia transcription factor (Mitf), a transcription factor for melanogenesis-related enzymes, and the inflammatory cytokines interleukin-1β and interleukin-6. TSS inhibits melanin production in melanocytes by suppressing the increase in the expression of melanogenesis-related enzymes caused by UV irradiation. These findings suggested that this effect of TSS is exerted through the combined regulation of MITF expression and anti-inflammatory responses. [Display omitted] • Tokishakuyakusan (TSS) inhibits melanin production caused by UV irradiation. • TSS suppresses the expression of melanogenesis-related enzymes in the skin. • TSS decreases the expression of Mc1r and Mitf in the skin. • TSS was suppressed the increase in inflammatory cytokines due to UV irradiation. • TSS is expected to have clinical application in the treatment of photoaging. [ABSTRACT FROM AUTHOR]

This is the first quantitative study investigating citizen-based river groups throughout Japan. Recently, river management faces multiple challenges, such as increased risk of disasters, the ageing of existing river protection facilities, and the growing awareness of environmental issues. However, funding for river management has been reduced because of a rapidly ageing and declining population. In this context, citizen-based river groups may be expected to cooperate with river managers to sustainably manage rivers. There are hundreds of river groups in Japan, but there are few reports detailing their information at a national level. The purpose of this study is to quantitatively investigate citizen-based river groups in Japan by analysing the following: (1) the number of people and amount of time they invest in river-related activities; (2) what kind of activities they do; and (3) when and where these activities occur. We investigated 207 river groups using questionnaires and interviews. Our results suggest that the total active mass of river groups accounts for 2% of that of river managers. Furthermore, the economic value of river group activities is estimated at 13% (65 million yen) of the official cost of river management in intangible sectors. [ABSTRACT FROM AUTHOR]