An intact pituitary vasopressin system is critical for building a robust circadian clock in the suprachiasmatic nucleus.

The circadian clock is a biological timekeeping system that oscillates with a circa-24-h period, reset by environmental timing cues, especially light, to the 24-h day-night cycle. In mammals, a "central" clock in the hypothalamic suprachiasmatic nucleus (SCN) synchronizes "peripheral" clocks throughout the body to regulate behavior, metabolism, and physiology. A key feature of the clock's oscillation is resistance to abrupt perturbations, but the mechanisms underlying such robustness are not well understood. Here, we probe clock robustness to unexpected photic perturbation by measuring the speed of reentrainment of the murine locomotor rhythm after an abrupt advance of the light-dark cycle. Using an intersectional genetic approach, we implicate a critical role for arginine vasopressin pathways, both central within the SCN and peripheral from the anterior pituitary.

An Exploratory Randomized Controlled Study to Investigate Concentration-Dependence of Green Tea Catechin Gargling on Acute Upper Respiratory Tract Infections.

Green tea (GT) catechins exhibit antiviral effects in experimental studies. However, we lack clinical evidence on the preventive effects of catechin concentrations in gargling against acute upper respiratory tract infections (URTIs). Therefore, we aimed to investigate the concentration-dependence of GT catechins in gargling on the incidence of URTIs. We conducted an open-label randomized study. The target population consisted of 209 students from the University of Shizuoka and Meiji University, who were randomly assigned to high-catechin (approximate catechin concentration: 76.4 mg/dL), low-catechin (approximate catechin concentration: 30.8 mg/dL), and a control water gargling (catechin concentration: 0 mg/dL) group. All participants gargled water or GT daily for 12 weeks. The symptoms of URTIs were recorded on a daily survey form by participants. The incidences of URTIs occurred in 6 (9.1%), 7 (10.8%), and 11 (15.7%) participants in the high-catechin, low-catechin, and water groups, respectively. Cox proportional hazards analysis, using background factors and prevention status as covariates, revealed a hazard ratio of 0.57 (95% Confidence Interval (CI): 0.21-1.55, p = 0.261) for the high-catechin vs. water group and 0.54 (95% CI: 0.20-1.50, p = 0.341) for the low-catechin vs. water group. Our findings showed the incidence of URTIs in a concentration-dependent GT gargling was not significantly different, partly owing to the low event rates caused by intense precautions against the coronavirus disease 2019 pandemic. Our study would serve as a foundation for the development of an advanced protocol with optimal concentrations and a larger number of participants.

Preventive effects of tea and tea catechins against influenza and acute upper respiratory tract infections: a systematic review and meta-analysis.

PURPOSE: Gargling with tea has protective effects against influenza infection and upper respiratory tract infection (URTI). To evaluate if tea and tea catechin consumption has the same protective effects as gargling with tea, we performed a systematic review and meta-analysis. METHODS: We performed a comprehensive literature search using the PubMed, Cochrane Library, Web of Science, and Ichu-shi Web databases. The search provided six randomized controlled trials (RCTs) and four prospective cohort studies (n = 3748). The quality of each trial or study was evaluated according to the Cochrane risk-of-bias tool or Newcastle-Ottawa Scale. We collected data from publications meeting the search criteria and conducted a meta-analysis of the effect of tea gargling and tea catechin consumption for preventing URTI using a random effects model. RESULTS: Tea gargling and tea catechin consumption had significant preventive effects against URTI (risk ratio [RR] = 0.74, 95% confidence interval [CI] 0.64-0.87). In sub-analyses, a significant preventive effect was observed by study type (prospective cohort study: RR = 0.67, 95% CI 0.50-0.91; RCT: RR = 0.79, 95% CI 0.66-0.94) and disease type (influenza: RR = 0.69, 95% CI 0.58-0.84; acute URTI: RR = 0.78, 95% CI 0.62-0.98). Both gargling with tea and consuming tea catechins effectively protected against URTI (tea and tea catechins consumption: RR = 0.68, 95% CI 0.52-0.87; tea gargling: RR = 0.83, 95% CI 0.72-0.96). CONCLUSION: Our findings suggest that tea gargling and tea catechin consumption may have preventive effects against influenza infection and URTI. The potential effectiveness of these actions as non-pharmaceutical interventions, however, requires further investigation.

Improvement of Depressed Mood with Green Tea Intake.

Being in a prolonged depressed state increases the risk of developing depression. To investigate whether green tea intake is effective in improving depression-like moods, we used an experimental animal model of depression with lipopolysaccharide (LPS) and clarified the effects of green tea on the biological stress response and inflammation in the brain. Regarding the stress reduction effect of green tea, we found that the sum of caffeine (C) and epigallocatechin gallate (E) relative to the sum of theanine (T) and arginine (A), the major components of green tea, or the CE/TA ratio, is important. The results showed that depression-like behavior, adrenal hypertrophy as a typical stress response, and brain inflammation were suppressed in mice fed green tea components with CE/TA ratios of 2 to 8. In addition, the expression of Npas4, which is reduced in anxiety and depression, was maintained at the same level as controls in mice that consumed green tea with a CE/TA ratio of 4. In clinical human trials, the consumption of green tea with CE/TA ratios of 3.9 and 4.7 reduced susceptibility to subjective depression. These results suggest that the daily consumption of green tea with a CE/TA ratio of 4-5 is beneficial to improving depressed mood.