The mechanisms of release, depletion, and refilling of endoplasmic reticulum (ER) Ca.sup.2+ were investigated in type I horizontal cells of the carp retina using a fluo-3-based Ca.sup.2+ imaging ...technique. Exogenous application of caffeine, a ryanodine receptor agonist, induced oscillatory intracellular free Ca.sup.2+ concentration (Ca.sup.2+ .sub.i) responses in a duration- and concentration-dependent manner. In Ca.sup.2+ -free Ringer's solution, Ca.sup.2+ .sub.i transients could also be induced by a brief caffeine application, whereas subsequent caffeine application induced no Ca.sup.2+ .sub.i increase, which implied that extracellular Ca.sup.2+ was required for ER refilling, confirming the necessity of a Ca.sup.2+ influx pathway for ER refilling. Depletion of ER Ca.sup.2+ by thapsigargin triggered a Ca.sup.2+ influx which could be blocked by the store-operated channel inhibitor 2-APB, which proved the existence of the store-operated Ca.sup.2+ entry pathway. Taken together, these results suggested that after being depleted by caffeine, the ER was replenished by Ca.sup.2+ influx via store-operated channels. These results reveal the fine modulation of ER Ca.sup.2+ signaling, and the activation of the store-operated Ca.sup.2+ entry pathway guarantees the replenishment of the ER so that the cell can be ready for response to the subsequent stimulus.
Caffeine ranks as one of the top most commonly consumed dietary ingredients throughout the world. It is naturally found in coffee beans, cacao beans, kola nuts, guarana berries, and tea leaves ...including yerba mate. The total daily intake, as well as the major source of caffeine varies globally; however, coffee and tea are the 2 most prominent sources. Soft drinks are also a common source of caffeine as well as energy drinks, a category of functional beverages. Moderate caffeine consumption is considered safe and its use as a food ingredient has been approved, within certain limits, by numerous regulatory agencies around the world. Performance benefits attributed to caffeine include physical endurance, reduction of fatigue, and enhancing mental alertness and concentration. Caffeine has also been recently linked to weight loss and consequent reduction of the overall risks for developing the metabolic syndrome. However, the caloric contribution of caffeine-sweetened beverages needs to be considered in the overall energy balance. Despite all these benefits the potential negative effects of excessive caffeine intake should also be considered, particularly in children and pregnant women.
Coffee is one of the most consumed beverages in the world; its production is based mainly on varieties of the Coffea arabica species. Mexico stands out for its specialty and organic coffee. In ...Guerrero, the production is done by small indigenous community cooperatives that market their product as raw material. Official Mexico Standards stipulate the requirements for its commercialization within the national territory. In this work, the physical, chemical, and biological characterizations of green, medium, and dark roasted beans from C. arabica varieties were carried out. Analysis by HPLC showed higher chlorogenic acid (55 mg/g) and caffeine (1.8 mg/g) contents in the green beans of the Bourbon and Oro Azteca varieties. The caffeine (3.88 mg/g) and melanoidin (97 and 29 mg/g) contents increased according to the level of roasting; a dissimilar effect was found in the chlorogenic acid content (14.5 mg/g). The adequate nutritional content and the sensory evaluation allowed the classification of dark-roasted coffee as premium coffee (84.25 points) and medium-roasted coffee as specialty coffee (86.25 points). The roasted coffees presented antioxidant activity without cytotoxic effects; the presence of CGA and caffeine supports the beneficial effects of drinking coffee. The results obtained will serve as a basis for making decisions on improvements to the coffees analyzed.
Abstract Tau pathology found in Alzheimer's disease (AD) is crucial in cognitive decline. Epidemiologic evidences support that habitual caffeine intake prevents memory decline during aging and ...reduces the risk to develop Alzheimer's disease. So far, experimental studies addressed the impact of caffeine in models mimicking the amyloid pathology of AD. However, in vivo effects of caffeine in a model of AD-like tauopathy remain unknown. Here, we evaluated effects of chronic caffeine intake (0.3 g/L through drinking water), given at an early pathologic stage, in the THY-Tau22 transgenic mouse model of progressive AD-like tau pathology. We found that chronic caffeine intake prevents from the development of spatial memory deficits in tau mice. Improved memory was associated with reduced hippocampal tau phosphorylation and proteolytic fragments. Moreover, caffeine treatment mitigated several proinflammatory and oxidative stress markers found upregulated in the hippocampus of THY-Tau22 animals. Together, our data support that moderate caffeine intake is beneficial in a model of AD-like tau pathology, paving the way for future clinical evaluation in AD patients.
Abstract
Introduction
We previously showed that relative to placebo (PL), caffeine (CAF) significantly improved psychomotor vigilance task (PVT) reaction time (RT) during the first 2 days (ACUTE ...phase), but not during the last 3 days (CHRONIC phase) of sleep restriction (SR) (Doty et al., 2018). However, while individual differences in RT during sleep deprivation have been previously documented, the interaction between CAF and individual vulnerability (VUL) during SR on PVT-RT is not well-known.
Methods
For statistical analysis, we computed trends in RTs (SLOPE) as follows; baseline, 1st and the 2nd SR days to represent ACUTE phase, and the 2nd, 3rd, 4th and 5th SR days for CHRONIC phase. Participants in each GROUP (CAF or PL) were split into 2 for VUL; high vulnerable (HIGHVUL), and low vulnerable (LOWVUL), depending on the number of minor lapses made during SR. We used 3-way ANOVA model with independent measures (2x2x2; GROUPxVULxPHASE) and a dependent measure (SLOPE).
Results
We found a main effect of VUL (F=12.69, p<0.001), an interaction between GROUP and PHASE (F=12.95, p<0.001) and an interaction between VUL, GROUP, and PHASE (F=8.04, p<.01). Resolving this 3-way interaction for ACUTE revealed a main effect of VUL (F=9.34, p<.005), a main effect of GROUP (F=5.96, p<.05). Although the interaction between VUL and GROUP failed to achieve significance (F=3.46, p=0.073), only for the LOWVUL, PL participants were significantly higher than CAF, p<0.01)). Resolving the 3-way interaction for CHRONIC revealed a main effect of GROUP (F=8.95, p<0.01), no significant of VUL (F=3.36, p=0.077) and an interaction between VUL and GROUP (F=6.11, p<0.05). Resolving this interaction showed that only for the LOWVUL participants in CAF, the slope was higher than PL (p<.001).
Conclusion
Performance enhancing effects of caffeine were only evident for low vulnerability participants, and for only the first few days of sleep restriction. At the tested dose level, caffeine did not result in meaningful improvements in performance in highly vulnerable participants during the sleep restriction period.
Support
Department of Defense Military Operational Medicine Research Program (MOMRP)
Abstract
Introduction
Young drivers are over-involved in sleepiness-related crashes. Daytime and nighttime exposure to light might shift the human circadian phase and alertness. The alerting effects ...of bright light were compared with those of caffeine in young drivers.
Methods
In a within-subjects study, 30 chronically sleep-deprived non-professional drivers (aged 18–24 years) completed two simulated daytime driving sessions per day across three consecutive days. Participants completed the first drive under a Baseline condition (non-caffeinated gum, 555 nm light, 0.3 µW/cm²), and the second drive under the randomized conditions of Light (500 nm, 230 µW/cm²), Caffeine (100 mg caffeinated gum) or the combination of Light and Caffeine. Using mixed-effects models, the alerting effects of these conditions on objective sleepiness (ECG beat-to-beat intervals), driving performance (lateral lane variability) and subjective sleepiness (scores on the Karolinska sleepiness scale; KSS) were examined.
Results
Compared to the Baseline condition, lateral lane variability decreased under the Light (P=0.011), Caffeine (P=0.0001), and the combination of Light and Caffeine (P=0.046). Lateral lane variability was lower under Caffeine when compared with the Light (P=0.009) or the combination of Light and Caffeine (P= 0.0001). Average beat-to-beat intervals increased from the Baseline condition to the Light (P=0.017), Caffeine (P=0. 0.0001), and the combination of Light and Caffeine conditions (P=0.0001). All three conditions significantly reduced subjective sleepiness compared to the Baseline condition (KSS= 4–5 vs KSS=6, P= 0.0001).
Conclusion
Bright light, either alone or combined with caffeine, improves driving performance and subjective sleepiness during daytime drives. Light might better improve objective sleepiness and other sleepiness indicators during nighttime when drivers are sleepier and have an increased sensitivity to the light. Further research would clarify how the circadian effects are aligned with the alerting effects of the light. Bright light, as an alternative to or combined with caffeine, could reduce sleep-related crashes on the road.
Support
NA
Caffeine use is increasing worldwide. The underlying motivations are mainly concentration
and memory enhancement and physical performance improvement. Coffee and caffeine-containing
products affect ...the cardiovascular system, with their positive inotropic and chronotropic effects, and
the central nervous system, with their locomotor activity stimulation and anxiogenic-like effects.
Thus, it is of interest to examine whether these effects could be detrimental for health. Furthermore,
caffeine abuse and dependence are becoming more and more common and can lead to caffeine
intoxication, which puts individuals at risk for premature and unnatural death. The present review summarizes the main
findings concerning caffeine's mechanisms of action (focusing on adenosine antagonism, intracellular calcium
mobilization, and phosphodiesterases inhibition), use, abuse, dependence, intoxication, and lethal effects. It also suggests
that the concepts of toxic and lethal doses are relative, since doses below the toxic and/or lethal range may play a causal
role in intoxication or death. This could be due to caffeine's interaction with other substances or to the individuals' preexisting
metabolism alterations or diseases.be due to caffeine's interaction with other substances or to individuals' pre-existing diseases or metabolism alterations.
PDF
