Dose-dependent Effects Of Caffeine Research Articles

Dose-dependent effects of caffeine in human Sertoli cells metabolism and oxidative profile: relevance for male fertility.

Caffeine is a widely consumed substance present in several beverages. There is an increasing consumption of energetic drinks, rich in caffeine, among young individuals in reproductive age. Caffeine has been described as a modulator of cellular metabolism. Hence, we hypothesized that it alters human Sertoli cells (hSCs) metabolism and oxidative profile, which are essential for spermatogenesis. For that purpose, hSCs were cultured with increasing doses of caffeine (5, 50, 500 μM). Caffeine at the lowest concentrations (5 and 50 μM) stimulated lactate production, but only hSCs exposed to 50 μM showed increased expression of glucose transporters (GLUTs). At the highest concentration (500 μM), caffeine stimulated LDH activity to sustain lactate production. Notably, the antioxidant capacity of hSCs decreased in a dose-dependent manner and SCs exposed to 500 μM caffeine presented a pro-oxidant potential, with a concurrent increase of protein oxidative damage. Hence, moderate consumption of caffeine appears to be safe to male reproductive health since it stimulates lactate production by SCs, which can promote germ cells survival. Nevertheless, caution should be taken by heavy consumers of energetic beverages and food supplemented with caffeine to avoid deleterious effects in hSCs functioning and thus, abnormal spermatogenesis.

Effect of a High and Low Dose of Caffeine on Antigen-Stimulated Activation of Human Natural Killer Cells After Prolonged Cycling

This study investigated the effect of a high and low dose of caffeine on antigen-stimulated natural killer (NK) cell (CD3- CD56+) activation after prolonged, strenuous cycling, as assessed by the early-activation molecule CD69. In a randomized crossover design, 12 healthy male endurance-trained cyclists cycled for 90 min at 70% VO2peak 60 min after ingesting either 0 (PLA), 2 (2CAF), or 6 (6CAF) mg/kg body mass of caffeine. Whole blood was stimulated with Pediacel (5 in 1) vaccine. A high dose of caffeine (6CAF) increased the number of CD3-CD56+ cells in the circulation immediately postexercise compared with PLA (p < .05). For both 2CAF and 6CAF, the geometric mean fluorescence intensity (GMFI) of CD69+ expression on unstimulated CD3-CD56+ cells was significantly higher than with PLA (both p < .05). When cells were stimulated with antigen, the GMFI of CD69 expression remained significantly higher with 2CAF than with PLA 1 hr postexercise (p < .05). Although not achieving statistical significance, 6CAF also followed a similar trend when stimulated (p = .09). There were no differences in GMFI of CD69 expression between 2CAF and 6CAF. These results suggest that a high (6 mg/kg) dose of caffeine was associated with the recruitment of NK cells into the circulation and that both a high and low (2 mg/kg) dose of caffeine increased unstimulated and antigen-stimulated NK-cell activation 1 hr after high-intensity exercise. Furthermore, there does not appear to be a dose-dependent effect of caffeine on NK-cell activation 1 hr after prolonged intensive cycling.

Dose-dependent effects of caffeine on behavior and thermoregulation in a chronic unpredictable stress model of depression in rats

The effects of the non-selective adenosine A 1/A 2 receptor antagonist caffeine on behavior and thermoregulation in chronic unpredictable stress (CUS) model of depression was studied in Wistar rats. In the open field (OF) test, caffeine dose-dependently increased motor activity while decreased grooming and time spent in the corner. Five-week exposure to CUS procedure had the opposite effect in rats. Caffeine reversed CUS-induced effects on the above mentioned parameters. Caffeine (40 mg/kg) increased the motor activity in plus maze (PM) test while at doses of 20 and 40 mg/kg it decreased the number of entries in the open arms. Whereas CUS did not change the level of anxiety, caffeine (2, 20 and 40 mg/kg) administered after CUS diminished it by increasing the time in open arms. Caffeine dose-dependently decreased the immobility time while CUS had the opposite increasing effect in forced swimming test (FST). Caffeine at doses of 20 and 40 mg/kg reversed the effect of CUS on immobility in FST. Caffeine produced dose-dependent rice of body temperature in both non-treated and CUS-treated rats. The hyperthermic effect in normal rats pretreated with caffeine lasted about 90 min while in caffeine-pretreated rats exposed to CUS it lasted about 150 min. High dose of caffeine (100 mg/kg) induced significant hypothermia between 90th and 150th minute in control rats and hyperthermia between 30th and 60th minute in CUS-treated rats. These results suggest a putative role of this methylxanthine in the adaptive responses to chronic unpredictable stress stimuli.

Dose-dependent effects of caffeine on physiology and behavior in adolescents

Dose-dependent effects of caffeine on physiology and behavior in adolescents

Dose-dependent effect of caffeine on reducing leg muscle pain during cycling exercise is unrelated to systolic blood pressure

Dose-dependent effect of caffeine on reducing leg muscle pain during cycling exercise is unrelated to systolic blood pressure

Dose-Dependent Effect of Caffeine on Reducing Leg Muscle Pain During Cycling

1513 PURPOSE: This double-blind, within-subjects experiment examined the effects of ingesting two doses of caffeine on perceptions of leg muscle pain and blood pressure during moderate intensity cycling exercise. METHODS: Low caffeine consuming college-aged males (N = 12) ingested one of two doses of caffeine (5 mg•kg−1 or 10 mg•kg−1 body weight) or placebo and 1 h later completed 30 min of moderate intensity cycling exercise (60% VO2peak). The order of drug administration was counterbalanced. Resting blood pressure and heart rate were recorded immediately before and 1 h after drug administration. Perceptions of leg muscle pain as well as work rate, blood pressure, heart rate, and oxygen uptake (VO2) were recorded during exercise. RESULTS: Caffeine increased resting systolic pressure in a dose-dependent fashion but these blood pressure effects were not maintained during exercise. Caffeine had a significant linear, dose-response effect on leg muscle pain ratings [F (2, 22) = 14.06, pp < .0001, eta2 = .56]. The mean pain intensity scores during exercise after ingesting 10 mg•kg−1 body weight caffeine, 5 mg•kg−1 body weight caffeine, and placebo were 2.1 ± 1.4, 2.6 ± 1.5, and 3.5 ± 1.7, respectively. CONCLUSION: Caffeine ingestion has dose-response effects on reducing leg muscle pain during exercise and these effects do not depend on caffeine-induced increases in systolic blood pressure during exercise.

Dose-Dependent Effect of Caffeine on Reducing Leg Muscle Pain During Cycling

Dose-Dependent Effect of Caffeine on Reducing Leg Muscle Pain During Cycling

Dose-dependent effect of caffeine on reducing leg muscle pain during cycling exercise is unrelated to systolic blood pressure

This double-blind, within-subjects experiment examined the effects of ingesting two doses of caffeine on perceptions of leg muscle pain and blood pressure during moderate intensity cycling exercise. Low caffeine consuming college-aged males ( N=12) ingested one of two doses of caffeine (5 or 10 mg·kg −1 body weight) or placebo and 1 h later completed 30 min of moderate intensity cycling exercise (60% V ̇ O 2 peak ). The order of drug administration was counter-balanced. Resting blood pressure and heart rate were recorded immediately before and 1 h after drug administration. Perceptions of leg muscle pain as well as work rate, blood pressure, heart rate, and oxygen uptake ( V ̇ O 2 ) were recorded during exercise. Caffeine increased resting systolic pressure in a dose-dependent fashion but these blood pressure effects were not maintained during exercise. Caffeine had a significant linear effect on leg muscle pain ratings [ F(2,22)=14.06; P<0.0001; η 2=0.56]. The mean (±SD) pain intensity scores during exercise after ingesting 10 mg·kg −1 body weight caffeine, 5 mg·kg −1 body weight caffeine, and placebo were 2.1±1.4, 2.6±1.5, and 3.5±1.7, respectively. The results support the conclusion that caffeine ingestion has a dose–response effect on reducing leg muscle pain during exercise and that these effects do not depend on caffeine-induced increases in systolic blood pressure during exercise.