Physiological Effects Of Caffeine Research Articles

Investigation of potential behavioral and physiological effects of caffeine on D. magna.

With the ever-increasing consumption of pharmaceutical compounds, their presence in the environment is now an undisputable reality. The majority of these compounds are released into the wild after their therapeutic use, as biotransformation products or in their original form. The presence of this class of compounds in the environment, due to their biological properties, can exert effects on non-target organisms, with adverse consequences. In addition, some bioactive substances, such as stimulants of the central nervous system, are also used by humans as part of their diet. The adverse consequences posed by such chemicals may be permanent or transient, if the exposure to xenobiotics is halted; it is thus of the paramount importance to study effects that result from long-term exposure to toxicants, but also the recovery of organisms previously exposed to such substances, especially if such chemicals may cause some type of addiction. Caffeine (1,3,7-trimethylxanthine) is a naturally occurring alkaloid found in many plants, being one of the most common stimulant/pharmaceutical compounds found in the environment. In addition, it is addictive, and strongly consumed by humans, a factor that contributes also for its continuous presence in the aquatic environment. The aim of this study was to evaluate the effects of environmentally relevant concentrations (0.08; 0.4; 2; 10; and 50μg/L) of caffeine on behavior and physiological parameters (that are proxies of metabolic traits, such as oxygen uptake and glycogen content), in individuals of the freshwater crustacean species Daphnia magna, of distinct ages, and with or without a recovery period in the absence of caffeine. Regarding behavior, the results indicated that caffeine exposure altered the moved distance of the test organisms, but not according to a coherent pattern; low concentrations of caffeine reduced the movement of exposed daphnids, while higher levels did not have any measurable effect on this parameter. In addition, it was possible to identify subtle withdrawal effects (animals exposed to caffeine during 21days and kept in uncontaminated media for 2days). Regarding the other two studied parameters, caffeine exposure did not result in any significant modification in oxygen uptake and glycogen stores/reserves of the test organisms, in animals continuously exposed, or in those subjected to a recovery period, suggesting that despite a behavioral stimulatory effect, this was not followed by any metabolic change, and no addictive effect was possible to infer. The results showed that the presence of caffeine in environmental concentrations can induce mild behavioral effects at low, albeit realistic levels, but not capable of establishing clear biochemical changes.

The physiological effects of caffeine on synaptic transmission and plasticity in the mouse hippocampus selectively depend on adenosine A1 and A2A receptors

Caffeine is the most consumed psychoactive drug worldwide and its intake in moderate amounts prevents neurodegenerative disorders. However, the molecular targets of caffeine to modulate activity in brain circuits are ill-defined. By electrophysiologically recording synaptic transmission and plasticity in Schaffer fibers-CA1 pyramid synapses of mouse hippocampal slices, we characterized the impact of caffeine using a concentration reached in the brain parenchyma upon moderate caffeine consumption. Caffeine (50 µM) facilitated synaptic transmission by 40%, while decreasing paired-pulse facilitation, and also decreased by 35% the amplitude of long-term potentiation (LTP). Clearance of extracellular adenosine with adenosine deaminase (2 U/mL) blunted all the effects of caffeine on synaptic transmission and plasticity. The A1R antagonist DPCPX (100 nM) only eliminated caffeine-induced facilitation of synaptic transmission while not affecting caffeine-induced depression of LTP; conversely, the genetic (using A2AR knockout mice) or the pharmacological blockade (with SCH58261, 50 nM) of A2AR eliminated the effect of caffeine on LTP while not affecting caffeine-induced facilitation of synaptic transmission. Finally, blockade of GABAA or of ryanodine receptors with bicuculline (10 μM) or dantrolene (10 μM), respectively, did not affect the ability of caffeine to alter synaptic transmission or plasticity. These results show that the effects of caffeine on synaptic transmission and plasticity in the hippocampus are selectively mediated by antagonizing adenosine receptors, where A1R are responsible for the impact of caffeine on synaptic transmission and A2AR regulate the impact of caffeine on LTP.

Caffeine: a boon or bane

Purpose The purpose of this paper is to explore the sources of caffeine and its utilization in different food products, along with its impact on human health in terms of benefits and adverse effect. Design/methodology/approach The papers reviewed were selected based on the following key descriptors such as caffeine, sources, trends of consumption, utilization, benefits and adverse effects, regulation and labelling. Findings There are many physiological effects of caffeine on respiratory, cardiovascular, gastrointestinal, reproductive and central nervous system. It has a positive effect in reducing the risk of diabetes, Alzheimer’s disease, Parkinson’s disease and liver injury and, at the same time, in improving mood, psychomotor performance and immune response. On the other hand, the negative effects of caffeine include addiction, cancer, heart diseases, insomnia, gastrointestinal disturbances and intoxication. As caffeine, when taken in large amount, is harmful, therefore as per the regulatory bodies, its concentration should not exceed the set limit, and its presence needs to be listed on the label of that particular food product. In a nutshell, it can be said that caffeine acts as a boon as well as bane because it possesses both beneficial and adverse effects. Originality/value This is a unique and comprehensive review that will provide a brief overview of sources, utilization, healthful as well as harmful effect of caffeine to the readers.

Combined Cardiovascular, Respiratory, and Neurobehavioral Telemetry Model in the Conscious Rat: A Novel Approach to Study the Acute Physiological Effects of Caffeine and Chlorpromazine Following Oral Administration

Combined Cardiovascular, Respiratory, and Neurobehavioral Telemetry Model in the Conscious Rat: A Novel Approach to Study the Acute Physiological Effects of Caffeine and Chlorpromazine Following Oral Administration

Testing Low Doses of Caffeine on Respiratory Resistance Using the Airflow Perturbation Device

Research reports on pulmonary function measurements often mention caffeine abstinence as a condition for testing subjects. Yet, the effects of caffeine on respiration are not well documented. This study was intended to investigate the physiological effects of caffeine on respiratory resistance measurements and the necessity of caffeine avoidance in such testing. Thirty-one subjects were administered caffeine in pill form for dosages in the range of 3 - 4.5 mg/kg body weight. Respiratory resistance was measured with the Airflow Perturbation Device every 15 minutes after caffeine ingestion until a full hour of elapsed time. No changes were noted in inhalation, exhalation, and average respiratory resistances during the times of measurements. The conclusion is that for low dosages of caffeine, respiratory resistance measurements are not affected by caffeine ingestion prior to testing.

Caffeine improves performance in double poling during acute exposure to 2,000-m altitude.

There is limited research on the physiological effects of caffeine (CAF) ingestion on exercise performance during acute hypoxia. The aim of the present study was therefore to test the effect of placebo (PLA) and CAF (4.5 mg/kg) on double poling (DP) performance during acute hypoxia. Thirteen male subelite cross-country skiers (V̇o2max 72.6 ± 5.68 ml·kg(-1)·min(-1)) were included. Performance was assessed as 1) an 8-km cross-country DP time-trial (C-PT), and 2) time until task failure at a set workload equal to ∼90% of DP V̇o2max. Testing was carried out in a hypobaric chamber, at 800 mbar (Pio2: ∼125 mmHg) corresponding to ∼2,000 m above sea level in a randomized double-blinded, placebo-controlled, cross-over design. CAF improved time to task failure from 6.10 ± 1.40 to 7.22 ± 1.30 min (P < 0.05) and velocity the first 4 km (P < 0.05) but not overall time usage for the 8-km C-PT. During submaximal exercise subjects reported lower pain in arms and rate of perceived exertion (RPE) following CAF ingestion. Throughout C-PTs similar RPE and pain was shown between treatments. However, higher heart rate was observed during the CAF 8 km (187 ± 7 vs. 185 ± 7; P < 0.05) and 90% C-PT (185 ± 7 vs. 181 ± 9) associated with increased ventilation, blood lactate, glucose, adrenaline, decreased pH, and bicarbonate. The present study demonstrates for the first time that CAF ingestion improves DP time to task failure although not consistently time trial performance during acute exposure to altitude. Mechanisms underpinning improvements seem related to reduced pain RPE and increased heart rate during CAF C-PTs.

Caffeine Affects Time to Exhaustion and Substrate Oxidation during Cycling at Maximal Lactate Steady State.

This study analyzed the effects of caffeine intake on whole-body substrate metabolism and exercise tolerance during cycling by using a more individualized intensity for merging the subjects into homogeneous metabolic responses (the workload associated with the maximal lactate steady state—MLSS). MLSS was firstly determined in eight active males (25 ± 4 years, 176 ± 7 cm, 77 ± 11 kg) using from two to four constant-load tests of 30 min. On two following occasions, participants performed a test until exhaustion at the MLSS workload 1 h after taking either 6 mg/kg of body mass of caffeine or placebo (dextrose), in a randomized, double-blinded manner. Respiratory exchange ratio was calculated from gas exchange measurements. There was an improvement of 22.7% in time to exhaustion at MLSS workload following caffeine ingestion (95% confidence limits of ±10.3%, p = 0.002), which was accompanied by decrease in respiratory exchange ratio (p = 0.001). These results reinforce findings indicating that sparing of the endogenous carbohydrate stores could be one of the several physiological effects of caffeine during submaximal performance around 1 h.

Malay

Caffeine had been shown to have an ergogenic effect on trained individuals; however, studies investigating the physiological effects of caffeine on the sedentary population are limited. The aim of this study was to examine the effect of caffeine on oxygen consumption and rating of perceived exertion during moderate intensity exercise among sedentary young adult females. Subjects comprised 16 female undergraduates aged between 22 to 24 years studying at Universiti Kebangsaan Malaysia. Eligibility criteria were based on low physical activity level and daily caffeine intake of less than 50 mg a day, which was screened using the International Physical Activity Questionnaire (short version) and caffeine consumption questionnaire, respectively. The design of this study is single-blind, crossover, placebo-controlled with all subjects serving as their own controls. Subjects were required to report to the physical activity laboratory for two experimental sessions after either ingesting placebo or caffeine capsule with an interval of 3 days between these two experimental sessions. Sixty minutes after ingesting placebo capsule (Glucolin, glucose) or 100 mg caffeine (Pro-plus, United Kingdom), subjects were required to run on a treadmill for 30 minutes at a standardized power output equivalent to 60% of maximal heart rate. Oxygen consumption, heart rate, and rating of perceived exertion were recorded at 20th, 25th and 30th minutes, while blood pressure was recorded immediately after subjects completed their 30 minutes run. Mean body fat percentage was 28.4 ± 5.4. Differences were recorded after every subject completed both the placebo and caffeine experiments. Paired t-tests showed no significant difference between placebo vs caffeine trials for oxygen consumption (13.99 ± 2.47 vs 14.49± 1.73, p = 0.440), rating of perceived exertion (12.3 ± 2.5 vs 12.3 ± 2.1, p = 1.000), systolic blood pressure (113 ± 10 vs 117 ± 11, p = 0.129), diastolic blood pressure (67 ± 8 vs 69 ± 10, p = 0.408) and heart rate (127.3 ± 11.0 vs 127.1 ± 11.6, p = 0.912). There was strong significant negative correlation between body fat percentage and oxygen consumption (r = –0.568, p < 0.05) and strong significant positive correlation between body fat percentage and rating of perceived exertion (r = 0.515, p < 0.05). The non-significance in the results obtained could be due to the small effect size of the study (d = 0.24). Hence, future studies with a larger number of participants should be carried out to examine the effects of caffeine during exercise in a sedentary population. DOI : http://dx.doi.org/10.17576/jskm-1101-2013-06

Child and Adolescent Anxiety Sensitivity, Perceived Subjective Effects of Caffeine and Caffeine Consumption

Background: Children and adolescents who are anxiety sensitive are attuned to bodily sensations and interpret them as threatening. The objectives of the current study were to test if anxiety sensitivity was related to perceiving greater subjective physiological effects of caffeine and, in turn, lowered levels of naturalistic caffeine use. Developmental differences between children and adolescents in these relations were also tested. Methods: Children (n=135) and adolescents (n=79) completed a measure of naturalistic caffeine intake, daily availability, and subjective effects of caffeine. Youth also completed a measure of anxiety sensitivity. Results: For both children and adolescents, anxiety sensitivity was positively associated with perceived stimulating and withdrawal effects, as well as greater perceived availability of caffeine. For children only, anxiety sensitivity was associated with greater perceived psychological effects of caffeine. Across both age groups, anxiety sensitivity predicted greater ...

Physiological effects of caffeine, epigallocatechin-3-gallate, and exercise in overweight and obese women

The aim of this study was to evaluate the combined effects of a 10-week exercise program with ingestion of caffeine and epigallocatechin-3-gallate (EGCG) on body composition, cardiovascular fitness, and strength in overweight and obese women. In a double-blind, placebo-controlled approach, overweight and obese women (n = 27) were randomly assigned to treatment groups with exercise (an active-supplementing group with exercise (EX-Act) and a placebo group with exercise (EX-PL)) or without exercise (an active-supplementing group without exercise (NEX-Act) and a placebo group without exercise (NEX-PL)). All participants consumed 1 drink per day for 10weeks; EX-Act and EX-PL participated in a concurrent endurance and resistance training program. Changes in body composition were assessed using a 4-compartment model. Changes in muscle mass (MM) were evaluated using a DXA-derived appendicular lean-soft tissue equation. There was a significant time× treatment interaction for MM (p = 0.026) and total cholesterol (TC) (p = 0.047), and a significant time× training interaction for peak oxygen consumption (p = 0.046) and upper-body and lower-body strength (p< 0.05). Significant differences between the EX groups and NEX groups for percentage change in MM and peak oxygen consumption, and upper-body and lower-body strength, were revealed. Clinical markers for hepatic and renal function revealed no adverse effects. TC significantly decreased for the active-supplementing groups (EX-Act, NEX-Act). The current study suggests that implementing a caffeine-EGCG-containing drink prior to exercise may improve MM, fitness, and lipid profiles in overweight women.

Current Trends in Producing Low Levels of Caffeine in Coffee Berry and Processed Coffee Powder

Caffeine is a bioactive compound present in coffee. The physiological effects of caffeine on human and animal models are well documented, and this has led the coffee industry to develop an artificially decaffeinated coffee based on solvent extraction process. An alternative to this approach would be to identify naturally occurring low caffeine lines, breeding for low caffeine coffee trait or to generate transgenic coffee with regulated caffeine pathway. This review is mainly focused on caffeine and its health effects; information on decaffeination processes; latest developments in the understanding of caffeine pathway and development of genetically engineered coffee with low caffeine.

The effects of caffeine on graded exercise performance in caffeine naive versus habituated subjects

The physiological effects of caffeine on subjects habituated to caffeine is relatively unstudied compared to those of caffeine naive subjects during graded exercise. Thus, the purpose of this investigation was to determine the effects of caffeine on maximal oxygen consumption (VO2max) and the anaerobic threshold in these two populations. Seventeen moderately trained males were classified according to caffeine usage: (1) caffeine consumption 25 mg.day-1 or less (CN) (n = 8) or (2) caffeine consumption above 300 mg.day-1 (CH) (n = 9). The subjects were tested post-absorptive on the same cycle ergometer on three occasions with 7 days separating the tests. One hour before each test the subject ingested either a gelatin capsule (C); 3 mg.kg-1 body weight of caffeine (C3); or 5 mg.kg-1 body weight of caffeine (C5). The subject then performed an incremental VO2max test beginning at 50 W and the work rate was increased 30 W every 2 min until the subject could not maintain the power output. Serial venous blood samples were drawn over 30 s at the end of each stage. The CN group significantly increased resting heart rate (fc) and expired ventilation volume (VE) after C3 and C5 and VO2 after C5. No significant differences were found for exercise VE, VO2, respiratory exchange ratio, fc or time to exhaustion. There were no significant differences (P less than 0.05) in the lactate threshold or the ventilatory threshold between treatment in either group. The CH subjects showed a significant increase (P less than 0.05) in resting plasma free fatty acid (FFA) concentration only during the C3 and C5 treatments.(ABSTRACT TRUNCATED AT 250 WORDS)

Caffeine-induced monaster cycling in fertilized eggs of the sea urchin Strongylocentrotus purpuratus

Caffeine has several highly visible effects on mitosis in eggs of the sea urchin Strongylocentrotus purpuratus. It increases the cell cycle length in a dose-dependent manner and at a concentration between 5 and 10 m M it prevents the normal separation and function of the mitotic centers, resulting in periodic monaster formation rather than division. If fertilized eggs are placed in seawater containing 10 m M caffeine at prometaphase, the spindle rapidly shrinks, moving the mitotic centers to the middle of the metaphase plate in less than 10 min. Within 30 min the eggs recover their ability to polymerize microtubules to form a large monaster, and from this time on they continue to cycle monasters in the presence of caffeine, with a period of about 150 min, where the normal second division time is 55 min. Other cell cycle functions, such as chromosome condensation, nuclear membrane breakdown and reformation, attempted furrowing and surface membrane addition continue for at least several cycles, but at the slower rate. Although the evidence strongly suggests that the rapid breakdown of the prometaphase spindle results from a calcium release induced by caffeine, these experiments do not rule out other physiological effects of caffeine on the longer-term changes in cycle length, centriole function, and ultimately on cell survival.

Physiological Effects of Caffeine in the Rat: Extracellular Cyclic AMP Status, Growth Pattern and Glucose Metabolism in Adipose Tissue

The authors investigated the effect of moderate caffeine intake on overall cyclic adenosine monophosphate (AMP) metabolism in the rat and its relationship to growth and glucose metabolism in adipose tissue. Male Sprague-Dawley weanling rats were divided into control and treatment groups. The latter received caffeine via drinking water (0.06 mg/ml H2O) during a 4-week period whereas controls received water only. At weekly intervals, urinary cyclic AMP excretion, food intake and weight gain were measured. Plasma cyclic AMP caffeine and glucose were determined at moment of death and in vitro lipogenesis and glycogen synthesis from [6-14C]glucose in epididymal adipose tissue were assayed. Although urinary cyclic AMP excretion was negatively correlated to caffeine intake during the 2nd week of the experiment, this did not reach significant levels, nor did this trend continue into the 4th week. Growth pattern and food efficiency were similar in both groups as were blood glucose and cyclic AMP values at moment of death. In vitro glycogen synthesis from [6-14C] glucose in adipose tissue showed a 40% increase, this parameter being positively correlated with plasma caffeine concentration. Glucose uptake and lipogenesis were unaltered in epididymal fat pads. These data suggest that regular intake of a moderate dose of caffeine leads to homeostasis of overall cyclic AMP metabolism and of selected physiological parameters under study. Alteration of glycogen synthesis in adipose tissue is discussed in relation to documented effects of caffeine ingestion on catecholamine secretion.caffeine extracellular cyclic AMP adipose tissue

Determination of glycogen in small tissue samples.

Determination of glycogen in small tissue samples.