Energy drinks and their component modulate attention, memory, and antioxidant defences in rats

Energy drinks and alcohol in a binge drinking protocol in Wistar rats: Male and female behavioral and reproductive effects

The consumption of energy drinks is common among adolescents and young adults. The possible effects (mainly behavioral and reproductive) of ingestion in this population remain unknown. For this reason, this study aimed to evaluate the behavioral and reproductive effects of energy drinks and their main constituents (caffeine and taurine), as well as their combinations with alcohol, via a binge drinking protocol in male and female Wistar rats during puberty. In this study, 100 male and 100 female rats were treated with a binge drinking protocol 3 days a week over 4 weeks from postnatal day (PND) 28 to PND 60, which included 10 mL/kg by oral gavage of distilled water, energy drink, caffeine (3.2 mg/kg), taurine (40 mg/kg), and their combinations with alcohol (2 g/kg). The animals were evaluated by behavioral tests from PND 56 to PND 60 (open field, plus maze and object recognition) and reproductive parameters (estrous cycle regularity, weight of sexual organs, oocyte quality, spermatid and sperm count, sperm morphology and testosterone level). Locomotor activity was increased in females in the groups combined with alcohol (except alcohol + caffeine) and in the caffeine group. Long-term memory was increased in males in the caffeine and taurine groups even when combined with alcohol. The combination of energy drinks and alcohol did not have significant effects on the reproductive parameters of either sex of rats during puberty. We concluded that energy drinks (and their main constituents) and alcohol combinations did not cause alterations in reproductive profiles, and locomotor activity and long-term memory were increased in females and males, respectively.

Effect of intermittent access to alcohol mixed in energy drink during adolescence on alcohol self-administration, anxiety, and memory during adulthood in rats

BACKGROUND

Mixing alcohol with caffeinated energy drinks is a common practice among young people. Consumption of alcohol mixed in energy drink is associated with increased risk of binge drinking and alcohol dependence. The purpose of this study was to determine whether voluntary intermittent access to alcohol mixed in energy drink in adolescent rats alters adult self-administration of alcohol, anxiety, and memory.

METHODS

For 10 weeks in the home-cage, two groups of adolescent female Sprague-Dawley rats had intermittent access to energy drink (ED) or 10% alcohol mixed in energy drink (AmED) with water concurrently available. Other rat groups had daily continuous access to ED or AmED. Anxiety was measured with an open field test and memory was assessed with a novel place recognition test. For self-administration, rats pressed levers for 10% alcohol alone on a fixed ratio (FR1) and on a progressive ratio (PR).

RESULTS

Intermittent access to AmED generated greater intake during the initial 30 min of access (AmED 1.70 ± 0.04 g/kg vs. ED 1.01 ± 0.06 g/kg) and during the subsequent 24 h (AmED 7.04 ± 0.25 g/kg vs. ED 5.60 ± 0.29 g/kg). Intermittent AmED caused a significant but small decrease in anxiety while neither ED nor AmED altered memory. During alcohol self-administration, group differences emerged only during PR testing during which intermittent AmED rats responded more than all other groups.

CONCLUSIONS

These findings suggest that intermittent access to AmED generates binge-like consumption that supports human findings that AmED generates greater alcohol consumption. Furthermore, experience with AmED may alter the motivational properties of alcohol into adulthood without necessarily causing a major impact on anxiety or memory.

Imidacloprid-based commercial pesticide causes behavioral, biochemical, and hematological impairments in Wistar rats

Imidacloprid (IMI) is a neonicotinoid insecticide employed worldwide for crop protection. IMI's mode of action occurs through the agonism of postsynaptic nicotinic acetylcholine receptors (nAChRs), with high specificity for insect nAChRs although there are reports of mammals' toxicity. Studies on IMI's neurotoxicity are not conclusive; therefore, the aim of this study was to evaluate the subchronic toxic effects of an IMI based commercial pesticide on rats. Adult male Wistar rats received an IMI suspension via the oral route at doses of 1.5, 5, and 15 mg/kg for 45 consecutive days. IMI caused an increase in rearing and time spent at the periphery in the locomotor activity test and a decrease in time spent to finish the OX maze task (p < 0.05; ANOVA/Bonferroni). In blood, there was a decrease in mean corpuscular hemoglobin and mean corpuscular hemoglobin concentration (p < 0.05; ANOVA/Bonferroni) and an increase in serum butyrylcholinesterase activity (p < 0.001; ANOVA/Bonferroni). Therefore, subchronic administration of an IMI-based-pesticide caused behavioral and systemic impairments in rats.

Effects of Energy Drink Acute Assumption in Gastrointestinal Tract of Rats

Energy drinks (EDs) are non-alcoholic beverages containing high amounts of caffeine and other psychoactive substances. EDs also contain herbal extract whose concentration is usually unknown. EDs can have several adverse effects on different organs and systems, but their effects on the gastrointestinal (GI) tract have been poorly investigated. To determine the acute effects of EDs on the GI tract, we administered EDs, coffee, soda cola, or water to Sprague–Dawley rats (n = 7 per group, randomly assigned) for up to five days, and analyzed the histopathological changes in the GI tract. Data were compared among groups by Kruskal–Wallis or Mann–Whitney tests. We found that, while EDs did not cause any evident acute lesion to the GI tract, they triggered eosinophilic infiltration in the intestinal mucosa; treatment with caffeine alone at the same doses found in EDs leads to the same effects, suggesting that it is caffeine and not other substances present in the EDs that causes this infiltration. The interruption of caffeine administration leads to the complete resolution of eosinophilic infiltration. As no systemic changes in pro-inflammatory or immunomodulating molecules were observed, our data suggest that caffeine present in ED can cause a local, transient inflammatory status that recruits eosinophils.

Ethanol combined with energy drinks: Two decades of research in rodents

Many studies raised concerns on alcoholic beverages consumption mixed with energy drinks (AmED), which can induce higher rates of binge drinking and earlier development of alcohol use disorders. After 20 years of research, few studies with laboratory animals have focused on the effects of this mixture and the neurobiological and pharmacological mechanisms underlying them. We found 16 articles on AmED administration to rodents evaluating its effects on voluntary consumption, locomotion, anxiety-like behavior, memory, influence on the onset time of seizures, biochemical and neurochemical measures. Some of these studies indicated energy drinks (ED) can alter the pattern of use and motivation to consume ethanol (EtOH); increase the expression of sensitization to EtOH stimulant effect and the proportion of sensitized mice; decrease the aversiveness of high concentrations of EtOH, among other effects. In addition AmED hastens the loss of righting reflex and its effects on memory are controversial. After acute administration no difference was found in blood ethanol concentration (BEC) of rodents which received EtOH with or without ED, but after 60 days of treatment, AmED group had lower BEC levels than EtOH group. Data on biochemical and neurochemical parameters after AmED are not consistent. Although the AmED group presented higher glucose levels than the EtOH group when drugs were administered by gavage, this was not observed in a self-administration protocol. AmED may induce higher kidney damage, higher levels of plasma urea, uric acid and creatinine when compared to EtOH. Chronic consumption of AmED causes an inflammatory response and oxidative stress, which may induce cell death in the cortex and hypothalamus of adult rats. These controversial results show that AmED diverse effects depend on sex, age and lineage of the animals, duration of the treatment and route of administration. Further research is necessary to evaluate the mechanisms underlying AmED biological effects.

The Effects of Direct Red Bull Administration to Isolated Hearts of Trained and Untrained Rats Who Regularly Consumed or Did Not Consume Energy Drink: Focus on Cardiodynamics and Oxidative Stress

Energy drinks (EDs) contain caffeine and other active ingredients which affect cardiovascular system. The aims of this study were to examine direct effects of Red Bull (RB) on cardiodynamics and oxidative stress in isolated hearts of rats. The rats were divided into four groups: untrained rats who never consumed ED (dEDUT); untrained rats who consumed ED 5 days a week during 4 weeks (ch+dED-UT); rats trained 5 times a week for 4 weeks, but did not consume ED (dED-T); rats trained and consumed ED 5 times a week for 4 weeks (ch+dED-T). After sacrificing, hearts were isolated and perfused according to Langendorff technique. Through the isolated heart of all rats in each group, RB was administered. The parameters of cardiac function were recorded, and the levels of prooxidants were measured in the coronary effluent during coronary autoregulation. Rats in ch+dED-UT group had significantly lower rates of myocardial contraction and relaxation compared to rats in dED-UT group. The same effect was recorded in the dED-T group compared to dED-UT group. The levels of hydrogen peroxide were significantly higher in trained rats. Rats in ch+dED-T group also had significantly higher levels of superoxide anion radical and index of lipid peroxidation, as well as lower levels of nitrites when compared to ch+dED-UT group, while opposite effect was recorded in rats in dED-T group compared to dEDUT group. The RB could have a potentially negative inotropic effect in chronic consumers. Prooxidative effect of RB was most pronounced in trained chronic consumers.

Effects of sub-chronic caffeine ingestion on memory and the hippocampal Akt, GSK-3β and ERK signaling in mice

Caffeine, one of the most widely consumed psychoactive substance in the world, has been shown to affect mood, memory, alertness, and cognitive performance. This study aimed to assess the effect of sub-chronic oral gavage of caffeine on memory and the phosphorylation levels of hippocampal Akt (protein kinase B), GSK-3β (Glycogen Synthase Kinase-3beta) and ERK (extracellular signal-regulated kinase) in mice. Adult male NMRI mice were administered with caffeine at the doses of 0.25, 0.5, 0.75 and 1.5 mg/kg/oral gavage for 10 days before behavioral assessments. Upon completion of the behavioral tasks, the hippocampi were isolated for western blot analysis to detect the phosphorylated and total levels of Akt, GSK-3β and ERK proteins. The results showed that sub-chronic caffeine ingestion at the dose of 0.5 mg/kg improves memory in mice both in passive avoidance and novel object recognition tasks. Furthermore, this memory enhancing dose of caffeine elevated the ratios of phosphorylated to total contents of hippocampal Akt, GSK-3β and ERK. This study suggests that sub-chronic low dose of caffeine improves memory and increases the phosphorylation of hippocampal Akt, GSK-3β and ERK proteins.

Developmental effects of environmental enrichment on selective and auditory sustained attention

Environmental enrichment (EE) has been used as a positive manipulation in different disease models. However, there is conflicting evidence reported in the literature about the effects of EE. Additionally, the time period that would be most beneficial in implementing environmental enrichment as an intervention is not clear. Our study aimed to systematically compare the prenatal, juvenile, mid-adolescence, and adulthood developmental trajectory to further the understanding of enriched environment's effects on selective and auditory sustained attention, corresponding to behavioral (conceived) and physiological-reflexive (non-conceived) measures. Rats were exposed for 21 days to enriched environment during various developmental periods and compared to age-matched controls. All groups were tested for long-term effects (at postnatal day 120 and onward) on selective and sustained attention. We found that the exposure to enriched environment during mid-adolescence has yielded the most significant and long-term pattern of effects, including selective and auditory sustained attention performance, increased foraging-like behavior and a significant decrease in corticosterone level. Similarly, the exposure to EE at juvenile period improved selective attention, increased foraging-like behavior, and reduced anxiety levels as reflected in the open field as well as in low corticosterone levels. These results specify a crucial period along the developmental trajectory for applying environmental enrichment. Mid-adolescence is suggested, in future basic and translational studies, as the sensitive time period that induces the most beneficial and long-term effects of EE on attention. The current findings suggest that the exposure to EE during mid-adolescence should be further considered and studied as behavioral alternative intervention, or as adjuvant behavioral therapy, aimed to decrease the probability to develop ADHD in post-adolescence period. This suggestion is highly relevant due to the debate regarding the pros and cons of screens usage (e.g. Facebook, online games, etc.) during early life that decreases environmental enrichment, especially, direct social interaction.

Anxiety-like behavior and whole-body cortisol responses to components of energy drinks in zebrafish (Danio rerio)

The current study investigated the independent and combined effects of caffeine and taurine on anxiety-like behavior and neuroendocrine responses in adult zebrafish (Danio rerio). Caffeine (1,3,7-trimethylpurine-2,6-dione), the world’s most commonly used psychoactive drug, acts as an adenosine receptor blocker and a mild central nervous system stimulant. However, excessive use of caffeine is associated with heightened anxiety levels. Taurine (2-aminoethanesulfonic acid), a semi-essential amino acid synthesized within the human brain, has been hypothesized to play a role in regulating anxiolytic behavior. Caffeine and taurine are two common additives in energy drinks and are often found in high concentrations in these beverages. However, few studies have investigated the interaction of these two chemicals with regards to anxiety measures. A suitable vertebrate to examine anxiety-like behavior and physiological stress responses is the zebrafish, which has shown promise due to substantial physiological and genetic homology with humans. Anxiety-like behavior in zebrafish can be determined by analyzing habituation to novelty when fish are placed into a novel tank and scototaxis (light avoidance) behavior in the light-dark test. Stress-related neuroendocrine responses can be measured in zebrafish by analyzing whole-body cortisol levels. The goal of this study was to determine if exposure to caffeine, taurine, or a combination of the two compounds altered anxiety-like behavior and whole-body cortisol levels in zebrafish relative to control. Zebrafish were individually exposed to either caffeine (100 mg/L), taurine (400 mg/L), or both for 15 min. Zebrafish in the control group were handled in the same manner but were only exposed to system tank water. After treatment, fish were transferred to the novel tank test or the light-dark test. Behavior was tracked for the first 6 min in the novel tank and 15 min in the light-tark test. Fifteen min after introduction to the behavioral task, fish were euthanized for the analysis of whole-body cortisol levels. The results demonstrate that caffeine treatment decreased the amount of exploration in the top of the novel tank and increased scototaxis behavior in the light-dark test, which supports the established anxiogenic effect of acute exposure to caffeine. Taurine alone did not alter basal levels of anxiety-like behavioral responses nor ameliorated the anxiogenic effects of caffeine on behavior when the two compounds were administered concurrently. None of the drug treatments altered basal levels of whole-body cortisol. The current results of this study suggest that, at least at this dose and time of exposure, taurine does not mitigate the anxiety-producing effects of caffeine when administered in combination, such as with energy drink consumption.

Impact of Energy Drinks on Health and Well-being

PURPOSE OF REVIEW

Energy drinks and energy shots are functional supplements with higher caffeine content marketed toward adolescents and young adults with the intention of boosting energy. Parallel to its rising popularity, there are safety concerns with the consumption of these beverages. Herein, we reviewed the impact these supplements produce on health and well-being.

RECENT FINDINGS

Most of the promoted benefits of the beverages can be attributed to caffeine. The physiologic effects, if any, of other ingredients such as vitamins and herbal extracts are unclear. The presence of a higher caffeine content as compared to soft drinks may predispose to caffeine intoxication in susceptible individuals. Also, the practice of co-ingestion of these beverages with alcohol is still prevalent and associated with serious consequences. Strict regulations (restriction of sales, clear warning labels, capping caffeine levels) and public education may help prevent the adverse outcomes from these beverages.

Perinatal exposure to energy drink induces oxidative damage in the liver, kidney and brain, and behavioral alterations in mice offspring

The worldwide consumption of energy drinks (EDs) has increased in recent years. EDs have several side effects and can be linked to liver injury, kidney damage and risk-seeking behavior. The impact of perinatal consumption of EDs on the newborns has not been previously investigated. In this study, we evaluated the effects of perinatal exposure to a caffeinated ED on the liver, kidney, brain, locomotor activity and anxiety in mice newborns. Pregnant mice received 2.5 or 5 ml ED by oral gavage from the first day of pregnancy until day 15 after birth. Perinatal exposure to the ED induced a significant increase in lipid peroxidation and declined antioxidant defenses in the liver, kidney, cerebrum, cerebellum and medulla oblongata of the newborns at days 21 and 35 after birth. ED induced several histological alterations, including vacuolations and lipid infiltration of hepatocytes, developing and degenerated glomeruli and dilated urinary spaces in the renal cortex, pyknosis and chromatolysis of the cerebral and medullary neurons, and degenerated and abnormal Purkinje cells in the cerebellum. In addition, ED increased the locomotion and induced anxiety-like behavior in mice newborns. In conclusion, perinatal exposure to EDs induces oxidative stress, tissue injury and behavioral alterations in the mice newborns. Therefore, the consumption of EDs during pregnancy and lactation has a negative impact on the newborns and should be treated as a significant health problem that warrants attention.

Organotins in Neuronal Damage, Brain Function, and Behavior: A Short Review

The consequences of exposure to environmental contaminants have shown significant effects on brain function and behavior in different experimental models. The endocrine-disrupting chemicals (EDC) present various classes of pollutants with potential neurotoxic actions, such as organotins (OTs). OTs have received special attention due to their toxic effects on the central nervous system, leading to abnormal mammalian neuroendocrine axis function. OTs are organometallic pollutants with a tin atom bound to one or more carbon atoms. OT exposure may occur through the food chain and/or contaminated water, since they have multiple applications in industry and agriculture. In addition, OTs have been used with few legal restrictions in the last decades, despite being highly toxic. In addition to their action as EDC, OTs can also cross the blood-brain barrier and show relevant neurotoxic effects, as observed in several animal model studies specifically involving the development of neurodegenerative processes, neuroinflammation, and oxidative stress. Thus, the aim of this short review is to summarize the toxic effects of the most common OT compounds, such as trimethyltin, tributyltin, triethyltin, and triphenyltin, on the brain with a focus on neuronal damage as a result of oxidative stress and neuroinflammation. We also aim to present evidence for the disruption of behavioral functions, neurotransmitters, and neuroendocrine pathways caused by OTs.