The Effect of Low-Doses of Caffeine and Taurine on Convulsive Seizure Parameters in Rats

Introduction: Caffeine, an adenosine-receptor blocker, is believed to have neuronal excitatory effects, while Taurine, a mammalian amino acid, was shown to have neuroinhibitory effects. Aim: The aim of this study was to investigate the effects of acute and chronic administration of low doses of Caffeine and Taurine on the seizure threshold in rats. Methods: Six-week-old Sprague-Dawley male rats (n = 280) were divided randomly into five groups (control, acute caffeine intake, acute taurine intake, chronic caffeine intake and chronic taurine intake), with five subgroups per group according to five different doses of Pentylenetetrazole (PTZ) injections. Each subgroup consisted of eight rats. Data was entered and analyzed using Microsoft EXCEL and Addinsoft^TM XLSTAT (Version 2012.6.06; New York, NY, USA). p-value = 0.05 was regarded as statistically significant. Results: There was a significant decrease in the latency of PTZ-induced seizures with both acute (p-value < 0.05) and chronic (p-value < 0.01) Caffeine treatment groups. Chronic exposure to Caffeine exhibited an increase in the probability of seizures (p-value < 0.05). However, acute exposure to Caffeine did not show a significant impact on the probability of seizures. Neither acute nor chronic exposures to Taurine had an effect on the probability of seizures, nor on the latency of PTZ-induced seizures. Discussion: Our study found that acute as well as chronic exposure to low doses of Caffeine (50 and 80 mg/kg) reduces the threshold, and hence increases the likelihood for seizures since it favors a state of neuronal hyper excitability through blocking of all adenosine receptors. On the other hand, acute or chronic exposure to Taurine did not show a significant effect on the PTZ-induced seizures parameters.

Effects of Physical Exercise Combined with Nutritional Supplements on Aging Brain Related Structures and Functions: A Systematic Review

Age-related decline in gray and white brain matter goes together with cognitive depletion. To influence cognitive functioning in elderly, several types of physical exercise and nutritional intervention have been performed. This paper systematically reviews the potential additive and complementary effects of nutrition/nutritional supplements and physical exercise on cognition. The search strategy was developed for EMBASE, Medline, PubMed, Cochrane, CINAHL, and PsycInfo databases and focused on the research question: “Is the combination of physical exercise with nutrition/nutritional supplementation more effective than nutrition/nutritional supplementation or physical exercise alone in effecting on brain structure, metabolism, and/or function?” Both mammalian and human studies were included. In humans, randomized controlled trials that evaluated the effects of nutrition/nutritional supplements and physical exercise on cognitive functioning and associated parameters in healthy elderly (>65 years) were included. The systematic search included English and German language literature without any limitation of publication date. The search strategy yielded a total of 3129 references of which 67 studies met the inclusion criteria; 43 human and 24 mammalian, mainly rodent, studies. Three out of 43 human studies investigated a nutrition/physical exercise combination and reported no additive effects. In rodent studies, additive effects were found for docosahexaenoic acid supplementation when combined with physical exercise. Although feasible combinations of physical exercise/nutritional supplements are available for influencing the brain, only a few studies evaluated which possible combinations of nutrition/nutritional supplementation and physical exercise might have an effect on brain structure, metabolism and/or function. The reason for no clear effects of combinatory approaches in humans might be explained by the misfit between the combinations of nutritional methods with the physical interventions in the sense that they were not selected on sharing of similar neuronal mechanisms. Based on the results from this systematic review, future human studies should focus on the combined effect of docosahexaenoic acid supplementation and physical exercise that contains elements of (motor) learning.

Taurine in drinking water recovers learning and memory in the adult APP/PS1 mouse model of Alzheimer's disease

Alzheimer's disease (AD) is a lethal progressive neurological disorder affecting the memory. Recently, US Food and Drug Administration mitigated the standard for drug approval, allowing symptomatic drugs that only improve cognitive deficits to be allowed to accelerate on to clinical trials. Our study focuses on taurine, an endogenous amino acid found in high concentrations in humans. It has demonstrated neuroprotective properties against many forms of dementia. In this study, we assessed cognitively enhancing property of taurine in transgenic mouse model of AD. We orally administered taurine via drinking water to adult APP/PS1 transgenic mouse model for 6 weeks. Taurine treatment rescued cognitive deficits in APP/PS1 mice up to the age-matching wild-type mice in Y-maze and passive avoidance tests without modifying the behaviours of cognitively normal mice. In the cortex of APP/PS1 mice, taurine slightly decreased insoluble fraction of Aβ. While the exact mechanism of taurine in AD has not yet been ascertained, our results suggest that taurine can aid cognitive impairment and may inhibit Aβ-related damages.

Differential cognitive effects of energy drink ingredients: caffeine, taurine, and glucose

Energy drinks containing caffeine, taurine, and glucose may improve mood and cognitive performance. However, there are no studies assessing the individual and interactive effects of these ingredients. We evaluated the effects of caffeine, taurine, and glucose alone and in combination on cognitive performance and mood in 24-hour caffeine-abstained habitual caffeine consumers. Using a randomized, double-blind, mixed design, 48 habitual caffeine consumers (18 male, 30 female) who were 24-hour caffeine deprived received one of four treatments (200 mg caffeine/0 mg taurine, 0 mg caffeine/2000 mg taurine, 200 mg caffeine/2000 mg taurine, 0 mg caffeine/0 mg taurine), on each of four separate days, separated by a 3-day wash-out period. Between-participants treatment was a glucose drink (50 g glucose, placebo). Salivary cortisol, mood and heart rate were measured. An attention task was administered 30-minutes post-treatment, followed by a working memory and reaction time task 60-minutes post-treatment. Caffeine enhanced executive control and working memory, and reduced simple and choice reaction time. Taurine increased choice reaction time but reduced reaction time in the working memory tasks. Glucose alone slowed choice reaction time. Glucose in combination with caffeine, enhanced object working memory and in combination with taurine, enhanced orienting attention. Limited glucose effects may reflect low task difficulty relative to subjects' cognitive ability. Caffeine reduced feelings of fatigue and increased tension and vigor. Taurine reversed the effects of caffeine on vigor and caffeine-withdrawal symptoms. No effects were found for salivary cortisol or heart rate. Caffeine, not taurine or glucose, is likely responsible for reported changes in cognitive performance following consumption of energy drinks, especially in caffeine-withdrawn habitual caffeine consumers.

Intracerebroventricular administration of taurine impairs learning and memory in rats

OBJECTIVES

Taurine is a semi-essential amino acid widely distributed in the body and we take in it from a wide range of nutritive-tonic drinks to improve health. To date, we have elucidated that oral supplementation of taurine does not affect learning and memory in the rat. However, there are few studies concerning the direct effects of taurine in the brain at the behavior level. In this study, we intracerebroventricularly administered taurine to rats and aimed to elucidate the acute effects on learning and memory using the Morris water maze method.

METHODS

Escape latency, swim distance, and distance to zone, which is the integral of the distance between the rats and the platform for every 0.16 seconds, were adopted as parameters of the ability of learning and memory. We also tried to evaluate the effect of intraperitoneal taurine administration.

RESULTS

Escape latency, swim distance, and distance to zone were significantly longer in the intracerebroventricularly taurine-administered rats than in the saline-administered rats. Mean swimming velocity was comparable between these two groups, although the physical performance was improved by taurine administration. Probe trials showed that the manner of the rats in finding the platform was comparable. In contrast, no significant differences were found between the intraperitoneally taurine-administered rats and the saline-administered rats.

DISCUSSION

These results indicate that taurine administered directly into the brain ventricle suppresses and delays the ability of learning and memory in rats. In contrast, it is implied that taurine administered peripherally was not involved in learning and memory.