Author Topic: Behavioral effects of L-theanine (+ a bit of pharmacology, mechanism of action)  (Read 2944 times)

gamesguru

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If you aren't able to afford or don't want to dish out the dough for premium tea, with higher amino acid ex) theanine content, a good choice is a cheaper tea or coffee combined with 200mg powdered theanine.

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The acute effects of L-theanine in comparison with alprazolam on anticipatory anxiety in humans.
L-Theanine (delta-glutamylethylamide) is one of the predominant amino acids ordinarily found in green tea, and historically has been used as a relaxing agent. The current study examined the acute effects of L-theanine in comparison with a standard benzodiazepine anxiolytic, alprazolam (Xanax) and placebo on behavioural measures of anxiety in healthy human subjects using the model of anticipatory anxiety (AA). Six<> healthy volunteers received alprazolam (1 mg), L-theanine (200 mg) or placebo in a double-blind placebo-controlled repeated measures design. The acute effects of alprazolam and L-theanine were assessed under a relaxed and experimentally induced anxiety condition. Subjective self-reports of anxiety including BAI, VAMS, STAI state anxiety, were obtained during both task conditions at pre- and post-drug administrations. The results showed some evidence for relaxing effects of L-theanine during the baseline condition on the tranquil-troubled subscale of the VAMS. Alprazolam did not exert any anxiolytic effects in comparison with the placebo on any of the measures during the relaxed state. Neither L-theanine nor alprazalam had any significant anxiolytic effects during the experimentally induced anxiety state. The findings suggest that while L-theanine may have some relaxing effects under resting conditions, neither L-theanine not alprazolam demonstrate any acute anxiolytic effects under conditions of increased anxiety in the AA model.

Behavioral and molecular evidence for psychotropic effects in L-theanine.

RATIONALE:
L-Theanine (N-ethyl-L: -glutamine) is an amino acid uniquely found in green tea and historically considered to be a relaxing agent. It is a glutamate derivative and has an affinity for glutamatergic receptors. However, its psychotropic effects remain unclear.
OBJECTIVES:
To elucidate effects of L: -theanine on psychiatric disease-related behaviors in mice and its molecular basis focusing on brain-derived neurotrophic factor (BDNF) and N-methyl-D: -aspartate (NMDA) receptor.
METHODS:
We examined the effects of L: -theanine on behaviors in mice by using the open-field test (OFT), forced swim test (FST), elevated plus-maze test (EPMT), and prepulse inhibition (PPI) of acoustic startle. By western blot analysis, we looked at the effect of L: -theanine on the expression of BDNF and related proteins in the hippocampus and cerebral cortex. To determine whether L: -theanine has agonistic action on the NMDA receptor, we performed Fluo-3 intracellular Ca(2+) imaging in cultured cortical neurons.
RESULTS:
Single administration of L: -theanine significantly attenuated MK-801-induced deficits in PPI. Subchronic administration (3-week duration) of L: -theanine significantly reduced immobility time in the FST and improved baseline PPI. Western blotting analysis showed increased expression of BDNF protein in the hippocampus after subchronic administration of L: -theanine. In cultured cortical neurons, L: -theanine significantly increased the intracellular Ca(2+) concentration, and this increase was suppressed by competitive and non-competitive NMDA receptor antagonists (AP-5 and MK-801, respectively).
CONCLUSIONS:
Our results suggest that L: -theanine has antipsychotic-like and possibly antidepressant-like effects. It exerts these effects, at least in part, through induction of BDNF in the hippocampus and the agonistic action of L: -theanine on the NMDA receptor.

Effectiveness of L-theanine and behavioral therapy in the treatment of noise phobias in dogs
Noise phobia is a profound and extreme fear response to an unexpected, loud and not gradual noise. It is one of the most frequent canine behavioral problems (Overall, 2002; Crowell-Davis et al., 2004; Dreschel et al., 2005).

L-Theanine reduces psychological and physiological stress responses.
L-Theanine is an amino acid contained in green tea leaves which is known to block the binding of L-glutamic acid to glutamate receptors in the brain. Because the characteristics of L-Theanine suggest that it may influence psychological and physiological states under stress, the present study examined these possible effects in a laboratory setting using a mental arithmetic task as an acute stressor. Twelve participants underwent four separate trials: one in which they took L-Theanine at the start of an experimental procedure, one in which they took L-Theanine midway, and two control trials in which they either took a placebo or nothing. The experimental sessions were performed by double-blind, and the order of them was counterbalanced. The results showed that L-Theanine intake resulted in a reduction in the heart rate (HR) and salivary immunoglobulin A (s-IgA) responses to an acute stress task relative to the placebo control condition. Moreover, analyses of heart rate variability indicated that the reductions in HR and s-IgA were likely attributable to an attenuation of sympathetic nervous activation. Thus, it was suggested that the oral intake of L-Theanine could cause anti-stress effects via the inhibition of cortical neuron excitation.

Effects of L-Theanine on Posttraumatic Stress Disorder Induced Changes in Rat Brain Gene Expression
Posttraumatic stress disorder (PTSD) is characterized by the occurrence of a traumatic event that is beyond the normal range of human experience. The future of PTSD treatment may specifically target the molecular mechanisms of PTSD. In the US, approximately 20% of adults report taking herbal products to treat medical illnesses. L-theanine is the amino acid in green tea primarily responsible for relaxation effects. No studies have evaluated the potential therapeutic properties of herbal medications on gene expression in PTSD. We evaluated gene expression in PTSD-induced changes in the amygdala and hippocampus of Sprague-Dawley rats. The rats were assigned to PTSD-stressed and nonstressed groups that received either saline, midazolam, L-theanine, or L-theanine + midazolam. Amygdala and hippocampus tissue samples were analyzed for changes in gene expression. One-way ANOVA was used to detect significant difference between groups in the amygdala and hippocampus. Of 88 genes examined, 17 had a large effect size greater than 0.138. Of these, 3 genes in the hippocampus and 5 genes in the amygdala were considered significant (P < 0.05) between the groups. RT-PCR analysis revealed significant changes between groups in several genes implicated in a variety of disorders ranging from PTSD, anxiety, mood disorders, and substance dependence.

Anxiolytic effects of L-theanine--a component of green tea--when combined with midazolam, in the male Sprague-Dawley rat.
The purpose of the study was to investigate the anxiolytic effects of L-theanine and its potential interaction with the GABAA receptor in Sprague-Dawley rats. L-theanine is a major component of green tea, which has traditionally been used as an herbal remedy in the treatment of many medical conditions, including anxiety. Herbals and supplements and their potential interactions perioperatively are a concern to anesthetists. Fifty-five rats were divided into 5 groups: control (saline); L-theanine (positive control); flumazenil (a known benzodiazepine receptor antagonist) and L-theanine; and midazolam and L-theanine. The behavioral component of anxiety was evaluated using the elevated plus-maze and calculated by the time spent in the open arm of the maze divided by total time in the maze. Data were analyzed using a 2-tailed multivariate analysis of variance and Sheffé posthoc test. The data suggest that L-theanine does not produce anxiolysis by modulation of the GABAA receptor; however, in combination with midazolam, a synergistic or additive effect was demonstrated by decreased anxiety and both fine and basic motor movements. These data may provide direction for further studies examining L-theanine and its effects on anxiety and motor activity.

L-theanine attenuates abstinence signs in morphine-dependent rhesus monkeys and elicits anxiolytic-like activity in mice
L-theanine, 2-Amino-4-(ethylcarbamoyl) butyric acid, an amino acid found in green tea (Camellia sinensis), is sold in the United States as a dietary supplement to reduce stress and improve cognition and mood. The observations that L-theanine has been shown to inhibit caffeine’s stimulatory effects and that caffeine produces precipitated withdrawal signs in opioid-addicted monkeys and some opioid withdrawal signs in some normal monkeys, suggest that L-theanine may suppress opioid withdrawal signs. Additionally, L-theanine produces anxiolytic effects in humans indicating that it has anti-anxiety properties. Thus, in these studies we determined whether L-theanine attenuates opioid-withdrawal signs in morphine-dependent rhesus monkeys, a model for spontaneous opioid withdrawal in human opioid addicts. We also evaluated whether L-theanine decreases anxiety-like behavior in mice, using the elevated plus maze and marble burying assays. L-theanine significantly attenuated designated opioid withdrawal signs, including fighting, rigid abdominal muscles, vocalizing on palpation of abdomen, pacing, retching, wet-dog shakes, and masturbation. It had a relatively quick onset of action that persisted for at least 2.5 h. L-theanine also produced anxiolytic-like effects in the elevated plus maze and the marble burying assay in naïve mice at doses that did not significantly affect motor behavior. The results of these studies suggest that L-theanine may be useful in the pharmacotherapy of treating opioid withdrawal as well as anxiety-associated behaviors.
« Last Edit: October 11, 2015, 08:28:05 PM by gamesguru »

newdawnherbals

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Hey there, gamesguru, great to have you at the boards. As you can see, for the moment at least, the conversation cupboard is bare so to speak, but we've not been live much longer than half a week, so hopefully in some time we'll manage build an active and informed community of neurosci and neuropharm enthusiasts.

Appreciate the 411 on one of my favorite amino acids, l-theanine. I try to get a cup or two of green tea in me per day and have done some cursory research on some of the background on one of the key "magic ingredients" of that ancient Asian herbal medicinal but you managed to dredge up some tasty tidbits that I wasn't familiar with, most notably the PTSD and noise phobia research and it's efficacy as an adjunctive therapy in morphine (opiate/opiod) withdrawal syndrome.