Anxiolytic Effect of a Combination of Green Tea Extract and L-theanine

The protective effect of L-theanine addition to a cryoprotectant on the storage viability of lactic acid bacteria

Lactic acid bacteria (LAB) that metabolize sugars to obtain energy and produce a large amount of lactate through the process are well known for their benefits. However, they can be used on a large scale only when good storage stability is guaranteed. The vitality and stability of several LAB strains were effectively protected in this investigation by L-theanine at 1% of the appropriate concentration (Lactiplantibacillus plantarum MG5023, Enterococcus faecium MG5232, Lactococcus lactis MG4668, Streptococcus thermophilus MG5140, and Bifidobacterium animalis subsp. lactis MG741). The inclusion of L-theanine as a protective agent significantly enhanced the viability of all strains throughout the freeze-drying process compared to that of the non-coated probiotics. The efficacy of L-theanine in improving bacterial stability and survivability was evaluated using accelerated stability tests, gastrointestinal (GI) tract survivability tests, and adhesion assays with intestinal epithelial cells. The cell surface was covered with substances including L-theanine, according to morphological findings, providing efficient defense against a variety of external stresses. Therefore, by exerting anti-freezing and anti-thawing properties, the adoption of L-theanine as a new and efficient protective agent may improve the stability and viability of a variety of probiotics.

L-theanine: an astounding sui generis amino acid in poultry nutrition

L-theanine (γ-Glutamylethylamide) is a nonprotein water soluble amino acid (AA) mostly found in leaves of Camellia sinensis (green tea). This is a key component of green tea and is considered as the most abundant form of total AAs in green tea (i.e., about 50%). L-theanine is an exclusive taste ingredient of tea producing an attractive flavor and aroma in tea. It has biological effects such as antioxidant, growth promoter, immune booster, anti-stresser, hepatoprotective, antitumor, antiaging, antimicrobial, anti-inflammatory, and antianxiety activities that are worth noticing. It could reduce the oxidative impairment by reducing the synthesis of reactive oxygen species, oxidative parameters, and lipid damage as well as increasing the activity of antioxidant enzymes. The oral ingestion of L-theanine enhanced γδ T-cell proliferation. Therefore, it is being considered an essential compound of green tea that has the ability to improve immune function. The L-theanine can be used as a potential treatment for hepatic injury and immune-related liver diseases via the downregulation of the inflammatory response through the initiation of nitric oxide synthesis and glutathione production which are likely to be critical for the control of hepatic diseases as well as for the improvement of immune function. In addition, it could be used as a best natural feed additive with a potent antistressor by decreasing the levels of corticosterone, dopamine, and noradrenaline. After systematically reviewing the literature, it is noticed that most studies were carried out on mice, pig, human, and butterfly; while dietary supplementation studies of L-theanine in animal and poultry especially among broilers are very limited because of less awareness of this AA. So, the aim of this review is to encourage the veterinarian and poultry researchers to conduct more research at the molecular level about this AA to expose its more beneficial effects and its mechanism of absorption for potential use of this unique green tea AA in poultry nutrition.

Nutritional applications and beneficial health applications of green tea and l-theanine in some animal species: A review

Green tea (Camellia sinensis) is a popular herbal plant with abundant health benefits, and thus, it has been used as a potent antioxidant for a long time. Based on the available literature, the diversity and the availability of multifunctional compounds in green tea offer its noteworthy potential against many diseases such as liver and heart diseases, inflammatory conditions and different metabolic syndromes. Owing to its bioactive constituents including caffeine, amino acids, l-theanine, polyphenols/flavonoids and carbohydrates among other potent molecules, green tea has many pharmacological and physiological effects. The effects of green tea include anti-oxidative, anti-inflammatory, anti-arthritic, anti-stress, hypolipidaemic, hypocholesterolaemic, skin/collagen protective, hepatoprotective, anti-diabetic, anti-microbial, anti-infective, anti-parasitic, anti-cancerous, inhibition of tumorigenesis and angiogenesis, anti-mutagenic, and memory and bone health-improving activities. Apart from its utilization in humans, green tea has also played a significant role in livestock production such as in dairy, piggery, goatry and poultry industries. Supplementation of animal feeds with green tea and its products is in line with the modern concepts of organic livestock production. Hence, incorporating green tea or green tea by-products into the diet of poultry and other livestock can enhance the value of the products obtained from these animals. Herein, an effort is made to extend the knowledge on the importance and useful applications of green tea and its important constituents in animal production including poultry. This review will be a guideline for researchers and entrepreneurs who want to explore the utilization of feeds supplemented with green tea and green tea by-products for the enhancement of livestock production.

Vaccinium bracteatum Leaf Extract Reverses Chronic Restraint Stress-Induced Depression-Like Behavior in Mice: Regulation of Hypothalamic-Pituitary-Adrenal Axis, Serotonin Turnover Systems, and ERK/Akt Phosphorylation

The leaves of Vaccinium bracteatum Thunb. are a source of traditional herbal medicines found in East Asia. The present study aimed to evaluate the mechanisms underlying the antidepressant-like effects of water extract of V. bracteatum Thunb. leaves (VBLW) in a mouse model of chronic restraint stress (CRS) and to identify the possible molecular in vitro mechanisms of the neuroprotective effects. The CRS-exposed mice were orally administered VBLW (100 and 200 mg/kg) daily for 21 days consecutively. The behavioral effects of VBLW were assessed through the forced swim test (FST) and the open field test (OFT). The levels of serum corticosterone (CORT), corticotropin releasing hormone (CRH), and adrenocorticotropin hormone (ACTH), brain monoamines, such as serotonin, dopamine, and norepinephrine, and serotonin turnover by tryptophan hydroxylase 2 (TPH2), serotonin reuptake (SERT), and monoamine oxidase A (MAO-A) were evaluated, in addition to the extracellular signal-regulated kinases (ERKs)/protein kinase B (Akt) signaling pathway. CRS-exposed mice treated with VBLW (100 and 200 mg/kg) showed significantly reduced immobility time and increased swimming and climbing times in the FST, and increased locomotor activity in the OFT. Moreover, CRS mice treated with VBLW exhibited significantly decreased CORT and ACTH, but enhanced brain monoamine neurotransmitters. In addition, CRS mice treated with VBLW had dramatically decreased protein levels of MAO-A and SERT, but increased TPH2 protein levels in the hippocampus and the PFC. Similarly, VBLW significantly upregulated the ERKs/Akt signaling pathway in the hippocampus and the PFC. Furthermore, VBLW showed neuroprotective effects via increased CREB phosphorylation in CORT-induced cell injury that were mediated through the ERK/Akt/mTOR signaling pathways. These results suggested that the antidepressant-like effects of VBLW might be mediated by the regulation of the HPA axis, glucocorticoids, and serotonin turnover, such as TPH2, SERT, and MAO-A, as well as the concentration of monoamine neurotransmitters, and the activities of ERK and Akt phosphorylation, which were possibly associated with neuroprotective effects.

Antidepressant-Like Effects of Vaccinium bracteatum in Chronic Restraint Stress Mice: Functional Actions and Mechanism Explorations

The fruit of Vaccinium bracteatum Thunb. (VBF) is commonly known as the oriental blueberry in Korea. The aim of this study was to evaluate the antidepressant-like effects of water VBF extract (VBFW) in a mouse model of chronic restraint stress (CRS) and to identify the underlying mechanisms of its action. The behavioral effects of VBFW were assessed in the forced swim test (FST) and open field test (OFT). The levels of serum corticosterone (CORT), brain monoamines, in addition to the extracellular signal-regulated kinases (ERKs)/protein kinase B (Akt) signaling pathway were evaluated. VBFW treatment significantly reduced the immobility time and increased swimming time in FST without altering the locomotor activity in unstressed mice. Furthermore, CRS mice treated with VBFW exhibited a significantly decreased immobility time in FST and serum CORT, increased locomotor activity in OFT, and enhanced brain monoamine neurotransmitters. Similarly, VBFW significantly upregulated the ERKs/Akt signaling pathway in the hippocampus and PFC. In addition, VBFW may reverse CORT-induced cell death by enhancing cyclic AMP-responsive element-binding protein expression through the up-regulation of ERKs/Akt signaling pathways. In addition, VBFW showed the strong antagonistic effect of the 5-HT[Formula: see text] receptor by inhibiting 5-HT-induced intracellular Ca[Formula: see text] and ERK1/2 phosphorylation. Our study provides evidence that antidepressant-like effects of VBFW might be mediated by the regulation of monoaminergic systems and glucocorticoids, which is possibly associated with neuroprotective effects and antagonism of 5-HT[Formula: see text] receptor.