Administration Of Green Tea Extract Research Articles

Green Tea Extract Increases the Expression of Genes Responsible for Regulation of Calcium Balance in Rat Slow-Twitch Muscles under Conditions of Exhausting Exercise.

We studied the role of calcium-regulating structures of slow- (m. soleus, SOL) and fast-twitch (m. extensor digitorum longus, EDL) skeletal muscles of rats during adaptation to exhausting physical activity and the possibility of modulating this adaptation with decaffeinated green tea extract. It was established that EDL adaptation is mainly aimed at Са2+ elimination from the sarcoplasm by Са-ATPase and its retention in the reticulum by calsequestrin. Administration of green tea extract increased endurance due to involvement of slow-twitch muscles whose adaptation is associated with enhanced expression of all the studied genes responsible for the regulation of Ca2+ balance.

The effect of Tributyltin on thyroid follicular cells of adult male albino rats and the possible protective role of green tea: a toxicological, histological and biochemical study

IntroductionTributyltin is one of the important and wide-spread persistent organic contaminants that accumulate in the food chain. It is suspected to cause endocrine-disrupting effects in mammals, due in part to its possible transfer through marine food chains and to the consumption of contaminated seafood.Aim of the workWas to study the possible toxic effect of Tributyltin on thyroid follicular cells of adult male albino rats and to evaluate the possible protective role of green tea.Material and methodsForty-five adult male albino rats were included and randomly divided into 3 equal groups: a control group (Group I); Group II: received tributyltin chloride (TBT) dissolved in corn oil orally in a dose of 5 mg/kg for 30 days. Group III: received tributyltin chloride in the same dose with concomitant oral administration of green tea extract for 30 days. At the end of the experiment, the animals were sacrificed and blood samples were subjected to hormonal assay for T3, T4 and TSH levels. Malondialdehyde and reduced glutathione were assessed. The thyroid tissue was processed for histological and ultrastructure examination. The colloid area of thyroid follicles was evaluated morphometrically and statistically analyzed.ResultsA significant decrease in T3 and T4 levels and serum reduced glutathione in the group II when compared with the other groups. Furthermore, a significant increase in serum Malondialdehyde and TSH levels was recorded in group II treated group by comparison to the other two groups. Histopathological and ultrastructural changes of thyroid gland follicles were detected in tributyltin treated rats; the follicular cells appeared swollen and vacuolated. Epithelial stratification was noticed in some foci with excessive vacuolation of the colloid. Dilated rough endoplasmic reticulum filled with flocculent material and increased number of lysosomes were also detected together with variation in shape and size of the nuclei. A marked improvement in the histological features of thyroid follicles was noticed in group III.ConclusionTributyltin induces oxidative stress in rats as well as anti-thyroid effect. The green tea extract is useful in combating tissue injury that is a result of tributyltin toxicity.

Hepatoprotective Effect of the Aqueous Extract of Camellia sinensis Against Methotrexate-induced Liver Damage in Rats

Methotrexate (MTX) is a folate antagonist widely used in the treatment of neoplastic diseases; its biotransformation in the liver produced active metabolites that promote hepatotoxicity. The present study was designed to evaluate the hepatoprotective effect of aqueous extract of Camellia sinensis (Green tea) against MTX-induced liver damage in rats. A model of liver injury in rats was induced by intraperitoneal injection of 20mg/kg MTX as a single dose followed by saline and 1.25% and 2.5% aqueous extract of green tea (GTE) were orally administered 7 days prior and 5 days after MTX-intoxication as a sole source of drinking water. After killing the animals, blood samples were obtained for evaluation of serum levels of alanine and aspartate aminotransferases (ALT and AST) and alkaline phosphatase (ALP) activities, while liver tissue homogenate was prepared to evaluate tissue levels of glutathione (GSH) and malondialdehyde (MDA). Additionally, liver tissue sections were prepared and stained with hematoxylin and eiosin for histological evaluation. The results showed that administration of green tea extract (GTE) significantly decreased the elevated levels of ALT, AST and ALP activities in the serum compared to MTX-treated group. Treatment of animals with GTE 7 days before and 5 days after MTX also elevates GSH levels and decreases MDA levels significantly compared to MTX-treated group, this was associated with improving histological features that already impaired due to exposure to MTX. In conclusion, treatment of rats with GTE protects hepatic tissue against MTX-induced liver damage in dose dependent manner.
 Key words: Green tea, Hepatotoxicity

Systemic Absorption of Catechins after Intraruminal or Intraduodenal Application of a Green Tea Extract in Cows.

Green tea catechins have various potential health benefits in humans including anti-inflammatory, anti-oxidative and hepato-protective effects. If present in the circulation, they might have similar effects in ruminants, which are exposed to oxidative stress and fatty liver disease such as dairy cows during the periparturient phase. However, the bioavailability of a substance is a prerequisite for any post absorptive effect in vivo. This study aimed to investigate the appearance of catechins from a green tea extract (GTE) in cattle plasma after intraruminal and intraduodenal administration because absorption is of major importance regarding the bioavailability of catechins. The studies were performed in 5 rumen-fistulated non-lactating heifers and 6 duodenally fistulated lactating dairy cows, respectively, equipped with indwelling catheters placed in a jugular vein. The GTE was applied intraruminally (10 and 50 mg/kg BW, heifers) or duodenally (10, 20 and 30 mg/kg BW, dairy cows) in a cross‐over design with a 2 d washout period between different dosages. Blood samples were drawn following the GTE administration at various pre-defined time intervals. The concentration of the major GTE catechins (gallocatechin, epigallocatechin, catechin, epicatechin, epigallocatechin-gallate, epicatechin-gallate) in plasma samples were analysed by HPLC with electrochemical detection. Irrespective of the dose, almost none of the catechins originally contained in the GTE were detected in plasma samples after intraruminal application. In contrast, intraduodenal administration of GTE resulted in increased plasma concentrations of epicatechin, epigallocatechin, epigallocatechin gallate in a dose‐dependent manner. Thus, we can conclude that intraruminally or orally administered catechins are intensively metabolized by ruminal microorganisms.

19. PENGARUH PEMBERIAN EKSTRAK TEH HIJAU (Camelia sinensis) TERHADAP PENURUNAN KADAR HEMOGLOBIN DAN NILAI HEMATOKRIT PADA TIKUS WISTAR (Rattus norvegicus) The Effect of Green Tea Extract (Camelia sinensis) on Haemoglobin and Hematocrit Levels of Wistar Rat (Rattus norvegicus)

The aim of this study was to determine the effect of green tea (Camelia sinensis) extract on hemoglobin and hematocrit level of Wistar rat (Rattus norvegicus). Sample animals used were 20 rats strain Wistar aged 2.5-3.0 months. Green tea extract was given for 30 days consecutively. Blood collection was conducted via orbitalis sinus for 2 ml using capillary pipette. Rats were fed with standart commercial food (Turbo Feed T.79-4) and aquadest as drinking water ad libitum. This study used completely randomized design (CRD) pattern with 4 treatments and 5 replications. The control group (P0) without any treatment, P1 was given green tea extract 0.045 g/ml/day, P2 was given green tea extract 0.060 g/ml/day, and P3 was given green tea extract 0.075 g/ml/day. Data were analyzed by oneway analysis of variance (Anova). The result showed that mean±SD of hemoglobin levels (g/dl) on each treatment group (P0, P1, P2, and P3) were 11.86±0.55, 12.58±1.40, 11.82±0.69, and 12.50±0.84 respectivey. Mean±SD of hematocrit levels (%) on each treatment group (P0, P1, P2, and P3) were 44.00±4.30, 43.40±1.14, 44.00±1.58, and 42.80±1.79. To conclude, the administration of green tea extract has no effect (P0.05) on haemoglobin and hematocrit levels of Wistar rat. ____________________________________________________________________________________________________________________ Key words: green tea, haemoglobin, haematocrit, Wistar rat

Development of a UFLC-MS/MS method for the simultaneous determination of seven tea catechins in rat plasma and its application to a pharmacokinetic study after administration of green tea extract

A rapid, sensitive and selective ultra-fast liquid chromatography-tandem mass spectrometry (UFLC-MS/MS) method was developed and validated for simultaneous determination of seven green tea catechins including catechin (C), (−)-epicatechin (EC), gallocatechin (GC), (−)-epigallocatechin (EGC), (−)-epicatechin-3-gallate (ECG), gallocatechin-3-gallate (GCG) and (−)-epigallocatechin-3-gallate (EGCG) in rat plasma. The plasma samples were firstly hydrolysed with the mixture of β-glucuronidase and sulfatase, which were then extracted by liquid-liquid extraction with ethyl acetate-isopropanol (1:1, v/v). The analytes were separated on a Venusil MP C18 column (Venusil, China) with a gradient elution at a flow rate of 0.4mL/min. The detection was performed in negative ionization and multiple reaction monitoring (MRM) mode. All the calibration curves exhibited good linearity (r>0.9943) with intra- and inter-day precisions of less than 14.3% and the accuracy deviations ranging from −8.8% to 7.5%. The extraction recoveries of the analytes and ethyl gallate (internal standard) were all more than 72%. The validated method was successfully applied to a pharmacokinetic study of seven catechins in rat plasma after oral administration of the green tea extract at different doses of 0.4, 1.2 and 2.0g/kg.

The Combination of Green Tea Extract and Eriodictyol Inhibited High-Fat/High-Sucrose Diet-Induced Cholesterol Upregulation Is Accompanied by Suppression of Cholesterol Synthesis Enzymes

Western diets induce obesity associated with an increased risk of hypercholesterolaemia. Indeed, obesity-induced hypercholesterolaemia is correlated with increased coronary cardiovascular disease (CVD) risk. Male C57BL/6J mice were fed a normal diet, high-fat and high-sucrose diet (HF/HS), HF/HS with green tea extract powder diet (HF/HS+GT), HF/HS with eriodictyol diet (HF/HS+Eri), or HF/HS with green tea extract powder and eriodictyol diet (HF/HS+GT+Eri) for 8 wk. Body weight was lower in the HF/HS+GT+Eri group than in the HF/HS group (-8.3%, p<0.01). The HF/HS diet elicited an upregulation of total cholesterol levels (-63%, p<0.001), and low-density lipoprotein (LDL) levels (-89%, p<0.001) were significantly suppressed by the GT+Eri diet. Conversely, no change (p>0.05) was observed in the HF/HS+GT and HF/HS+Eri groups. The HF/HS diet-induced hepatic mRNA increase in 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) was ameliorated (-73%) by the oral administration of green tea extract and eriodictyol. Moreover, the GT+Eri diet suppressed HF/HS diet-induced upregulation of 3-hydroxy-3-methylglutaryl-coenzyme A synthase (HMGCS) (-75%, p<0.05). Furthermore, the LDL receptor (LDLR) levels were higher in the HF/HS+GT+Eri group (+50%, p<0.05) than in the HF/HS group. These results suggest that a combination of green tea and eriodictyol decreases cholesterol levels, particularly LDL levels, accompanied by the suppression of HMGCR and HMGCS levels and upregulation of LDLR levels in the liver.

Effect of green tea on the ultrastructure of the zona glomerulosa of the adrenal cortex in diabetic rats

Introduction Green tea is reported to have hypoglycemic effect on diabetic rats. However, studies about its effect on the structure of the zona glomerulosa of the adrenal cortex are limited. Aim This work aimed at studying the ultrastructural changes induced by green tea on the zona glomerulosa of the adrenal cortex in diabetic rats. Materials and methods Forty adult male Wistar albino rats were divided into four groups of 10 each: group I was the control group; group II received green tea extract at a dose of 300 mg/kg/day intragastrically; group III included rats with streptozotocin (STZ)-induced diabetes; and group IV received green tea extract after inducing diabetes. Rats were sacrificed after 12 weeks, and the adrenal glands were processed for semithin and ultrathin sections. Plasma level of aldosterone, total thickness of both the adrenal cortex and the zona glomerulosa, volume of both mitochondrial and lipid droplet, and surface area of mitochondrial cristae and smooth endoplasmic reticulum were measured. Results STZ-induced diabetes resulted in a significant decrease in body weight and serum aldosterone level and a significant increase in adrenal weight and thickness and thickness of the zona glomerulosa compared with the other groups. Zona glomerulosa cells in STZ-induced diabetic rats showed a significant increase in the number and size of lipid droplets and degenerated mitochondria. In addition, STZ-induced diabetes resulted in a significant decrease in volume of mitochondrial droplet, surface area of mitochondrial cristae, and surface area of smooth endoplasmic reticulum, as well as a significant increase in the volume of lipid droplet compared with the other groups. The green tea-treated diabetic rat group showed a significant increase in body weight, a significant decrease in adrenal weight, a significant increase in aldosterone level in serum, and decrease in the thickness of the adrenal cortex and the zona glomerulosa compared with the diabetic group. The ultrastructure of the zona glomerulosa was nearly similar to that of the control group. Conclusion Green tea extract administration improved the biochemical and ultrastructural changes induced by diabetes in the zona glomerulosa.

Effect of green tea on amiodarone-induced lung injury in albino rats

Introduction Amiodarone (AM) is an antiarrhythmic agent used in the treatment and prophylaxis of postoperative atrial fibrillation. It has some serious side effects, including pulmonary toxicity. Green tea is among the most popular beverages. It is characterized by the presence of catechins, a subgroup of polyphenols, known as a powerful antioxidant. Aim The aim of the study was to determine the toxic effects of AM as an animal model on lung injury and evaluate the possible role of green tea extract against these effects in albino rats. Materials and methods The study included 21 adult male albino rats weighing 180–200 g. They were divided into three equal groups, comprising seven rats each. Group I was considered the control group. Group II rats were given AM orally at 30 mg/kg daily for 2 weeks. Group III rats were given green tea extract orally at 150 mg/kg daily for 2 weeks concomitantly with AM as in group II. The lungs were dissected out and processed for histological and immunohistochemical study. Morphometric and statistical studies were also carried out. Results Administration of AM in group II resulted in obvious distortion to the lung architecture. Collapsed alveoli, vacuolar degeneration of pneumocytes type II, thickening of interalveolar septa, and significant increase in collagen deposition were observed. Significantly increased number of macrophages was observed in group II. However coadministration of green tea extract with AM in group III showed obvious preservation of the lung architecture. Conclusion Administration of AM in rats induced severe lung damage, whereas concomitant administration of green tea extract effectively ameliorated lung tissue damage.

Investigations into Concurrent Exposure to Green Tea Extract and Phenytoin on the Incidence of Cleft Palate in CD-1 Mice

Phenytoin (PHT) is an efficacious anticonvulsant agent that is commonly used in the treatment of epileptic seizures. However, the use of phenytoin during pregnancy is associated with a group of birth defects known as Fetal Hydantoin Syndrome (FHS), which include cleft palate and retarded growth. Phenytoin may cause its adverse effects through the production of reactive oxygen species (ROS). Green tea extract (GTE) contains epigallocatechin-3-gallate (EGCG), which exhibits free radical scavenging activity and may attenuate the effects of ROS. The purpose of this study was to investigate the potential of administration of GTE to attenuate teratogenic effects induced by phenytoin. Phenytoin sodium salt (in DI water adjusted to pH 11) was administered via gavage on gestation days (GD) 12 and 13, and its controls were dosed with pH-adjusted water on GD 12 and 13. GTE or DI water was administered from GD 8–16 to mated CD-1 mice. Controls received both vehicles (DI water and pH-adjusted water). Mated females wer...

Goitrogenic and Antithyroid Potential of Green Tea of Indian Origin

Polyphenolic flavonoids, specially catechins are major constituents of tea. Antithyroidal and goitrogenic effect of flavonoids have been reported however such effects of green tea on thyroid physiology has not been explored earlier. Green tea is derived from the tea leaves of Camellia sinensis and widely consumed globally. The green tea extracts(GTE) at different concentrations (1.25g% a” 5 cups of tea/ day; 2.5g% a” 10 cups of tea/ day and 5.0g% a” 20 cups of tea/ day) were orally fed to male rats for 30 days. Similarly, pure catechin was administered orally to male albino rats for 30 days at doses of 25, 50 and 100 mg/kg body weight that are equivalent to above doses of green tea extract in terms of its total catechin content and the morphological and functional changes of the thyroid have been investigated. The overall results reveal that oral administration of green tea extract at 2.5g% and 5.0g% concentrations for 30 days changed the morphology and histology resembling hypertrophy of thyroid follicles with differential colloid sizes as found in hypothyroid due to environment influences associated with significant inhibited activities of thyroid peroxidase(TPO) and 5’ monodeiodinase (5’ DI1) with elevated Na+,K+ ATPase and concomitant decrease in serum thyroxine (T4), triiodothyronine (T3) and increase in serum thyrotropin (TSH) levels developing a state of absolute biochemical hypothyroidism. All these suggest that catechin present in green tea has the antithyroidal as well as goitrogenic potential and its regular consumption at relatively high doses pose a threat to the functioning of thyroid. DOI: http://dx.doi.org/10.3329/jbsp.v9i2.22807 Bangladesh Soc Physiol. 2014, December; 9(2): 105-116

Effect of oral administration of green tea extract in various dosage schemes on oxidative stress status of mice in vivo.

Green tea is a favorite beverage and its extracts are popular components of dietary supplements. The aim of the present in vivo study was to obtain detailed information about the effect of a standard green tea extract (Polyphenon, P), at different doses, on antioxidant enzymes and oxidative stress markers in murine blood, liver, small and large intestine. In all doses, P improved the oxidative stress status via an increased content of plasmatic SH-groups (by 21-67 %). Regarding antioxidant enzymes in tissues, the low dose of P had the best positive effect as it elevated the activity of NADPH quinone reductase in liver and small intestine, thioredoxin reductase in small intestine and hepatic superoxide dismutase. Based on these facts, consumption of green tea seems to be safe and beneficial, while consumption of dietary supplements containing high doses of catechins may disturb oxidative balance by lowering the activity of thioredoxin reductase, glutathione S-transferase, glutathione reductase and superoxide dismutase.

Efficacy of green tea extract in two exercise models.

Oral administration of green tea extract in a dose of 6 mg/kg twice a day (before and after exercise) over 2 weeks significantly increased swimming times on week 1 and 2 in comparison with control animals receiving water. The 7-day and final exhaustive running in rats was accompanied by a significant decrease in spleen weight and iron serum levels associated with developed reticulocytosis. Administration of green tea extract in a dose of 12 mg/kg once a day (before exercise) for 2 weeks did not affect the duration of the running, but prevented the decrease in serum iron and spleen weight, that, along with a significantly increased concentration of reduced glutathione in erythrocytes, can indicate a normalizing effect of green tea extract on hemopoiesis and stimulating effect on the antioxidant system of erythrocytes.

Green tea extract attenuates CCl4-induced hepatic injury in male hamsters via inhibition of lipid peroxidation and p53-mediated apoptosis

Keeping in mind the beneficial effects of GTE administration on liver damage, the present study was undertaken to evaluate the hepatoprotective effect of green tea extract (GTE) against carbon tetrachloride (CCl4)-induced liver injuries in male hamsters for 8 weeks. Twenty hamsters were equally divided into 4 groups, the control ones (group I) received only dis. water. Hamsters of group II had free access to 10% of GTE, while hamsters of group III received 1ml/kg of 50% CCl4 in corn oil via gavage daily. Hamsters of group IV (GTE+CCl4) received a free access to GTE supplementation in combination with 1ml/kg of 50% CCl4 in corn oil via gavage daily. Lipid profile, hepatic enzyme levels and apoptosis molecular marker (p53) were investigated in hamsters. GTE+CCl4 treated hamsters showed lower levels of hepatic malondialdehyde (MDA) than CCl4 exposed hamsters. Hepatic activity levels of GSH, ALD and cytochrome 450 reductase were declined after CCl4 administration while they were remarkably improved with GTE administration. Serum lipid profiles as T-cholesterol (TC), triglyceride (TG) and low density lipoproteins (LDL) were improved in GTE and CCl4 treated hamsters than CCl4 group. Moreover, hepatic tissue damage and p53 expression induced with CCl4 were improved with the treatment of GTE. These results suggested that GTE possesses hepatoprotective properties against the effect of CCl4.

The effect of green tea extract supplementation on exercise-induced oxidative stress parameters in male sprinters.

BackgroundAlthough research suggests that antioxidant supplementation can protect against exercise-induced muscle damage and oxidative stress, also delayed post-exercise muscle recovery and hindered adaptation to training were reported in the supplemented athletes. PurposeThe purpose of the study was to evaluate the effects of green tea extract (GTE) supplementation on selected blood markers of oxidative stress and muscle damage in sprinters during preparatory phase of their training cycle.MethodsSixteen sprinters participated in a double-blind, randomized, placebo (PL)-controlled crossover study, including two 4-week treatment periods with PL and GTE (980 mg polyphenols daily). The sprinters performed two repeated cycle sprint tests (RST; 4 × 15 s, with 1-min rest intervals), after PL and GTE supplementation. Blood was sampled before (at rest), 5 min after RST, and after the 24-h recovery. The activities of superoxide dismutase (SOD) and glutathione peroxidase were measured in erythrocytes, and total polyphenols, total antioxidant capacity (TAC), uric acid (UA), albumin (AL), malondialdehyde (MDA), and creatine kinase (CK) were determined in blood plasma.ResultsRepeated cycle sprint test performed after PL induced an increase in MDA, TAC, and SOD. Moreover, an increase in UA, AL, and CK was observed after RST irrespective of experimental conditions (PL, GTE). Supplementation with GTE caused an increase in total polyphenols and TAC at rest, and a decrease in MDA and SOD after RST. No significant changes in sprint performance were noted after GTE, as compared to PL.ConclusionsSupplementation with GTE prevents oxidative stress induced by RST in sprinters. Furthermore, GTE supplementation does not seem to hinder training adaptation in antioxidant enzyme system. On the other hand, neither prevention of exercise-induced muscle damage, nor an improvement in sprint performance is noted after GTE administration.

Green tea extract treatment alleviates ocular inflammation in a rat model of endotoxin-induced uveitis.

Green tea extract (GTE) ingested by rats exerted anti-oxidative activities in various ocular tissues as shown in our previous studies. The present work investigated anti-inflammatory effects of GTE on endotoxin-induced uveitis (EIU). EIU was generated in adult rats by a footpad injection of 1 mg/kg lipopolysaccharide (LPS). Oral administration of GTE (550 mg/kg) was given one, two or four times after LPS injection. Twenty-four hours later, LPS produced severe hyperemia and edema in the iris. Immunocytochemical examinations showed an accumulation of infiltrating cells in the aqueous humor that were immunopositive for cluster of differentiation 43 (CD43) and CD68, markers for leucocytes and macrophages, respectively. Analyses of the aqueous humor showed an increase in pro-inflammatory mediators including tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6) and monocyte chemoattractant protein-1 (MCP-1). GTE treatments improved the clinical manifestations and reduced infiltrating cells and protein exudation in the aqueous humor, which were not observed under half dose of GTE (275 mg/kg). The number of CD68 positive macrophages residing in the iris and ciliary was also reduced. GTE suppressed production of TNF-α, IL-6 and MCP-1 in the aqueous humor, which was associated with a down-regulation of LPS receptor complex subunits, Toll-like receptor 4 (TLR-4) and CD14, and suppression of nuclear factor-kappa Bp65 (NF-κBp65) in the iris and ciliary body. Our findings show that GTE is a potent anti-inflammatory agent against the inflammation of EIU, and suggest a potential use in treatment of acute uveitis.

Intravesical administration of green tea extract attenuates the inflammatory response of bacterial cystitis – a rat model

To explore the effect of intravesical instillation of green tea extract (GTE) on a rat model of bacterial cystitis. In vitro bactericidal properties of GTE were analysed by adding GTE to a suspension of uropathogenic E. coli (UPEC), streaking on MacConkey agar, and incubating overnight. In vivo effects of intravesical instillation of GTE on bacterial cystitis was analysed using a rat model of bacterial cystitis. In all, 42 female Sabra rats weighing 200-260 g were divided into five groups. Parameters measured were bladder weight (percentage of the total rat weight), dipstick urine analysis and histopathological changes in the bladder. Histological changes evaluated were degree of oedema, mixed inflammatory infiltration, urothelial epithelial invasion by neutrophils and reactive atypia. No in vitro bactericidal activity was detected for GTE. Intravesical instillation of GTE did not cause damage to the rat bladders. Intravesical instillation of GTE attenuated the inflammatory response to UPEC-SR71-induced bacterial cystitis in this rat model. Intravesical instillation of GTE attenuated the inflammatory response to UPEC-SR71-induced bacterial cystitis and is a novel approach to the treatment of bacterial cystitis. High concentrations of intravesical GTE did not cause histologically evident damage to the rat bladder. The results of this study are preliminary and further studies will be needed to explore the feasibility of using this approach in humans.

Green tea supplementation in mice mitigates senescence-induced changes in brain antioxidant abilities

Catechin composition of green tea extract and its anti-senescence effect was investigated with a study of senescence-related redox imbalance in the brains of aged mice. Oral administration of green tea extract at doses of 125, 625 and 1250mg/kg for 4weeks alleviated the senescence-mediated redox imbalance, as observed from the significantly reduced (p<0.05) levels of thiobarbituric acid-reactive substances (TBARS) in the serum and increased glutathione (GSH) and total thiol levels in the plasma compared with that in the aged control group. Moreover, the activities of superoxide dismutase (SOD), catalase, glucose-6-phosphate dehydrogenase (G6PD), glutathione peroxidase (GSH-Px) and glutathione reductase (GSH-Rd) in the brain were also increased, whereas protein carbonyls were reduced. Taken together, these results clearly indicate that green tea extract exhibits potent protective effects against senescence-mediated redox imbalance in the brains of mice by inhibiting oxidative damage and increasing antioxidant enzyme activities.

Prefrontal Deficits in a Murine Model Overexpressing the Down Syndrome Candidate GeneDyrk1a

The gene Dyrk1a is the mammalian ortholog of Drosophila minibrain. Dyrk1a localizes in the Down syndrome (DS) critical region of chromosome 21q22.2 and is a major candidate for the behavioral and neuronal abnormalities associated with DS. PFC malfunctions are a common denominator in several neuropsychiatric diseases, including DS, but the contribution of DYRK1A in PFC dysfunctions, in particular the synaptic basis for impairments of executive functions reported in DS patients, remains obscure. We quantified synaptic plasticity, biochemical synaptic markers, and dendritic morphology of deep layer pyramidal PFC neurons in adult mBACtgDyrk1a transgenic mice that overexpress Dyrk1a under the control of its own regulatory sequences. We found that overexpression of Dyrk1a largely increased the number of spines on oblique dendrites of pyramidal neurons, as evidenced by augmented spine density, higher PSD95 protein levels, and larger miniature EPSCs. The dendritic alterations were associated with anomalous NMDAR-mediated long-term potentiation and accompanied by a marked reduction in the pCaMKII/CaMKII ratio in mBACtgDyrk1a mice. Retrograde endocannabinoid-mediated long-term depression (eCB-LTD) was ablated in mBACtgDyrk1a mice. Administration of green tea extracts containing epigallocatechin 3-gallate, a potent DYRK1A inhibitor, to adult mBACtgDyrk1a mice normalized long-term potentiation and spine anomalies but not eCB-LTD. However, inhibition of the eCB deactivating enzyme monoacylglycerol lipase normalized eCB-LTD in mBACtgDyrk1a mice. These data shed light on previously undisclosed participation of DYRK1A in adult PFC dendritic structures and synaptic plasticity. Furthermore, they suggest its involvement in DS-related endophenotypes and identify new potential therapeutic strategies.

A comparative histological, immunohistochemical, and biochemical study of the effect of green tea extracts or chromium picolinate administration on the white visceral adipose tissue and liver in albino rats fed on high-fat diet

Background Obesity has become a major health problem, as a growing proportion of the population worldwide is overweight. The coincidence of obesity, insulin resistance, hypertension, dyslipidemia, and hepatic steatosis is commonly referred to as the ‘metabolic syndrome’. The investigation of the antiobesity properties of food components is a popular field of research and one of these natural agents of interest is green tea extract (GTE). Nevertheless, chromium picolinate (CP) is also postulated to have an effect on the body fat composition. Objective The present study aimed to assess the changes in the visceral white adipose tissue and the liver of adult male albino rats that are fed on high-fat diet (HFD) following administration of GTE or CP supplements histologically, immunohistochemically, and biochemically. Materials and methods A total of 60 adult male albino rats (120–150g) were randomly assigned into four groups. Group I (the control group) included 30 rats and were subdivided into three equal subgroups (Ia, Ib, Ic); all were fed on standard rat chow. Groups Ib and Ic were given GTE and CP, respectively, orally through an orogastric tube. Group II included 10 rats that were allowed a free access to HFD. Group III (the GTE and HFD group) included 10 rats that received GTE orally (200 mg/kg body weight/day) in conjunction with HFD. Group IV (the CP and HFD group) included 10 rats that received CP orally (80 μg/kg body weight/day) in conjunction with HFD. The experiment continued for 3 months. Perinephric white adipose tissue (PWAT) and liver specimens were dissected from all rats at the end of the experiment for histological and immunohistochemical examination. Blood samples were taken for estimation of fasting blood glucose (FBG) and fasting blood insulin (FBI) levels. Results Histologically, groups Ib and Ic revealed almost the control pattern of the liver and PWAT similar to group Ia. Group II showed focal areas of cellular infiltration and congestion of the blood vessels of the liver sections. Most hepatocytes appeared swollen with cytoplasmic vacuolation. PWAT revealed a marked increase in the amount and size of the adipocytes. Groups III and IV revealed almost the control pattern of the liver except for few areas of cellular infiltrations in group IV. Groups III and IV showed a marked decrease in the amount of PWAT, which was more remarkable in group IV. Decrease in the size of many adipocytes was more manifested in group IV. Immunohistochemically, increased expression of insulin receptors in the adipocytes of PWAT and to a lesser extent in the hepatocytes of group III was noticed. Group IV showed more noticeable increased expression of insulin receptors compared with group III. Biochemically, FBI in the obesity group was higher as compared with the control group. Groups III and IV revealed a significant decrease in the FBI level. Fasting blood glucose level showed significant increase in group II only. Conclusion Supplementation with either GTE or CP may be useful as antiobesity agents and can be used to prevent the impact of obesity on the liver and to improve insulin resistance.