Neuroprotective effects of exogenous brain-derived neurotrophic factor on amyloid-beta 1-40-induced retinal degeneration.

Amyloid-beta (Aß)-related alterations, similar to those found in the brains of patients with Alzheimer's disease, have been observed in the retina of patients with glaucoma. Decreased levels of brain-derived neurotrophic factor (BDNF) are believed to be associated with the neurotoxic effects of Aß peptide. To investigate the mechanism underlying the neuroprotective effects of BDNF on Aß1-40-induced retinal injury in Sprague-Dawley rats, we treated rats by intravitreal administration of phosphate-buffered saline (control), Aß1-40 (5 nM), or Aß1-40 (5 nM) combined with BDNF (1 µg/mL). We found that intravitreal administration of Aß1-40 induced retinal ganglion cell apoptosis. Fluoro-Gold staining showed a significantly lower number of retinal ganglion cells in the Aß1-40 group than in the control and BDNF groups. In the Aß1-40 group, low number of RGCs was associated with increased caspase-3 expression and reduced TrkB and ERK1/2 expression. BDNF abolished Aß1-40-induced increase in the expression of caspase-3 at the gene and protein levels in the retina and upregulated TrkB and ERK1/2 expression. These findings suggest that treatment with BDNF prevents RGC apoptosis induced by Aß1-40 by activating the BDNF-TrkB signaling pathway in rats.

Neuroprotection by Trans-Resveratrol in Rats With Intracerebral Hemorrhage: Insights into the Role of Adenosine A1 Receptors.

Given the neuroprotective effects of trans-resveratrol (RV), this study aimed to investigate the involvement of the adenosine A1 receptor (A1R) in RV-mediated neuroprotection in a rat intracerebral hemorrhage (ICH) model induced by intrastriatal injection of collagenase. Rats were divided into 5 groups: (1) control, (2) sham-operated, (3) ICH pretreated with vehicle, (4) ICH pretreated with RV, and (5) ICH pretreated with RV and the A1R antagonist DPCPX. At 48 hours after ICH, the rats were subjected to neurological testing. Brain tissues were assessed for neuronal density and morphological features using routine and immunohistochemical staining. Expression of tumor necrosis factor-α (TNF-α), caspase-3, and RIPK3 proteins was examined using ELISA. A1R, MAPK P38, Hsp90, TrkB, and BDNF genes were examined using RT-qPCR. RV protected against neurological deficits and neuronal depletion, restored the expression of TNF-α, CASP3, RIPK3, A1R, and Hsp90, and increased BDNF/TrkB. DPCPX abolished the effects of RV on neurological outcomes, neuronal density, CASP3, RIPK3, A1R, Hsp90, and BDNF. These data indicate that the neuroprotection by RV involves A1R and inhibits CASP3-dependent apoptosis and RIPK3-dependent necroptosis in the perihematoma region; this is likely to be mediated by crosstalk between A1R and the BDNF/TrkB pathway.

Temozolomide Efficacy and Metabolism: The Implicit Relevance of Nanoscale Delivery Systems.

The most common primary malignant brain tumors in adults are gliomas. Glioblastoma is the most prevalent and aggressive tumor subtype of glioma. Current standards for the treatment of glioblastoma include a combination of surgical, radiation, and drug therapy methods. The drug therapy currently includes temozolomide (TMZ), an alkylating agent, and bevacizumab, a recombinant monoclonal IgG1 antibody that selectively binds to and inhibits the biological activity of vascular endothelial growth factor. Supplementation of glioblastoma radiation therapy with TMZ increased patient survival from 12.1 to 14.6 months. The specificity of TMZ effect on brain tumors is largely determined by special aspects of its pharmacokinetics. TMZ is an orally bioavailable prodrug, which is well absorbed from the gastrointestinal tract and is converted to its active alkylating metabolite 5-(3-methyl triazen-1-yl)imidazole-4-carbozamide (MTIC) spontaneously in physiological condition that does not require hepatic involvement. MTIC produced in the plasma is not able to cross the BBB and is formed locally in the brain. A promising way to increase the effectiveness of TMZ chemotherapy for glioblastoma is to prevent its hydrolysis in peripheral tissues and thereby increase the drug concentration in the brain that nanoscale delivery systems can provide. The review discusses possible ways to increase the efficacy of TMZ using nanocarriers.

Effect of trans-resveratrol on glutamate clearance and visual behaviour in rats with glutamate induced retinal injury.

Glutamate-induced excitotoxic injury is widely described as a prominent pathophysiological mechanism in several neurodegenerative diseases including glaucoma. Glaucoma, the leading cause of irreversible blindness, is characterized by loss of retinal ganglion cells (RGC). Currently, the treatment focuses on lowering intraocular pressure (IOP) and no neuroprotective therapies are available. Since excessive glutamate-mediated neurotransmission underlies glaucomatous RGC apoptosis, enhancing synaptic glutamate clearance by glutamate transporters in glial cells is expected to protect against excitotoxic injury. Trans-resveratrol is known for its neuroprotective effects; however, its effects on the expression of glutamate transporters and glutamate clearance in retina remain unclear. Hence, in the current study, we investigated the protective effects of trans-resveratrol against glutamate-induced retinal injury in rats. Rats were intravitreally injected with glutamate alone or glutamate with trans-resveratrol as pre- and post-treatment. Animals were subjected to Open Field Test (OFT) on day six and a two-chamber mirror test on day seven post-injection. Subsequently, rats were sacrificed and retinal expression of excitatory amino acid transporter (EAAT)1 and EAAT2 gene and protein was determined using PCR and ELISA, respectively. Retinal glutamate concentration was measured using ELISA and retinal morphology was studied on H&E-stained retinal sections. It was observed that pre-treatment with trans-resveratrol causes gene expression for EAAT1 and EAAT2 to increase by 2.51 and 1.93 folds compared to glutamate-treated group (p < 0.001 and p < 0.01, respectively); while the same in trans-resveratrol post-treatment group showed a 1.58- and 1.44 folds upregulation (p < 0.05).The retinal EAAT1 and EAAT2 protein expression was significantly greater in trans-resveratrol pre-treatment group compared to glutamate-treated group (p < 0.05) but not in post-treatment group. Retinal glutamate concentration was1.64 folds greater in glutamate-treated group than the vehicle-treated group (p < 0.01) but the same was 1.27-fold lower in trans-resveratrol pre-treatment group compared to glutamate-treated group (p < 0.01). Corresponding to these findings, we observed preservation of retinal morphology and visual behaviour in trans-resveratrol pre-treatment group compared to glutamate-treated group. We did not observe similar effects of trans-resveratrol when it was given as post-treatment after glutamate administration. In conclusion, current study showed that pre-treatment with trans-resveratrol protects against glutamate induced changes in retinal morphology and visual behaviour by increasing the expression of EAAT1 and EAAT2 and increasing glutamate clearance in rat retinas. The results of this study may be relevant to disease conditions involving excitotoxic neuronal injury.

Safety and efficacy of very low carbohydrate diet in patients with diabetic kidney disease-A randomized controlled trial.

INTRODUCTION: There is limited data on the effects of low carbohydrate diets on renal outcomes particularly in patients with underlying diabetic kidney disease. Therefore, this study determined the safety and effects of very low carbohydrate (VLCBD) in addition to low protein diet (LPD) on renal outcomes, anthropometric, metabolic and inflammatory parameters in patients with T2DM and underlying mild to moderate kidney disease (DKD). MATERIALS AND METHODS: This was an investigator-initiated, single-center, randomized, controlled, clinical trial in patients with T2DM and DKD, comparing 12-weeks of low carbohydrate diet (<20g daily intake) versus standard low protein (0.8g/kg/day) and low salt diet. Patients in the VLCBD group underwent 2-weekly monitoring including their 3-day food diaries. In addition, Dual-energy x-ray absorptiometry (DEXA) was performed to estimate body fat percentages. RESULTS: The study population (n = 30) had a median age of 57 years old and a BMI of 30.68kg/m2. Both groups showed similar total calorie intake, i.e. 739.33 (IQR288.48) vs 789.92 (IQR522.4) kcal, by the end of the study. The VLCBD group showed significantly lower daily carbohydrate intake 27 (IQR25) g vs 89.33 (IQR77.4) g, p<0.001, significantly higher protein intake per day 44.08 (IQR21.98) g vs 29.63 (IQR16.35) g, p<0.05 and no difference in in daily fat intake. Both groups showed no worsening of serum creatinine at study end, with consistent declines in HbA1c (1.3(1.1) vs 0.7(1.25) %) and fasting blood glucose (1.5(3.37) vs 1.3(5.7) mmol/L). The VLCBD group showed significant reductions in total daily insulin dose (39(22) vs 0 IU, p<0.001), increased LDL-C and HDL-C, decline in IL-6 levels; with contrasting results in the control group. This was associated with significant weight reduction (-4.0(3.9) vs 0.2(4.2) kg, p = <0.001) and improvements in body fat percentages. WC was significantly reduced in the VLCBD group, even after adjustments to age, HbA1c, weight and creatinine changes. Both dietary interventions were well received with no reported adverse events. CONCLUSION: This study demonstrated that dietary intervention of very low carbohydrate diet in patients with underlying diabetic kidney disease was safe and associated with significant improvements in glycemic control, anthropometric measurements including weight, abdominal adiposity and IL-6. Renal outcomes remained unchanged. These findings would strengthen the importance of this dietary intervention as part of the management of patients with diabetic kidney disease.

Methanolic Extract of Piper sarmentosum Attenuates Obesity and Hyperlipidemia in Fructose-Induced Metabolic Syndrome Rats.

Obesity and hyperlipidemia are metabolic dysregulations that arise from poor lifestyle and unhealthy dietary intakes. These co-morbidity conditions are risk factors for vascular diseases. Piper sarmentosum (PS) is a nutritious plant that has been shown to pose various phytochemicals and pharmacological actions. This study aimed to investigate the effect of PS on obesity and hyperlipidemia in an animal model. Forty male Wistar rats were randomly divided into five experimental groups. The groups were as follows: UG-Untreated group; CTRL-control; FDW-olive oil + 20% fructose; FDW-PS-PS (125 mg/kg) + 20% fructose; FDW-NGN-naringin (100 mg/kg) + 20% fructose. Fructose drinking water was administered daily for 12 weeks ad libitum to induce metabolic abnormality. Treatment was administered at week 8 for four weeks via oral gavage. The rats were sacrificed with anesthesia at the end of the experimental period. Blood, liver, and visceral fat were collected for further analysis. The consumption of 20% fructose water by Wistar rats for eight weeks displayed a tremendous increment in body weight, fat mass, percentage fat, LDL, TG, TC, HMG-CoA reductase, leptin, and reduced the levels of HDL and adiponectin as well as adipocyte hypertrophy. Following the treatment period, FDW-PS and FDW-NGN showed a significant reduction in body weight, fat mass, percentage fat, LDL, TG, TC, HMG-CoA reductase, and leptin with an increment in the levels of HDL and adiponectin compared to the FDW group. FDW-PS and FDW-NGN also showed adipocyte hypotrophy compared to the FDW group. In conclusion, oral administration of 125 mg/kg PS methanolic extract to fructose-induced obese rats led to significant amelioration of obesity and hyperlipidemia through suppressing the adipocytes and inhibiting HMG-CoA reductase. PS has the potential to be used as an alternative or adjunct therapy for obesity and hyperlipidemia.

Magnesium acetyltaurate prevents retinal damage and visual impairment in rats through suppression of NMDA-induced upregulation of NF-κB, p53 and AP-1 (c-Jun/c-Fos).

Magnesium acetyltaurate (MgAT) has been shown to have a protective effect against N-methyl-D-aspartate (NMDA)-induced retinal cell apoptosis. The current study investigated the involvement of nuclear factor kappa-B (NF-κB), p53 and AP-1 family members (c-Jun/c-Fos) in neuroprotection by MgAT against NMDA-induced retinal damage. In this study, Sprague-Dawley rats were randomized to undergo intravitreal injection of vehicle, NMDA or MgAT as pre-treatment to NMDA. Seven days after injections, retinal ganglion cells survival was detected using retrograde labelling with fluorogold and BRN3A immunostaining. Functional outcome of retinal damage was assessed using electroretinography, and the mechanisms underlying antiapoptotic effect of MgAT were investigated through assessment of retinal gene expression of NF-κB, p53 and AP-1 family members (c-Jun/c-Fos) using reverse transcription-polymerase chain reaction. Retinal phospho-NF-κB, phospho-p53 and AP-1 levels were evaluated using western blot assay. Rat visual functions were evaluated using visual object recognition tests. Both retrograde labelling and BRN3A immunostaining revealed a significant increase in the number of retinal ganglion cells in rats receiving intravitreal injection of MgAT compared with the rats receiving intravitreal injection of NMDA. Electroretinography indicated that pre-treatment with MgAT partially preserved the functional activity of NMDA-exposed retinas. MgAT abolished NMDA-induced increase of retinal phospho-NF-κB, phospho-p53 and AP-1 expression and suppressed NMDA-induced transcriptional activity of NF-κB, p53 and AP-1 family members (c-Jun/c-Fos). Visual object recognition tests showed that MgAT reduced difficulties in recognizing the visual cues (i.e. objects with different shapes) after NMDA exposure, suggesting that visual functions of rats were relatively preserved by pre-treatment with MgAT. In conclusion, pre-treatment with MgAT prevents NMDA induced retinal injury by inhibiting NMDA-induced neuronal apoptosis via downregulation of transcriptional activity of NF-κB, p53 and AP-1-mediated c-Jun/c-Fos. The experiments were approved by the Animal Ethics Committee of Universiti Teknologi MARA (UiTM), Malaysia, UiTM CARE No 118/2015 on December 4, 2015 and UiTM CARE No 220/7/2017 on December 8, 2017 and Ethics Committee of Belgorod State National Research University, Russia, No 02/20 on January 10, 2020.

Protective Effect of Palm Oil-Derived Tocotrienol-Rich Fraction Against Retinal Neurodegenerative Changes in Rats with Streptozotocin-Induced Diabetic Retinopathy.

: Oxidative stress plays an important role in retinal neurodegeneration and angiogenesis associated with diabetes. In this study, we investigated the effect of the tocotrienol-rich fraction (TRF), a potent antioxidant, against diabetes-induced changes in retinal layer thickness (RLT), retinal cell count (RCC), retinal cell apoptosis, and retinal expression of vascular endothelial growth factor (VEGF) in rats. Additionally, the efficacy of TRF after administration by two different routes was compared. The diabetes was induced in Sprague-Dawley rats by intraperitoneal injection of streptozotocin. Subsequently, diabetic rats received either oral or topical treatment with vehicle or TRF. Additionally, a group of non-diabetic rats was included with either oral or topical treatment with a vehicle. After 12 weeks of the treatment period, rats were euthanized, and retinas were collected for measurement of RLT, RCC, retinal cell apoptosis, and VEGF expression. RLT and RCC in the ganglion cell layer were reduced in all diabetic groups compared to control groups (p < 0.01). However, at the end of the experimental period, oral TRF-treated rats showed a significantly greater RLT compared to topical TRF-treated rats. A similar observation was made for retinal cell apoptosis and VEGF expression. In conclusion, oral TRF supplementation protects against retinal degenerative changes and an increase in VEGF expression in rats with streptozotocin-induced diabetic retinopathy. Similar effects were not observed after topical administration of TRF.

Neuroprotective effect of poly(lactic-co-glycolic acid) nanoparticle-bound brain-derived neurotrophic factor in a permanent middle cerebral artery occlusion model of ischemia in rats.

Poly (lactide­co­glycolide) (PLGA) nanoparticles (NPs) are biodegradable carriers that participate in the transport of neuroprotective drugs across the blood brain barrier (BBB). Targeted brain­derived neurotrophic factor (BDNF) delivery across the BBB could provide neuroprotection in brain injury. We tested the neuroprotective effect of PLGA nanoparticle­bound BDNF in a permanent middle cerebral artery occlusion (pMCAO) model of ischemia in rats. Sprague­Dawley rats were subjected to pMCAO. Four hours after pMCAO, two groups were intravenously treated with BDNF and NP­BDNF, respectively. Functional outcome was assessed at 2 and 24 h after pMCAO, using the modified neurologic severity score (mNSS) and rotarod performance tests. Following functional assessments, rats were euthanized blood was taken to assess levels of the neurobiomarkers neuron­specific enolase and S100 calcium­binding protein ß (S100ß), and the brain was evaluated to measure the infarct volume. The NP­BDNF­treated group showed significant improvement in mNSS compared with pMCAO and BDNF­treated groups and showed improved rotarod performance. The infarct volume in rats treated with NP­BDNFs was also significantly smaller. These results were further corroborated by correlating differences in estimated NSE and S100ß. NP­BDNFs exhibit a significant neuroprotective effect in the pMCAO model of ischemia in rats.

Magnesium acetyltaurate protects against endothelin-1 induced RGC loss by reducing neuroinflammation in Sprague dawley rats.

Endothelin-1 (ET-1), a potent vasoconstrictor, plays a significant role in the pathophysiology of ocular conditions like glaucoma. Glaucoma is characterized by apoptotic loss of retinal ganglion cells (RGCs) and loss of visual fields and is a leading cause of irreversible blindness. In glaucomatous eyes, retinal ischemia causes release of pro-inflammatory mediators such as interleukin (IL)-1ß, IL-6 and tumor necrosis factor (TNF)-α and promotes activation of transcription factors such as nuclear factor kappa B (NFKB) and c-Jun. Magnesium acetyltaurate (MgAT) has previously been shown to protect against ET-1 induced retinal and optic nerve damage. Current study investigated the mechanisms underlying these effects of MgAT, which so far remain unknown. Sprague dawley rats were intravitreally injected with ET-1 with or without pretreatment with MgAT. Seven days post-injection, retinal expression of IL-1ß, IL-6, TNF-α, NFKB and c-Jun protein and genes was determined using multiplex assay, Western blot and PCR. Animals were subjected to retrograde labeling of RGCs to determine the extent of RGC survival. RGC survival was also examined using Brn3A staining. Furthermore, visual functions of rats were determined using Morris water maze. It was observed that pre-treatment with MgAT protects against ET-1 induced increase in the retinal expression of IL-1ß, IL-6 and TNF-α proteins and genes. It also protected against ET-1 induced activation of NFKB and c-Jun. These effects of MgAT were associated with greater RGC survival and preservation of visual functions in rats. In conclusion, MgAT prevents ET-1 induced RGC loss and loss of visual functions by suppressing neuroinflammatory reaction in rat retinas.

Neuroprotection by trans-resveratrol against collagenase-induced neurological and neurobehavioural deficits in rats involves adenosine A1 receptors.

Objective: Trans-resveratrol has been shown to have neuroprotective effects and could be a promising therapeutic agent in the treatment of intracerebral haemorrhage (ICH). This study aimed to investigate the involvement of the adenosine A1 receptor (A1R) in trans-resveratrol-induced neuroprotection in rats with collagenase-induced ICH.Methods: Sixty male Sprague-Dawley rats weighing 330-380 g were randomly divided into five groups (n = 12): (i) control, (ii) sham-operated rats, (iii) ICH rats pretreated with vehicle (0.1% DMSO saline, i.c.v.), (iv) ICH rats pretreated with trans-resveratrol (0.9 µg, i.c.v.) and (v) ICH rats pretreated with trans-resveratrol (0.9 µg) and the A1R antagonist, DPCPX (2.5 µg, i.c.v.). Thirty minutes after pretreatment, ICH was induced by intrastriatal injection of collagenase (0.04 U). Forty-eight hours after ICH, the rats were assessed using a variety of neurobehavioural tests. Subsequently, rats were sacrificed and brains were subjected to gross morphological examination of the haematoma area and histological examination of the damaged area.Results: Severe neurobehavioural deficits and haematoma with diffuse oedema were observed after intrastriatal collagenase injection. Pretreatment with trans-resveratrol partially restored general locomotor activity, muscle strength and coordination, which was accompanied with reduction of haematoma volume by 73.22% (P < 0.05) and damaged area by 60.77% (P < 0.05) in comparison to the vehicle-pretreated ICH group. The trans-resveratrol-induced improvement in neurobehavioural outcomes and morphological features of brain tissues was inhibited by DPCPX pretreatment.Conclusion: This study demonstrates that the A1R activation is possibly the mechanism underlying the trans-resveratrol-induced neurological and neurobehavioural protection in rats with ICH.

Neuroprotective effects of brain-derived neurotrophic factor against amyloid beta 1-40-induced retinal and optic nerve damage.

Brain-derived neurotrophic factor (BDNF) could be considered a potential neuroprotective therapy in amyloid beta (Aß)-associated retinal and optic nerve degeneration. Hence, in this study we investigated the neuroprotective effect of BDNF against Aß1-40-induced retinal and optic nerve injury. In this study, exposure to Aß1-40 was associated with retinal and optic nerve injury. TUNEL staining showed significant reduction in the apoptotic cell count in the BDNF-treated group compared with Aß1-40 group. H&E-stained retinal sections also showed a striking reduction in neuronal cells in the ganglion cell layer (GCL) of retinas fourteen days after Aß1-40 exposure. By contrast, number of retinal cells was preserved in the retinas of BDNF-treated animals. After Aß1-40 exposure, visible axonal swelling was observed in optic nerve sections. However, the BDNF-treated group showed fewer changes in optic nerve; axonal swelling was less frequent and less marked. In the present study, exposure to Aß was associated with oxidative stress, whereas levels of retinal glutathione (GSH), superoxide dismutase (SOD) and catalase were significantly increased in BDNF-treated than in Aß1-40-treated rats. Both visual object recognition tests using an open-field arena and a Morris water maze showed that BDNF improved rats' ability to recognise visual cues (objects with different shapes) after Aß1-40 exposure, thus demonstrating that the visual performance of rats was relatively preserved following BDNF treatment. In conclusion, intravitreal treatment with BDNF prevents Aß1-40-induced retinal cell apoptosis and axon loss in the optic nerve of rats by reducing retinal oxidative stress and restoring retinal BDNF levels.

Dose-dependent effects of NMDA on retinal and optic nerve morphology in rats.

AIM: To investigate dose-dependent effects of N-methyl-D-aspartate (NMDA) on retinal and optic nerve morphology in rats. METHODS: Sprague Dawley rats, 180-250 g in weight were divided into four groups. Groups 1, 2, 3 and 4 were intravitreally administered with vehicle and NMDA at the doses 80, 160 and 320 nmol respectively. Seven days after injection, rats were euthanized, and their eyes were taken for optic nerve toluidine blue and retinal hematoxylin and eosin stainings. The TUNEL assay was done for detecting apoptotic cells. RESULTS: All groups treated with NMDA showed significantly reduced ganglion cell layer (GCL) thickness within inner retina, as compared to control group. Group NMDA 160 nmol showed a significantly greater GCL thickness than the group NMDA 320 nmol. Administration of NMDA also resulted in a dose-dependent decrease in the number of nuclei both per 100 µm GCL length and per 100 µm2 of GCL. Intravitreal NMDA injection caused dose-dependent damage to the optic nerve. The degeneration of nerve fibres with increased clearing of cytoplasm was observed more prominently as the NMDA dose increased. In accordance with the results of retinal morphometry analysis and optic nerve grading, TUNEL staining demonstrated NMDA-induced excitotoxic retinal injury in a dose-dependent manner. CONCLUSION: Our results demonstrate dose-dependent effects of NMDA on retinal and optic nerve morphology in rats that may be attributed to differences in the severity of excitotoxicity and oxidative stress. Our results also suggest that care should be taken while making dose selections experimentally so that the choice might best uphold study objectives.

Blood pressure lowering effect of Ficus deltoidea var kunstleri in spontaneously hypertensive rats: possible involvement of renin-angiotensin-aldosterone system, endothelial function and anti-oxidant system.

This study investigated the effects of a standardised ethanol and water extract of Ficus deltoidea var. Kunstleri (FDK) on blood pressure, renin-angiotensin-aldosterone system (RAAS), endothelial function and antioxidant system in spontaneously hypertensive rats (SHR). Seven groups of male SHR were administered orally in volumes of 0.5 mL of either FDK at doses of 500, 800, 1000 and 1300 mg kg- 1, or captopril at 50 mg kg- 1 or losartan at 10 mg kg- 1 body weight once daily for 4 weeks or 0.5 mL distilled water. Body weight, systolic blood pressures (SBP) and heart rate (HR) were measured every week. 24-hour urine samples were collected at weeks 0 and 4 for electrolyte analysis. At week 4, sera from rats in the control and 1000 mg kg- 1 of FDK treated groups were analyzed for electrolytes and components of RAAS, endothelial function and anti-oxidant capacity. SBP at week 4 was significantly lower in all treatment groups, including captopril and losartan, when compared to that of the controls. Compared to the controls, ACE activity and concentrations of angiotensin I, angiotensin II and aldosterone were lower whereas concentrations of angiotensinogen and angiotensin converting enzyme 2 were higher in FDK treated rats. Concentration of eNOS and total anti-oxidant capacity were higher in FDK treated rats. Urine calcium excretion was higher in FDK treated rats. In conclusion, it appears that ethanol and water extract of FDK decreases blood pressure in SHR, which might involve mechanisms that include RAAS, anti-oxidant and endothelial system.

Preventive Effect of Naringin on Metabolic Syndrome and Its Mechanism of Action: A Systematic Review.

BACKGROUND: Metabolic syndrome (MetS), which consists of cluster of conditions, hypertension, hyperlipidemia, hyperglycemia, and visceral obesity, is affecting population worldwide. Studies have shown that plant derived flavonoids have the ability to alleviate MetS. Naringin is a type of glycoside flavonoid found in most plant and it plays a critical role in the treatment of MetS due to its antioxidant activity and ability to regulate cytokines. METHODS: A systematic review was done to study the effects of naringin on the metabolic diseases using electronic databases which include Ovid and Scopus using specific descriptors published from the year 2010 till present to provide updated literature on this field. The articles were assessed and chosen based on the criteria in which the mechanisms and effects of naringin on different metabolic diseases were reported. RESULTS: Thirty-four articles were identified which referred to the studies that correspond to the previously stated criteria. Subsequently after screening for the articles that were published after the year 2010, finally, 19 articles were selected and assessed accordingly. Based on the assessment, naringin could alleviate MetS by reducing visceral obesity, blood glucose, blood pressure, and lipid profile and regulating cytokines. CONCLUSIONS: Naringin is an antioxidant that appears to be efficacious in alleviating MetS by preventing oxidative damage and proinflammatory cytokine release. However, the dosage used in animal studies might not be achieved in human trials. Thus, adequate investigation needs to be conducted to confirm naringin's effects on humans.

Intraocular pressure-lowering effects of imidazo[1,2-a]- and pyrimido[1,2-a]benzimidazole compounds in rats with dexamethasone-induced ocular hypertension.

Ocular hypertension is believed to be involved in the etiology of primary open-angle glaucoma. Although many pharmaceutical agents have been shown to be effective for the reduction of intraocular pressure (IOP), a significant opportunity to improve glaucoma treatments remains. Thus, the aims of the present study were: (1) to evaluate the IOP-lowering effect of four compounds RU-551, RU-555, RU-839 (pyrimido[1,2-a]benzimidazole), and RU-615 (imidazo[1,2-a]benzimidazole) on steroid-induced ocular hypertension in rats after single drop and chronic applications; and (2) to test in silico and in vitro conventional rho-associated kinase (ROCK) inhibitory activity of the selected compound. This study demonstrated that RU-551, RU-555, RU-839, and RU-615 significantly reduced IOP in Sprague Dawley rats with dexamethasone (DEXA) induced ocular hypertension after single drop administration (0.1%), however RU-615 showed the best IOP lowering effect as indicated by maximum IOP reduction of 22.32% from baseline. Repeated dose topical application of RU-615 caused sustained reduction of IOP from baseline throughout the 3 weeks of treatment with maximum IOP reduction of 30.31% on day 15. This study also showed that the steroid-induced increase in IOP is associated with increased retinal oxidative stress and significant retinal ganglion cells (RGCs) loss. Prolonged treatment with RU-615 over 3 weeks results in normalization of IOP in DEXA-treated rats with partial restoration of retinal antioxidant status (catalase, glutathione and superoxide dismutase) and subsequent protective effect against RGC loss. Thus, IOP lowering activity of RU-615 together with antioxidant properties might be the factors that contribute to prevention of further RGC loss. In vitro part of this study explored the ROCK inhibitory activity of RU-615 using dexamethasone-treated human trabecular meshwork cells as a possible mechanism of action of its IOP lowering activity. However, this study didn't show conventional ROCK inhibition by RU-615 which was later confirmed by in silico consensus prediction. Therefore, in the future studies it is important to identify the upstream target receptors for RU-615 and then delineate the involved intracellular signalling pathways which are likely to be other than ROCK inhibition.

Taurine protects against NMDA-induced retinal damage by reducing retinal oxidative stress.

This study aimed to evaluate effect of TAU on NMDA-induced changes in retinal redox status, retinal cell apoptosis and retinal morphology in Sprague-Dawley rats. Taurine was injected intravitreally as pre-, co- or post-treatment with NMDA and 7 days post-treatment retinae were processed for estimation of oxidative stress, retinal morphology using H&E staining and retinal cell apoptosis using TUNEL staining. Treatment with TAU, particularly pre-treatment, significantly increased retinal glutathione, superoxide dismutase and catalase levels compared to NMDA-treated rats; whereas, the levels of malondialdehyde reduced significantly. Reduction in retinal oxidative stress in TAU pre-treated group was associated with significantly greater fractional thickness of ganglion cell layer within inner retina and retinal cell density in inner retina. TUNEL staining showed significantly reduced apoptotic cell count in TAU pre-treated group compared to NMDA group. It could be concluded that TAU protects against NMDA-induced retinal injury in rats by reducing retinal oxidative stress.

Antiapoptotic effect of taurine against NMDA-induced retinal excitotoxicity in rats.

OBJECTIVE: N-methyl-D-aspartate (NMDA) excitotoxicity has been proposed to mediate apoptosis of retinal ganglion cells (RGCs) in glaucoma. Taurine (TAU) has been shown to have neuroprotective properties, thus we examined anti-apoptotic effect of TAU against retinal damage after NMDA exposure. METHODOLOGY: Sprague-Dawley rats were divided into 5 groups of 33 each. Group 1 was administered intravitreally with PBS and group 2 was similarly injected with NMDA (160 nmol). Groups 3, 4 and 5 were injected with TAU (320 nmol) 24 hours before (pre-treatment), in combination (co-treatment) and 24 hours after (post-treatment) NMDA exposure respectively. Seven days after injection, rats were sacrificed; eyes were enucleated, fixed and processed for morphometric analysis, TUNEL and caspase-3 staining. Optic nerve morphology assessment was done using toluidine blue staining. The estimation of BDNF, pro/anti-apoptotic factors (Bax/Bcl-2) and caspase-3 activity in retina was done using ELISA technique. RESULTS: Severe degenerative changes were observed in retinae after intravitreal NMDA exposure. The retinal morphology in the TAU pre-treated group appeared more similar to the control retinae and demonstrated a higher number of nuclei than the NMDA group both per 100 µm length (by 1.5-fold, p < 0.001) and per 100 µm2 area (by 1.41-fold, p < 0.05) of the GCL. After NMDA exposure, visible axonal swelling was observed in optic nerve sections. In comparison with the changes observed in the NMDA treated group, the TAU treated group showed fewer prominent changes; axonal swelling was less frequent and less marked. Additionally, no marked glial cell changes were observed in the TAU-pretreated group. All TAU treated groups, particularly the pre-treated group, showed a significant decrease in the NMDA-induced optic nerve damage, with a 50% reduction (p < 0.001) in the mean grading compared to NMDA group. For the same, there was 25% decrease in co- and post-treatment groups, as compared with the NMDA group. Pre-treatment with TAU abolished apoptotic response to NMDA as indicated by decrease in the number of TUNEL- and caspase-3-positive cells. TAU pre-treatment also increased the Bcl-2 level (by 2.80-fold, p < 0.001) and decreased the level of Bax (by 34%, p < 0.01), and activity of caspase-3 (by 36%, p < 0.001) compared to NMDA group. IN CONCLUSION: our study revealed that pre-treatment with TAU prevents NMDA-induced retinal cell apoptosis more effectively than co- and post-treatment with TAU.

Taurine protects against retinal and optic nerve damage induced by endothelin-1 in rats via antioxidant effects.

Endothelin-1 (ET-1), a potent vasoconstrictor, is involved in retinal vascular dysregulation and oxidative stress in glaucomatous eyes. Taurine (TAU), a naturally occurring free amino acid, is known for its neuroprotective and antioxidant properties. Hence, we evaluated its neuroprotective properties against ET-1 induced retinal and optic nerve damage. ET-1 was administered intravitreally to Sprague-Dawley rats and TAU was injected as pre-, co- or post-treatment. Animals were euthanized seven days post TAU injection. Retinae and optic nerve were examined for morphology, and were also processed for caspase-3 immunostaining. Retinal redox status was estimated by measuring retinal superoxide dismutase, catalase, glutathione, and malondialdehyde levels using enzyme-linked immuosorbent assay. Histopathological examination showed significantly improved retinal and optic nerve morphology in TAU-treated groups. Morphometric examination showed that TAU pre-treatment provided marked protection against ET-1 induced damage to retina and optic nerve. In accordance with the morphological observations, immunostaining for caspase showed a significantly lesser number of apoptotic retinal cells in the TAU pre-treatment group. The retinal oxidative stress was reduced in all TAU-treated groups, and particularly in the pre-treatment group. The findings suggest that treatment with TAU, particularly pre-treatment, prevents apoptosis of retinal cells induced by ET-1 and hence prevents the changes in the morphology of retina and optic nerve. The protective effect of TAU against ET-1 induced retinal and optic nerve damage is associated with reduced retinal oxidative stress.

IOP lowering effect of topical trans-resveratrol involves adenosine receptors and TGF-ß2 signaling pathways.

Trans-resveratrol was earlier shown to lower intraocular pressure (IOP) in rats; however, its mechanisms of action remain unclear. It has been shown to modulate adenosine receptor (AR) and TGF-ß2 signaling, both of which play a role in regulating IOP. Hence, we investigated effects of trans-resveratrol on AR and TGF-ß2 signaling. Steroid-induced ocular hypertensive (SIOH) rats were pretreated with A1AR, phospholipase C (PLC) and ERK1/2 inhibitors and were subsequently treated with single drop of trans-resveratrol. Metalloproteinases (MMP)-2 and -9 were measured in aqueous humor (AH). In another set of experiments, effect of trans-resveratrol on AH level of tissue plasminogen activator (tPA) and urokinase plasminogen activator (uPA) was determined after single and multiple drop administration in SIOH rats. Effect of trans-resveratrol on ARs expression, PLC and pERK1/2 activation and MMPs, tPA and uPA secretion was determined using human trabecular meshwork cells (HTMC). Further, effect of trans-resveratrol on TGF-ß2 receptors, SMAD signaling molecules and uPA and tPA expression by HTMC was determined in the presence and absence of TGF-ß2. Pretreatment with A1AR, PLC and ERK1/2 inhibitors antagonized the IOP lowering effect of trans-resveratrol and caused significant reduction in the AH level of MMP-2 in SIOH rats. Trans-resveratrol increased A1AR and A2AAR expression, cellular PLC, pERK1/2 levels and MMP-2, tPA and uPA secretion by HTMC. Additionally, it produced TGFßRI downregulation and SMAD 7 upregulation. In conclusion, IOP lowering effect of trans-resveratrol involves upregulation of A1AR expression, PLC and ERK1/2 activation and increased MMP-2 secretion. It downregulates TGFßRI and upregulates SMAD7 hence, inhibits TGF-ß2 signaling.