Amelioration of diabetes-induced neurobehavioral and neurochemical changes by melatonin and nicotinamide: Implication of oxidative stress–PARP pathway

Distinct Hippocampal Expression Profiles of lncRNAs in Obese Type 2 Diabetes Mice Exhibiting Cognitive Impairment

Cognitive dysfunction has been accepted as a possible complication of type 2 diabetes (T2D), but few studies revealed the potential roles of Long non‑coding RNAs (lncRNAs) in cognitive dysfunction in T2D. The current research aims to demonstrate the specific expression patterns of lncRNA-mRNA in the hippocampi of T2D db/db mice exhibiting cognitive impairment. In this study, the results from behavioral tests showed that T2D db/db mice displayed short-term and spatial working memory deficits compared to db/m mice. Furthermore, western blot analysis demonstrated that compared with db/m mice, p-GSK3β (ser9) protein levels were markedly elevated in T2D db/db mice (P < 0.01). In addition, though not statistically significant, the ratio of p-Tau (Ser396) to Tau 46, α-Synuclein expression, and p-GSK3α (ser21) expression were also relatively higher in T2D db/db mice than in db/m mice. The microarray profiling revealed that 75 lncRNAs and 26 mRNAs were dysregulated in T2D db/db mice (> 2.0 fold change, P < 0.05). GO analysis demonstrated that the differentially expressed mRNAs participated in immune response, extracellular membrane-bounded organelle, and extracellular region. KEGG analysis revealed that the differentially expressed mRNAs were mainly involved in one carbon pool by folate, glyoxylate and dicarboxylate metabolism, autophagy, glycine, serine and threonine metabolism, and B cell receptor signaling pathway. A lncRNA‑mRNA coexpression network containing 71 lncRNAs and 26 mRNAs was built to investigate the interaction between lncRNA and mRNA. Collectively, these results revealed the differential hippocampal expression profiles of lncRNAs in T2D mice with cognitive dysfunction, and the findings from this study provide new clues for exploring the potential roles of lncRNAs in the pathogenesis of cognitive dysfunction in T2D.

Neuroprotective Effects of Sodium-Glucose Cotransporter-2 (SGLT2) Inhibitors (Gliflozins) on Diabetes-Induced Neurodegeneration and Neurotoxicity: A Graphical Review

Diabetes is a chronic endocrine disorder that negatively affects various body systems, including the nervous system. Diabetes can cause or exacerbate various neurological disorders, and diabetes-induced neurodegeneration can involve several mechanisms such as mitochondrial dysfunction, activation of oxidative stress, neuronal inflammation, and cell death. In recent years, the management of diabetes-induced neurodegeneration has relied on several types of drugs, including sodium-glucose cotransporter-2 (SGLT2) inhibitors, also called gliflozins. In addition to exerting powerful effects in reducing blood glucose, gliflozins have strong anti-neuro-inflammatory characteristics that function by inhibiting oxidative stress and cell death in the nervous system in diabetic subjects. This review presents the molecular pathways involved in diabetes-induced neurodegeneration and evaluates the clinical and laboratory studies investigating the neuroprotective effects of gliflozins against diabetes-induced neurodegeneration, with discussion about the contributing roles of diverse molecular pathways, such as mitochondrial dysfunction, oxidative stress, neuro-inflammation, and cell death. Several databases-including Web of Science, Scopus, PubMed, Google Scholar, and various publishers, such as Springer, Wiley, and Elsevier-were searched for keywords regarding the neuroprotective effects of gliflozins against diabetes-triggered neurodegenerative events. Additionally, anti-neuro-inflammatory, anti-oxidative stress, and anti-cell death keywords were applied to evaluate potential neuronal protection mechanisms of gliflozins in diabetes subjects. The search period considered valid peer-reviewed studies published from January 2000 to July 2023. The current body of literature suggests that gliflozins can exert neuroprotective effects against diabetes-induced neurodegenerative events and neuronal dysfunction, and these effects are mediated via activation of mitochondrial function and prevention of cell death processes, oxidative stress, and inflammation in neurons affected by diabetes. Gliflozins can confer neuroprotective properties in diabetes-triggered neurodegeneration, and these effects are mediated by inhibiting oxidative stress, inflammation, and cell death.

Plant-Derived Bioactive Compounds: Exploring Neuroprotective, Metabolic, and Hepatoprotective Effects for Health Promotion and Disease Prevention

There is a growing trend among consumers to seek out natural foods and products with natural ingredients. This shift in consumer preferences had a direct impact on both food and pharmaceutical industries, leading to a focus of scientific research and commercial efforts to meet these new demands. The aim of this work is to review recent available scientific data on foods of interest, such as the artichoke, gooseberry, and polygonoideae plants, as well as olive oil and red raspberries. Interestingly, the urgency of solutions to the climate change emergency has brought new attention to by-products of grapevine bunch stem and cane, which have been found to contain bioactive compounds with potential health benefits. There is a pressing need for a faster process of translating scientific knowledge from the laboratory to real-world applications, especially in the face of the increasing societal burden associated with non-communicable diseases (NCDs), environmental crises, the post-pandemic world, and ongoing violent conflicts around the world.

Supplementation of probiotic Bifidobacterium breve Bif11 reverses neurobehavioural deficits, inflammatory changes and oxidative stress in Parkinson's disease model

Human gut microbiota are thought to affect different physiological processes in the body, including brain functions. Gut dysbiosis has been linked to the progression of Parkinson's disease (PD) and thus, restoring the healthy gut microbiota with supplementation of putative probiotic strains can confer some benefits in PD. In the current study, we explored the neuroprotective potential of Bifidobacterium breve Bif11 supplementation in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine hydrochloride (MPTP) treated female Sprague Dawley rats. This study investigated the behavioural, molecular and biochemical parameters in the MPTP rat model. A pharmacological intervention of Bif11 at doses of 1 × 1010 CFU and 2 × 1010 CFU for 21 days was found to attenuate the cognitive and motor changes in the MPTP rat model. Furthermore, it also increased the tyrosine hydroxylase levels, reduced pro-inflammatory markers and decreased oxidative and nitrosative stress in the mid brain of MPTP-lesioned rats. Bif11 supplementation even restored the levels of short-chain fatty acids and decreased intestinal epithelial permeability in MPTP-induced PD model rats. In summary, these findings demonstrate that B. breve Bif11 has the potential to ameliorate symptoms of PD. However, this therapy needs to be further investigated with in-depth mechanistic insights in the future for the treatment of PD.

Evaluating the effectiveness of melatonin in reducing the risk of foot ulcers in diabetic patients

Objectives

Diabetes and its complications, as a major health concern, are associated with morbidity and mortality around the world. One of these complications is diabetic foot ulcer. Factors such as hyperglycemia, neuropathy, vascular damage and impaired immune system can cause foot ulcers. The present review aims to study the potential effects of melatonin, the main product of pineal glands, on diabetic foot ulcers.

Methods

A narrative review was performed using present literature in an attempt to identify the different aspects of melatonin's impact on diabetic foot ulcers by searching related keywords in electronic databases without any restriction.

Results

This review shows that, melatonin has anti-diabetic effects. It is effective in reducing the risk of hyperglycemia, neuropathy, vascular damage and immune system impairment in diabetic patients. By reducing these complications with melatonin, correspondingly, the incidence of diabetic foot ulcers may also decrease in these patients.

Conclusions

The results of this study indicate promising properties of melatonin while dealing with diabetic foot ulcers and their common underlying conditions, but still, it needs to be investigated more in future studies.

Insulin effects on core neurotransmitter pathways involved in schizophrenia neurobiology: a meta-analysis of preclinical studies. Implications for the treatment

Impairment of insulin action and metabolic dysregulation have traditionally been associated with schizophrenia, although the molecular basis of such association remains still elusive. The present meta-analysis aims to assess the impact of insulin action manipulations (i.e., hyperinsulinemia, hypoinsulinemia, systemic or brain insulin resistance) on glutamatergic, dopaminergic, γ-aminobutyric acid (GABA)ergic, and serotonergic pathways in the central nervous system. More than one hundred outcomes, including transcript or protein levels, kinetic parameters, and other components of the neurotransmitter pathways, were collected from cultured cells, animals, or humans, and meta-analyzed by applying a random-effects model and adopting Hedges'g to compare means. Two hundred fifteen studies met the inclusion criteria, of which 180 entered the quantitative synthesis. Significant impairments in key regulators of synaptic plasticity processes were detected as the result of insulin handlings. Specifically, protein levels of N-methyl-D-aspartate receptor (NMDAR) subunits including type 2A (NR2A) (Hedges' g = -0.95, 95%C.I. = -1.50, -0.39; p = 0.001; I2 = 47.46%) and 2B (NR2B) (Hedges'g = -0.69, 95%C.I. = -1.35, -0.02; p = 0.043; I2 = 62.09%), and Postsynaptic density protein 95 (PSD-95) (Hedges'g = -0.91, 95%C.I. = -1.51, -0.32; p = 0.003; I2 = 77.81%) were found reduced in insulin-resistant animal models. Moreover, insulin-resistant animals showed significantly impaired dopamine transporter activity, whereas the dopamine D2 receptor mRNA expression (Hedges'g = 3.259; 95%C.I. = 0.497, 6.020; p = 0.021; I2 = 90.61%) increased under insulin deficiency conditions. Insulin action modulated glutamate and GABA release, as well as several enzymes involved in GABA and serotonin synthesis. These results suggest that brain neurotransmitter systems are susceptible to insulin signaling abnormalities, resembling the discrete psychotic disorders' neurobiology and possibly contributing to the development of neurobiological hallmarks of treatment-resistant schizophrenia.

Amelioration of Parkinson's disease by pharmacological inhibition and knockdown of redox sensitive TRPC5 channels: Focus on mitochondrial health

AIMS

Transient receptor potential canonical 5 (TRPC5) channels are redox-sensitive cation-permeable channels involved in temperature and mechanical sensation. Increased expression and over-activation of these channels has been implicated in several central nervous system disorders such as epilepsy, depression, traumatic brain injury, anxiety, Huntington's disease and stroke. TRPC5 channel activation causes increased calcium influx which in turn activates numerous downstream signalling pathways involved in the pathophysiology of neurological disorders. Therefore, we hypothesized that pharmacological blockade and knockdown of TRPC5 channels could attenuate the behavioural deficits and molecular changes seen in CNS disease models such as MPTP/MPP⁺ induced Parkinson's disease (PD).

MATERIALS AND METHODS

In the present study, PD was induced after bilateral intranigral infusion of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to the Sprague Dawley rats. Additionally, SH-SY5Y neurons were exposed to 1-methyl-4-phenylpyridinium (MPP⁺) to further determine the role of TRPC5 channels in PD.

KEY FINDINGS

We used clemizole hydrochloride, a potent TRPC5 channel blocker, to reverse the behavioural deficits, molecular changes and biochemical parameters in MPTP/MPP⁺-induced-PD. Furthermore, knockdown of TRPC5 expression using siRNA also closely phenocopies these effects. We further observed restoration of tyrosine hydroxylase levels and improved mitochondrial health following clemizole treatment and TRPC5 knockdown. These changes were accompanied by diminished calcium influx, reduced levels of reactive oxygen species and decreased apoptotic signalling in the PD models.

SIGNIFICANCE

These findings collectively suggest that increased expression of TRPC5 channels is a potential risk factor for PD and opens a new therapeutic window for the development of pharmacological agents targeting neurodegeneration and PD.

2-Aminoethoxydiphenyl borate ameliorates mitochondrial dysfunctions in MPTP/MPP+ model of Parkinson's disease

Mitochondrial dysfunction is closely linked with the pathophysiology of several neurodegenerative disorders including Parkinson's disease (PD). Despite several therapeutic advancements related to symptomatic modification of PD pathology, strategies targeting mitochondrial dysfunctions remain largely elusive. Recently, transient receptor potential (TRP) channels have been shown to play a pivotal role in the control of mitochondrial and neuronal functioning in PD. In this study, the effect of 2-aminoethoxydiphenyl borate (2-APB), TRP channel blocker was investigated in the context of mitochondrial dysfunctions in 1-methyl-4-phenylpyridinium (MPP⁺)-treated SH-SY5Y cells and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-administered Sprague Dawley rats. MPP⁺-treated SH-SY5Y cells exhibited reductions in cell viability, generation of reactive oxygen species (ROS) and loss of mitochondrial membrane potential. Co-treatment with 2-APB led to an increase in cell viability, reduction in intracellular and mitochondrial ROS and improvement in mitochondrial membrane potential compared to MPP⁺-treated SH-SY5Y cells. In addition, intranigral administration of MPTP led to a significant reduction in motor function in the rats. Fourteen days of 2-APB (3 and 10 mg/kg, i.p.) treatment improved behavioural parameters. MPTP-induced decrease in complex I activity and mitochondrial potential were also blocked by 2-APB in the mitochondria isolated from the brain regions i.e. midbrain and striatum. MPTP-induced decrease in tyrosine hydroxylase levels were also restored by 2-APB. Moreover, MPTP-induced reduction in proteins involved in mitochondrial biogenesis, viz. peroxisome proliferator-activated-receptor-gamma coactivator and mitochondrial transcription factor-A were increased after 2-APB treatment in vivo. In summary, 2-APB has a promising neuroprotective role in the MPP⁺/MPTP models of PD via targeting mitochondrial dysfunctions and biogenesis.

Analysis of Melatonin-Modulating Effects Against Tartrazine-Induced Neurotoxicity in Male Rats: Biochemical, Pathological and Immunohistochemical Markers

Tartrazine (E-102) is one of the most widely used artificial food azo-colors that can be metabolized to highly sensitizing aromatic amines such as sulphanilic acid. These metabolites are oxidized to N-hydroxy derivatives that cause neurotoxicity. Melatonin is a neurohormone. That possesses a free-radical scavenging effect. The present work was mainly designed to evaluate the possible ameliorative role of melatonin against tartrazine induced neurotoxicity in cerebral cortex and cerebellum of male rats. Adult male rats were administered orally with tartrazine (7.5 mg/kg) with or without melatonin (10 mg/kg) daily for four weeks. The data revealed that tartrazine induced redox disruptions as measured by significant (p < 0.05) increased malondialdehyde (MDA) level and inhibition of (GSH) concentration and catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx) antioxidant enzyme activities. Besides, brain acetyl cholin (Ach) and gamma-aminobutyric acid (GABA) were elevated while, dopamine (DA) was depleted in trtrazine -treated rats. Moreover, tartrazine caused a significant (p < 0.05) increase in the brain interleukin-6 (IL-6), interleukin-1β (IL-1 β) and tumor necrosis factor-α (TNFα). At the tissue level, tartrazine caused severe histopathological changes in the cerebellum and cerebral cortex of rats. The immunohistochemical results elucidated strong positive expression for Caspase-3 and GFAP and weak immune reaction for BcL2 and synaptophysin in tatrazine- treated rats. The administration of melatonin to tartrazine -administered rats remarkably alleviated all the aforementioned tartrzine-induced effects. It could be concluded that, melatonin has a potent ameliorative effect against tartrazine induced neurotoxicity via the attenuation of oxidative/antioxidative responses.

Neuroprotective Potential of HC070, a Potent TRPC5 Channel Inhibitor in Parkinson's Disease Models: A Behavioral and Mechanistic Study

Transient receptor potential canonical 5 (TRPC5) channels are predominantly expressed in the striatum and substantia nigra of the brain. These channels are permeable to calcium ions and are activated by oxidative stress. The physiological involvement of TRPC5 channels in temperature and mechanical sensation is well documented; however, evidence for their involvement in the pathophysiology of neurodegenerative disorders like Parkinson's disease (PD) is sparse. Thus, in the present study, the role of TRPC5 channels and their associated downstream signaling was elucidated in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine/1-methyl-4-phenylpyridinium (MPTP/MPP⁺) model of PD. Bilateral intranigral administration of MPTP and 24 h MPP⁺ exposure were performed to induce PD in the Sprague-Dawley rats and SH-SY5Y cells, respectively. MPTP led to behavioral anomalies and TRPC5 overexpression accompanied by increased calcium influx, apoptosis, oxidative stress, and mitochondrial dysfunctions. In addition, tyrosine hydroxylase (TH) expression was significantly lower in the midbrain and substantia nigra compared to sham animals. Intraperitoneal administration of potent and selective TRPC5 inhibitor, HC070 (0.1 and 0.3 mg/kg) reversed the cognitive and motor deficits seen in MPTP-lesioned rats. It also restored the TH and TRPC5 expression both in the striatum and midbrain. Furthermore, in vitro and in vivo studies suggested improvements in mitochondrial health along with reduced oxidative stress, apoptosis, and calcium-mediated excitotoxicity. Together, these results showed that inhibition of TRPC5 channels plays a crucial part in the reversal of pathology in the MPTP/MPP⁺ model of Parkinson's disease.

New Advances on Pathophysiology of Diabetes Neuropathy and Pain Management: Potential Role of Melatonin and DPP-4 Inhibitors

Pre-diabetes and diabetes are growing threats to the modern world. Diabetes mellitus (DM) is associated with comorbidities such as hypertension (83.40%), obesity (90.49%), and dyslipidemia (93.43%), creating a substantial burden on patients and society. Reductive and oxidative (Redox) stress level imbalance and inflammation play an important role in DM progression. Various therapeutics have been investigated to treat these neuronal complications. Melatonin and dipeptidyl peptidase IV inhibitors (DPP-4i) are known to possess powerful antioxidant and anti-inflammatory properties and have garnered significant attention in the recent years. In this present review article, we have reviewed the recently published reports on the therapeutic efficiency of melatonin and DPP-4i in the treatment of DM. We summarized the efficacy of melatonin and DPP-4i in DM and associated complications of diabetic neuropathy (DNP) and neuropathic pain. Furthermore, we discussed the mechanisms of action and their efficacy in the alleviation of oxidative stress in DM.

Pharmacological Modulation of TRPM2 Channels via PARP Pathway Leads to Neuroprotection in MPTP-induced Parkinson's Disease in Sprague Dawley Rats

Transient receptor potential melastatin-2 (TRPM2) channels are cation channels activated by oxidative stress and ADP-ribose (ADPR). Role of TRPM2 channels has been postulated in several neurological disorders, but, it has not been explored in animal models of Parkinson's disease (PD). Thus, the role of TRPM2 and its associated poly (ADPR) polymerase (PARP) signaling pathways were investigated in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD rat model using TRPM2 inhibitor, 2-aminoethyl diphenyl borinate (2-APB), and PARP inhibitor, N-(6-Oxo-5,6-dihydrophenanthridin-2-yl)-(N,N-dimethylamino) acetamide hydrochloride (PJ-34). PD was induced by using a bilateral intranigral administration of MPTP in rats, and different parameters were evaluated. An increase in oxidative stress was observed, leading to locomotor and cognitive deficits in the PD rats. PD rats also showed an increased TRPM2 expression in the striatum and mid-brain accompanied by reduced expression of tyrosine hydroxylase (TH) in comparison to sham animals. Intraperitoneal administration of 2-APB and PJ-34 led to an improvement in the locomotor and cognitive deficits in comparison to MPTP-induced PD rats. These improvements were accompanied by a reduction in the levels of oxidative stress and an increase in TH levels in the striatum and mid-brain. In addition, these pharmacological interventions also led to a decrease in the expression of TRPM2 in PD in the striatum and mid-brain. Our results provide a rationale for the development of potent pharmacological agents targeting the TRPM2-PARP pathway to provide therapeutic benefits for the treatment of neurological diseases like PD.

Effects of Melatonin on Diabetic Neuropathy and Retinopathy

Diabetes mellitus (DM) leads to complications, the majority of which are nephropathy, retinopathy, and neuropathy. Redox imbalance and inflammation are important components of the pathophysiology of these complications. Many studies have been conducted to find a specific treatment for these neural complications, and some of them have investigated the therapeutic potential of melatonin (MEL), an anti-inflammatory agent and powerful antioxidant. In the present article, we review studies published over the past 21 years on the therapeutic efficacy of MEL in the treatment of DM-induced neural complications. Reports suggest that there is a real prospect of using MEL as an adjuvant treatment for hypoglycemic agents. However, analysis shows that there is a wide range of approaches regarding the doses used, duration of treatment, and treatment times in relation to the temporal course of DM. This wide range hinders an objective analysis of advances and prospective vision of the paths to be followed for the unequivocal establishment of parameters to be used in an eventual therapeutic validation of MEL in neural complications of DM.

Acute Diallyl Disulfide Administration Prevents and Reveres Lipopolysaccharide-Induced Depression-Like Behaviors in Mice via Regulating Neuroinflammation and Oxido-Nitrosative Stress

Neuroinflammation and oxidative stress play critical roles in pathogenesis of depression. Diallyl disulfide (DADS), an active compound in garlic oil, has been shown to exhibit obvious anti-inflammatory and anti-oxidative activities. Preliminary evidence indicates that depression is associated with high levels of pro-inflammatory cytokines and oxidative markers, suggesting that inhibition of neuroinflammatory response and oxidative stress may be beneficial for depression interruption. Here, we investigated the antidepressant effect of DADS as well as it mechanisms in a depression-like model induced by lipopolysaccharide (LPS). Similarly to imipramine (10 mg/kg), a clinical antidepressant, DADS (40 or 80 mg/kg), which was administered 1 h before LPS treatment (pre-LPS) or 1.5 h and 23.5 h after LPS treatment (post-LPS), prevented and reversed LPS (100 μg/kg)-induced increase in immobility time in the tail suspension test (TST) and forced swim test (FST) in mice. Mechanistic studies revealed that DADS pre-treatment or post-treatment at the dose of 40 and 80 mg/kg prevented and reversed (i) LPS-induced increases in interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and nitric oxide (NO) levels in the hippocampus and prefrontal cortex, (ii) LPS-induced increases in contents of malondialdehyde (MDA), a parameter reflecting high levels of oxidative stress, and (iii) LPS-induced decreases in contents of GSH, a marker reflecting weakened anti-oxidative ability, in the hippocampus and prefrontal cortex in mice. These results indicate that DADS is comparable to imipramine in effectively ameliorating LPS-induced depression-like behaviors in mice, providing a potential value for DADS in prevention and/or therapy of depression.

Synthesis and Biological Evaluation of Benzimidazole Derivatives as Potential Neuroprotective Agents in an Ethanol-Induced Rodent Model

Alzheimer's disease (AD) is the most devastating and progressive neurodegenerative disease in middle to elder aged people, which can be exacerbated by lifestyle factors. Recent longitudinal studies demonstrated that alcohol consumption exacerbates memory impairments in adults. However, the underlying mechanism of alcohol-induced memory impairment is still elusive. The increased cellular manifestation of reactive oxygen species (ROS) and the production of numerous proinflammatory markers play a critical role in the neurodegeneration and pathogenesis of AD. Therefore, reducing neurodegeneration by decreasing oxidative stress and neuroinflammation may provide a potential therapeutic roadmap for the treatment of AD. In this study, eight new benzimidazole acetamide derivatives (FP1, FP2, FP5-FP10) were synthesized and characterized to investigate its neuroprotective effects in ethanol-induced neurodegeneration in a rat model. Further, three derivatives (FP1, FP7, and FP8) were selected for in vivo molecular analysis based on preliminary in vitro antioxidant screening assay. Molecular docking analysis was performed to assess the affinity of synthesized benzimidazole acetamide derivatives against selected proinflammatory targets (TNF-α, IL-6). Biochemical analysis revealed elevated expression of neuroinflammatory markers (TNF-α, NF-κB, IL-6, NLRP3), increased cellular oxidative stress, and reduced antioxidant enzymes in ethanol-exposed rats brain. Notably, pretreatment with new benzimidazole acetamide derivatives (FP1, FP7, and FP8) significantly modulated the ethanol-induced memory deficits, oxidative stress, and proinflammatory markers (TNF-α, NF-κB, IL-6, NLRP3) in the cortex. The multipurpose nature of acetamide containing benzimidazole nucleus and its versatile affinity toward numerous receptors highlight its multistep targeting potential. These results indicated the neuroprotective potential of benzimidazole acetamide derivatives (FP1, FP7, and FP8) as novel therapeutic candidates in ethanol-induced neurodegeneration which may partially be due to inhibition of the neuroinflammatory-oxidative stress vicious cycle.

Melatonin ameliorates diabetes-induced brain injury in rats

Diabetic brain is a serious complication of diabetes, and it is associated with oxidative stress and neuronal injury. This study investigated the protective effect of melatonin (MLT) on diabetes-induced brain injury. A rat model of type 2 diabetes mellitus was produced by intraperitoneal injection of nicotinamide 100 mg/kg, followed by intraperitoneal injection of streptozotocin 55 mg/kg. The diabetic rats were orally administered MLT 10 mg/kg of body weight for 15 days. MLT remarkably downregulated serum glucose levels. It also improved levels of the lipid peroxidation product 4-hydroxynonenal, improved levels of antioxidants including glutathione, glutathione peroxidase and glutathione reductase in the brains of the diabetic rats, and this is indicative of the antioxidant potential of MLT. MLT also prevented increase in homocysteine, amyloid-β42 and tau levels in diabetic rats, and this suggests that it can reduce the risk of dementia. This is associated with reduction in the levels of the dopamine, serotonin, and glutamate and is indicative of the regulatory effect of MLT on neurotransmitters. Treatment with MLT improved diabetes-induced structural alteration in the hippocampus and cerebral cortex. MLT significantly reduced caspase-3 and Bax as well as significantly increase Bcl-2 protein and GFAP-positive astrocytes indicating its anti-apoptotic effect. MLT showed remarkable ameliorative effect against biochemical and molecular alterations in the brains of diabetic rats most likely through its antioxidant property.

Nicotinamide Improves Cognitive Function in Mice With Chronic Cerebral Hypoperfusion

Normal brain function requires steady blood supply to maintain stable energy state. When blood supply to the brain becomes suboptimal for a long period of time, chronic cerebral hypoperfusion (CCH) and a variety of brain changes may occur. CCH causes white matter injury and cognitive impairment. The present study investigated the effect of nicotinamide (NAM) on CCH-induced cognitive impairment and white matter damage in mice. Male C57Bl/6J mice aged 10–12 weeks (mean age = 11 ± 1 weeks) and weighing 24 - 29 g (mean weight = 26.5 ± 2.5 g) were randomly assigned to three groups (eight mice/group): sham group, CCH group and NAM group. Chronic cerebral hypoperfusion (CCH) was induced using standard methods. The treatment group mice received intraperitoneal injection of NAM at a dose of 200 mg/kg body weight (bwt) daily for 30 days. Learning, memory, anxiety, and depression-like behaviors were measured using Morris water maze test (MWMT), open field test (OFT), sucrose preference test (SPT), and forced swim test (FST), respectively. White matter damage and remodeling were determined via histological/ immunohistochemical analyses, and western blotting, respectively. The results showed that the time spent in target quadrant, number of crossings and escape latency were significantly lower in CCH group than in sham group, but they were significantly increased by NAM (p < 0.05). Mice in NAM group moved significantly faster and covered longer distances, when compared with those in CCH group (p < 0.05). The percentage of time spent in open arms and the number of entries to the open arms were significantly lower in CCH group than in NAM group (p < 0.05). Moreover, anhedonia and histologic scores (index of myelin injury) were significantly higher in CCH group than in sham group, but they were significantly reduced by NAM (p < 0.05). The results of immunohistochemical staining and Western blotting showed that the protein expressions of 2′, 3′-cyclic-nucleotide 3′-phosphodiesterase (CNPase) and synaptophysin were significantly downregulated in CCH group, relative to sham group, but they were significantly upregulated by NAM (p < 0.05). These results indicate that NAM improves cognitive function in mice with CCH.

Sesamin alleviates diabetes-associated behavioral deficits in rats: The role of inflammatory and neurotrophic factors

Neuroinflammation and loss of neurotrophic support have key roles in the pathophysiology of diabetes-associated behavioral deficits (DABD). Sesamin (Ses), a major lignan of sesame seed and its oil, shows anti-hyperglycemic, anti-oxidative, and neuroprotective effects. The present study was designed to assess the potential protective effects of Ses against DABD and investigate the roles of inflammatory markers and neurotrophic factors in streptozotocin (STZ)-induced diabetic rats. After confirmation of diabetes, Ses (30 mg/kg/day; P.O.) or insulin (6 IU/rat/day; S.C.) was administered to rats for eight consecutive weeks. During the eighth-week period of the study, behavioral functions of the animals were evaluated by employing standard behavioral paradigms. Moreover, inflammation status, neurotrophic factors, and histological changes were assessed in the cerebral cortex and hippocampal regions of the rats. The results of behavioral tests showed that STZ-induced diabetes increased anxiety-/depression-like behaviors, decreased locomotor/exploratory activities, and impaired passive avoidance learning and memory. These DABD were accompanied by neuroinflammation, lack of neurotrophic support, and neuronal loss in both cerebral cortex and hippocampus of the rats. Intriguingly, chronic treatment with Ses improved all the above-mentioned diabetes-related behavioral, biochemical, and histological deficits, and in some cases, it was even more effective than insulin therapy. In conclusion, the results suggest that Ses was capable of improving DABD, which might be ascribed, at least partly, to the reduction of blood glucose level, inhibition of neuroinflammation, and potentiation of neurotrophic factors.

Association of Serum Melatonin Level with Mild Cognitive Impairment in Type 2 Diabetic Patients: A Cross-Sectional Study

OBJECTIVES

Melatonin is an essential neuroendocrine hormone that participates in the regulation of sleep rhythm and cognitive function. This study aimed to determine serum melatonin levels with mild cognitive impairment (MCI) in patients with type 2 diabetes (T2DM).

METHODS

A total of 247 T2DM patients were recruited in this retrospective study and divided into 75 subjects with MCI and 172 with normal cognition. Cognitive function was evaluated by the Montreal Cognitive Assessment (MoCA). Their blood sample was examined for the level of melatonin and other biochemical parameters.

RESULTS

Melatonin concentration was decreased in MCI patients to non-MCI patients (P < 0.001). Melatonin level was negatively correlated with age (r = -0.202; P = 0.001), diabetes duration (r = -0.282; P < 0.001), serum HbA1c (r = -0.195; P = 0.002), hs-CRP (r = -0.324; P < 0.001), and TSH (r = -0.184; P = 0.004) levels and positively correlated with MoCA score, serum HDL-C (r = 0.145; P < 0.001), FT3 (r = 0.241; P < 0.001), and FT4 (r = 0.169; P = 0.008) levels. The multivariable analysis indicated that fewer years of formal education, longer diabetes duration, higher serum HbA1c, higher serum hs-CRP, and lower serum melatonin are the predisposing factors for MCI.

CONCLUSION

Lower melatonin level was associated with cognitive impairment in patients with T2DM. Melatonin might serve as a potential protective molecule against cognitive dysfunction in T2DM.

Neuroprotective Effect of 2-Aminoethoxydiphenyl Borate (2-APB) in Amyloid β-Induced Memory Dysfunction: A Mechanistic Study

β-Amyloid (Aβ) peptide is a characteristic feature of Alzheimer's disease (AD) and accumulation of Aβ is associated with loss of synaptic plasticity and neuronal cell death. Aggregation of Aβ initiates numerous molecular signalling pathways leading to oxidative stress, mitochondrial dysfunction as well as an imbalance of calcium ion influx homeostasis. Recently, it has been shown that transient receptor potential melastatin 2 (TRPM2), a non-selective calcium-permeable cation channel has been postulated to play a vital role in the neuronal death, indicating the potential of TRPM2 inhibition in CNS disease. In this study, neuroprotective potential of 2-aminoethoxydiphenyl borate (2-APB), a broad-spectrum calcium channels blocker was investigated in Aβ-induced memory deficits in rats. In addition, effect of 2-APB on TRPM2 channels gene and protein expressions and also on calcium and memory related proteins was investigated in the hippocampus. Intracerebroventricular (I.C.V.) administration of Aβ (Aβ_25-35, 10 μg) markedly induced cognitive impairment and upregulation of mRNA and protein expression of TRPM2 in the hippocampus. In addition, AChE activity was also increased in the cortex of the Aβ administered animals. Three-week treatment with 2-APB led to the down-regulation of TRPM2 mRNA and protein expression in the hippocampus and also improved the cognitive functions which was evident from the behavioral parameters. Moreover, 2-APB treatment also increased the calcium and memory associated proteins namely p-CaMKII, p-GSK-3β, p-CREB and PSD-95 in the hippocampus and reduced the mRNA level of calcium buffering proteins and calcineurin A (PPP3CA) in the hippocampus. Furthermore, 2-APB treatment significantly reduced the AChE activity in the cortex. Thus, our findings suggest the neuroprotective effect of 2-APB in Aβ-induced cognitive impairment.

Biochemical Evidence Indicates the Preventive Effect of Resveratrol and Nicotinamide in the Treatment of STZ-induced Diabetic Cataract

PURPOSE

High glucose level is a strong initiator of both oxidative stress and DNA damage to various cellular proteins. This activates the poly ADP-ribose polymerase (PARP) enzyme, which is responsible for disturbing physiological energy metabolic homeostasis. The present study aimed to elucidate the association between stress and the PARP pathway by using resveratrol (RSV) and nicotinamide (NAM, PARP inhibitor) to treat diabetic cataract.

METHOD

Albino rats were used for the experimental study. A single streptozotocin administration (55 mg/kg, i.p.) prompted diabetes in the animals. The experimental groups were the normal group (non-diabetic) and the diabetic groups: the diabetic control animals (group D), the diabetic animals treated with RSV at 40 mg/kg/day, i.p. (D+ RSV group), NAM at 100 and 300 mg/kg/day, i.p. (D+ NAM100, D+ NAM300 groups, respectively), and a combination of RSV and NAM i.p. (D+ RSV+NAM100 = Combi 1 group, D+ RSV+NAM300 = Combi 2 group). Glucose levels and the eyes were examined biweekly; various cataractogenic parameters in the lenses were examined after completion of the eight-week experimental protocol.

RESULTS

Compared to diabetic control, RSV monotherapy significantly decreased hyperglycemia and other lenticular alterations. NAM at the high dose only showed beneficial effects without altering the blood glucose level, lenticular aldose reductase (AR) activity, and sorbitol content, primarily restored the lenticular NAD level and decreased oxidative stress in diabetic rats. These findings regarding NAM treatment indicate that a pathway other than the antioxidant defense system and the polyol pathway, which might be due to PARP inhibition, is involved in diabetic cataracts. Moreover, compared to RSV monotherapy, combination treatments were effective.

CONCLUSION

These results indicate that hyperglycemia and oxidative-osmotic-nitrosative stress play central roles in the pathophysiology of diabetic cataracts. Moreover, our study also revealed that concurrent treatment with the RSV and NAM may prove useful in the pharmacotherapy of diabetes and its secondary complications such as cataract.

Melatonin: new insights on its therapeutic properties in diabetic complications

Diabetes and diabetic complications are considered as leading causes of both morbidity and mortality in the world. Unfortunately, routine medical treatments used for affected patients possess undesirable side effects, including kidney and liver damages as well as gastrointestinal adverse reactions. Therefore, exploring the novel therapeutic strategies for diabetic patients is a crucial issue. It has been recently shown that melatonin, as main product of the pineal gland, despite its various pharmacological features including anticancer, anti-aging, antioxidant and anti-inflammatory effects, exerts anti-diabetic properties through regulating various cellular mechanisms. The aim of the present review is to describe potential roles of melatonin in the treatment of diabetes and its complications.

Amelioration of Repeated Restraint Stress-Induced Behavioral Deficits and Hippocampal Anomalies with Taurine Treatment in Mice

Taurine, an essential neutraceutical, has been reported to exhibit antioxidant and anti-inflammatory properties. Substantial evidence indicates that prolonged stress is one of the leading causes of psychological and physiological anomalies. Restraint stress (RS) rat model is the most widely used experimental model for the induction of chronic psycho-emotional stress. In the present study, Swiss albino male mice were restrained for 6 h/day for 28 consecutive days. Animals were divided into four groups: control, RS, RS + taurine, and taurine control group. Taurine, a potent antioxidant, was administered (200 mg/kg) orally along with RS for 28 days. The taurine intervention significantly restored the RS-induced neurobehavioral alterations evident by the elevated plus-maze, Morris water maze test, forced swim test, tail suspension test, and a sucrose preference test. Moreover, taurine significantly prevented hippocampal oxidative stress (lipid peroxidation, reduced glutathione, and nitrite) and other neurochemical (acetylcholinesterase, and IL-1β) anomalies. Using western blotting analyses, we demonstrate that taurine treatment significantly ameliorated the alterations in Brain-derived neurotrophic factor, caspase-3, and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) level in the hippocampus. Thus, Taurine effectively inhibited RS-induced oxidative stress, neuroinflammation, and apoptosis via a mechanism involving the inhibition of the NF-κB signaling pathway. In summary, our study is the first to demonstrate that NF-κB and caspase-3 inhibition, as well as BDNF augmentation, was involved in neuroprotective potential of taurine against RS-induced behavioural anomalies.

Graviola (Annona muricata) attenuates behavioural alterations and testicular oxidative stress induced by streptozotocin in diabetic rats

Oxidative stresses intensify the progression of diabetes-related behavioural changes and testicular injuries. Graviola (Annona muricata), a small tree of the Annonaceae family, has been investigated for its protective effects against diabetic complications, oxidative stress, and neuropathies. This study was planned to investigate the effects of graviola on behavioural alterations and testicular oxidative status of streptozotocin (STZ; 65 mg/kg)-induced diabetic rats. Forty adult male Wistar rats were equally allocated into four groups: control (received normal saline 8 ml/kg orally once daily), diabetic (received normal saline orally once daily), graviola (GR; received 100 mg/kg/day; orally once daily), and diabetic with graviola (Diabetic+GR; received 100 mg/kg/day; once daily). Behavioural functions were assessed using standard behavioural paradigms. Also, oxidative statuses of testis were evaluated. Results of behavioural observations showed that diabetes induced depression-like behaviours, reduction of exploratory and locomotor activities, decreased memory performance, and increased stress-linked behaviours. These variations in diabetic rats were happened due to oxidative stress. Interestingly, treatment of diabetic rats with graviola for four weeks alleviated all behavioural changes due to diabetes. Also, rats in graviola-treated groups had greater testicular testosterone and estradiol levels compared with diabetic rats due to significant rise in testicular acetyl-CoA acetyltransferase 2 expression. In the same context, graviola enhanced the antioxidant status of testicular tissues by significantly restoring the testicular glutathione and total superoxide dismutase that fell during diabetes. In addition, Graviola significantly decreased the expression of apoptotic (Bax) and inflammatory (interleukin-1β) testicular genes. In conclusion, these data propose that both the hypoglycemic and antioxidative potential of graviola are possible mechanisms that improve behavioural alterations and protect testis in diabetic animals. Concomitantly, further clinical studies in human are required to validate the current study.

Protective Role of Epigallocatechin Gallate in a Rat Model of Cisplatin-Induced Cerebral Inflammation and Oxidative Damage: Impact of Modulating NF-κB and Nrf2

Cisplatin is a widely used chemotherapeutic agent in treating various types of cancers. However, it can induce neurotoxicity and nephrotoxicity, limiting its dose and clinical use. Although previous studies indicated the direct link between cisplatin-induced central neurotoxicity and oxidative stress, the exact mechanism is not completely understood. Therefore, herein we investigated the effects of prophylactic and concurrent treatment with (-)-epigallocatechin-3-gallate (EGCG), a natural polyphenolic neuroprotective antioxidant, on cisplatin-induced brain toxicity in rats to delineate its molecular mechanism of action. We found that cisplatin initiated a cascade of genetic, biological, and histopathological changes in the brain cortex, inducing inflammatory cytokines, appearance of scattered inflammatory cells, nitro-oxidative stress, and apoptotic proteins in the cerebral cortex. However, EGCG not only protected against cisplatin-induced inflammatory burden but also ameliorated the induction of nitro-oxidative stress and apoptotic proteins triggered by cisplatin in the cerebral cortex of pre- and co-treated rats with respect to their unprotected counterparts. EGCG anti-inflammatory effect here may be attributed to the downregulation of nuclear factor kappa B (NF-κB). Additionally, this natural polyphenol significantly ameliorated cisplatin-elicited reduction in cerebral cortex brain-derived neurotrophic factor and acetylcholine esterase. Upregulation of nuclear factor erythroid 2-related factor 2 (Nrf2) and its downstream heme oxygenase-1 (HO-1) by EGCG prophylactic and concurrent administration here seems also to play a key role in the protective impact of EGCG against cisplatin toxicity through enhancing total antioxidant capacity. Thus, EGCG can be used as a promising prophylactic adjuvant for preventing the development of brain inflammation and oxidative damage associated with cisplatin chemotherapy.

Ellagic acid protects against diabetes-associated behavioral deficits in rats: Possible involved mechanisms

AIMS

Diabetes mellitus (DM), a chronic metabolic disease, is associated with behavioral deficits. It has been suggested that ellagic acid (EA), a natural polyphenol compound, has potent anti-diabetic, anti-inflammatory, and neuroprotective properties. The present study was aimed to explore the potential protective effects of EA against diabetes-associated behavioral deficits and verified possible involved mechanisms.

MAIN METHODS

Fifty adult male Wistar rats were randomly divided into five groups: i.e., CON: normal rats treated with vehicle (5 ml/kg/day; P.O.), EA: normal rats treated with EA (50 mg/kg/day; P.O.), STZ: diabetic rats treated with vehicle (5 ml/kg/day; P.O.), STZ + INS: diabetic rats treated with insulin (6 IU/rat/day; S.C.), STZ + EA: diabetic rats treated with EA (50 mg/kg/day; P.O.). All the groups were under treatment for eight consecutive weeks. During the seventh and eighth weeks, behavioral functions of the rats were assessed by commonly used behavioral tests. Subsequently, pro- and anti-inflammatory cytokines, neurotrophic factors, and also histological changes were evaluated in both cerebral cortex and hippocampus of the rats.

KEY FINDINGS

Chronic EA treatment attenuated anxiety/depression-like behaviors, improved exploratory/locomotor activities, and ameliorated cognitive deficits in diabetic rats. These results were accompanied by decreased blood glucose levels, modulation of inflammation status, improved neurotrophic support, and amelioration of neuronal loss in diabetic rats. In some aspects, treatment with EA was even more effective than insulin therapy.

SIGNIFICANCE

The current work's data confirms that EA could potentially serve as a novel, promising, and accessible protective agent against diabetes-associated behavioral deficits, owing to its anti-hyperglycemic, anti-inflammatory, and neurotrophic properties.

A multifunctional bis-(-)-nor-meptazinol-oxalamide hybrid with metal-chelating property ameliorates Cu(II)-induced spatial learning and memory deficits via preventing neuroinflammation and oxido-nitrosative stress in mice

Excess copper exposure is a risk factor of neurodegeneration related to Alzheimer's disease (AD). Evidence indicates that, besides promoting amyloid β aggregation, activation of neuroinflammation and oxido-nitrosative stress (two key pathophysiological processes of AD) may also play important roles in Cu(II)-induced neuronal injury. Therefore, the copper-chelating strategy has gained attention in search for new anti-AD drugs. We previously reported a novel multifunctional compound N¹,N²-bis(3-(S)-meptazinol-propyl) oxalamide (ZLA), a bis-(-)-nor-meptazinol-oxalamide hybrid with properties of dual binding site acetylcholinesterase (AChE) inhibition and Cu(II)/Zn(II) chelation. The present study was aimed to explore its effect on cognitive deficits caused by intrahippocampal injection of Cu(II) in mice. Results showed that ZLA (2, 5 mg/kg; i.p.) treatment significantly ameliorated the Cu(II)-induced impairment of hippocampus-dependent learning and memory, whereas rivastigmine, an AChE inhibitor showing a similar potency of enzyme inhibition to ZLA, had no obvious effect. Immunohistochemical and Western blot analyses revealed that ZLA attenuated the decrease in hippocampal expression of microtubule-associated protein 2 (MAP2, a dendritic marker) in Cu(II)-challenged mice. Further analysis showed that ZLA suppressed the Cu(II)-evoked microglial activation. Moreover, it inhibited the Cu(II)-evoked production of pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and IL-1β and expression of inducible nitric oxide synthase in the hippocampus. The Cu(II)-induced oxidative and nitrosative stress in the hippocampus was also attenuated after ZLA treatment. Collectively, these results suggest that ZLA ameliorates the Cu(II)-caused cognitive deficits. Inhibition of neuroinflammation and oxido-nitrosative stress, and thus ameliorating neuronal injury, may be the potential mechanism for the anti-amnesic effect of ZLA.

Voluntary alcohol consumption exacerbated high fat diet-induced cognitive deficits by NF-κB-calpain dependent apoptotic cell death in rat hippocampus: Ameliorative effect of melatonin

Modern sedentary lifestyle with altered dietary habits imposes the risk of human health towards several metabolic disorders such as obesity. The metabolic insults negatively affect the mental health status and quality life of affected individuals. Melatonin is a potent antioxidant with anti-inflammatory and neuroprotective properties. The aim of the present study was to investigate the protective effect of melatonin on the cognitive and neurochemical deficits induced by the high-fat diet (HFD) and alcohol (ALC) alone or in combination (HFD + ALC) in rats. Male Wistar rats were given ALC (3-15% i.e. increased gradually) and HFD for 12 weeks in different experimental groups. After 12 weeks, we found that simultaneous consumption of HFD and ALC exacerbates cognitive dysfunction and neurochemical anomalies. However, melatonin (10 mg/kg/day, i.p.) treatment for four weeks significantly prevented memory deficits, oxidative stress and neuroinflammation in HFD, ALC and HFD + ALC groups. RT-PCR analysis showed down-regulation of nuclear factor erythroid 2-related factor 2 (Nrf-2) and heme oxygenase-1 (HO-1) in ALC and HFD + ALC groups. Moreover, caspase-3 and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) mRNA expression level were found up-regulated in hippocampus of HFD, ALC and HFD + ALC groups. However, calpain expression was found up-regulated only in the hippocampus of HFD + ALC group. Chronic treatment with melatonin significantly restored the aberrant gene expression level in HFD, ALC and HFD + ALC group. In conclusion, our findings indicated that melatonin can mitigate the HFD and ALC-induced cognitive deficits via attenuation of oxidative stress and calpain-1 dependent as well as independent caspase-3 mediated neuronal cell death.

Endoplasmic reticulum stress-induced neuronal inflammatory response and apoptosis likely plays a key role in the development of diabetic encephalopathy

We assumed that diabetic encephalopathy (DEP) may be induced by endoplasmic reticulum (ER)-mediated inflammation and apoptosis in central nervous system. To test this notion, here we investigated the neuronal ER stress and associated inflammation and apoptosis in a type 2 diabetes model induced with high-fat diet/streptozotocin in Sprague-Dawley rats. Elevated expressions of ER stress markers, including glucose-regulated protein 78 (GRP78), activating transcription factor-6 (ATF-6), X-box binding protein-1 (XBP-1), and C/EBP homologous protein, and phosphor-Jun N-terminal kinase (p-JNK) were evident in the hippocampus CA1 of diabetic rats. These changes were also accompanied with the activation of NF-κB and the increased levels of inflammatory cytokines, tumor necrosis factor-α (TNF-α) and Interleukin-6 (IL-6). Mechanistic study with in vitro cultured hippocampus neurons exposed to high glucose (HG), which induced a diabetes-like effects, shown by increased ER stress, JNK and NF-κB activation, and inflammatory response. Inhibition of ER stress by 4-phenylbutyrate (4-PBA) or blockade of JNK activity by specific inhibitor or transfection of DN-JNK attenuated HG-induced inflammation and associated apoptosis. To validate the in vitro finding, in vivo application of 4-PBA resulted in a significant reduction of diabetes-induced neuronal ER stress, inflammation and cell death, leading to the prevention of DEP. These results suggest that diabetes-induced neuronal ER stress plays the critical role for diabetes-induced neuronal inflammation and cell death, leading to the development of DEP.

2, 3, 5, 4'-Tetrahydroxystilbene-2-O-β-D-glucoside prevention of lipopolysaccharide-induced depressive-like behaviors in mice involves neuroinflammation and oxido-nitrosative stress inhibition

Although numerous hypotheses have been raised in recent years, the exact mechanisms that promote the development of major depression are largely unknown. Recently, strategies targeting the process of neuroinflammation and oxidative stress in depression have been attracting greater attention. 2, 3, 5, 4'-Tetrahydroxystilbene-2-O-β-D-glucoside (TSG), a compound purified from a traditional Chinese herbal medicine polygonummultiflorum, has been widely reported to inhibit neuroinflammation and oxidative stress. In this context, we investigated whether TSG affects lipopolysaccharide (LPS)-induced depressive-like behaviors in a manner associated with neuroinflammation and oxido-nitrosative stress. Results showed that administration of ICR mice with 0.83 mg/kg of LPS-induced typical depressive-like behaviors in the experiments of the tail-suspension test, the forced-swimming test, and sucrose preference, and these behaviors were prevented by TSG treatment (30 and 60 mg/kg). Further analysis showed that TSG pretreatment at the doses of 30 and 60 mg/kg not only inhibited the production of proinflammatory cytokines induced by LPS, such as interleukin-1β, interleukin-6, and tumor necrosis factor-α, but also prevented the LPS-induced enhancement of oxido-nitrosative stress in mouse hippocampus and prefrontal cortex. The LPS-induced decreases in brain-derived neurotrophic factor levels in the hippocampus and prefrontal cortex were also prevented by TSG treatment. Generally, our data provide evidence to show that TSG could be used to cope with depressive-like symptoms by inhibition of neuroinflammation and oxido-nitrosative stress.

Berberine Improves Diabetic Encephalopathy Through the SIRT1/ER Stress Pathway in db/db Mice

The association between diabetes and dementia has been well demonstrated by epidemiologic studies. Berberine (BBR) has been reported to ameliorate diabetes and diabetic encephalopathy (DE). However, the mechanism is still unknown. In this study, we employ a diabetic model, db/db mice, to explore whether BBR could protect DE through the SIRT1/endoplasmic reticulum (ER) stress pathway. Behavioral results (Morris water maze, Y-maze spontaneous alternation test, and fear conditioning test) showed that oral administration of BBR (50 mg/kg) improved the learning and memory ability. Furthermore, BBR promoted lipid metabolism and decreased fasting glucose in db/db mice. Moreover, western blot analysis revealed that BBR increased the synapse- and nerve-related protein expression (PSD95, SYN, and NGF) and decreased the protein expression of inflammatory factors (TNF-α and NF-κB) in the hippocampus of db/db mice. BBR also increased the protein expression of SIRT1 and downregulated ER stress-associated proteins (PERK, IRE-1α, eIF-2α, PDI, and CHOP) in the hippocampus of db/db mice. Taken together, the present results suggest that the SIRT1/ER stress pathway might be a crucial mechanism in the neuroprotective effect of BBR against DE.

Melatonin successfully rescues hippocampal bioenergetics and improves cognitive function following drug intoxication by promoting Nrf2-ARE signaling activity

Prolonged exposure to gamma-hydroxybutyric acid (GHB) would cause drug intoxication in which impaired cognitive function results from enhanced hippocampal oxidative stress may serve as a major symptom in this deficiency. Considering melatonin possesses significant anti-oxidative efficacy, this study aimed to determine whether melatonin would successfully promote the nuclear factor erythroid 2-related factor 2 and antioxidant responsive element (Nrf2-ARE) signaling, depress oxidative stress, and rescue hippocampal bioenergetics and cognitive function following drug intoxication injury. Adolescent rats subjected to 10 days of GHB were received melatonin at doses of either 10 or 100 mg/kg. Time-of-flight secondary ion mass spectrometry, biochemical assay, quantitative histochemistry, [¹⁴ C]-2-deoxyglucose analysis, together with Morris water maze were employed to detect the molecular signaling, oxidative status, bioenergetic level, as well as the cognitive performances, respectively. Results indicated that in GHB-intoxicated rats, enhanced oxidative stress, increased cholesterol level, and decreased anti-oxidative enzymes activities were detected in hippocampal regions. Intense oxidative stress paralleled well with reduced bioenergetics and poor performance in behavioral testing. However, in rats treated with melatonin following GHB intoxication, all above parameters and cognitive function were gradually returned to nearly normal levels. Melatonin also remarkably promoted the translocation of Nrf2 from cytoplasm to nucleus in a dose-dependent manner, thereby increased the Nrf2-ARE signaling-related downstream anti-oxidative enzymes activities. As melatonin effectively rescues hippocampal bioenergetics through depressing the oxidative stress by promoting Nrf2-ARE molecular machinery, this study thus highlights for the first time that clinical use of melatonin may serve as a therapeutic strategy to improve the cognitive function in unsuspecting victims suffered from GHB intoxication injury.

Piperine Augments the Protective Effect of Curcumin Against Lipopolysaccharide-Induced Neurobehavioral and Neurochemical Deficits in Mice

The aim of the present study was to investigate the protective effects of curcumin alone and in combination with piperine against lipopolysaccharide (LPS)-induced neurobehavioral and neurochemical deficits in the mice hippocampus. Mice were treated with curcumin (100, 200, and 400 mg/kg, p.o.) and piperine (20 mg/kg, p.o.) for 7 days followed by LPS (0.83 mg/kg, i.p.) administration. Animals exhibited anxiety and depressive-like phenotype after 3 and 24 h of LPS exposure, respectively. LPS administration increased the oxido-nitrosative stress as evident by elevated levels of malondialdehyde, nitrite, and depletion of glutathione level in the hippocampus. Furthermore, we found raised level of pro-inflammatory cytokines (IL-1β and TNF-α) in the hippocampus of LPS-treated mice. Pretreatment with curcumin alleviated LPS-induced neurobehavioral and neurochemical deficits. Furthermore, co-administration of curcumin with piperine significantly potentiated the neuroprotective effect of curcumin. These results demonstrate that piperine enhanced the neuroprotective effect of curcumin against LPS-induced neurobehavioral and neurochemical deficits.

Sodium Phenylbutyrate and Edaravone Abrogate Chronic Restraint Stress-Induced Behavioral Deficits: Implication of Oxido-Nitrosative, Endoplasmic Reticulum Stress Cascade, and Neuroinflammation

Chronic stress exposure can produce deleterious effects on the hippocampus (HC) which eventually leads to cognitive impairment and depression. Endoplasmic reticulum (ER) stress has been reported as one of the major culprits in the development of stress-induced cognitive impairment and depression. We investigated the neuroprotective efficacy of sodium phenylbutyrate (SPB), an ER stress inhibitor, and edaravone, a free radical scavenger, against chronic restraint stress (CRS)-induced cognitive deficits and anxiety- and depressive-like behavior in mice. Adult male Swiss albino mice were restrained for 6 h/day for 28 days and injected (i.p.) with SPB (40 and 120 mg/kg) or edaravone (3 and 10 mg/kg) for the last seven days. After stress cessation, the anxiety- and depressive-like behavior along with spatial learning and memory were examined. Furthermore, oxido-nitrosative stress, proinflammatory cytokines, and gene expression level of ER stress-related genes were assessed in HC and prefrontal cortex (PFC). CRS-exposed mice showed anxiety- and depressive-like behavior, which was significantly improved by SPB and edaravone treatment. In addition, SPB and edaravone treatment significantly alleviated CRS-induced spatial learning and memory impairment. Furthermore, CRS-evoked oxido-nitrosative stress, neuroinflammation, and depletion of Brain-derived neurotrophic factor were significantly ameliorated by SPB and edaravone treatment. We found significant up-regulation of ER stress-related genes in both HC and PFC regions, which were suppressed by SPB and edaravone treatment in CRS mice. Our study provides evidence that SPB and edaravone exerted neuroprotective effects on CRS-induced cognitive deficits and anxiety- and depressive-like behavior, which is possibly coupled with inhibition of oxido-nitrosative stress, neuroinflammation, and ER stress cascade.

Edaravone alleviates cisplatin-induced neurobehavioral deficits via modulation of oxidative stress and inflammatory mediators in the rat hippocampus

Cisplatin is a chemotherapeutic agent used in the treatment of malignant tumors. A major clinical limitation of cisplatin is its potential toxic effects, including neurotoxicity. Edaravone, a potent free radical scavenger, has been reported to have the neuroprotective effect against neurological deficits. The aim of the present study was to determine the neuroprotective effect of edaravone against cisplatin-induced behavioral and biochemical anomalies in male Wistar rats. Our results showed that cisplatin (5mg/kg/week, i.p.) administration for seven weeks caused marked cognitive deficits and motor incoordination in rats. This was accompanied by oxido-nitrosative stress, neuroinflammation, NF-κB activation and down-regulation of Nrf2/HO-1 gene expression level in the hippocampus. Edaravone (10mg/kg/week, i.p.) treatment for seven weeks inhibited the aforementioned neurobehavioral and neurochemical deficits. Furthermore, edaravone was found to up-regulate the gene expression level of Nrf2/HO-1 and prevented the cisplatin-induced NF-κB activation. These findings demonstrated that oxido-nitrosative stress and inflammatory signaling mediators play a key role in the development of cisplatin-induced neurobehavioral deficits which were prevented by edaravone treatment.

Hesperidin and Silibinin Ameliorate Aluminum-Induced Neurotoxicity: Modulation of Antioxidants and Inflammatory Cytokines Level in Mice Hippocampus

Mounting evidence suggests that long-term aluminum exposure results in severe toxic effects, including neurobehavioral and neurochemical anomalies. The present study was performed to examine the neuroprotective potential of hesperidin and silibinin against aluminum chloride (AlCl3)-induced neurotoxicity in mice. AlCl3 (100 mg/kg/day) was injected daily through oral gavage for 42 days. Concomitantly, hesperidin (50 and 100 mg/kg/day, p.o.) and silibinin (100 and 200 mg/kg/day, p.o.) was administered for 42 days in different groups. The extent of cognitive impairment was assessed by Morris water maze and novel object recognition test on the 43rd day. Neurotoxicity was assessed by measuring oxido-nitrosative stress and proinflammatory cytokines in the hippocampus of mice. Six weeks treatment with AlCl3 caused cognitive impairment as indicated by an increase in the retention latency time and reduction in the percentage of recognition index. AlCl3-treated group showed oxido-nitrosative stress as indicated by increase in the level of lipid peroxidation, nitrite and depleted reduced glutathione, catalase activity in the hippocampus. Moreover, the chronic AlCl3 administration raised the proinflammatory cytokines (interleukin-1β and tumor necrosis factor-α) level and increased acetylcholinesterase activity and reduced the BDNF content in the hippocampus of AlCl3-treated animals. However, chronic treatment with hesperidin and silibinin at higher doses significantly ameliorated the AlCl3-induced cognitive impairment and hippocampal biochemical anomalies. The present study clearly indicated that hesperidin and silibinin exert neuroprotective effects against AlCl3-induced cognitive impairment and neurochemical changes. Amelioration of cognitive impairment may be attributed to the impediment of oxido-nitrosative stress and inflammation in the hippocampus.

Quantitative-profiling of neurotransmitter abnormalities in the disease progression of experimental diabetic encephalopathy rat

Diabetic encephalopathy (DE) is one of the most prevalent chronic complications of diabetes mellitus (DM), with neither effective prevention nor proven therapeutic regimen. This study aims to uncover the potential dysregulation pattern of the neurotransmitters in a rat model of streptozotocin (STZ)-induced experimental DE. For that purpose, male Sprague–Dawley (SD) rats were treated with a single intraperitoneal injection of STZ. Cognitive performance was detected with the Morris water maze (MWM) test. Serum, cerebrospinal fluid (CSF), and brain tissues were collected to measure the levels of neurotransmitters. Compared with the control rats, the acetylcholine (ACh) levels in serum, CSF, hippocampus, and cortex were all significantly down-regulated as early as 6 weeks in the STZ treatment group. In contrast, the glutamate (Glu) levels were decreased in CSF and the hippocampus, but unaffected in the serum and cortex of STZ-treated rats. As for γ-aminobutyric acid (GABA), it was down-regulated in serum, but up-regulated in CSF, hippocampus, and the cortex in the STZ-treated group. The mRNA expressions of neurotransmitter-related rate limiting enzymes (including AChE, GAD1, and GAD2) and pro-inflammatory cytokines (including IL-1β and TNF-α) were all increased in the DE rats. Our data suggest that DM induces isoform-dependent and tissue-specific neurotransmitter abnormalities, and that neuroinflammation may underlay the nervous system dysfunction observed in the progression of DE.

Edaravone abrogates LPS-induced behavioral anomalies, neuroinflammation and PARP-1

Poly(ADP-ribose) polymerase-1 (PARP-1) is a DNA nick-sensor enzyme that functions at the center of cellular stress response and affects the immune system at several key points, and thus modulates inflammatory diseases. Our previous study demonstrated that lipopolysaccharide (LPS)-induced depressive-like behavior in mice can be ameliorated by 3-aminobenzamide, which is a PARP-1 inhibitor. In the present study we've examined the effect of a free radical scavenger, edaravone pretreatment against LPS-induced anxiety and depressive-like behavior as well as various hippocampal biochemical parameters including PARP-1. Male Swiss albino mice were treated with edaravone (3 & 10mg/kgi.p.) once daily for 14days. On the 14th day 30min after edaravone treatment mice were challenged with LPS (1mg/kgi.p.). After 3h and 24h of LPS administration we've tested mice for anxiety and depressive-like behaviors respectively. Western blotting analysis of PARP-1 in hippocampus was carried out after 12h of LPS administration. Moreover, after 24h of LPS administration serum corticosterone, hippocampal BDNF, oxido-nitrosative stress and pro-inflammatory cytokines were estimated by ELISA. Results showed that pretreatment of edaravone (10mg/kg) ameliorates LPS-induced anxiety and depressive-like behavior. Western blotting analysis showed that LPS-induced anomalous expression of PARP-1 significantly reverses by the pretreatment of edaravone (10mg/kg). Biochemical analyses revealed that LPS significantly diminishes BDNF, increases pro-inflammatory cytokines and oxido-nitrosative stress in the hippocampus. However, pretreatment with edaravone (10mg/kg) prominently reversed all these biochemical alterations. Our study emphasized that edaravone pretreatment prevents LPS-induced anxiety and depressive-like behavior, mainly by impeding the inflammation, oxido-nitrosative stress and PARP-1 overexpression.

Inhibition of poly-ADP ribose polymerase enzyme activity prevents hyperglycemia-induced impairment of angiogenesis during wound healing

We previously reported a zebrafish model of type I diabetes mellitus (DM) that can be used to study the hyperglycemic (HG) and metabolic memory (MM) states within the same fish. Clinically, MM is defined as the persistence of diabetic complications even after glycemic control is pharmacologically achieved. In our zebrafish model, MM occurs following β-cell regeneration, which returns fish to euglycemia. During HG, fish acquire tissue deficits reflective of the complications seen in patients with DM and these deficits persist after fish return to euglycemia (MM). The unifying mechanism for the induction of diabetic complications involves a cascade of events that is initiated by the HG stimulation of poly-ADP ribose polymerase enzyme (Parp) activity. Additionally, recent evidence shows that the HG induction of Parp activity stimulates changes in epigenetic mechanisms that correlate with the MM state and the persistence of complications. Here we report that wound-induced angiogenesis is impaired in DM and remains impaired when fish return to a euglycemic state. Additionally, inhibition of Parp activity prevented the HG-induced wound angiogenesis deficiency observed. This approach can identify molecular targets that will provide potential new avenues for therapeutic discovery as angiogenesis imbalances are associated with all HG-damaged tissues.

Poly (ADP-ribose) polymerase-1 inhibitor, 3-aminobenzamide pretreatment ameliorates lipopolysaccharide-induced neurobehavioral and neurochemical anomalies in mice

Poly (ADP-ribose) polymerase-1 (PARP-1) functions at the center of cellular stress and sways the immune system at several key points, thus modulates inflammatory diseases. The antiinflammatory properties of PARP-1 inhibitors have been demonstrated ameliorating effect in various neuroinflammatory disorders. It has been reported that there is a close relationship between the inflammatory processes and major depressive disorder. In the present study, we have elucidated the role of oxidative-nitrosative stress-PARP-1 pathway in lipopolysaccharide (LPS)-induced neurobehavioral and neurochemical alterations in mice. 3-Aminobenzamide (10 and 30mg/kg) and imipramine (10 and 30mg/kg) were administered once daily for 14days. Mice were challenged with LPS (1mg/kg, i.p.) 30min after drug administration on the 14th day. The mRNA expression level of PARP-1 (12h after LPS injection) in the hippocampus was measured through quantitative real-time PCR. All the behavioral and biochemical parameters were assessed at 24h after LPS injection. The expression level of PARP-1mRNA was found significantly up-regulated in the hippocampus at 12h after LPS administration. Results showed that the LPS-challenged mice exhibited an increase in immobility time seen in forced swimming test and tail suspension test. LPS increased the levels of proinflammatory cytokines and oxido-nitrosative stress parameters in the hippocampus. However, pretreatment with 3-aminobenzamide (30mg/kg) significantly reversed the LPS-induced alterations in behavioral parameters, proinflammatory cytokines, oxidative-nitrosative stress and PARP-1 mRNA levels. Imipramine failed to prevent the up-regulation of PARP-1 induced by LPS administration. Our results emphasized that oxidative-nitrosative stress-PARP-1 cascade can play a key role in LPS-induced neurobehavioral and neurochemical anomalies.

Mangiferin ameliorates aluminium chloride-induced cognitive dysfunction via alleviation of hippocampal oxido-nitrosative stress, proinflammatory cytokines and acetylcholinesterase level

Mangiferin is a phytochemical primarily present in the stem, leaves and bark of Mangifera indica. It offers neuroprotection mainly through inhibition of oxidative stress, and decreasing proinflammatory cytokines level in the brain. Aluminium has been reported to cause oxidative stress-associated damage in the brain. In the present investigation, protective effect of mangiferin against aluminium chloride (AlCl3)-induced neurotoxicity and cognitive impairment was studied in male Swiss albino mice. AlCl3 (100 mg/kg) was administered once daily through oral gavage for 42 days. Mangiferin (20 and 40 mg/kg, p.o.) was given to mice for last 21 days of the study. We found cognitive dysfunction in AlCl3-treated group, which was assessed by Morris water maze test, and novel object recognition test. AlCl3-treated group showed elevated level of oxidative stress markers, proinflammatory cytokines level and lowered hippocampal brain-derived neurotrophic factor (BDNF) content. Mangiferin (40 mg/kg) prevented the cognitive deficits, hippocampal BDNF depletion, and biochemical anomalies induced by AlCl3-treatment. In conclusion, our data demonstrated that mangiferin offers neuroprotection in AlCl3-induced neurotoxicity and it may be a potential therapeutic approach in the treatment of oxido-nitrosative stress and inflammation-associated neurotoxicity.

Honokiol abrogates lipopolysaccharide-induced depressive like behavior by impeding neuroinflammation and oxido-nitrosative stress in mice

Depression is an inflammatory, commonly occurring and lethal psychiatric disorder having high lifetime prevalence. Preclinical and clinical studies suggest that activation of immuno-inflammatory and oxido-nitrosative stress pathways play major role in the pathophysiology of depression. Honokiol (HNK) is a biphenolic neolignan possessing multiple biological activities including antioxidant, anti-inflammatory, anxiolytic, antidepressant and neuroprotective. The present study investigated the effect of HNK (2.5 and 5 mg/kg, i.p.) pretreatment (30 min prior to LPS) on lipopolysaccharide (LPS) (0.83 mg/kg, i.p.) induced depressive like behavior, neuroinflammation, and oxido-nitrosative stress in mice. HNK pretreatment at both the doses significantly attenuated LPS induced depressive-like behavior by reducing the immobility time in forced swim and tail suspension test, and by improving the anhedonic behavior observed in sucrose preference test. HNK pretreatment ameliorated LPS induced neuroinflammation by reducing IL-1β, IL-6 and TNF-α level in hippocampus (HC) and prefrontal cortex (PFC). HNK pretreatment prevented LPS evoked oxidative/nitrosative stress via improving reduced glutathione level along with reduction in the lipid peroxidation and nitrite level in HC and PFC. Pretreatment with HNK also prevented the increase in plasma corticosterone (CORT) and decrease in hippocampal BDNF level in LPS challenged mice. In conclusion, current investigation suggested that HNK pretreatment provided protection against LPS-induced depressive like behavior which may be mediated by repression of pro-inflammatory cytokines as well as oxido-nitrosative stress in HC and PFC. Our results strongly speculated that HNK could be a therapeutic approach for the treatment of depression and other pathophysiological conditions which are closely associated with neuroinflammation and oxido-nitrosative stress.