Pharmacological investigations on potential of peroxisome proliferator-activated receptor-gamma agonists in hyperhomocysteinemia-induced vascular dementia in rats

A Comprehensive Review on Preclinical Alzheimer's Disease Models: Evaluating their Clinical Relevance

Alzheimer's disease (AD) is a neurological disorder that increases with age and must be treated immediately by worldwide healthcare systems. Internal neurofibrillary tau tangles and extracellular amyloid accumulation have been widely recognized as the primary causes of Alzheimer's disease. These degenerative age-related ailments are expected to proliferate exponentially as life expectancy rises. Experimental models of AD are essential for acquiring a deep knowledge of its pathogenesis and determining the viability of novel therapy options. Although there isn't a model that encompasses all the characteristics of real AD, these models are nonetheless highly helpful for the research of various modifications associated with it, even though they are only partially indicative of the disease circumstances being studied. Better knowledge of the advantages and disadvantages of each of the different models, as well as the use of more than one model to evaluate potential medications, would increase the effectiveness of therapy translation from preclinical research to patients. We outline the pathogenic characteristics and limitations of the main experimental models of AD in this review, including transgenic mice, transgenic rats, primates and non-primate models along with in-vitro cell culture models in humans. Additionally, it highlights the possible future of experimental modeling of AD and includes the co-morbid models.

Integrated transcriptome and metabolome analysis to investigate the mechanism of intranasal insulin treatment in a rat model of vascular dementia

Introduction: Insulin has an effect on neurodegenerative diseases. However, the role and mechanism of insulin in vascular dementia (VD) and its underlying mechanism are unknown. In this study, we aimed to investigate the effects and mechanism of insulin on VD. Methods: Experimental rats were randomly assigned to control (CK), Sham, VD, and insulin (INS) + VD groups. Insulin was administered by intranasal spray. Cognitive function was evaluated using the Morris's water maze. Nissl's staining and immunohistochemical staining were used to assess morphological alterations. Apoptosis was evaluated using TUNEL-staining. Transcriptome and metabolome analyses were performed to identify differentially expressed genes (DEGs) and differentially expressed metabolites (DEMs), respectively. Results: Insulin significantly improved cognitive and memory functions in VD model rats (p < 0.05). Compared with the VD group, the insulin + VD group exhibited significantly reduced the number of Nissl's bodies numbers, apoptosis level, GFAP-positive cell numbers, apoptosis rates, and p-tau and tau levels in the hippocampal CA1 region (p < 0.05). Transcriptomic analysis found 1,257 and 938 DEGs in the VD vs. CK and insulin + VD vs. VD comparisons, respectively. The DEGs were mainly enriched in calcium signaling, cAMP signaling, axon guidance, and glutamatergic synapse signaling pathways. In addition, metabolomic analysis identified 1 and 14 DEMs between groups in negative and positive modes, respectively. KEGG pathway analysis indicated that DEGs and DEMs were mostly enriched in metabolic pathway. Conclusion: Insulin could effectively improve cognitive function in VD model rats by downregulating tau and p-tau expression, inhibiting astrocyte inflammation and neuron apoptosis, and regulating genes involved in calcium signaling, cAMP signaling, axon guidance, and glutamatergic synapse pathways, as well as metabolites involved in metabolic pathway.

Palm Oil Derived Tocotrienol-Rich Fraction Attenuates Vascular Dementia in Type 2 Diabetic Rats

Vascular dementia (VaD) is a serious global health issue and type 2 diabetes mellitus (T2DM) patients are at higher risk. Palm oil tocotrienol-rich fraction (TRF) exhibits neuroprotective properties; however, its effect on VaD is not reported. Hence, we evaluated TRF effectiveness in T2DM-induced VaD rats. Rats were given a single dose of streptozotocin (STZ) and nicotinamide (NA) to develop T2DM. Seven days later, diabetic rats were given TRF doses of 30, 60, and 120 mg/kg orally for 21 days. The Morris water maze (MWM) test was performed for memory assessment. Biochemical parameters such as blood glucose, plasma homocysteine (HCY) level, acetylcholinesterase (AChE) activity, reduced glutathione (GSH), superoxide dismutase (SOD) level, and histopathological changes in brain hippocampus and immunohistochemistry for platelet-derived growth factor-C (PDGF-C) expression were evaluated. VaD rats had significantly reduced memory, higher plasma HCY, increased AChE activity, and decreased GSH and SOD levels. However, treatment with TRF significantly attenuated the biochemical parameters and prevented memory loss. Moreover, histopathological changes were attenuated and there was increased PDGF-C expression in the hippocampus of VaD rats treated with TRF, indicating neuroprotective action. In conclusion, this research paves the way for future studies and benefits in understanding the potential effects of TRF in VaD rats.

Bergenin ameliorates cognitive deficits and neuropathological alterations in sodium azide-induced experimental dementia

Background: Bergenin, 4-O-methyl gallic acid glucoside, is a bioactive compound found in the cortex of Mallotus japonicus (L.f.) Müll.Arg. along with many other natural resources including that from Bergenia species. The present study delineates the neuroprotective potential of bergenin through the modulation of PPAR-γ receptors. Method: Dementia was induced in the Wistar rats by intraperitoneal (i.p.) administration of sodium azide (12.5 mg/kg for the first 5 days followed by 10 mg/kg for the next 9 days). The rats were then exposed to the Morris water maze test to assess the effect on cognitive abilities followed by a series of biochemical and histopathological evaluations. Results: Sodium azide-treated rats exhibited a severe deterioration of memory as suggested by poor performance in the spatial learning task in addition to the enhancement of brain acetylcholinesterase potential, oxidative stress, inflammation, and amyloid-β (Aβ) accumulation. Administration of bergenin to sodium azide-treated rats significantly recovered cognition and related biochemical variations. Further, co-administration of Bisphenol A diglycidyl ether (BADGE), a PPAR-γ antagonist with bergenin challenged its neuroprotective effects. Conclusions: The findings of our study exhibit that the cognitive restoration potential of bergenin may be attributed to its modulatory effects against cholinesterase, oxidative stress, and inflammatory markers, as well as its neuroprotective actions, thus aligning it as a possible therapy for Alzheimer's disease-related dementia. The study also fortifies the significance of PPAR-γ receptors in dementia.

<em>Gardenia jasminoides</em> J. Ellis extract GJ-4 attenuates hyperlipidemic vascular dementia in rats via regulating PPAR-γ-mediated microglial polarization

Background

GJ-4 is extracted from Gardenia jasminoides J. Ellis (Fructus Gardenia) with crocin composition and has been demonstrated to improve memory deficits in several dementia models in our previous studies.

Objective

This study aimed to evaluate the effects of GJ-4 on hyperlipidemic vascular dementia (VD) and explore the underlying mechanisms.

Design

In the current study, we employed a chronic hyperlipidemic VD rat model by permanent bilateral common carotid arteries occlusion (2-VO) based on high-fat diet (HFD), which is an ideal model to mimic the clinical pathogenesis of human VD.

Results

Our results showed that GJ-4 could significantly reduce serum lipids level and improve cerebral blood flow in hyperlipidemic VD rats. Additionally, treatment with GJ-4 remarkedly ameliorated memory impairment and alleviated neuronal injury. Mechanistic investigation revealed that the neuroprotective effects of GJ-4 might be attributed to the inhibition of microglia-mediated neuro-inflammation via regulating the M1/M2 polarization. Our data further illustrated that GJ-4 could regulate the phenotype of microglia through activating the peroxisome proliferator-activated receptor-γ (PPAR-γ) and subsequently inhibited nuclear factor-κB (NF-κB) nuclear translocation and increased CCAAT/enhancer-binding protein β (C/EBPβ) expression.

Conclusion

Our results implied that GJ-4 might be a promising drug to improve VD through the regulation of microglial M1/M2 polarization and the subsequent inhibition of neuro-inflammation.

Hyperhomocysteinemia: Metabolic Role and Animal Studies with a Focus on Cognitive Performance and Decline-A Review

Disturbances in the one-carbon metabolism are often indicated by altered levels of the endogenous amino acid homocysteine (HCys), which is additionally discussed to causally contribute to diverse pathologies. In the first part of the present review, we profoundly and critically discuss the metabolic role and pathomechanisms of HCys, as well as its potential impact on different human disorders. The use of adequate animal models can aid in unravelling the complex pathological processes underlying the role of hyperhomocysteinemia (HHCys). Therefore, in the second part, we systematically searched PubMed/Medline for animal studies regarding HHCys and focused on the potential impact on cognitive performance and decline. The majority of reviewed studies reported a significant effect of HHCys on the investigated behavioral outcomes. Despite of persistent controversial discussions about equivocal findings, especially in clinical studies, the present evaluation of preclinical evidence indicates a causal link between HHCys and cognition-related- especially dementia-like disorders, and points out the further urge for large-scale, well-designed clinical studies in order to elucidate the normalization of HCys levels as a potential preventative or therapeutic approach in human pathologies.

Dose-dependent effects of prenatal exposure of pioglitazone, the PPARγ agonist, on the hippocampus development and learning and memory performance of rat offspring

It is known that pioglitazone, defined as a PPARγ agonist, has neuron-protective properties in nervous system disorders. The aim of this study is to investigate the effects of pioglitazone administration at different doses during prenatal period on the neurons, glial cells and learning-memory levels in the hippocampus of rat offspring. Pregnant rats were divided into three groups; Low-Dose Pioglitazone (LDP), High-Dose Pioglitazone (HDP) and control (C) (n = 3). Pregnant rats in the HDP and LDP groups were given pioglitazone at 30 mg/kg and 5 mg/kg doses, respectively, by gavage once a day during their pregnancy. No procedure was applied to the rats in the control group. Morris water tank test was applied to offspring obtained from postnatal 24th to 28th day. The offspring were sacrificed on the 29th postal day and their brain tissues removed. Stereological, histopathological and immunohistochemical techniques were used to analyze brain tissues. As a result of the analysis, it was observed that there were delays in learning and memory, the number of pyramidal neurons decreased, and the density of cells stained with glial fibrillar acidic protein (GFAP) positive increased in the HDP group compared to the other groups (p < 0.05). No significant difference was found between the LDP and control groups in terms of these parameters (p > 0.05). Our results showed that pioglitazone administered in the prenatal period had an effect on the hippocampus development and learning and memory performance of rats, depending on the dose.

Pioglitazone Ameliorates Lipopolysaccharide-Induced Behavioral Impairment, Brain Inflammation, White Matter Injury and Mitochondrial Dysfunction in Neonatal Rats

Previous studies have demonstrated that pioglitazone, a peroxisome proliferator-activated receptor gamma (PPARγ) agonist, inhibits ischemia-induced brain injury. The present study was conducted to examine whether pioglitazone can reduce impairment of behavioral deficits mediated by inflammatory-induced brain white matter injury in neonatal rats. Intraperitoneal (i.p.) injection of lipopolysaccharide (LPS, 2 mg/kg) was administered to Sprague-Dawley rat pups on postnatal day 5 (P5), and i.p. administration of pioglitazone (20 mg/kg) or vehicle was performed 5 min after LPS injection. Sensorimotor behavioral tests were performed 24 h after LPS exposure, and changes in biochemistry of the brain was examined after these tests. The results show that systemic LPS exposure resulted in impaired sensorimotor behavioral performance, reduction of oligodendrocytes and mitochondrial activity, and increases in lipid peroxidation and brain inflammation, as indicated by the increment of interleukin-1β (IL-1β) levels and number of activated microglia in the neonatal rat brain. Pioglitazone treatment significantly improved LPS-induced neurobehavioral and physiological disturbances including the loss of body weight, hypothermia, righting reflex, wire-hanging maneuver, negative geotaxis, and hind-limb suspension in neonatal rats. The neuroprotective effect of pioglitazone against the loss of oligodendrocytes and mitochondrial activity was associated with attenuation of LPS-induced increment of thiobarbituric acid reactive substances (TBARS) content, IL-1β levels and number of activated microglia in neonatal rats. Our results show that pioglitazone prevents neurobehavioral disturbances induced by systemic LPS exposure in neonatal rats, and its neuroprotective effects are associated with its impact on microglial activation, IL-1β induction, lipid peroxidation, oligodendrocyte production and mitochondrial activity.

Berberine Ameliorates Brain Inflammation in Poloxamer 407-Induced Hyperlipidemic Rats

Purpose

Hyperlipidemia, which promotes the development of atherosclerosis, ischemic stroke, and other forms of brain injury, can be induced by poloxamer-407. Berberine is a primary pharmacological active component of Coptidis Rhizoma that has a number of therapeutic activities. This study investigated the effects of berberine on poloxamer-407-induced brain inflammation by evaluating its effects on short-term memory, cell proliferation, inflammation, and apoptosis in the hippocampus.

Methods

To induce hyperlipidemia in a rat model, 500 mg/kg of poloxamer-407 was injected intraperitoneally. Berberine was orally administered to the rats in the berberine-treated groups once a day for 4 weeks. The step-down task avoidance task was performed to measure short-term memory. An analysis of serum lipids, immunohistochemistry for 5-bromo-2′-deoxyuridine, glial fibrillary acidic protein (GFAP), and ionized calcium-binding adapter molecule 1 (Iba1) in the dentate gyrus, and western blot analysis for Bax, Bcl-2, and cytochrome c in the hippocampus were performed.

Results

In hyperlipidemic rats, berberine reduced the levels of triglycerides, total cholesterol, and low-density lipoprotein cholesterol and increased the level of high-density lipoprotein cholesterol in hyperlipidemic rats. Berberine also increased cell proliferation and short-term memory, as well as decreasing the expression of GFAP, Iba1, Bax, and cytochrome c and increasing Bcl-2 expression.

Conclusions

Berberine treatment improved short-term memory in hyperlipidemia by increasing neuronal proliferation and inhibiting neuronal apoptosis. Berberine treatment also improved lipid metabolism.

Beneficial effects of pioglitazone, a selective peroxisome proliferator-activated receptor-γ agonist in prenatal valproic acid-induced behavioral and biochemical autistic like features in Wistar rats

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder in children. It is diagnosis by two main behavioral phenotypes i.e. social-communication impairments and repetitive behavior. ASD is complex disorder with unsolved etiology due to multiple genes involvement, epigenetic mechanism and environmental factors. Valproic acid (VPA), a teratogen is known to induce characteristic features related to ASD in rodents. Numerous studies suggest the potential therapeutic effects of peroxisome proliferator-activated receptor-gamma (PPAR-γ) in different brain disorders. This research evaluates the utility of selective agonist of PPAR-γ, pioglitazone in prenatal VPA induced experimental ASD symptomatology in Wistar rats. The prenatal administration of VPA has induced social impairment, repetitive behavior, hyperlocomotion, anxiety and low exploratory activity in rats. Also, prenatal VPA-treated rats have shown higher levels of oxidative stress (increased in thiobarbituric acid reactive species, and decreased in reduced glutathione level) and inflammation (increased in interleukin-6, tumor necrosis factor-alpha and decreased in interleukin-10) in the cerebellum, brainstem and prefrontal cortex. Treatment with pioglitazone significantly attenuated the prenatal VPA-induced social impairment, repetitive behavior, hyperactivity, anxiety and low exploratory activity. Furthermore, pioglitazone also reduced the prenatal VPA-induced oxidative stress and neuroinflammation in aforementioned brain regions. Hence, it may be concluded that pioglitazone may provide neurobehavioral and biochemical benefits in prenatal VPA-induced autistic phenotypes in rats.

Hesperidin, a citrus flavonoid, protects against l-methionine-induced hyperhomocysteinemia by abrogation of oxidative stress, endothelial dysfunction and neurotoxicity in Wistar rats

CONTEXT

Hesperidin (HSP), a flavanoglycone found in citrus fruits, has antioxidant, anti-inflammatory and neuroprotective properties.

OBJECTIVE

This study evaluates the protective effect of HSP on l-methionine-induced hyperhomocysteinemia (HHcy) in rats.

MATERIALS AND METHODS

Male Wistar rats were randomly divided into seven groups as DMSO, l-methionine, HSP (25, 50 and 100 mg/kg), HSP-per se (100 mg/kg) and donepezil (0.1 mg/kg). HHcy was induced by oral administration of l-methionine (1.7 g/kg) for 32 days. From the 14^th day of study HSP (25, 50 and 100 mg/kg) and donepezil was administered orally to l-methionine-treated rats. Cognitive impairment induced by HHcy was determined using the Morris water maze (MWM) and Y-maze on video tracking system (28^th-32^nd day). Different biomarkers of HHcy in serum and brain and vascular reactivity were evaluated and histopathology (thoracic aorta and brain) was done.

RESULTS

HSP (100 mg/kg) treatment in l-methionine-treated rats exhibited significant (p < 0.001) dose-dependent activity and reduced behavioural deficits, brain acetylcholinesterase (25.99 ± 2.36 versus 10.73 ± 1.26 μmoles/mg), brain lipid peroxidation (15.25 ± 1.65 versus 6.18 ± 0.74 nM/mg), serum homocysteine (Hcy) (22.37 ± 0.30 versus 11.01 ± 1.01 μg/mL) and serum cholesterol (182.7 ± 2.15 versus 101.5 ± 2.76 mg/dL) and increased brain antioxidant levels. HSP significantly (p < 0.001) reduced endothelial dysfunction (ED) by abolishing the effect of l-methionine on acetylcholine-induced endothelial-dependent relaxation and increased serum nitrite and vascular nitric oxide bioavailability along with the restoration of histological aberrations.

CONCLUSION

HSP exerts a protective effect on HHcy by abrogating oxidative stress, ED and neurotoxicity.

Neuroprotective effects of pretreatment with quercetin as assessed by acetylcholinesterase assay and behavioral testing in poloxamer-407 induced hyperlipidemic rats

Hyperlipidemia is a group of disorders characterized by excessive lipids in the bloodstream. It is associated with the incidence of cardiovascular diseases and recognized as the most important factor underlying the occurrence of atherosclerosis. This study was conducted to investigate whether pretreatment with quercetin can protect against possible memory impairment and deterioration of the cholinergic system in hyperlipidemic rats. Animals were divided into ten groups (n=7): saline/control, saline/quercetin 5mg/kg, saline/quercetin 25mg/kg, saline/quercetin 50mg/kg, saline/simvastatin (0.04mg/kg), hyperlipidemia, hyperlipidemia/quercetin 5mg/kg, hyperlipidemia/quercetin 25mg/kg, hyperlipidemia/quercetin 50mg/kg and hyperlipidemia/simvastatin. The animals were pretreated with quercetin by oral gavage for a period of 30days and hyperlipidemia was subsequently induced by intraperitoneal administration of a single dose of 500mg/kg of poloxamer-407. Simvastatin was administered after the induction of hyperlipidemia. The results demonstrated that hyperlipidemic rats had memory impairment compared with the saline control group (P<0.001). However, pretreatment with quercetin and simvastatin treatment attenuated the damage caused by hyperlipidemia compared with the hyperlipidemic group (P<0.05). Acetylcholinesterase (AChE) activity in the cerebral hippocampus was significantly (P<0.001) reduced in the hyperlipidemic group compared with the control saline group. Pretreatment with quercetin and simvastatin treatment in the hyperlipidemic groups significantly (P<0.05) increased AChE activity compared with the hyperlipidemic group. Our results thus suggest that quercetin may prevent memory impairment, alter lipid metabolism, and modulate AChE activity in an experimental model of hyperlipidemia.

Experimental models of Alzheimer's disease for deciphering the pathogenesis and therapeutic screening (Review)

Despite decades of laboratory and clinical research, Alzheimer's disease (AD) is still the leading cause of dementia in adults and there are no curative therapies currently available for this disease. This may be due to the pathological features of AD, which include extensive extracellular amyloid plaques and intracellular neurofibrillary tangles, as well as subsequent neuronal and synaptic loss, which begin to appear several years prior to memory loss and the damge is already irreversible and extensive at the time of clinical diagnosis. The poor therapeutic effects of current treatments necessitate the introduction of experimental models able to replicate AD pathology, particularly in the pre-symptomatic stage, and then to explore preventive and therapeutic strategies. In response to this necessity, various experimental models reproducing human AD pathology have been developed, which are also useful tools for therapeutic screening. Although none of these models fully reproduce the key features of human AD, the experimental models do provide important insight into the pathological changes which occur in AD. This review summarizes the commonly used experimental models of AD and also discusses how the models may be used to decipher the pathogenesis underlying AD and to screen novel therapies for this disease.

Neuroprotective effect of selective DPP-4 inhibitor in experimental vascular dementia

Vascular risk factors are associated with a higher incidence of dementia. Diabetes mellitus is considered as a main risk factor for Alzheimer's disease and vascular dementia. Both forms of dementia are posing greater risk to the world population and are increasing at a faster rate. In the past we have reported the induction of vascular dementia by experimental diabetes. This study investigates the role of vildagliptin, a dipeptidyl peptidase-4 inhibitor in the pharmacological interdiction of pancreatectomy diabetes induced vascular endothelial dysfunction and subsequent vascular dementia in rats. Attentional set shifting and Morris water-maze test were used for assessment of learning and memory. Vascular endothelial function, blood brain barrier permeability, serum glucose, serum nitrite/nitrate, oxidative stress (viz. aortic superoxide anion, brain thiobarbituric acid reactive species and brain glutathione), brain calcium and inflammation (myeloperoxidase) were also estimated. Pancreatectomy diabetes rats have shown impairment of endothelial function, blood brain barrier permeability, learning and memory along with increase in brain inflammation, oxidative stress and calcium. Administration of vildagliptin has significantly attenuated pancreatectomy induced impairment of learning, memory, endothelial function, blood brain barrier permeability and biochemical parameters. It may be concluded that vildagliptin, a dipeptidyl peptidase-4 inhibitor may be considered as potential pharmacological agents for the management of pancreatectomy induced endothelial dysfunction and subsequent vascular dementia. The selective modulators of dipeptidyl peptidase-4 may further be explored for their possible benefits in vascular dementia.

Memory restorative ability of clioquinol in copper-cholesterol-induced experimental dementia in mice

CONTEXT

Results from various studies indicate that the presence of certain heavy metals such as aluminum (Al), arsenic (As), copper (Cu), lead (Pb), and mercury (Hg) may enhance the aggregation of Aβ and oxidative stress levels leading to neuronal toxicity and Alzheimer's disease (AD). Studies also reveal that anomalous brain copper-cholesterol (Cu-Ch) homeostasis may lead to memory deficits in Swiss albino mice.

OBJECTIVE

The present study investigates the anti-amnesic potential of clioquinol (5-chloro-7-iodoquinolin-8-ol) in cognitive deficits associated with experimental dementia induced by Cu-Ch.

MATERIALS AND METHODS

Administration of Cu-Ch {0.21 mg/kg, per os - 2% w/v, per os for 8 weeks} was used to induce dementia in Swiss albino mice. The Morris water maze (MWM) test was performed to assess the effect on learning and memory. A battery of biochemical estimations was performed following the MWM test such as brain-reduced glutathione (GSH), superoxide dismutase (SOD), thiobarbituric acid reactive species (TBARS), acetylcholinestrase (AChE) activity, and serum cholesterol levels.

RESULTS

Administration of Cu-Ch produced a marked decline in MWM performance measured during the acquisition (78.9 ± 3.3) and retrieval trials (9.5 ± 2.4), reflecting impairment of learning and memory. Cu-Ch-treated mice also exhibited a marked accentuation of AChE activity (5.8 ± 0.55) and TBARS levels (9.74 ± 1.9) along with a decline in the GSH level (15.4 ± 3.3) and the SOD level (26 ± 2.5) when compared with the untreated control group. Administration of clioquinol significantly attenuated Cu-Ch-induced memory deficits and biochemical alterations.

DISCUSSION AND CONCLUSION

The findings demonstrate memory restorative ability of clioquinol which may be attributed to its anti-cholinesterase, antioxidative, and cholesterol-lowering potential.

Pharmacological inhibition of inducible nitric oxide synthase (iNOS) and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, convalesce behavior and biochemistry of hypertension induced vascular dementia in rats

Cognitive disorders are likely to increase over the coming years (5-10). Vascular dementia (VaD) has heterogeneous pathology and is a challenge for clinicians. Current Alzheimer's disease drugs have had limited clinical efficacy in treating VaD and none have been approved by major regulatory authorities specifically for this disease. Role of iNOS and NADPH-oxidase has been reported in various pathological conditions but there role in hypertension (Hypt) induced VaD is still unclear. This research work investigates the salutiferous effect of aminoguanidine (AG), an iNOS inhibitor and 4'-hydroxy-3'-methoxyacetophenone (HMAP), a NADPH oxidase inhibitor in Hypt induced VaD in rats. Deoxycorticosterone acetate-salt (DOCA-S) hypertension has been used for development of VaD in rats. Morris water-maze was used for testing learning and memory. Vascular system assessment was done by testing endothelial function. Mean arterial blood pressure (MABP), oxidative stress [aortic superoxide anion, serum and brain thiobarbituric acid reactive species (TBARS) and brain glutathione (GSH)], nitric oxide levels (serum nitrite/nitrate) and cholinergic activity (brain acetyl cholinesterase activity-AChE) were also measured. DOCA-S treated rats have shown increased MABP with impairment of endothelial function, learning and memory, reduction in serum nitrite/nitrate & brain GSH levels along with increase in serum & brain TBARS, and brain AChE activity. AG as well as HMAP significantly convalesce Hypt induced impairment of learning, memory, endothelial function, and alterations in various biochemical parameters. It may be concluded that AG, an iNOS inhibitor and HMAP, a NADPH-oxidase inhibitor may be considered as potential agents for the management of Hypt induced VaD.

Salutary effect of NFκB inhibitor and folacin in hyperhomocysteinemia-hyperlipidemia induced vascular dementia

Dementia of vascular origin or vascular dementia (VaD) is considered as the second commonest form of dementia after Alzheimer's disease (AD). In the last ten years various researchers have reported a strong association of hyperhomocysteinemia (HHcy), hyperlipidemia (HL) and dementia. This study investigates the salutary effect of natrium diethyl dithio carbamate trihydrate (NDDCT), a nuclear factor-kappaB (NF-κB) inhibitor as well as folacin (Vitamin-B(9)) in HHcy-HL induced VaD. l-methionone was used to induce HHcy-HL and associated VaD. Morris water-maze (MWM) was used for testing learning and memory. Vascular system assessment was done by testing endothelial function. Biochemical estimations were performed to assess HHcy (serum homocysteine), HL (serum cholesterol), oxidative stress (aortic superoxide anion, serum and brain thiobarbituric acid reactive species and brain glutathione), nitric oxide levels (serum nitrite/nitrate) and cholinergic activity (brain acetyl cholinesterase activity). L-methionine treated animals have shown HHcy-HL, endothelial dysfunction, impairment of learning, memory, reduction in serum nitrite/nitrate levels and brain glutathione (GSH) along with increase in serum and brain thiobarbituric acid reactive species (TBARS), and brain acetylcholinesterase activity. NDDCT, folacin and donepezil (positive control) significantly improved HHcy-HL induced impairment of learning, memory, endothelial dysfunction, and changes in various biochemical parameters. l-methionine induced HHcy-HL has caused VaD development in rats. NFκ-B inhibitors and folacin may be considered as potential agents for the management of HHcy-HL induced VaD.

Rosiglitazone treatment reduces hippocampal neuronal damage possibly through alleviating oxidative stress in chronic cerebral hypoperfusion

Oxygen free radicals and lipid peroxidation may play significant roles in the progress of injury induced by chronic cerebral hypoperfusion of the central nervous system. Rosiglitazone, a well known activator of PPARγ, has neuroprotective properties in various animal models of acute central nervous system damage. In the present study, we evaluate the possible impact of rosiglitazone on chronic cerebral hypoperfused-rats in regard to the levels of oxidative stress, reduced glutathione, and hippocampal neuronal damage. Chronic cerebral hypoperfusion was generated by permanent ligation of both common carotid arteries of Wistar rats for one month. Animals in treatment group were given rosiglitazone orally at doses of 1.5, 3, or 6mg/kg per day of the 1month duration. The treatment significantly lowered the levels of both malondialdehyde and neuronal damage, while elevated the reduced glutathione level markedly. These findings suggest that the beneficial effect of rosiglitazone on hypoperfusion-induced hippocampal neuronal damage might be the result of inhibition of oxidative insult.