Effect of donepezil and lercanidipine on memory impairment induced by intracerebroventricular streptozotocin in rats

Chemical Profile and Potential Application of Agri-food Waste Products for Counteracting Diabetes Induced Neuropathy in Rats

This study aimed to prepare defatted ethanol extract of Abelmoschus esculentus leaves, Morus nigra leaves and Punica granatum peel, to identify the chemical composition of these extracts and to explore their efficacy in counteracting diabetic neuropathy. LC-ESI-MS spectrometry was the hyphenated tool for component identification of these extracts. Behavioral, biochemical, and histopathological investigations were carried out after treatments of diabetic rats. The phenolic contents in the extracts are 16.38, 34.75 and 40.57 mg GAE/g extract regarding A. esculentus leaves, M. nigra leaves and P. granatum peel respectively. Chemodiversity of the phenolic contents was observed from the LC/Mass, where A. esculentus extract contained isoflavonoids and flavanones, M. nigra extract consisted of benzofurans, prenylated flavonoids, stilbenes, and xanthones, and P. granatum extract was rich in ellagitanins, condensed tannins, and anthocyanins. The extracts normalize of blood glucose levels, enhance the explorative behavior of the rats and their response time to thermal pain, restore the oxidant/antioxidant balance, attenuate inflammation, augment brain monoamines levels and modulate MAO-A and Ache enzyme activity. Furthermore, they recovered brain histopathological alterations. Conclusively, this study offers experimental evidence for the neuroprotective impact of studied defatted ethanol extracts against diabetic neuropathy via their hypoglycemic effect, antioxidant activity, and anti-inflammatory potential.

Lycium Barbarum Polysaccharides Improves Cognitive Functions in ICV-STZ-Induced Alzheimer's Disease Mice Model by Improving the Synaptic Structural Plasticity and Regulating IRS1/PI3K/AKT Signaling Pathway

Lycium barbarum polysaccharide (LBP) have a certain curative effect on hypoglycemic and neuroprotective effects, but the specific mechanism is unclear and needs to be further explored. This study aimed to clarify the mechanisms of LBP in the treatment of ICV-STZ mice model of AD from the perspectives of insulin resistance, IRS1/PI3K/AKT signaling pathway, and synaptic protein expression. We used male C57BL/6J mice injected with STZ (3 mg/kg) in the lateral ventricle as an AD model. After treatment with LBP, the learning and memory abilities of ICV-STZ mice were enhanced, and the pathological changes in brain tissue were alleviated. LBP can regulate the expression of proteins related to the IRS1/PI3K/AKT signaling pathway and thereby reducing Aβ deposition and tau protein phosphorylation in the brain of ICV-STZ mice. In addition, LBP also can up-regulate the expression of synaptic proteins. The results indicated that LBP played a neuroprotective role by regulating the IRS1/PI3K/AKT pathway, inhibiting tau protein hyperphosphorylation and improving the expression levels of synapse-related proteins.

Lercanidipine alleviates doxorubicin-induced lung injury by regulating PERK/CHOP and Bax/Bcl 2/Cyt c pathways

Doxorubicin (DOX), which is used to treat various cancers and hematological malignancies, has limited therapeutic application due to its toxicity in tissues and organs. These toxic effects occur through alterations in intracellular calcium regulation, elevated cell stress and oxidative damage, and increased apoptosis. Lercanidipine (LRD) is a long-acting antihypertensive calcium channel blocker with anti-inflammatory, anti-apoptotic, and antioxidant effects. The aim of this study was to investigate the effect of LRD on DOX-induced lung toxicity. Four groups (control, DOX, DOX + 0.5 LRD, and DOX + 2 LRD) totaling 32 rats were established. TNF-α levels in the lung tissues were detected by immunohistochemistry, and the tissues were subjected to histopathological examination. In determining oxidative stress, total antioxidant status (TAS) and total oxidative stress (TOS) were determined using spectrophotometry, and the oxidative stress index (OSI) value was calculated. The mRNA relative expression levels of the genes were evaluated by RT-qPCR. It was determined that inflammatory and oxidative stress markers and pro-apoptotic gene levels were increased and anti-apoptotic gene levels were decreased in the lung tissues of the DOX-administered group. In addition, histopathological changes were significantly increased. Although it was not statistically significant, inflammation, oxidative stress, and apoptosis were reduced, as were other histopathological indicators, in the group that received LRD (0.5 mg/kg). Inflammation, oxidative stress, and apoptosis were found to be statistically reduced and corroborated by histological findings in the group given LRD (2 mg/kg). In conclusion, it was determined that LRD had an ameliorative effect on DOX-induced lung toxicity in an experimental animal model.

Vitamin D alleviates cognitive dysfunction and brain damage induced by copper sulfate intake in experimental rats: focus on its combination with donepezil

This study aimed to demonstrate the potential benefits of donepezil (DPZ) and vitamin D (Vit D) in combination to counteract the neurodegenerative disorders induced by CuSO4 intake in experimental rats. Neurodegeneration (Alzheimer-like) was induced in twenty-four male Wistar albino rats by CuSO4 supplement to drinking water (10 mg/L) for 14 weeks. AD rats were divided into four groups: untreated AD group (Cu-AD) and three treated AD groups; orally treated for 4 weeks with either DPZ (10 mg/kg/day), Vit D (500 IU/kg/day), or DPZ + Vit D starting from the 10th week of CuSO4 intake. Another six rats were used as normal control (NC) group. The hippocampal tissue content of β-amyloid precursor protein cleaving enzyme 1 (BACE1), phosphorylated Tau (p-tau), clusterin (CLU), tumor necrosis factor-α (TNF-α), caspase-9 (CAS-9), Bax, and Bcl-2 and the cortical content of acetylcholine (Ach), acetylcholinesterase (AChE), total antioxidant capacity (TAC), and malondialdehyde (MDA) were measured. Cognitive function tests (Y-maze) and histopathology studies (hematoxylin and eosin and Congo red stains) and immunohistochemistry for neurofilament. Vit D supplementation alleviated CuSO4-induced memory deficits including significant reduction hippocampal BACE1, p-tau, CLU, CAS-9, Bax, and TNF-α and cortical AChE and MDA. Vit D remarkably increased cortical Ach, TAC, and hippocampal Bcl-2. It also improved neurobehavioral and histological abnormalities. The effects attained by Vit D treatment were better than those attained by DPZ. Furthermore, Vit D boosted the therapeutic potential of DPZ in almost all AD associated behavioral and pathological changes. Vit D is suggested as a potential therapy to retard neurodegeneration.

Exploring the potential of a novel phenoxyethyl piperidine derivative with cholinesterase inhibitory properties as a treatment for dementia: Insights from STZ animal model of dementia

Alzheimer's disease (AD) is a neurodegenerative disease, often characterized by progressive deficits in memory and cognitive functions. Cholinesterase inhibitors have been introduced as promising agents to enhance cognition and memory in both human patients and animal models of AD. In the current study, we assessed the effects of a synthetic phenoxyethyl piperidine derivative, compound 7c, as a novel dual inhibitor of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE), on learning and memory, as well as serum and hippocampal AChE levels in an animal model of AD. The model of dementia was induced by intracerebroventricular injection of streptozotocin (STZ, 2 mg/kg) to male Wistar rats. STZ-treated rats received compound 7c (3, 30, and 300 µg/kg) for five consecutive days. ​Passive avoidance (PA) learning and memory, as well as spatial learning and memory using Morris water maze, were evaluated. The level of AChE was measured in the serum and the left and right hippocampus. Findings demonstrated that compound 7c (300 µg/kg) was able to reverse STZ-induced impairments in PA memory, while also reduced the increased AChE level in the left hippocampus. Taken together, compound 7c appeared to act as a central AChE inhibitor, and its role in alleviating cognitive deficits in the AD animal model suggests that it may have therapeutic potential in AD dementia. Further research is required to assess the effectiveness of compound 7c in more reliable models of AD in light of these preliminary findings.

Neuroprotective Efficacy of Europinidin in Streptozotocin-Induced Memory Impairment by Modulation of Oxidative Stress, Inflammatory Mediators, and Cholinesterase Activity in Rats

Materials and Methods

Oral acute toxicity studies were performed to evaluate the toxicological effects of europinidin in animals. In this study, four different animal groups (n = 6) were used. Group I was the normal control, group II was the STZ-induced diabetes control, group III was STZ + europinidin-treated (10 mg/kg), and group IV was STZ + europinidin-treated (10 mg/kg). The efficacy of europinidin at a dose of 10 mg/kg and 20 mg/kg was studied with single-dose administration of streptozotocin, which experimentally induced memory impairments in Wistar male rats for 38 days. The mean body weight and blood glucose levels were recorded at the initial and end of the study. The two behavioural paradigms (Y-maze and Morris water maze) were performed to evaluate spatial and working memory in rats. The biochemical parameters such as acetylcholinesterase, choline acetyltransferase, superoxide dismutase, glutathione transferase, malonaldehyde, catalase, and nitric oxide level as hallmarks of oxidative stress were measured. Additionally, the proinflammatory parameters were also determined to evaluate the neuroinflammatory responses associated with streptozotocin such as tumor necrosis factor-alpha (TNF-α) interleukin-1β (IL-1β), interleukin (IL-6), nuclear factor-kappa B (NF-ƙB), interleukin (IL-10), and nuclear factor-erythroid factor 2-related factor 2 (Nrf2) in the perfused brain.

Results

The rats in the europinidin-treated group exhibited a significant restoration of body weight and blood glucose level as compared with the streptozotocin control group. Furthermore, europinidin significantly modulated the spatial and working memory in rats, when assessed through behavioural paradigms. Streptozotocin caused a significant alteration in biochemical, neuronal enzymatic, and neuroinflammatory parameters, which were significantly restored to normal levels by europinidin.

Conclusion

The present study attributed the neuroprotective efficacy of europinidin in experimental animal models by subsiding the several biomarkers of oxidative stress, neuroinflammation, and neuronal enzymatic activities.

Performance of the intracerebroventricularly injected streptozotocin Alzheimer's disease model in a translationally relevant, aged and experienced rat population

The intracerebroventricularly (icv) injected streptozotocin (STZ) induced brain state is a widely used model of sporadic Alzheimer-disease (AD). However, data have been generated in young, naive albino rats. We postulate that the translationally most relevant animal population of an AD model should be that of aged rats with substantial learning history. The objective of the study was thus to probe the model in old rats with knowledge in various cognitive domains. Long-Evans rats of 23 and 10 months age with acquired knowledge in five-choice serial reaction time task (5-CSRTT), a cooperation task, Morris water-maze (MWM) and "pot-jumping" exercise were treated with 3 × 1.5 mg/kg icv. STZ and their performance were followed for 3 months in the above and additional behavioral assays. Both STZ-treated age groups showed significant impairment in the MWM (spatial learning) and novel object recognition test (recognition memory) but not in passive avoidance and fear conditioning paradigms (fear memory). In young STZ treated rats, significant differences were also found in the 5CSRTT (attention) and pot jumping test (procedural learning) while in old rats a significant increase in hippocampal phospho-tau/tau protein ratio was observed. No significant difference was found in the cooperation (social cognition) and pairwise discrimination (visual memory) assays and hippocampal β-amyloid levels. STZ treated old animals showed impulsivity-like behavior in several tests. Our results partly coincide with partly deviate from those published on young, albino, unexperienced rats. Beside the age, strain and experience level of the animals differences can also be attributed to the increased dose of STZ, and the applied food restriction regime. The observed cognitive and non-cognitive activity pattern of icv. STZ in aged experienced rats call for more extensive studies with the STZ model to further strengthen and specify its translational validity.

Rosinidin Protects Streptozotocin-Induced Memory Impairment-Activated Neurotoxicity by Suppressing Oxidative Stress and Inflammatory Mediators in Rats

Background and Objectives: To assess the antioxidant and neuroprotective role of rosinidin on rat memory impairment that is induced by streptozotocin. Materials and Methods: Wistar rats were given an intraperitoneal (i.p) injection of streptozotocin (60 mg/kg) followed by treatment with rosinidin at selective doses (10 and 20 mg/kg) for 30 days. The behavioral parameters were estimated by Y-maze test and Morris water test. Biochemical parameters such as acetylcholinesterase (AChE), choline aacetyltransferase (ChAT), and nitric oxide, and antioxidants such as glutathione transferase (GSH), superoxide dismutase (SOD) IL-6, IL-10, Nrf2, and BDNF, were determined. Results: The study results revealed that rosinidin improved cognition by reverting the behavioral parameters. The treatment with rosinidin restored the antioxidant enzymes and inflammatory cytokines. Conclusions: From the results, it has been proven that rosinidin possesses antioxidant, anti-amnesic, and anti-inflammatory activity. Rosinidin improved the cognitive and behavioral deficits that were induced by streptozotocin. Furthermore, 20 mg/kg rosinidin was found to have strong protective action against streptozotocin-induced toxicity.

Exercise and Syzygium aromaticum reverse memory deficits, apoptosis and mitochondrial dysfunction of the hippocampus in Alzheimer's disease

ETHNOPHARMACOLOGICAL RELEVANCE

Alzheimer's disease (AD), the most common disease in the brain, is associated with cognitive and mitochondrial dysfunction. Emerging evidence suggests that endurance training and Syzygium aromaticum (L.) Merrill and Perry (Myrtaceae) (commonly referred to as clove) are effective interventions to maintain oxidative balance and improve cognitive function.

AIM OF THE STUDY

The present study aimed to investigate the effect of endurance training and clove oil affect spatial memory, apoptosis, mitochondrial homeostasis, and cognitive function in Alzheimer's rats.

MATERIALS AND METHODS

81 rats were randomly assigned to 9 groups: Healthy (H), sham (sh), Healthy-exercise (HE), Healthy-clove (HC), Healthy-exercise-clove (HEC), Alzheimer's (A), Alzheimer's-exercise (AE), Alzheimer's-clove (AC), and Alzheimer's-exercise-clove (AEC). Alzheimer's induction was induced by the injection of 1-42 amyloid into the CA1 region of the hippocampus. The exercise training protocol was performed for 3 weeks, every day for 30 min in swimming training, and clove oil supplementation (0.1 mg/kg) was gavaged daily for 3 weeks in the supplement rat. Shuttle box test was used to measure spatial memory after the last training session, and to determine the mRNAs and protein levels and apoptosis, Real-Time PCR, immunofluorescent, and tunnel methods were used, respectively.

RESULTS

Alzheimer's caused a significant decrease in the PRDX6 and GCN5L1 mRNAs and protein levels and a significant increase in apoptosis in the hippocampus of the Alzheimer's group compared to the control group (P = 0.001). Alzheimer's also reduced the time delay in entering the dark environment and increased the time spent in the dark environment (P = 0.001). Following endurance training and consumption of clove oil, spatial memory (P = 0.001), apoptosis (P = 0.001) and mRNAs and protein levels of PRDX6 (P = 0.001) and GCN5L1 (P = 0.017), were recovered in AE, AC and AEC groups, as compared with A group.

CONCLUSION

Swimming training and consumption of clove can possibly be considered as an effective intervention to maintain oxidative balance and improve mitochondrial homeostasis in Alzheimer's disease.

Potential Roles of Glucagon-Like Peptide-1 and Its Analogues in Dementia Targeting Impaired Insulin Secretion and Neurodegeneration

Dementia is a chronic, irreversible condition marked by memory loss, cognitive decline, and mental instability. It is clinically related to various progressive neurological diseases, including Parkinson’s disease, Alzheimer’s disease, and Huntington’s. The primary cause of neurological disorders is insulin desensitization, demyelination, oxidative stress, and neuroinflammation accompanied by various aberrant proteins such as amyloid-β deposits, Lewy bodies accumulation, tau formation leading to neurofibrillary tangles. Impaired insulin signaling is directly associated with amyloid-β and α-synuclein deposition, as well as specific signaling cascades involved in neurodegenerative diseases. Insulin dysfunction may initiate various intracellular signaling cascades, including phosphoinositide 3-kinase (PI3K), c-Jun N-terminal kinases (JNK), and mitogen-activated protein kinase (MAPK). Neuronal death, inflammation, neuronal excitation, mitochondrial malfunction, and protein deposition are all influenced by insulin. Recent research has focused on GLP-1 receptor agonists as a potential therapeutic target. They increase glucose-dependent insulin secretion and are beneficial in neurodegenerative diseases by reducing oxidative stress and cytokine production. They reduce the deposition of abnormal proteins by crossing the blood-brain barrier. The purpose of this article is to discuss the role of insulin dysfunction in the pathogenesis of neurological diseases, specifically dementia. Additionally, we reviewed the therapeutic target (GLP-1) and its receptor activators as a possible treatment of dementia.

Quercetin Exhibits α7nAChR/Nrf2/HO-1-Mediated Neuroprotection Against STZ-Induced Mitochondrial Toxicity and Cognitive Impairments in Experimental Rodents

The objective of the present study was to investigate the α7nAChR-mediated Nrf2-dependant protective activity against streptozotocin (STZ)-induced brain mitochondrial toxicity in Alzheimer's disease (AD)-like rats. STZ (3 mg/kg) was injected through an intracerebroventricular route to induce AD-like dementia. Repeated Quercetin (50 mg/kg, i.p.) administration attenuated cognitive impairments in the STZ-challenged animals during Morris water-maze and Y-maze tests. Quercetin significantly mitigated the STZ-induced increase in cholinergic dysfunction, such as the increase in acetylcholinesterase activity, decrease in acetylcholine level, and activity of choline acetyltransferase, and increase in amyloid-beta aggregation and mitochondrial toxicity in respect of mitochondrial bioenergetics, integrity, and oxidative stress in memory-challenged rat hippocampus, prefrontal cortex and, amygdala. Further, Quercetin significantly attenuated STZ-induced reduction in the α7nAChRs and HO-1 expression levels in the selected rat brain regions. On the contrary, trigonelline (10 mg/kg, i.p.) and methyllycaconitine (2 mg/kg; i.p.) abolished the neuroprotective effects of Quercetin against STZ-induced behavioral, molecular, and biochemical alterations in the AD-like animals. Hence, Quercetin exhibits α7nAChR/Nrf2/HO-1-mediated neuroprotection against STZ-challenged AD-like animals. Thus, Quercetin could be considered as a potential therapeutic option in the management of AD.

Tau Cleavage Contributes to Cognitive Dysfunction in Strepto-Zotocin-Induced Sporadic Alzheimer's Disease (sAD) Mouse Model

Tau cleavage plays a crucial role in the onset and progression of Alzheimer’s Disease (AD), a widespread neurodegenerative disease whose incidence is expected to increase in the next years. While genetic and familial forms of AD (fAD) occurring early in life represent less than 1%, the sporadic and late-onset ones (sAD) are the most common, with ageing being an important risk factor. Intracerebroventricular (ICV) infusion of streptozotocin (STZ)—a compound used in the systemic induction of diabetes due to its ability to damage the pancreatic β cells and to induce insulin resistance—mimics in rodents several behavioral, molecular and histopathological hallmarks of sAD, including memory/learning disturbance, amyloid-β (Aβ) accumulation, tau hyperphosphorylation, oxidative stress and brain glucose hypometabolism. We have demonstrated that pathological truncation of tau at its N-terminal domain occurs into hippocampi from two well-established transgenic lines of fAD animal models, such as Tg2576 and 3xTg mice, and that it’s in vivo neutralization via intravenous (i.v.) administration of the cleavage-specific anti-tau 12A12 monoclonal antibody (mAb) is strongly neuroprotective. Here, we report the therapeutic efficacy of 12A12mAb in STZ-infused mice after 14 days (short-term immunization, STIR) and 21 days (long-term immunization regimen, LTIR) of i.v. delivery. A virtually complete recovery was detected after three weeks of 12A12mAb immunization in both novel object recognition test (NORT) and object place recognition task (OPRT). Consistently, three weeks of this immunization regimen relieved in hippocampi from ICV-STZ mice the AD-like up-regulation of amyloid precursor protein (APP), the tau hyperphosphorylation and neuroinflammation, likely due to modulation of the PI3K/AKT/GSK3-β axis and the AMP-activated protein kinase (AMPK) activities. Cerebral oxidative stress, mitochondrial impairment, synaptic and histological alterations occurring in STZ-infused mice were also strongly attenuated by 12A12mAb delivery. These results further strengthen the causal role of N-terminal tau cleavage in AD pathogenesis and indicate that its specific neutralization by non-invasive administration of 12A12mAb can be a therapeutic option for both fAD and sAD patients, as well as for those showing type 2 diabetes as a comorbidity.

Administration of Selenium Nanoparticles Reverses Streptozotocin-Induced Neurotoxicity in the male rats

Alzheimer's disease is the most common neurodegenerative disease associated with deposition of amyloid-beta and the increased oxidative stress. High free radical scavenging ability of selenium nanoparticles (SeNPs) has been acknowledged, so in the present study, the effects of treatment with SeNPs on Streptozotocin (STZ)-induced neurotoxicity were evaluated in the male rats. Learning and memory impairment was induced by intraventricular injection of STZ. Following induction of memory impairment, the rats received 0.4 mg/kg of SeNPs daily for one month. Memory function, antioxidant capacity, and deposition of Amyloid β (Aβ) were assessed using the shuttle box task, biochemical methods, and Congo red staining. Injection of STZ caused memory impairment, a decrease in the level of total thiol group (TTG), and an increase in the malondialdehyde (MDA) content and deposition of Aβ. Administration of SeNPs reversed the neurotoxicity induced by STZ. It seems that SeNPs likely had neuroprotective effects on the animal model of Alzheimer's disease through increasing antioxidants҆ capacity.

Intracerebroventricularly Injected Streptozotocin Exerts Subtle Effects on the Cognitive Performance of Long-Evans Rats

Intracerebroventricularly injected streptozotocin (STZ)-induced learning impairment has been an increasingly used rat model of Alzheimer disease. The evoked pathological changes involve many symptoms of the human disease (cognitive decline, increase in β-amyloid and phospho-tau level, amyloid plaque-like deposits). However, the model has predominantly been used with Wistar rats in the literature. The objective of the current study was to transfer it to Long-Evans rats with the ulterior aim to integrate it in a complex cognitive test battery where we use this strain because of its superior cognitive capabilities. We performed two experiments (EXP1, EXP2) with three months old male animals. At EXP1, rats were treated with 2 × 1.5 mg/kg STZ (based on the literature) or citrate buffer vehicle injected bilaterally into the lateral ventricles on days 1 and 3. At EXP2 animals were treated with 3 × 1.5 mg/kg STZ or citrate buffer vehicle injected in the same way as in EXP1 at days 1, 3, and 5. Learning and memory capabilities of the rats were then tested in the following paradigms: five choice serial reaction time test (daily training, started from week 2 or 8 post surgery in Exp1 or Exp2, respectively, and lasting until the end of the experiment); novel object recognition (NOR) test (at week 8 or 14), passive avoidance (at week 11 or 6) and Morris water-maze (at week 14 or 6). 15 or 14 weeks after the STZ treatment animals were sacrificed and brain phospho-tau/tau protein ratio and β -amyloid level were determined by western blot technique. In EXP1 we could not find any significant difference between the treated and the control groups in any of the assays. In EXP2 we found significant impairment in the NOR test and elevated β-amyloid level in the STZ treated group in addition to slower learning of the five-choice paradigm and a trend for increased phospho-tau/tau ratio. Altogether our findings suggest that the Long-Evans strain may be less sensitive to the STZ treatment than the Wistar rats and higher doses may be needed to trigger pathological changes in these animals. The results also highlight the importance of strain diversity in modelling human diseases.

Natural products as pharmacological modulators of mitochondrial dysfunctions for the treatments of Alzheimer's disease: A comprehensive review

Alzheimer's disease (AD) is the most common progressive neurodegenerative disorder characterized by neuronal loss and cognitive impairment that harshly affect the elderly individuals. Currently, the available anti-AD pharmacological approaches are purely symptomatic to alleviate AD symptoms, and the curative effects of novel anti-AD drugs focused on Aβ target are disappointing. Hence, there is a tremendous need to adjust AD therapeutic targets and discover novel anti-AD agents. In AD, mitochondrial dysfunction gradually triggers neuronal death from different aspects and worsens the occurrence and progress of AD. Consequently, it has been proposed that the intervention of impaired mitochondria represents an attractive breakthrough point for AD treatments. Due to chemical diversity, poly-pharmacological activities, few adverse effects and multiple targeting, natural products (NPs) have been identified as a valuable treasure for drug discovery and development. Multiple lines of studies have scientifically proven that NPs display ameliorative benefits in AD treatment in relation to mitochondrial dysfunction. This review surveys the complicated implications for mitochondrial dysregulation and AD, and then summarizes the potentials of NPs and their underlying molecular mechanisms against AD via reducing or improving mitochondrial dysfunction. It is expected that this work may open the window to speed up the development of innovative anti-AD drugs originated from NPs and improve upcoming AD therapeutics.

Optimization of intracerebroventricular streptozotocin dose for the induction of neuroinflammation and memory impairments in rats

Intracerebroventricular (ICV) injection of streptozotocin (STZ) is a well established procedure to induce neuroinflammation leading to dementia in experimental animals. However, the optimal dose of STZ has not been determined. In the present study, rats were ICV injected with 1.5, 3 and 6 mg of STZ per kg of body weight. After 21 days, neuroinflammatory markers i.e. TNF-α, IL-1β, ROS and nitrite were quantified in the hippocampus. Memory function was assessed by the radial arm maze test after 9, 12, 15, 18, 21 days following STZ injection. STZ treatment significantly increased neuroinflammatory markers and decreased memory functions in a dose dependent manner showing optimum effects at the dose of 3 mg/kg.

Critical Review of the Alzheimer's Disease Non-Transgenic Models: Can They Contribute to Disease Treatment?

Alzheimer's disease (AD) is a growing neurodegenerative disease without effective treatments or therapies. Despite the use of different approaches and an extensive variety of genetic amyloid based models, therapeutic strategies remain elusive. AD is characterized by three main pathological hallmarks that include amyloid-β plaques, neurofibrillary tangles, and neuroinflammatory processes; however, many other pathological mechanisms have been described in the literature. Nonetheless, the study of the disease and the screening of potential therapies is heavily weighted toward the study of amyloid-β transgenic models. Non-transgenic models may aid in the study of complex pathological states and provide a suitable complementary alternative to evaluating therapeutic biomedical and intervention strategies. In this review, we evaluate the literature on non-transgenic alternatives, focusing on the use of these models for testing therapeutic strategies, and assess their contribution to understanding AD. This review aims to underscore the need for a shift in preclinical research on intervention strategies for AD from amyloid-based to alternative, complementary non-amyloid approaches.

Intracerebroventricular streptozotocin administration impairs mitochondrial calcium homeostasis and bioenergetics in memory-sensitive rat brain regions

Alzheimer's disease (AD) is a progressive neurodegenerative disorder with cardinal manifestation of cognitive dysfunction. The limitation to avail a successful drug candidate encourages researchers to establish an appropriate animal model in the novel anti-AD drug discovery process. In this context, the mechanism of mitochondrial dysfunction in cognitive deficit animals is yet to be established for intracerebroventricular injection of streptozotocin (ICV-STZ). Experimental dementia was induced in male rats by ICV-STZ on day-1 (D-1) of the experimental protocol at a sub-diabetogenic dose (3 mg/kg) twice at an interval of 48 h into both rat lateral ventricles. ICV-STZ caused cognitive decline in terms of increase in the escape latency on D-14 to D-17 and, decrease in the time spent and percentage of distance travelled in the target quadrant during Morris water maze and decrease in the spontaneous alteration behavior during Y-maze tests in rats. Further, ICV-STZ decreased the level of acetylcholine and activity of choline acetyltransferase and increased the activity of acetylcholinesterase in rat hippocampus, pre-frontal cortex and amygdala. Interestingly, ICV-STZ increased the mitochondrial calcium in addition to decrease in the mitochondrial function, integrity and bioenergetics in all rat brain regions. Further, ICV-STZ enhanced the levels of expression of NR1 subunit of N-methyl-D-aspartate receptor, mitochondrial calcium uniporter and sodium-calcium exchanger in these rat brain regions. Thus, NR1-dependent mitochondrial calcium accumulation could be considered as a major attribute to the animal model of ICV-STZ-induced AD-like manifestations. Further, drugs targeting to manage mitochondrial calcium homeostasis could best be studied in this animal model.

Ruthenium red, mitochondrial calcium uniporter inhibitor, attenuates cognitive deficits in STZ-ICV challenged experimental animals

Alzheimer's disease (AD) is a progressive neurodegenerative disorder with cardinal features of cognitive dysfunction in an individual. Recently, the blockade of mitochondrial calcium uniporter (MCU) exhibits neuroprotective activity in experimental animals. However, the therapeutic potential of MCU has not yet been established in the management of AD. Therefore, the present study explored the therapeutic potential of either Ruthenium red (RR), a MCU blocker, or Spermine, a MCU opener, on the extent of mitochondrial calcium accumulation, function, integrity and bioenergetics in hippocampus, pre-frontal cortex and amygdale of ICV-STZ challenged rats. Experimental AD was induced in male rats by intracerebroventricular injection of streptozotocin (ICV-STZ) on day-1 (D-1) of the experimental protocol at a sub-diabetogenic dose (3 mg/kg) twice at an interval of 48 h into both rat lateral ventricles. RR attenuated ICV-STZ-induced memory-related behavioral abnormalities in Morris water maze and Y-maze tests. RR also attenuated ICV-STZ-induced decrease in the level of acetylcholine and activity of choline acetyltransferase and, increase in the activity of acetylcholinestarase in memory-sensitive rat brain regions. Further, RR attenuated mitochondrial toxicity in terms of reducing mitochondrial calcium accumulation and improving the mitochondrial function, integrity and bioenergetics in memory-sensitive brain regions of ICV-STZ challenged rats. Furthermore, RR attenuated the percentage of apoptotic cells in ICV-STZ challenged rat brain regions. However, Spermine did not alter ICV-STZ-induced behavioral, biochemical and molecular observations in any of the brain regions. These observations indicate the fact that the MCU blockage could be a potential therapeutic option in the management of sporadic type of AD.

1 H NMR metabolomic profiling elucidated attenuation of neurometabolic alterations by lercanidipine in MCAo model in rats

OBJECTIVES

Stroke is a leading cause of death and disability worldwide with limited therapeutic interventions. The current study explored proton nuclear magnetic resonance spectroscopy (¹ H NMR)-based metabolomic approach to elucidate the effect of lercanidipine on neurometabolic alterations in transient model of ischaemic stroke in rats.

METHODS

In the present investigation, male Wistar rats were subjected to middle cerebral artery occlusion (MCAo) for 2 h followed by reperfusion using intraluminal filament method. Rats were randomly divided into three groups as vehicle-treated sham control, vehicle-treated MCAo control and lercanidipine-treated MCAo. Vehicle or lercanidipine (0.5 mg/kg, i.p.) was administered 120 min post-reperfusion. The rat brain cortex tissues were isolated 24 h post-MCAo and were investigated by ¹ H NMR spectroscopy through perchloric extraction method.

KEY FINDINGS

A total of 23 metabolites were altered significantly after cerebral ischaemic-reperfusion injury in MCAo control as compared to sham control rats. Lercanidipine significantly reduced the levels of valine, alanine, lactate, acetate and tyrosine, while N-acetylaspartate, glutamate, glutamine, aspartate, creatine/phosphocreatine, choline, glycerophosphorylcholine, taurine, myo-inositol and adenosine di-phosphate were elevated as compared to MCAo control.

CONCLUSIONS

Present study illustrates effect of lercanidipine on neurometabolic alterations which might be mediated through its antioxidant, anti-inflammatory, vasodilatory and anti-apoptotic property in MCAo model of stroke.

Allium cepa fraction attenuates STZ-induced dementia via cholinesterase inhibition and amelioration of oxidative stress in mice

Background An earlier study demonstrated significant antioxidant and anticholinesterase activities of hydromethanol extract (HME) of Allium cepa. The aim of the study was to investigate the component responsible for these activities followed by an in vivo study. Methods In vitro antioxidant and anticholinesterase activities of standardized ethylacetate fraction (EAF) of HME were assessed. Bioactivity-guided fractionation showed that, as compared with its subfractions, EAF had most significant activity in 2,2-diphenyl-1-picrylhydrazyl and Ellman assays. Thus, EAF was further examined using a streptozotocin (STZ)-induced model of Alzheimer's disease in mice. STZ was injected intracerebroventricularly on days 1 and 3 (3 mg/kg) in mice. EAF was thereafter administered (42, 84, and 168 mg/kg b.w./day p.o.) from days 9 to 22. The Morris water maze test was used to evaluate learning and memory in mice. Acetylcholinesterase (AChE) activity and oxidative stress markers were assessed in the brain homogenates of mice. Additionally, histopathological studies were performed to observe effects in the brain at the cellular level. EAF was standardized based on quercetin and quercetin 4'-O-glucoside content using a validated thin layer chromatography densitometric method. Results STZ produced significant (p < 0.05) memory impairment along with oxidative stress and a cholinergic deficit in mice. EAF treatment ameliorated STZ-induced behavioral deficits and biochemical alterations in mice in a significant and dose-dependent manner. Conclusions Our results show that EAF is efficacious in improving memory and learning via AChE inhibition and antioxidant activity in the mice brain. Thus, AC could be explored further to find out a lead candidate for Alzheimer's disease.

Virgin Coconut Oil Ameliorates Colchicine Induced Cognitive Dysfunction- A Preclinical Study

Background : Virgin coconut oil (VCO) has been identified as a potential cognitive strengthener associated with Alzheimer’s disease (AD). It contains medium chain fatty acids (MCFA) which are absorbed and easily metabolized by the liver to form ketone bodies. Ketone bodies are converted to acetyl Co-A in the brain which then enters the citric acid cycle to provide ATP and also serves as precursors of acetylcholine in neurons. Sunflower oil (SO) contains poly unsaturated fatty acids which has both anti-inflammatory and neuroprotective actions. To compare the neuroprotective effects of VCO and SO on biochemical parameters involved in the cognitive dysfunction induced by colchicine through intracerebroventricular (i.c.v) route.To assess the role of polyphenols and MCFA present in VCO in preventing oxidative stress and its influence on in neuroprotection and memory enhancement. Methods: In the present study, we induced dementia through i.c.v injection of colchicine after giving the diet enriched VCO and SO in rats for 60 days. Rats were sacrificed on the 22nd day after the administration of colchicine. Behavioral parameters were assessed during the study period and biochemical estimations were performed using frontal cortex and hippocampus isolated from rat brain. Results: From the memory and learning tests by Morris water maze, VCO treated group performed better than SO treated rats. VCO reversed the antagonistic effects induced by colchicine by decreasing the acetylcholinesterase and malondialdehyde levels and increasing the levels of catalase and superoxide dismutase. SO only reduced malondialdehyde levels in cortex and hippocampus. Conclusion: The results demonstrated potential beneficiary effects of VCO in the cognitive dysfunction induced by colchicine by enhancing acetylcholine levels in the frontal cortex and hippocampus and also by reducing oxidative stress induced by physiological oxidants.

Phosphoinositide 3-kinase inhibitor AS605240 ameliorates streptozotocin-induced Alzheimer's disease like sporadic dementia in experimental rats

The quest for chemical entities able to curb the action of the phosphoinositide 3-kinase, (PI3K)/protein kinase B (AKT) signaling pathways is evolving as a potential therapeutic strategy for the treatment and/or prevention of neurodegenerative disorders including Alzheimer's disease (AD). In this study, the effects of a PI3K inhibitor, AS605240 on cognitive dysfunction and antioxidative defense parameters against intra-cerebroventricular-streptozotocin (ICV-STZ)-induced rat model of sporadic AD was evaluated. ICV administration of a single dose of STZ (3 mg/kg) was performed to induce behavioral and biochemical changes in rats using the stereotaxic technique. Animals were administered with varying doses of AS605240 (5, 10 and 15 mg/kg) orally, 1 h before ICV-STZ on day 1 and continued once daily for four weeks. The behavioral parameters (passive avoidance and Morris water maze), antioxidative defense parameters, amyloid-beta (Aβ) protein expression by Western blotting and immunostaining technique were estimated in brain tissue. AS605240 dose-dependently and significantly (p < 0.05 and p < 0.01 and p < 0.001) improved ICV-STZ-induced cognitive impairment and attenuated the altered antioxidative related parameters including superoxide dismutase, lipid peroxidation, glutathione and nitrite levels. Further, the increased Aβ protein expression levels in brain tissue were markedly restored with AS605240 treatment. In conclusion, our study demonstrated that AS605240 exhibited immense potential in attenuating STZ-induced sporadic AD features in rats and may be developed as a therapeutic agent in the treatment and management of sporadic AD.

Evaluation of sodium valproate loaded nanoparticles in acute and chronic pentylenetetrazole induced seizure models

BACKGROUND AND PURPOSE

Efficacy of sodium valproate in epilepsy is limited by its poor blood brain barrier penetration and side effects. Nanoparticles may offer a better drug delivery system to overcome these limitations. This study evaluated the efficacy of sodium valproate encapsulated in nanoparticles in pentylenetetrazole (PTZ) induced acute and kindling models of seizures in male Wistar rats.

METHODS

Poly lactic-co-glycolic acid (PLGA) based, polysorbate 80 stabilized sodium valproate loaded nanoparticles (nano sodium valproate) and rhodamine loaded nanoparticles (RLN) were formulated by double emulsion- solvent evaporation method and characterized for their size, shape, zeta potential and drug loading percentage. RLN was used to demonstrate blood brain barrier (BBB) permeability of nanoparticles. Serum drug levels were estimated using high performance liquid chromatography. The efficacy of standard sodium valproate (300 mg/kg) and nano sodium valproate (∼300, ∼150 and ∼75 mg/kg of sodium valproate) were evaluated in experimental animal models of seizures along with their effects on behavioral and oxidative stress parameters. Drugs were administered 60 min before PTZ in acute model. In the kindling model, drugs were administered every day while PTZ was administered on alternate days 60 min after drug administration. All the study drugs/compounds were administered intraperitoneally.

RESULTS

RLN were observed to be clustered in cortex which implied that the nanoparticles crossed BBB. Both standard sodium valproate and nano sodium valproate reached therapeutic serum level at 15 min and 1 h, but were undetectable in serum at 24 h. In acute PTZ (60 mg/kg) model, nano sodium valproate (∼300 mg/kg of sodium valproate) and standard sodium valproate showed protection against seizures till 6 h and 4 h, respectively. There were significant behavioral impairment and oxidative stress with standard sodium valproate in acute model as compared to nano sodium valproate at 6 h. In kindling model, induced with PTZ (30 mg/kg, every alternate day for 42 days), complete protection from seizures was observed with nano sodium valproate (∼150 mg/kg and ∼75 mg/kg of sodium valproate) and standard sodium valproate (300 mg/kg). Similarly, significant protection from behavioral impairment and oxidative stress was observed with standard sodium valproate and nano sodium valproate as compared to PTZ.

CONCLUSION

When compared to conventional therapy, nano sodium valproate showed protection from seizures at reduced doses and for a longer duration in animal models of epilepsy. This study suggests the potential of nano sodium valproate in the treatment of epilepsy.

Effects of Euterpe oleracea to Enhance Learning and Memory in a Conditioned Nicotinic and Muscarinic Receptor Response Paradigm by Modulation of Cholinergic Mechanisms in Rats

Euterpe oleracea (EO) includes a large number of polyphenolic compounds such as phenolics, flavonoids, and anthocyanins that have antioxidant activities. E. oleracea was suggested to ease the oxidative stress and inflammation in brain cells. Our aim was to analyze the effects of E. oleracea on learning and memory. Seventy-two (250 ± 25 g) male Wistar albino rats were used for this study. The groups consisted of control, EO100 mg/kg, EO300 mg/kg, scopolamine 1.5 mg/kg, mecamylamine 7.5 mg/kg, combinations of scopolamine with EO100 mg/kg, EO300 mg/kg, and rivastigmine 1.5 mg/kg; and mecamylamine combined with EO100 mg/kg. Before the start of the study, E. oleracea doses were provided once a day for a period of 15 days and for a 6-day experimental period. Thirty minutes after intraperitoneal scopolamine and mecamylamine injections, gastrogavage was applied to each group. Ninety minutes after the drug treatments, locomotor activity and Morris water maze tests were performed. Rats were killed and each hippocampus was used for the quantification of acetylcholine (Ach). Statistical analyses were calculated using one-way and two-way analyses of variance (ANOVA), and a value of P < .05 was considered significant. In groups EO100 mg/kg and EO300 mg/kg the results did not show any significant changes on learning and memory compared with the control group. Mecamylamine and scopolamine enhanced the latency for the escape platform, and decreased the time spent in escape platform quadrant when the memory tests were applied in reference to the control value of P < .05. Scopolamine and mecamylamine combinations of EO100 mg/kg, EO300 mg/kg, and rivastigmine were proven to improve the memory. There was significant difference between the first and fifth days of the learning tests in all the groups, but no significant difference occurred between the groups. Ach levels in hippocampi supported all memory tests. We suggest that E. oleracea made no alterations on learning and memory, but still improved nicotinic and muscarinic receptor-mediated and impaired memory just as rivastigmine.

Calcium signals that determine vascular resistance

Small arteries in the body control vascular resistance, and therefore, blood pressure and blood flow. Endothelial and smooth muscle cells in the arterial walls respond to various stimuli by altering the vascular resistance on a moment to moment basis. Smooth muscle cells can directly influence arterial diameter by contracting or relaxing, whereas endothelial cells that line the inner walls of the arteries modulate the contractile state of surrounding smooth muscle cells. Cytosolic calcium is a key driver of endothelial and smooth muscle cell functions. Cytosolic calcium can be increased either by calcium release from intracellular stores through IP3 or ryanodine receptors, or the influx of extracellular calcium through ion channels at the cell membrane. Depending on the cell type, spatial localization, source of a calcium signal, and the calcium-sensitive target activated, a particular calcium signal can dilate or constrict the arteries. Calcium signals in the vasculature can be classified into several types based on their source, kinetics, and spatial and temporal properties. The calcium signaling mechanisms in smooth muscle and endothelial cells have been extensively studied in the native or freshly isolated cells, therefore, this review is limited to the discussions of studies in native or freshly isolated cells. This article is categorized under: Biological Mechanisms > Cell Signaling Laboratory Methods and Technologies > Imaging Models of Systems Properties and Processes > Mechanistic Models.

Arbutin reduces cognitive deficit and oxidative stress in animal model of Alzheimer's disease

Objectives: Recent evidences have shown the beneficial effects of natural products for treating of Alzheimer's disease (AD). Arbutin is derived from Pyrus biossieriana and exerts a wide range of pharmacological activities including anti-inflammatory and anti-oxidant effects. The present study was designed to examine the protective effects of arbutin on streptozotocin (STZ)-induced neurotoxicity in rats. Materials and methods: The spatial memory impairment was induced by intracerebroventricular (i.c.v) microinjection of STZ (3 mg/kg, 10 μL). Animals received the pretreatment of arbutin (50 mg/kg) for 21 days before STZ injection. The Morris Water maze (MWM) task was used to study the spatial learning and memory. The levels of oxidative stress markers including malondialdehyde (MDA), nitrite and carbonyl were measured in serum and hippocampus samples. In addition, antioxidant level was assessed by ferric reducing antioxidant power (FRAP) test. Results: The obtained result indicated that administration of STZ is led to memory impairment and increases the levels of oxidative stress markers in the hippocampus tissues. Conversely, arbutin improves spatial memory and reduces oxidative and nitrosative stress, as evidenced by a significant decrease in the amount of MDA and nitrite in the serum and hippocampus. In addition, an increase in FRAP levels of hippocampus was observed in arbutin receiving animals. The protein carbonyl content was not reduced in arbutin receiving animals. Conclusion: It could be concluded that arbutin protects the brain against STZ-induced memory impairment and oxidative damage in the hippocampus. The neuroprotective effect of arbutin might be mediated through its antioxidant and free radical scavenging effects.

Targeting central β2 receptors ameliorates streptozotocin-induced neuroinflammation via inhibition of glycogen synthase kinase3 pathway in mice

Alzheimer's disease (AD) is portrayed by progressive cognitive decline and pathological deposition of amyloid plaques as well as neurofibrillary tangles. Most of AD cases are sporadic, resulting from overlap of various environmental and genetic factors. Intra-cerebroventricular injection of streptozotocin (STZ) leads to insulin resistance brain state accompanied by memory decline, oxidative stress, and neuro-degeneration which mimic the pathologies associated with sporadic Alzheimer's disease (SAD). In the current study, protective effects of formoterol in STZ-induced SAD were studied. Formoterol-induced improvement in cognition was confirmed using Morris water maze and Y maze together with histopathological evidences. Moreover, prominent declines in oxidative stress, neuro-inflammation, and apoptotic parameters were recorded upon its injection in STZ-induced SAD mouse model. This was manifested by the decrement of malondialdehyde, hydrogen peroxide, interleukin-1β, interleukin-6, tumor necrosis factor-α, and caspase-3levels contrary to reduced glutathione and interleukin-10 increments. Formoterol also reversed STZ-induced alteration in acetylcholine and glutamate levels. Furthermore, it could be concluded that formoterol was capable of combating STZ-induced neuro-inflammation and retarding the development of the main pathological hallmarks of AD through glycogen synthase kinase-3 deactivation.

Neuroprotective effects of tenuigenin on neurobehavior, oxidative stress, and tau hyperphosphorylation induced by intracerebroventricular streptozotocin in rats

BACKGROUND:

Tenuigenin (TEN), a major active component of the Chinese herb Polygala tenuifolia root, has been used to improve memory and cognitive function in Traditional Chinese Medicine for centuries.

PURPOSE:

The present study was designed to explore the possible neuroprotective effect of TEN on the streptozotocin (STZ)-induced rat model of sporadic Alzheimer's disease (sAD).

METHODS:

STZ was injected twice intracerebroventrically (3 mg/kg, ICV) on alternate days (day 1 and day 3) in Rats. Daily treatment with TEN (2, 4, and 8 mg/kg) starting from the first dose of STZ for 28 days. Memory-related behaviors were evaluated using the Morris water maze test. Hyperphosphorylation of tau proteins in hippocampus were measured by western blot assay. Superoxide dismutase activities, malondialdehyde, glutathione peroxidase and 4-hydroxy-2-nonenal adducts contents were also measured in the hippocampus.

RESULTS:

Treatment with TEN significantly improved STZ-induced cognitive damage, markedly reduced changes in malondialdehyde and 4-hydroxy-2-nonenal adducts, and significantly inhibited STZ-induced reduction in superoxide dismutase and glutathione peroxidase activities in the hippocampus. In addition, TEN decreased hyperphosphorylation of tau resulting from intracerebroventricular STZ (ICV-STZ) injection, and Nissl staining results showed that TEN has protective effects on hippocampal neurons.

CONCLUSION:

These results provide experimental evidence demonstrating preventive effect of TEN on cognitive dysfunction, oxidative stress, and hyperphosphorylation of tau in ICV-STZ rats. This study indicates that TEN may have beneficial effects in the treatment of neurodegenerative disorders such as AD.

Inosine improves cognitive function and decreases aging-induced oxidative stress and neuroinflammation in aged female rats

In the present study, the effect of inosine was evaluated on learning and memory of 18 months old aged female rats. Inosine (50, 100 and 200 mg/kg; i.p.) was administered to separate groups of rats for 15 successive days. Donepezil (1 mg/kg; i.p.), an acetylcholinesterase inhibitor, was used as a standard drug. Behavioral models such as Morris water maze and elevated plus maze were used to evaluate the effect of drugs on learning and memory of rats. After behavioral studies, animals were killed and their brain was isolated and further processed for estimation of various biochemical parameters such as acetylcholinesterase activity, oxidative stress markers, proinflammatory marker and histological examinations. Inosine (100 and 200 mg/kg) significantly improved learning and memory of aged rats. Further, inosine significantly reduced lipid peroxidation and nitrite, and increased the levels of reduced glutathione and superoxide dismutase. However, no significant difference in AChEs activity was observed in inosine-treated rats as compared to aged control rats. TNF-α level was found to be ameliorated in aged rats by inosine. Histopathological evaluation showed that inosine-treated aged rats have less number of pyknotic neurons in hippocampal CA1 region as compared to aged control rats. In conclusion, inosine significantly improved learning and memory of aged female rats possibly through its antioxidant as well as anti-inflammatory effect and improvement of neuronal survival in the hippocampal CA1 region. However, additional studies are required to further explore the downstream signaling pathways involved in the neuroprotective effect of inosine in aged animals.

Protective effects of evodiamine in experimental paradigm of Alzheimer's disease

Evodiamine, a major component of Evodia rutaecarpa, has been reported to possess various pharmacological activities, including anti-inflammatory, antioxidative stress, and neuroprotective effects. Our previous study has shown that the potential effects of evodiamine on the learning and memory impairments in the transgenic mouse model of Alzheimer's disease (AD). The present study was designed to investigate neuroprotective mechanism and therapeutic potential of evodiamine against intracerebroventricular streptozotocin (ICV-STZ)-induced experimental sporadic Alzheimer's disease in mice. STZ was injected twice intracerebroventrically (3 mg/kg ICV) on alternate days (day 1 and day 3) in mice. Daily oral administration with evodiamine (50 or 100 mg/kg per day) starting from the first dose of STZ for 21 days showed an improvement in STZ induced cognitive deficits as assessed by novel object recognition and Morris water maze test. Evodiamine significantly decreased STZ induced elevation in acetylcholinesterase activity and malondialdehyde level, and significantly increased STZ induced reduction in glutathione activities and superoxide dismutase activities in the hippocampus compared to control. Furthermore, evodiamine inhibited significantly glial cell activation and neuroinflammation (TNF-α, IL-1β, and IL-6 levels) in the hippocampus. Moreover, evodiamine increased the activity of AKT/GSK-3β signalling pathway and inhibited the activity of nuclear factor κB. In summary, our study suggests that evodiamine can be a novel therapeutic agent for the management of sporadic AD.

Evaluation of neuroprotective effect of quercetin with donepezil in scopolamine-induced amnesia in rats

Objective:

The objective of this study was to evaluate the neuroprotective effect of quercetin with donepezil in scopolamine-induced amnesia in rats.

Materials and Methods:

Five groups of adult male Wistar rats (12 months old) weighing 180–200 g (n = 6) were used. The normal control group received normal saline and test group animals were pretreated orally with quercetin (25 mg/kg), donepezil (3 mg/kg), and a combination of quercetin (25 mg/kg) with donepezil (3 mg/kg), respectively, dosed at every 24 h interval for 14 consecutive days, afterward amnesia was induced by scopolamine (3 mg/kg) on the 14^th day through intraperitoneal route. Cognitive performance was assessed by the Morris water maze, elevated plus maze, and passive avoidance paradigm. Acetylcholinesterase enzyme (AchE) level, biochemical markers such as lipid peroxidase (LPO), glutathione (GSH), β amyloid_1-42level, and histopathological study of rat brain were estimated. Statistical analysis was done by one-way analysis of variance, followed by Dunnett's post hoc test. P ≥ 0.05 was considered statistically significant.

Results:

Pretreatment with quercetin, donepezil, and their combination showed a significant increase in escape latency, step-through latency, and decreased transfer latency in respective cognitive models of the Morris water maze, passive avoidance test, and elevated plus maze. Further coadministration significantly decreased AchE level, β amyloid_1-42level as compared to individual therapy. Biochemical markers such as elevated GSH, decreased LPO were observed, and histopathological studies revealed the reversal of neuronal damage in the treatment group (P < 0.05) as compared to scopolamine-treated control group.

Conclusion:

Pretreatment with quercetin potentiates the action of donepezil in scopolamine-induced amnesia in rats. The improved cognitive memory could be due to the synergistic effect of the drugs by decreasing AchE level, β amyloid_1-42level, and antioxidant action in rat brain.

Coenzyme Q10 and niacin mitigate streptozotocin- induced diabetic encephalopathy in a rat model

Diabetic encephalopathy is an important complication of diabetes characterized by cognitive impairment, neurochemical and structural abnormalities. This study aimed to investigate the effect of coenzyme Q10 (CoQ10) and niacin as well as their combination in the treatment of encephalopathy associated with streptozotocin (STZ)- induced diabetes in rats. Glibenclamide (reference diabetic drug) and donepezil hydrochloride (acetylcholinesterase inhibitor) were also evaluated. Diabetes was induced by a single intraperitoneal injection of STZ (60 mg/kg). One month after STZ injection, diabetic rats were treated with the aforementioned drugs for two weeks. The evaluation was done through measuring glucose level, total antioxidant capacity (TAC), interleukin 6 (IL6), DNA degradation as well as serotonin and noradrenaline as neurotransmitters. The present data illustrated that combining CoQ10 and niacin exhibiting the most potent effect in improving the measured parameters and ameliorating some of diabetes complications.

Long Acting Ionically Paired Embonate Based Nanocrystals of Donepezil for the Treatment of Alzheimer's Disease: a Proof of Concept Study

PURPOSE

The aim of the present study was to prepare a patient friendly long acting donepezil (D) nanocrystals (NCs) formulation, with a high payload for i.m administration. As the native D hydrochloride salt has high aqueous solubility it is necessary to increase its hydrophobicity prior to the NCs formation.

METHODS

D was ionically paired with embonic acid (E) in aqueous media and was successfully characterized using techniques like DSC, PXRD, FT-IR, NMR etc. Later, we converted the bulk ion pair into NCs using high pressure homogenization technique to study further in-vitro and in-vivo.

RESULTS

The bulk ion pair has a drug content of 66% w/w and an 11,000 reduced solubility in comparison to native D hydrochloride. Also, its crystalline nature was confirmed by DSC and PXRD. The possible interaction sites responsible for the ion pair formation were identified though NMR. The prepared NCs has mean particle size 677.5 ± 72.5 nm and PDI 0.152 ± 0.061. In-vitro release showed a slow dissolution of NCs. Further, excellent bio compatibility of NCs were demonstrated in 3T3 cells. Following i.m administration of single dose of NCs, the D plasma level was found to be detectable up to 18 days. In vivo pharmacodynamic studies revealed that the single dose NCs i.m injection improved spatial memory learning and retention in ICV STZ model.

CONCLUSION

Our results suggest that the developed formulation has a potential to replace the current daily dosing regimen to a less frequent dosing schedule. Graphical Abstract Improved pharmacokinetic and pharmacodynamic profile after administration of single dose donpezil embonate nanocrystals in Rats.

Vitamin D3 attenuates cognitive deficits and neuroinflammatory responses in ICV-STZ induced sporadic Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by intracellular neurofibrillary tangles and extracellular Aβ deposition. Growing experimental evidence indicate diverse biological effects of vitamin D₃ including antioxidant, neuroprotective, anti-inflammatory and cardiovascular benefits. However, the underlying neuroprotective mechanism of vitamin D₃ is still largely elusive. Therefore, the present study was aimed to investigate the neuroprotective effects of vitamin D₃ on ICV-STZ induced sporadic AD. Our study demonstrated that vitamin D3 pretreatment significantly improved spatial learning and memory functions and effectively mitigated ICV-STZ mediated neuronal oxidative stress, mitochondrial aberrations and improved cholinergic functions. Moreover, vitamin D₃ attenuated hippocampal neuroinflammatory response and reduced neuronal death in cortex and hippocampus. Our findings indicated that prophylactic vitamin D₃ supplementation ameliorated ICV-STZ mediated neurobehavioral alterations, oxidative stress and neuroinflammation thereby improving cholinergic functions and reversed degenerative changes in brain. Thus, our study further provides evidence for its therapeutic supplementation for various neurodegenerative disorders including AD.

Caffeic Acid Phenethyl Ester (CAPE) Prevents Development of STZ-ICV Induced dementia in Rats

BACKGROUND

Chronic oxidative stress and inflammation severely affect the normal physiology of neurons and lead to neurodegenerative disorders such as Alzheimer's disease (AD). Polyphenols proved a boon in the prevention of dementia due to their antioxidant and neuroprotective potential. Caffeic acid phenethyl ester (CAPE) is a natural polyphenolic compound attributed with antioxidant, immunomodulatory, and neuroprotective properties.

OBJECTIVE

The present study investigates the effect of CAPE on experimental dementia in rats.

METHODS

Intracerebroventricle (ICV) injection of streptozotocin (STZ; 3 mg/kg) was given to Wistar rats (200 g, either sex) on days 1 and 3 to induce dementia of AD type. CAPE (3 and 6 mg/kg, i.p.) was administered to separate groups of rats for 28 successive days daily. Morris water maze and elevated plus maze served as exteroceptive behavioral models to measure the memory of the rats.

RESULTS

The present study illustrated that CAPE treatment for 28 consecutive days arrested the development of cognitive deficits in STZ-ICV-treated rats, that is, a significant (P < 0.05) reduction in the mean escape latency during acquisition trial and increased (P < 0.05) time spent in target quadrant during retrieval trial in Morris water maze test and reduction (P < 0.05) in transfer latency in elevated plus maze test. Furthermore, both the doses of CAPE when administered to rats that were previously treated with STZ-ICV prevented the rise of brain thiobarbituric acid reactive substance as well as TNF-α and simultaneously enhanced the GSH content.

CONCLUSION

CAPE administration ameliorated STZ-ICV-induced dementia through the attenuation of oxidative stress and inflammation.

SUMMARY

Intracerebroventricular administration of streptozotocin (STZ-ICV) induced cognitive deficits, enhanced brain oxidative stress as well as inflammation in rats.Treatment with Caffeic Acid Phenethyl Ester (CAPE; dose 3 and 6 mg/kg, i.p.) for 28 days once daily, enhanced the memory and prevented the development of STZ-ICV-induced dementia in rats.The CAPE treated rats showed decrease in mean escape latency and increase in time spent in target quadrant in Morris Water Maze test. A decline in transfer latency of CAPE treated rats was observed in Elevated Plus Maze model.Profound rise in brain GSH levels and diminution of TBARS as well as TNF-α content was observed in brains of CAPE treated rats. Hence, the memory enhancing activity of CAPE against STZ-ICV-induced dementia is attributed to its robust antioxidant and anti-inflammatory property. Abbreviation used: AD: Alzheimer's disease, ANOVA: Analysis of Variance, aCSF: Artificial cerebrospinal fluid, CAPE: Caffeic acid phenethylester, EPM: Elevated plus maze, ELT: Escape latency time, GSH: Reduced glutathione, IL: Interleukin, ICV: Intracerebroventricular, MDA: Malondialdehyde, MEL: Mean escape latency, MWM: Morris water maze, NFTs: Neurofibrillary tangles, RNS: Reactive nitrogen species, ROS: Reactive oxygen species, SEM: Standard error of mean, STZ: Streptozotocin, TBARS: Thiobarbituric reactive substances, TSTQ: Time spent in target quadrant, TL: Transfer latency, TNF-α: Tumor necrosis factor alpha.

Protective effect of valproic acid in streptozotocin-induced sporadic Alzheimer's disease mouse model: possible involvement of the cholinergic system

Sporadic Alzheimer's disease (SAD) is a slowly progressive neurological disorder that is the most common form of dementia. Cholinergic system dysfunction and amyloid beta formation are the two main underlying pathological mechanisms for the disease development. In recent studies, insulin receptor desensitization and disturbances in the downstream effects of insulin receptor signaling were observed in the brains of Alzheimer's patients. Currently, intracereberoventricular (ICV) injection of streptozotocin (STZ) is found to induce behavioral, neurochemical, and structural alterations in animals resembling those found in SAD patients. Valproic acid (VPA), a histone deacetylase inhibitor (HDACi), was recently shown to regulate the transcription of several genes in both in vivo and in vitro models of Alzheimer's disease. The aim of the current study is to investigate the potential effect of different doses of valproic acid, in an ICV-STZ-induced animal model of SAD. Streptozotocin-injected mice showed cognitive and spatial memory dysfunction in the Y-maze, object recognition test, and Morris water maze (MWM) neurobehavioral tests. The mice also exhibited a decrease in acetylcholine (ACh) and neprilysin (NEP) levels accompanied by an increase in acetylcholinesterase (AChE) activity. For the first time to our knowledge, our findings have shown that VPA is capable of restoring ACh levels in ICV-STZ-injected mice, as well as normalizing both NEP levels and AChE activity. Via this mechanism, an enhancement of cognitive functions is observed. Thus, VPA is suggested to be a promising therapeutic approach against SAD.

Mitochondrial protective and anti-apoptotic effects of Rhodiola crenulata extract on hippocampal neurons in a rat model of Alzheimer's disease

In our previous study, we found that the edible alcohol extract of the root of the medicinal plant Rhodiola crenulata (RCE) improved spatial cognition in a rat model of Alzheimer's disease. Another study from our laboratory showed that RCE enhanced neural cell proliferation in the dentate gyrus of the hippocampus and prevented damage to hippocampal neurons in a rat model of chronic stress-induced depression. However, the mechanisms underlying the neuroprotective effects of RCE are unclear. In the present study, we investigated the anti-apoptotic effect of RCE and its neuroprotective mechanism of action in a rat model of Alzheimer's disease established by intracerebroventricular injection of streptozotocin. The rats were pre-administered RCE at doses of 1.5, 3.0 or 6.0 g/kg for 21 days before model establishment. ATP and cytochrome c oxidase levels were significantly decreased in rats with Alzheimer's disease. Furthermore, neuronal injury was obvious in the hippocampus, with the presence of a large number of apoptotic neurons. In comparison, in rats given RCE pretreatment, ATP and cytochrome c oxidase levels were markedly increased, the number of apoptotic neurons was reduced, and mitochondrial injury was mitigated. The 3.0 g/kg dose of RCE had the optimal effect. These findings suggest that pretreatment with RCE prevents mitochondrial dysfunction and protects hippocampal neurons from apoptosis in rats with Alzheimer's disease.

Effect of canagliflozin and metformin on cortical neurotransmitters in a diabetic rat model

BACKGROUND

The rapid economic development in the Arabian Gulf has resulted in lifestyle changes that have increased the prevalence of obesity and type 2 diabetes, with the greatest increases observed in Kuwait. Dyslipidemia and diabetes are risk factors for disruptions in cortical neurotransmitter homeostasis. This study investigated the effect of the antidiabetic medications canagliflozin (CAN) and metformin (MET) on the levels of cortical neurotransmitters in a diabetic rat model.

MATERIALS AND METHODS

The rats were assigned to the control (C) group, the diabetic group that did not receive treatment (D) or the diabetic group treated with either CAN (10 mg/kg) or MET (100 mg/kg) for 2 or 4 weeks. Blood and urine glucose levels and cortical acetylcholinesterase (AChE) activity were assayed, and amino acid and monoamine levels were measured using HPLC.

RESULTS

The diabetic group exhibited a significant increase in AChE activity and a decrease in monoamine and amino acid neurotransmitter levels. In the CAN group, AChE was significantly lower than that in the D and D + MET groups after 2 weeks of treatment. In addition, a significant increase in some cortical monoamines and amino acids was observed in the D + MET and D + CAN groups compared with the D group. Histopathological analysis revealed the presence of severe focal hemorrhage, neuronal degeneration, and cerebral blood vessel congestion, with gliosis in the cerebrum of rats in the D group. The CAN-treated group exhibited severe cerebral blood vessel congestion after 2 weeks of treatment and focal gliosis in the cerebrum after 4 weeks of treatment. Focal gliosis in the cerebrum of rats in the MET-treated group was observed after 2 and 4 weeks of treatment.

CONCLUSIONS

We conclude that the effect of CAN and MET on neurotransmitters is potentially mediated by their antihyperglycemic and antihyperlipidemic effects. In addition, the effects of CAN on neurotransmitters might be associated with its receptor activity, and the effect of MET on neurotransmitters might be associated with cerebral metabolism.

Caffeic acid attenuates oxidative stress, learning and memory deficit in intra-cerebroventricular streptozotocin induced experimental dementia in rats

Oxidative stress has been implicated in cognitive decline as seen during normal aging and in sporadic Alzheimer's disease (AD). Caffeic acid, a polyphenolic compound, has been reported to possess potent antioxidant and neuroprotective properties. The role of caffeic acid in experimental dementia is not fully understood. Thus the present study was designed to investigate the therapeutic potential of caffeic acid in streptozotocin (STZ)-induced experimental dementia of Alzheimer's type in rats. Streptozotocin (STZ) was administered intracerebroventrically (ICV) on day 1 and 3 (3mg/kg, ICV bilaterally) in Wistar rats. Caffeic acid was administered (10, 20 and 40mg/kg/day p.o.) 1h following STZ infusion upto 21st day. Morris water maze and object recognition task were used to assess learning and memory in rats. Terminally, acetylcholinesterase (AChE) activity and the levels of oxido-nitrosative stress markers were determined in cortical and hippocampal brain regions of rats. STZ produced significant (p<0.001) learning and memory impairment, oxido-nitrosative stress and cholinergic deficit in rats. Whereas, caffeic acid treatment significantly (p<0.001) and dose dependently attenuated STZ induced behavioral and biochemical abnormalities in rats. The observed cognitive improvement following caffeic acid in STZ treated rats may be due to its antioxidant activity and restoration of cholinergic functions. Our results suggest the therapeutic potential of caffeic acid in cognitive disorders such as AD.

Possible role of P-glycoprotein in the neuroprotective mechanism of berberine in intracerebroventricular streptozotocin-induced cognitive dysfunction

RATIONALE

The therapeutic potential of berberine has been well documented in various neurological problems. However, the neurological mechanism of berberine remains untapped in the light of its P-glycoprotein (P-gp)-mediated gut efflux properties responsible for reduced bioavailability. Verapamil, a well known L-type calcium channel blocker, has additional inhibitory activity against P-gp efflux pump. Thus, there is a strong scientific rationale to explore the interaction of berberine with verapamil as a possible neuroprotective strategy.

OBJECTIVE

The present study was designed to evaluate the effect of berberine, verapamil, and their combination on behavioral alterations, oxidative stress, mitochondrial dysfunction, neuroinflammation, and histopathological modifications in intracerebroventricular streptozocin (ICV-STZ)-induced sporadic dementia of Alzheimer's type in rats.

METHODS

Single bilateral ICV-STZ (3 mg/kg) administration was used as an experimental model of sporadic dementia of Alzheimer's type.

RESULTS

Berberine (25, 50, and 100 mg/kg, oral gavage) or verapamil (2.5 and 5 mg/kg, intraperitoneally) were used as treatment drugs, and memantine (5 mg/kg, intraperitoneally) was used as a standard. Berberine and verapamil significantly attenuated behavioral, biochemical, cellular, and histological alterations, suggesting their neuroprotective potential. Further, treatment of berberine (25 and 50 mg/kg) with verapamil (2.5 and 5.0 mg/kg) combinations respectively significantly potentiated their neuroprotective effect which was significant as compared to their effect per se in ICV-STZ-treated animals.

CONCLUSION

The augmentative outcome of verapamil on the neuroprotective effect of berberine can be speculated due to the inhibition of P-gp efflux mechanism and the prevention of calcium homeostasis alteration. Additionally, anti-inflammatory and antioxidant effects of both berberine and verapamil could also contribute in their protective effect.

Puerarin attenuates learning and memory impairments and inhibits oxidative stress in STZ-induced SAD mice

Puerarin (PUE), an isoflavone purified from the root of Pueraria lobata (Chinese herb), has been reported to attenuate learning and memory impairments in the transgenic mouse model of Alzheimer's disease (AD). In the present study, we tested PUE in a sporadic AD (SAD) mouse model which was induced by the intracerebroventricular injection of streptozotocin (STZ). The mice were administrated PUE (25, 50, or 100mg/kg/d) for 28 days. Learning and memory abilities were assessed by the Morris water maze test. After behavioral test, the biochemical parameters of oxidative stress (glutathione peroxidase (GSH-Px), superoxide dismutases (SOD), and malondialdehyde (MDA)) were measured in the cerebral cortex and hippocampus. The SAD mice exhibited significantly decreased learning and memory ability, while PUE attenuated these impairments. The activities of GSH-Px and SOD were decreased while MDA was increased in the SAD animals. After PUE treatment, the activities of GSH-Px and SOD were elevated, and the level of MDA was decreased. The middle dose PUE was more effective than others. These results indicate that PUE attenuates learning and memory impairments and inhibits oxidative stress in STZ-induced SAD mice. PUE may be a promising therapeutic agent for SAD.

Streptozotocin Intracerebroventricular-Induced Neurotoxicity and Brain Insulin Resistance: a Therapeutic Intervention for Treatment of Sporadic Alzheimer's Disease (sAD)-Like Pathology

Alzheimer's disease (AD) is a neurodegenerative disorder that is remarkably characterized by pathological hallmarks which include amyloid plaques, neurofibrillary tangles, neuronal loss, and progressive cognitive loss. Several well-known genetic mutations which are being used for the development of a transgenic model of AD lead to an early onset familial AD (fAD)-like condition. However, these settings are only reasons for a small percentage of the total AD cases. The large majorities of AD cases are considered as a sporadic in origin and are less influenced by a single mutation of a gene. The etiology of sporadic Alzheimer's disease (sAD) remains unclear, but numerous risk factors have been identified that increase the chance of developing AD. Among these risk factors are insulin desensitization/resistance state, oxidative stress, neuroinflammation, synapse dysfunction, tau hyperphosphorylation, and deposition of Aβ in the brain. Subsequently, these risk factors lead to development of sAD. However, the underlying molecular mechanism is not so clear. Streptozotocin (STZ) produces similar characteristic pathology of sAD such as altered glucose metabolism, insulin signaling, synaptic dysfunction, protein kinases such as protein kinase B/C, glycogen synthase-3β (GSK-3β) activation, tau hyperphosphorylation, Aβ deposition, and neuronal apoptosis. Further, STZ also leads to inhibition of Akt/PKB, insulin receptor (IR) signaling molecule, and insulin resistance in brain. These alterations mediated by STZ can be used to explore the underlying molecular and pathophysiological mechanism of AD (especially sAD) and their therapeutic intervention for drug development against AD pathology.

A Novel 1,4-Dihydropyridine Derivative Improves Spatial Learning and Memory and Modifies Brain Protein Expression in Wild Type and Transgenic APPSweDI Mice

Ca²⁺ blockers, particularly those capable of crossing the blood-brain barrier (BBB), have been suggested as a possible treatment or disease modifying agents for neurodegenerative disorders, e.g., Alzheimer’s disease. The present study investigated the effects of a novel 4-(N-dodecyl) pyridinium group-containing 1,4-dihydropyridine derivative (AP-12) on cognition and synaptic protein expression in the brain. Treatment of AP-12 was investigated in wild type C57BL/6J mice and transgenic Alzheimer’s disease model mice (Tg APP_SweDI) using behavioral tests and immunohistochemistry, as well as mass spectrometry to assess the blood-brain barrier (BBB) penetration. The data demonstrated the ability of AP-12 to cross the BBB, improve spatial learning and memory in both mice strains, induce anxiolytic action in transgenic mice, and increase expression of hippocampal and cortical proteins (GAD67, Homer-1) related to synaptic plasticity. The compound AP-12 can be seen as a prototype molecule for use in the design of novel drugs useful to halt progression of clinical symptoms (more specifically, anxiety and decline in memory) of neurodegenerative diseases, particularly Alzheimer’s disease.

Expression of β-site APP-cleaving enzyme 1 in the hippocampal tissue of an insulin-resistant rat model of Alzheimer's disease

The aim of this study was to investigate the expression of β-site APP-cleaving enzyme 1 (BACE1) in the hippocampal tissue of an insulin-resistant rat model, and thereby explore the roles of BACE1 and insulin resistance (IR) in the pathogenesis of Alzheimer's disease (AD). A total of 36 male Sprague-Dawley rats, aged 2 months, were randomly divided into three groups. These were an insulin-resistant (experimental) group, a high fat control group and a blank control group. The cognitive function and behavioral changes of the rats were tested by a Morris water maze experiment. Amyloid β (Aβ) deposition was detected by an immunohistochemical method. The expression levels of BACE1 in the rat hippocampal tissues were detected by enzyme-linked immunosorbent assay, western blotting and reverse transcription-quantitative polymerase chain reaction technology. The rats in the experimental group had evident learning and memory impairment, with significantly decreased learning memory. The modeling was successful; in the experimental group, the rats exhibited IR and their glucose metabolism was significantly abnormal. However, there was no characteristic pathology of AD. The expression of BACE1 in the brain tissue of rats in the experimental group was significantly higher than that in high fat control and blank control groups (P<0.01). In conclusion, the expression of BACE1 in the brain tissue of insulin-resistant rats increased, and IR was indicated to participate in the pathogenesis of AD.

Bacopa monniera ameliorates cognitive impairment and neurodegeneration induced by intracerebroventricular-streptozotocin in rat: behavioral, biochemical, immunohistochemical and histopathological evidences

The standardized extract of Bacopa monniera (BM) is a complex mixture of ingredients with a uniquely wide spectrum of neuropharmacological influences upon the central nervous system including enhanced learning and memory with known antioxidant potential and protection of the brain from oxidative damage. The present study demonstrates the therapeutic efficacy of BM on cognitive impairment and oxidative damage, induced by intracerebroventricular injection of streptozotocin (ICV-STZ) in rat models. Male Wistar rats were pre-treated with BM at a selected dose (30 mg/Kg) given orally for 2 weeks and then were injected bilaterally with ICV-STZ (3 mg/Kg), while sham operated rats were received the same volume of vehicle. Behavioral parameters were subsequently monitored 2 weeks after the surgery using the Morris water maze (MWM) navigation task then were sacrificed for biochemical, immunohistochemical (Cu/Zn-SOD) and histopathological assays. ICV-STZ-infused rats showed significant loss in learning and memory ability, which were significantly improved by BM supplementation. A significant increase in thiobarbituric acid reactive species and a significant decrease in reduced glutathione, antioxidant enzymes in the hippocampus were observed in ICV-STZ rats. Moreover, decrease in Cu/Zn-SOD expression positive cells were observed in the hippocampus of ICV-STZ rats. BM supplementation significantly ameliorated all alterations induced by ICV-STZ in rats. The data suggest that ICV-STZ might cause its neurotoxic effects via the production of free radicals. Our study demonstrates that BM is a powerful antioxidant which prevents cognitive impairment, oxidative damage, and morphological changes in the ICV-STZ-infused rats. Thus, BM may have therapeutic value for the treatment of cognitive impairment.

Investigation of the role of non-selective calcium channel blocker (flunarizine) on cerebral ischemic-reperfusion associated cognitive dysfunction in aged mice

The present study was designed to investigate the role of flunarizine (a non-selective calcium channel blocker) on cerebral ischemic-reperfusion associated cognitive dysfunction in aged mice. Bilateral carotid artery occlusion of 12min followed by reperfusion for 24h was given to induce cerebral injury in male Swiss mice. The assessment of learning & memory was performed by Morris water maze test; motor in-coordination was evaluated by rota rod, lateral push and inclined beam walking tests; cerebral infarct size was quantified by triphenyltetrazolium chloride staining. In addition, reduced glutathione (GSH), total calcium and acetylcholinesterase (AChE) activity were also estimated in aged brain tissue. Donepezil treated group served as a positive control in this study. Ischemia reperfusion (I/R) injury produced significant increase in cerebral infarct size. A significant loss of memory along with impairment of motor performance was also noted. Further, I/R injury also produced significant increase in levels of total calcium, AChE activity and decrease in GSH levels. Pretreatment of flunarizine significantly attenuated I/R induced infarct size, behavioral and biochemical changes. Hence, it may be concluded that, a non-selective calcium channel blocker can be useful in I/R associated cognitive dysfunction due to its anti-oxidant, anti-infarct and modulatory actions of neurotransmitters & calcium channels.