Anandamide Effects in a Streptozotocin-Induced Alzheimer's Disease-Like Sporadic Dementia in Rats

Oxyresveratrol-β-cyclodextrin mitigates streptozotocin-induced Alzheimer's model cognitive impairment, histone deacetylase activity in rats: in silico & in vivo studies

Alzheimer's disease (AD) is associated with cognitive deficits and epigenetic deacetylation that can be modulated by natural products. The role of natural oxyresveratrol-β-cyclodextrin (ORV) on cognition and histone deacetylase activity in AD is unclear. Herein, in-silico docking and molecular dynamics simulation analysis determined that oxyresveratrol potentially targets histone deacetylase-2 (HDAC2). We therefore evaluated the in vivo ameliorative effect of ORV against cognitive deficit, cerebral and hippocampal expression of HDAC in experimental AD rats. Intracerebroventricular injection of STZ (3 mg/kg) induced experimental AD and the rats were treated with low dose (200 mg/kg), high dose (400 mg/kg) of ORV and donepezil (10 mg/kg) for 21 days. The STZ-induced AD caused cognitive and behavioural deficits demonstrated by considerable increases in acetylcholinesterase activity and escape latency compared to sham control. The levels of malondialdehyde (MDA) and HDAC activity were significantly increased in AD disease group comparison to the sham. Interestingly, the ORV reversed the cognitive-behavioural deficit and prominently reduced the MDA and HDAC levels comparable to the effect of the standard drug, donepezil. The findings suggest anti-AD role of ORV via antioxidant effect and inhibition of HDAC in the hippocampal and frontal cortical area of rats for AD.

Proteomic Analysis of a Rat Streptozotocin Model Shows Dysregulated Biological Pathways Implicated in Alzheimer's Disease

Alzheimer's Disease (AD) is an age-related neurodegenerative disorder characterized by progressive memory loss and cognitive impairment, affecting 35 million individuals worldwide. Intracerebroventricular (ICV) injection of low to moderate doses of streptozotocin (STZ) in adult male Wistar rats can reproduce classical physiopathological hallmarks of AD. This biological model is known as ICV-STZ. Most studies are focused on the description of behavioral and morphological aspects of the ICV-STZ model. However, knowledge regarding the molecular aspects of the ICV-STZ model is still incipient. Therefore, this work is a first attempt to provide a wide proteome description of the ICV-STZ model based on mass spectrometry (MS). To achieve that, samples from the pre-frontal cortex (PFC) and hippocampus (HPC) of the ICV-STZ model and control (wild-type) were used. Differential protein abundance, pathway, and network analysis were performed based on the protein identification and quantification of the samples. Our analysis revealed dysregulated biological pathways implicated in the early stages of late-onset Alzheimer's disease (LOAD), based on differentially abundant proteins (DAPs). Some of these DAPs had their mRNA expression further investigated through qRT-PCR. Our results shed light on the AD onset and demonstrate the ICV-STZ as a valid model for LOAD proteome description.

Impact of TRPV1 on Pathogenesis and Therapy of Neurodegenerative Diseases

Transient receptor potential vanilloid 1 (TRPV1) is a transmembrane and non-selective cation channel protein, which can be activated by various physical and chemical stimuli. Recent studies have shown the strong pathogenetic associations of TRPV1 with neurodegenerative diseases (NDs), in particular Alzheimer's disease (AD), Parkinson's disease (PD) and multiple sclerosis (MS) via regulating neuroinflammation. Therapeutic effects of TRPV1 agonists and antagonists on the treatment of AD and PD in animal models also are emerging. We here summarize the current understanding of TRPV1's effects and its agonists and antagonists as a therapeutic means in neurodegenerative diseases, and highlight future treatment strategies using natural TRPV1 agonists. Developing new targets and applying natural products are becoming a promising direction in the treatment of chronic disorders, especially neurodegenerative diseases.

Insight into the emerging and common experimental in-vivo models of Alzheimer's disease

Alzheimer's disease (AD) is a multifactorial, rapidly progressing neurodegenerative disorder. As the exact cause of the disease is still unclear, the drug development is very challenging. This review encompasses the commonly used AD models involving various chemicals, heavy metals and endogenous substances induced models and the transgenic models. It also provides insight into the reliable emerging models of AD that may overcome the shortcomings associated with available models. Chemicals like streptozotocin, scopolamine, colchicine and okadaic acid render the animal susceptible to neuroinflammation and oxidative stress induced neurodegeneration along with amyloid-β deposition and tau hyperphosphorylation. Similarly, endogenous substances like acrolein and amyloid-β 1-42 are efficient in inducing the major pathologies of AD. Heavy metals like aluminum and fluoride and mixture of these have been reported to induce neurotoxicity therefore are used as animal models for AD. Transgenic models developed as a result of knock-in or knock-out of certain genes associated with AD including PDAPP, APP23, Tg2576, APP/PS1, 3 × Tg and 5 × FAD have also been incorporated in this study. Further, emerging and advanced pathomimetic models of AD are provided particular interest here which will add on to the current knowledge of animal models and may aid in the drug development process and deepen our understanding related to AD pathogenesis. These newly discovered models include oAβ25-35 model, transgenic model expressing 82-kDa ChAT, oDGal mouse and APP knock-in rat. This study may aid in the selection of suitable model for development of novel potent therapeutics and for exploring detailed pathogenic mechanism of AD.

Memory impairment was ameliorated by corticolimbic microinjections of arachidonylcyclopropylamide (ACPA) and miRNA-regulated lentiviral particles in a streptozotocin-induced Alzheimer's rat model

The present study aimed to investigate the effect of corticolimbic cannabinoid CB1 receptors activity on memory impairment in the intracerebroventricular (ICV)-streptozotocin (STZ) animal model of Alzheimer's like-disease. This study also assessed whether the corticolimbic overexpression of miRNA-137 or -let-7a could increase the endocannabinoids by inhibiting the monoglyceride lipase (MAGL) to ameliorate STZ response. The results showed that ICV microinjection of STZ (3 mg/kg/10 μl) impaired passive avoidance memory retrieval. The chronic microinjection of arachidonylcyclopropylamide (ACPA; 10 ng/0.5 μl), a selective cannabinoid CB1 receptor agonist, into the hippocampal CA1 region, the central amygdala (CeA) or the medial prefrontal cortex (mPFC) ameliorated the amnesic effect of ICV-STZ. Intra-CA1 or -CeA microinjection of ACPA alone did not affect memory retrieval, while its microinjection into the mPFC impaired memory formation. Based on bioinformatics analysis and verification of the MAGL gene, miRNA-137 and -let-7a were chosen to target the expression levels of MAGL in the corticolimbic regions. The chronic corticolimbic microinjection of lentiviral particles containing miRNA-137 or -let-7a ameliorated ICV-STZ-induced memory impairment. The high transfection efficiency was determined for each virus using comparing fluorescent and conventional vision. Corticolimbic overexpression of miRNA-137 or -let-7a decreased the MAGL gene expression that encodes the MAGL enzyme to increase the endocannabinoids. Thus, among the molecular mechanisms and signaling pathways involved in the pathophysiology of Alzheimer's disease (AD), it is worth mentioning the role of endocannabinoids in the corticolimbic regions. CB1 receptor agonists, miRNA-137 or -let-7a, may be potential therapeutic targets against cognitive decline in AD.

Subject classification and cross-time prediction based on functional connectivity and white matter microstructure features in a rat model of Alzheimer's using machine learning

BACKGROUND

The pathological process of Alzheimer's disease (AD) typically takes decades from onset to clinical symptoms. Early brain changes in AD include MRI-measurable features such as altered functional connectivity (FC) and white matter degeneration. The ability of these features to discriminate between subjects without a diagnosis, or their prognostic value, is however not established.

METHODS

The main trigger mechanism of AD is still debated, although impaired brain glucose metabolism is taking an increasingly central role. Here, we used a rat model of sporadic AD, based on impaired brain glucose metabolism induced by an intracerebroventricular injection of streptozotocin (STZ). We characterized alterations in FC and white matter microstructure longitudinally using functional and diffusion MRI. Those MRI-derived measures were used to classify STZ from control rats using machine learning, and the importance of each individual measure was quantified using explainable artificial intelligence methods.

RESULTS

Overall, combining all the FC and white matter metrics in an ensemble way was the best strategy to discriminate STZ rats, with a consistent accuracy over 0.85. However, the best accuracy early on was achieved using white matter microstructure features, and later on using FC. This suggests that consistent damage in white matter in the STZ group might precede FC. For cross-timepoint prediction, microstructure features also had the highest performance while, in contrast, that of FC was reduced by its dynamic pattern which shifted from early hyperconnectivity to late hypoconnectivity.

CONCLUSIONS

Our study highlights the MRI-derived measures that best discriminate STZ vs control rats early in the course of the disease, with potential translation to humans.

Evidence of disturbed insulin signaling in animal models of Alzheimer's disease

Since glucose reuptake by neurons is mostly independent of insulin, it has been an intriguing question whether insulin has or not any roles in the brain. Consequently, the identification of insulin receptors in the central nervous system has fueled investigations of insulin functions in the brain. It is also already known that insulin can influence glucose reuptake by neurons, mostly during activities that have the highest energy demand. The identification of high density of insulin receptors in the hippocampus also suggests that insulin may present important roles related to memory. In this context, studies have reported worse performance in cognitive tests among diabetic patients. In addition, alterations in the regulation of central insulin pathways have been observed in the brains of Alzheimer's disease (AD) patients. In fact, some authors have proposed AD as a third type of diabetes and recently, our group proposed insulin resistance as a common link between different AD hypotheses. Therefore, in the present narrative review, we intend to revise and gather the evidence of disturbed insulin signaling in experimental animal models of AD.

Animal models of Alzheimer's disease: An originof innovativetreatments and insight to the disease's etiology

Alzheimer's disease (AD) is a progressive neurodegenerative disorder. The main pathogenic features are the development and depositionof senile plaques and neurofibrillary tangles in brain. Recent developments in the knowledge of the pathophysiological mechanisms behind Alzheimer's disease and other cognitive disorders have suggested new approaches to treatment development. These advancements have been significantly aided by the use of animal models, which are also essential for the assessment of therapies. Various approaches as transgenic animal model, chemical models, brain injury are used. This review will presentAD pathophysiology and emphasize several Alzheimer like dementia causingchemical substances, transgenic animal model and stereotaxy in order to enhance our existing knowledge of their mechanism of AD induction, dose, and treatment duration.

Artemisin and human endometrial-derived stem cells improve cognitive function and synaptic plasticity in a rat model of Alzheimer disease and diabetes

Alzheimer disease (AD) is a common form of dementia associated with loss of memory and disruption of synaptic plasticity. There is a strong correlation between the pathophysiological features of AD and diabetes, including induction of oxidative stress, inflammation, and abnormality in blood vessels. Considering the brain's limited capacity to repair damage and the potential of stem cell-derived neural cells in the repair of neurodegenerative disease, we investigated the effects of artemisinin and TSP‑1‑human endometrial-derived-derived stem cells (TSP‑1‑hEDSCs) on the cognitive function and synaptic plasticity in AD-diabetes rats. The authors previously showed that artemisinin and TSP‑1‑hEDSCs suppressed oxidative stress and inflammation in AD-diabetes rats. Thrombospondins-1 (TSPs-1) is a glycoprotein that inhibits angiogenesis. AD and diabetes were induced using streptozotocin. Synaptic plasticity and learning and memory function were studied using the Morris water maze and electrophysiological test, respectively. Streptozotocin increased traveled swimming distance and escape latency in the morris water maze test, decreased the percent time spent in the target quadrant, inhibited the long-term potentiation (LTP), and increased the blood glucose levels. Simultaneous or separate administration of artemisinin and TSP‑1‑hEDSCs decreased the blood levels of glucose and improved cognitive tasks and synaptic plasticity by considerably reducing traveled swimming distance and escape latency, increasing the percent time spent in the target quadrant, and retrieval of the LTP; therefore, they could be utilized as an adjunct treatment for AD treatment. These results may be due to a decrease in oxidative stress and inflammation.

Policosanol protects against Alzheimer's disease-associated spatial cognitive decline in male rats: possible involved mechanisms

RATIONALE

Alzheimer's disease (AD) is a chronic neurodegenerative disorder characterized by cognitive decline and synaptic failure.

OBJECTIVE

The present study was designed to explore the possible protective effects of policosanol (PCO) on spatial cognitive capacity, long-term potentiation (LTP) induction, oxidant/antioxidant status, and Aβ plaques formation in an AD rat model induced by intracerebroventricular (ICV) injection of Aβ_1-40.

METHODS

Healthy adult male Wistar rats were randomly divided into control, sham (ICV injection of 5 µl phosphate-buffered saline), AG (50 mg/kg; P.O., as PCO vehicle), PCO (50 mg/kg; P.O.), AD model (ICV injection of 5 µl Aβ), AD + AG (50 mg/kg; P.O.), and AD + PCO (50 mg/kg; P.O.). Treatments were performed for eight consecutive weeks. At the end of the treatment course, spatial learning and memory functions, hippocampal long-term potentiation (LTP) induction, malondialdehyde (MDA), and total thiol group (TTG) levels, as well as the formation of Aβ plaques, were examined.

RESULTS

The results showed that injection of Aβ reduced spatial learning and memory abilities in the Barnes maze test, which was accompanied by decreases in field excitatory postsynaptic potential (fEPSP) slope, population spike (PS) amplitude, and TTG level and increases in Aβ plaque accumulation and MDA content. In contrast, PCO treatment improved all the above-mentioned changes in the Aβ-infused rats.

CONCLUSIONS

The results suggest that amelioration of hippocampal synaptic plasticity impairment, modulation of oxidant/antioxidant status, and inhibition of Aβ plaque formation by PCO may be the mechanisms behind its protective effect against AD-associated spatial cognitive decline.

Naringin Prevents Cognitive Dysfunction in Aging Rats by Inhibiting Toll-Like Receptor 4 (TLR4)/NF-κB Pathway and Endoplasmic Reticulum Stress

Objective

Naringin is a flavonoid derived from Chinese herbs. According to earlier studies, naringin may have the potential to alleviate aging-induced cognitive dysfunction. Therefore, this study attempted to explore the protective effect and underlying mechanism of naringin on aging rats with cognitive dysfunction.

Methods

After the construction of a model of aging rats with cognitive dysfunction through subcutaneous injection of D-galactose (D-gal; 150 mg/kg), intragastric administration of naringin (100 mg/kg) was performed for treatment. Behavioral tests, including Morris water maze test (MWM), novel object recognition test (NORT), and fear conditioning test, were used to measure the cognitive function; ELISA and biochemical tests were used to determine the levels of interleukin (IL)-1β, IL-6, monocyte chemoattractant protein-1 (MCP-1), brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), malondialdehyde (MDA), and glutathione peroxidase (GSH-Px) in the hippocampus of rats in each group, respectively; H&E staining was used to observe the pathological changes in the hippocampus; Western blot was used to examine the expression of toll-like receptor 4 (TLR4)/NF-κB pathway-related proteins and endoplasmic reticulum (ER) stress-related proteins in the hippocampus.

Results

The model was successfully constructed by subcutaneous injection of D-gal (150 mg/kg). The behavioral test results showed that naringin could ameliorate the cognitive dysfunction and alleviate the histopathological damage of hippocampus. Moreover, naringin significantly improve the inflammatory response (the levels of IL-1β, IL-6, and MCP-1 were decreased), oxidative stress response (MDA level was increased while GSH-Px activity was decreased), and ER stress (the expression of glucose-regulated protein 78 (GRP78), C/-EBP homologous protein (CHOP), and transcription factor 6 (ATF6) expression was downregulated), and increased the levels of neurotrophic factors BDNF and NGF in D-gal rats. Besides, further mechanistic studies revealed the downregulation of naringin on TLR4/NF-κB pathway activity.

Conclusion

Naringin may inhibit inflammatory response, oxidative stress, and ER stress by downregulating TLR4/NF-κB pathway activity, thereby improving cognitive dysfunction and alleviating histopathological damage of hippocampus in aging rats. Briefly, naringin is an effective drug for the treatment of cognitive dysfunction.

Synaptic loss and gliosis in the nucleus tractus solitarii with streptozotocin-induced Alzheimer's disease

Obstructive sleep apnea is highly prevalent in Alzheimer's disease (AD). However, brainstem centers controlling respiration have received little attention in AD research, and mechanisms behind respiratory dysfunction in AD are not understood. The nucleus tractus solitarii (nTS) is an important brainstem center for respiratory control and chemoreflex function. Alterations of nTS integrity, like those shown in AD patients, likely affect neuronal processing and adequate control of breathing. We used the streptozotocin-induced rat model of AD (STZ-AD) to analyze cellular changes in the nTS that corroborate previously documented respiratory dysfunction. We used 2 common dosages of STZ (2 and 3 mg/kg STZ) for model induction and evaluated the early impact on cell populations in the nTS. The hippocampus served as control region to identify site-specific effects of STZ. There was significant atrophy in the caudal nTS of the 3 mg/kg STZ-AD group only, an area known to integrate chemoafferent information. Also, the hippocampus had significant atrophy with the highest STZ dosage tested. Both STZ-AD groups showed respiratory dysfunction along with multiple indices for astroglial and microglial activation. These changes were primarily located in the caudal and intermediate nTS. While there was no change of astrocytes in the hippocampus, microglial activation was accompanied by a reduction in synaptic density. Together, our data demonstrate that STZ-AD induces site-specific effects on all major cell types, primarily in the caudal/intermediate nTS. Both STZ dosages used in this study produced a similar outcome and can be used for future studies examining the initial symptoms of STZ-AD.

Fatty acid amide hydrolase and 9-lipoxygenase modulate cotton seedling growth by ethanolamide oxylipin levels

Polyunsaturated N-acylethanolamines (NAEs) can be hydrolyzed by fatty acid amide hydrolase (FAAH) or oxidized by lipoxygenase (LOX). In Arabidopsis (Arabidopsis thaliana), the 9-LOX product of linoleoylethanolamide, namely, 9-hydroxy linoleoylethanolamide (9-NAE-HOD), is reported to negatively regulate seedling development during secondary dormancy. In upland cotton (Gossypium hirsutum L.), six putative FAAH genes (from two diverged groups) and six potential 9-LOX genes are present; however, their involvement in 9-NAE-HOD metabolism and its regulation of seedling development remain unexplored. Here, we report that in cotton plants, two specific FAAH isoforms (GhFAAH Ib and GhFAAH IIb) are needed for hydrolysis of certain endogenous NAEs. Virus-induced gene silencing (VIGS) of either or both FAAHs led to reduced seedling growth and this coincided with reduced amidohydrolase activities and elevated quantities of endogenous 9-NAE-HOD. Transcripts of GhLOX21 were consistently elevated in FAAH-silenced tissues, and co-silencing of GhLOX21 and GhFAAH (Ib and/or IIb) led to reversal of seedling growth to normal levels (comparable with no silencing). This was concomitant with reductions in the levels of 9-NAE-HOD, but not of 13-NAE-HOD. Pharmacological experiments corroborated the genetic and biochemical evidence, demonstrating that direct application of 9-NAE-HOD, but not 13-NAE-HOD or their corresponding free fatty acid oxylipins, inhibited the growth of cotton seedlings. Additionally, VIGS of GhLOX21 in cotton lines overexpressing AtFAAH exhibited enhanced growth and no detectable 9-NAE-HOD. Altogether, we conclude that the growth of cotton seedlings involves fine-tuning of 9-NAE-HOD levels via FAAH-mediated hydrolysis and LOX-mediated production, expanding the mechanistic understanding of plant growth modulation by NAE oxylipins to a perennial crop species.

Cognitive Dysfunction and Anxiety Resulting from Synaptic Downscaling, Hippocampal Atrophy, and Ventricular Enlargement with Intracerebroventricular Streptozotocin Injection in Male Wistar Rats

Insulin-resistant brain state is proposed to be the early sign of Alzheimer's disease (AD), which can be studied in the intracerebroventricular streptozotocin (ICV-STZ) rodent model. ICV-STZ is reported to induce sporadic AD with the majority of the disease hallmarks as phenotype. On the other hand, available experimental evidence has used varying doses of STZ (< 1 to 3 mg/kg) and studied its effect for different study durations, ranging from 14 to 270 days. Though these studies suggest 3 mg/kg of ICV-STZ to be the optimum dose for progressive pathogenesis, the reason for such is elusive. Here, we sought to investigate the mechanism of action of 3 mg/kg ICV-STZ on cognitive and non-cognitive aspects at a follow-up interval of 2 weeks for 2 months. On the 60th day, we examined the layer thickness, cell density, ventricular volume, spine density, protein expression related to brain metabolism, and mitochondrial function by histological examination. The findings suggest a progressive loss of a spatial, episodic, and avoidance memory with an increase in anxiety in a span of 2 months. Furthermore, hippocampal neurodegeneration, ventricular enlargement, diffused amyloid plaque deposition, loss of spine in the dentate gyrus, and imbalance in energy homeostasis were found on the 60th day post-injection. Interestingly, AD rats showed a uniform fraction of time spent in four quadrants of the water maze with a change in strategy when they were exposed to height. Our findings reveal that ICV-STZ injection at a dose of 3 mg/kg can cause cognitive and neuropsychiatric abnormalities due to structural loss both at the neuronal as well as the synaptic level, which is tightly associated with the change in neuronal metabolism.

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.

Protective effect of miR-34c antagomir against STZ-induced memory impairment by targeting mTOR and PSD-95 in the hippocampus of rats

After long times of ongoing research, still there is no appropriate cure for Alzheimer's disease (AD). Recently, epigenetic alterations, particularly miRNA, have gotten attention in AD research. Among various miRNA, miR-34c has been addressed to be elevated in the brain of AD patients, however, its exact role and downstream mechanisms have not been elucidated yet. This study aimed to investigate the therapeutic potential of miR-34c antagomir on cognitive dysfunction induced by streptozocin (STZ), considering postsynaptic density protein 95 (PSD-95) and mammalian target of rapamycin expression (mTOR). Forty rats were cannulated intraventricularly under deep anesthesia using stereotaxic apparatus and divided into five groups: saline + saline, STZ + saline, STZ + miR-34c antagomir, STZ + lipofectamine, and STZ + scrambled, and received the related treatments for two weeks. At the end of the treatments, spatial memory and locomotor activity were assessed by Morris water maze (MWM), and open fields, respectively. Finally, PSD-95 and mTOR levels were measured by quantitative real-time PCR (qPCR) and western blotting on hippocampal samples. Results showed that miR-34c antagomir markedly ameliorated spatial learning and memory deficits induced by STZ, and significantly enhanced PSD-95 and mTOR levels in the hippocampus. In conclusion, miR-34c antagomir may be considered as a promising novel therapeutic target for AD patients.

Effect of the MAGL/FAAH Dual Inhibitor JZL-195 on Streptozotocin-Induced Alzheimer's Disease-like Sporadic Dementia in Mice with an Emphasis on Aβ, HSP-70, Neuroinflammation, and Oxidative Stress

Alzheimer's disease is identified by pathological hallmarks such as intracellular neurofibrillary tangles (NFTs) and extracellular amyloid β plaques. Several hypotheses exist to define the neurodegeneration including microglial activation associated with neuroinflammatory processes. Recently, pharmacological inhibition of endocannabinoid (eCB)-degrading enzymes, fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL), is being investigated to modulate the pathology of Alzheimer's disease. While MAGL inhibitors upregulate 2-acyl glycerol (2-AG) levels and reduce neuroinflammation, FAAH inhibitors elevate anandamide (AEA) levels and prevent the degradation of HSP-70, thereby preventing the phosphorylation of tau protein and formation of NFTs in neural cells. We investigated the possible neuroprotective potential of the dual MAGL/FAAH inhibitor JZL-195 (20 mg/kg) against ICV-STZ-induced sporadic Alzheimer's disease (SAD) in Swiss albino mice using donepezil (5 mg/kg) as the standard. The protective effects of JZL-195 were observed by the reversal of altered levels of Aβ_1-42, HSP-70, neuroinflammatory cytokines, and oxidative stress markers. However, JZL-195 expressed no cognitive improvement when assessed by spontaneous alternation behavior and Morris water maze tests and no effects on the AChE enzyme level in the hippocampal tissues of mice. Therefore, the findings of the present study indicate that although JZL-195 exhibited no improvement in cognitive deficits associated with sporadic Alzheimer's disease, it displayed significant reversal of the biochemical anomalies, thereby suggesting its therapeutic potential against the sporadic Alzheimer's disease model.

Protection of Beta Boswellic Acid against Streptozotocin-induced Alzheimer's Model by Reduction of Tau Phosphorylation Level and Enhancement of Reelin Expression

Alzheimer's disease is a growing general health concern with huge implications for individuals and society. Beta boswellic acid, a major compound of the Boswellia serrata plant, has long been used for the treatment of various inflammatory diseases. The exact mechanism of beta boswellic acid action in Alzheimer's disease pathogenesis remains unclear. In the current study, the protective effect of beta boswellic acid on streptozotocin-induced sporadic Alzheimer's disease was surveyed. Alzheimer's disease model was induced using streptozotocin followed by an assessment of the treatment effects of beta boswellic acid in the presence of streptozotocin. The prevention effect of beta boswellic acid on Alzheimer's disease induction by streptozotocin was evaluated. Behavioral activities in the treated rats were evaluated. Histological analysis was performed. Phosphorylation of tau protein at residues Ser396 and Ser404 and the expression of reelin protein were determined. Glial fibrillary acidic protein immunofluorescence staining was applied in the hippocampus regions. Our findings indicated that beta boswellic acid decreased traveled distance and escape latency in the prevention (beta boswellic acid + streptozotocin) and treatment (streptozotocin + beta boswellic acid) groups compared to control during the acquisition test. It increased "time spent" (%) in the target quadrant. Reelin level was enhanced in rats treated with beta boswellic acid. Tau hyperphosphorylation (p-tau404) and glial fibrillary acidic protein were decreased in the prevention group while the expression of reelin protein in both groups was increased. We could suggest that the anti-inflammatory property of beta boswellic acid is one of the main factors involving in the improvement of learning and memory in rats. Therefore the antineurodegenerative effect of beta boswellic acid may be due to its ability to reactivate reelin protein.

Effect of curcumin nanoparticles on streptozotocin-induced male Wistar rat model of Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disease that afflicts millions of people all over the world. Intracerebroventricular (ICV) injection of a sub-diabetogenic dose of streptozotocin (STZ) was established as an experimental animal model of AD. The present study was conducted to evaluate the efficacy of curcumin nanoparticles (CNs) against the behavioral, neurochemical and histopathological alterations induced by ICV-STZ. The animals were divided into: control animals, the animal model of AD that received a single bilateral ICV microinjection of STZ, and the animals protected by a daily oral administration of CNs for 6 days before the ICV-STZ injection. The animals of all groups were subjected to surgical operation on the 7th day of administration. Then the administration of distilled water or CNs was continued for 8 days. The ICV-STZ microinjection produced cognitive impairment as evident from the behavioral Morris water maze (MWM) test and induced oxidative stress in the cortex and hippocampus as indicated by the significant increases in lipid peroxidation and nitric oxide (NO) levels and the significant decrease in reduced glutathione (GSH) levels. It also produced a significant increase in acetylcholinesterase (AChE) and tumor necrosis-alpha (TNF-ɑ) and a significant decrease in Na+,K + -ATPase. In addition, a significant increase in amino acid neurotransmitters occurred in the hippocampus, whereas a significant decrease was obtained in the cortex of STZ-induced AD rats. CNs ameliorated the behavioral, immunohistochemical and most of the neurochemical alterations induced by STZ in the hippocampus and cortex. It may be concluded that CNs might be considered as a promising therapeutic agent for the treatment of AD.

Bezafibrate Exerts Neuroprotective Effects in a Rat Model of Sporadic Alzheimer’s Disease

Bezafibrate, a pan-peroxisome proliferator-activated receptor (PPAR) agonist, reportedly attenuated tau pathology in a transgenic mouse model of primary tauopathy. Since tau pathology is a neuropathological hallmark of Alzheimer’s disease (AD), bezafibrate may be a potential drug for the treatment of AD. However, no study has investigated its effects in AD models. Thus, we aimed to evaluate whether bezafibrate has neuroprotective effects in a sporadic AD model induced by streptozotocin (STZ) intracerebroventricular (ICV) injection. Rats were administered STZ-ICV (3 mg/kg) followed by bezafibrate (50 mg/kg/day, intraperitoneal) for 4 weeks. Behavior tests and positron emission tomography (PET) were performed to evaluate longitudinal changes in cognitive function, tau pathology, and cerebral glucose metabolism. Immunofluorescence staining was performed to assess neuronal survival and microglial accumulation. STZ-ICV administration induced significant cognitive impairment and substantial neuronal loss, tau pathology, glucose hypometabolism, and microgliosis in the cortex and hippocampus, while bezafibrate effectively attenuated these abnormalities. This study demonstrated that bezafibrate has long-lasting neuroprotective effects in a sporadic AD model. Our data indicate that the neuroprotective effects of bezafibrate might be associated with its ability to ameliorate tau pathology, brain glucose hypometabolism, and neuroinflammation. These findings suggest that bezafibrate is a potential multi-target drug candidate for the treatment of AD.

Inhibition of anandamide hydrolysis does not rescue respiratory abnormalities observed in an animal model of Parkinson's disease

NEW FINDINGS

What is the central question of this study? The respiratory frequency to hypercapnia is attenuated in an animal model of Parkinson's disease (PD): what is the therapeutic potential of inhibition of anandamide hydrolysis for this respiratory deficit? What is the main finding and its importance? In an animal model of PD there is an increased variability in resting respiratory frequency and an impaired tachypnoeic response to hypercapnia, which is accompanied by diminished expression of Phox2b immunoreactivity in the retrotrapezoid nucleus (RTN). Inhibition of anandamide hydrolysis also impaired the response to hypercapnia and decreased the number of Phox2b immunoreactive cells in the RTN. This strategy does not reverse the respiratory deficits observed in an animal model of PD.

ABSTRACT

Parkinson's disease (PD) is characterized by severe classic motor symptoms along with various non-classic symptoms. Among the non-classic symptoms, respiratory dysfunctions are increasingly recognized as contributory factors to complications in PD. The endocannabinoid system has been proposed as a target to treat PD and other neurodegenerative disorders. Since symptom management of PD is mainly focused on the classic motor symptoms, in this work we aimed to test the hypothesis that increasing the actions of the endocannabinoid anandamide by inhibiting its hydrolysis with URB597 reverses the respiratory deficits observed in an animal model of PD. Results show that bilateral injection of 6-hydroxydopamine hydrochloride (6-OHDA) in the dorsal striatum leads to neurodegeneration of the substantia nigra, accompanied by reduced expression of Phox2b in the retrotrapezoid nucleus (RTN), an increase in resting respiratory frequency variability and an impaired tachypnoeic response to hypercapnia. URB597 treatment in control animals was associated with an impaired tachypnoeic response to hypercapnia and a reduced expression of Phox2b in the RTN, whereas treatment of 6-OHDA-lesioned animals with URB597 was not able to reverse the deficits observed. These results suggest that targeting anandamide may not be a suitable strategy to treat PD since this treatment mimics the respiratory deficits observed in the 6-OHDA model of PD.

Corticosterone differentially modulates time-dependent fear generalization following mild or moderate fear conditioning training in rats

Stressful and emotionally arousing experiences create strong memories that seem to lose specificity over time. It is uncertain, however, how the stress system contributes to the phenomenon of time-dependent fear generalization. Here, we investigated whether post-training corticosterone (CORT-HBC) injections, given after different training intensities, affect contextual fear memory specificity at several time points. We trained male Wistar rats on the contextual fear conditioning (CFC) task using two footshock intensities (mild CFC, 3 footshocks of 0.3 mA, or moderate CFC, 3x 0.6 mA) and immediately after the training session we administered CORT-HBC systemically. We first tested the animals in a novel context and then in the training context at different intervals following training (2, 14, 28 or 42 days). By measuring freezing in the novel context and then contrasting freezing times shown in both contexts, we inferred contextual fear generalization for each rat, classifying them into Generalizers or Discriminators. Following mild CFC training, the glucocorticoid injection promoted an accurate contextual memory at the recent time point (2 days), and increase the contextual memory accuracy 28 days after training. In contrast, after the moderate CFC training, CORT-HBC facilitated contextual generalization at 14 days, compared to the control group that maintained contextual discrimination at this timepoint. For this training intensity, however, CORT-HBC did not have any effect on recent memory specificity. These findings indicate that treatment with CORT-HBC immediately after the encoding of mild or moderately arousing experiences may differentially modulate memory consolidation and time-dependent fear generalization.

The role of endocannabinoid pathway in the neuropathology of Alzheimer's disease: Can the inhibitors of MAGL and FAAH prove to be potential therapeutic targets against the cognitive impairment associated with Alzheimer's disease?

Alzheimer's disease is a neurodegenerative disease characterized by progressive decline of cognitive function in combination with neuronal death. Current approved treatment target single dysregulated pathway instead of multiple mechanism, resulting in lack of efficacy in slowing down disease progression. The proclivity of endocannabinoid system to exert neuroprotective action and mitigate symptoms of neurodegeneration condition has received substantial interest. Growing evidence suggest the endocannabinoids (eCB) system, viz. anadamide (AEA) and arachidonoyl glycerol (2-AG), as potential therapeutic targets with the ability to modify Alzheimer's pathology by targeting the inflammatory, neurodegenerative and cognitive aspects of the disease. In order to modulate endocannabinoid system, number of agents have been reported amongst which are inhibitors of the monoacylglycerol (MAGL) and fatty acid amide hydrolase (FAAH), the enzymes that hydrolyses 2-AG and AEA respectively. However, little is known regarding the exact mechanistic signalling and their effects on pathophysiology and cognitive decline associated with Alzheimer's disease. Both MAGL and FAAH inhibitors possess fascinating properties that may offer a multi-faceted approach for the treatment of Alzheimer's disease such as potential to protect neurons from deleterious effect of amyloid-β, reducing phosphorylation of tau, reducing amyloid-β induced oxidative stress, stimulating neurotrophin to support brain intrinsic repair mechanism etc. Based on empirical evidence, MAGL and FAAH inhibitors might have potential for therapeutic efficacy against cognitive impairment associated with Alzheimer's disease. The aim of this review is to summarize the experimental studies demonstrating the polyvalent properties of MAGL or FAAH inhibitor compounds for the treatment of Alzheimer's disease, and also effect of these on learning and types of memories, which together encourage to study these compounds over other therapeutics targets. Further research in this direction would enhance the molecular mechanisms and development of applicable interventions for the treatment of Alzheimer's disease, which nevertheless stay as the primary unmet need.

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.

Thiamme2-G, a Novel O-GlcNAcase Inhibitor, Reduces Tau Hyperphosphorylation and Rescues Cognitive Impairment in Mice

BACKGROUND

Abnormal hyperphosphorylation of microtubule-associated protein tau plays a pivotal role in Alzheimer's disease (AD). We previously found that O-GlcNAcylation inversely correlates to hyperphosphorylation of tau in AD brain, and downregulation of brain O-GlcNAcylation promotes tau hyperphosphorylation and AD-like neurodegeneration in mice.

OBJECTIVE

Herein we investigated the effect of increasing O-GlcNAcylation by using intermittent dosing with low doses of a potent novel O-GlcNAcase (OGA) inhibitor on AD-like brain changes and cognitive function in a mouse model of sporadic AD (sAD) induced by intracerebroventricular (ICV) injection of streptozotocin (STZ).

METHODS

STZ was injected into the lateral ventricle of C57BL/6J mice. From the second day, Thiamme2-G (TM2G) or saline, as a vehicle control, was orally administered to the ICV-STZ mice three times per week for five weeks. A separate group of ICV-saline mice treated with saline was used as a baseline control. Behavioral tests, including open field and novel object recognition, were conducted three weeks after the first dose of the TM2G or saline. Protein O-GlcNAcylation, tau hyperphosphorylation, synaptic proteins, and neuroinflammation in the mouse brain were assessed by western blotting.

RESULTS

ICV-STZ caused decreased protein O-GlcNAcylation. Enhancement of O-GlcNAcylation to moderate levels by using low-dose OGA inhibitor in ICV-STZ mice prevented STZ-induced body weight loss, rescued cognitive impairments, and restored AD-like pathologies, including hyperphosphorylation of tau and abnormalities in synaptic proteins and neuroinflammation.

CONCLUSION

These findings suggest that moderately increasing protein O-GlcNAcylation by using low doses of OGA inhibitor may be a suitable therapeutic strategy for sAD.

Downregulation of Candidate Gene Expression and Neuroprotection by Piperine in Streptozotocin-Induced Hyperglycemia and Memory Impairment in Rats

There is accumulating evidence showing that hyperglycemia conditions like diabetes possess a greater risk of impairment to the neuronal system because high glucose levels exacerbate oxidative stress, accumulation of amyloid-beta peptides, and mitochondrial dysfunction, and impair cognitive functions and cause neurodegeneration conditions like Alzheimer’s diseases. Due to the extensive focus on pharmacological intervention to prevent neuronal cells’ impairment induced by hyperglycemia, the underlying molecular mechanism that links between Diabetes and Alzheimer’s is still lacking. Given this, the present study aimed to evaluate the protective effect of piperine on streptozotocin (STZ) induced hyperglycemia and candidate gene expression. In the present study, rats were divided into four groups: control (Vehicle only), diabetic control (STZ only), piperine treated (20 mg/kg day, i.p), and sitagliptin (Positive control) treated. The memory function was assessed by Morris water maze and probe test. After treatment, biochemical parameters such as HOMA index and lipid profile were estimated in the serum, whereas histopathology was evaluated in pancreatic and brain tissue samples. Gene expression studies were done by real-time PCR technique. Present data indicated that piperine caused significant memory improvement as compared to diabetic (STZ) control. The assessment of HOMA indices in serum samples showed that piperine and sitagliptin (positive control, PC) caused significant alterations of insulin resistance, β cell function, and insulin sensitivity. Assessment of brain and pancreas histopathology shows significant improvement in tissue architecture in piperine and sitagliptin treated groups compared to diabetic control. The gene expression profile in brain tissue shows significantly reduced BACE1, PSEN1, APAF1, CASPASE3, and CATALASE genes in the piperine and sitagliptin (PC) treated groups compared to Diabetic (STZ) control. The present study demonstrated that piperine not only improves memory in diabetic rats but also reduces the expression of specific AD-related genes that can help design a novel strategy for therapeutic intervention at the molecular level.

Impaired Learning and Memory Ability Induced by a Bilaterally Hippocampal Injection of Streptozotocin in Mice: Involved With the Adaptive Changes of Synaptic Plasticity

Background: Alzheimer's disease (AD) is a neurodegenerative disease characterized by progressive cognitive decline, psychiatric symptoms and behavioral disorders, resulting in disability, and loss of self-sufficiency. Objective: To establish an AD-like mice model, investigate the behavioral performance, and explore the potential mechanism. Methods: Streptozotocin (STZ, 3 mg/kg) was microinjected bilaterally into the dorsal hippocampus of C57BL/6 mice, and the behavioral performance was observed. The serum concentrations of insulin and nesfatin-1 were measured by ELISA, and the activation of hippocampal microglia and astrocytes was assessed by immunohistochemistry. The protein expression of several molecular associated with the regulation of synaptic plasticity in the hippocampus and the pre-frontal cortex (PFC) was detected via western blotting. Results: The STZ-microinjected model mice showed a slower bodyweight gain and higher serum concentration of insulin and nesfatin-1. Although there was no significant difference between groups with regard to the ability of balance and motor coordination, the model mice presented a decline of spontaneous movement and exploratory behavior, together with an impairment of learning and memory ability. Increased activated microglia was aggregated in the hippocampal dentate gyrus of model mice, together with an increase abundance of Aβ_1-42 and Tau in the hippocampus and PFC. Moreover, the protein expression of NMDAR2A, NMDAR2B, SynGAP, PSD95, BDNF, and p-β-catenin/β-catenin were remarkably decreased in the hippocampus and the PFC of model mice, and the expression of p-GSK-3β (ser9)/GSK-3β were reduced in the hippocampus. Conclusion: A bilateral hippocampal microinjection of STZ could induce not only AD-like behavioral performance in mice, but also adaptive changes of synaptic plasticity against neuroinflammatory and endocrinal injuries. The underlying mechanisms might be associated with the imbalanced expression of the key proteins of Wnt signaling pathway in the hippocampus and the PFC.

The posterior insular cortex is necessary for the consolidation of tone fear conditioning

The insular cortex (IC) is notably implicated in emotional and cognitive processing; however, little is known regarding to what extent its two main subregions play functionally distinct roles on memory consolidation of conditioned fear tasks. Here we verified the effects of temporary functional inactivation of the anterior (aIC) and posterior IC (pIC) on contextual and tone fear memory. Rats received post-training bilateral infusions of the GABA_A receptor agonist muscimol into either the aIC or pIC and were tested 48 and 72 h after the delay tone fear conditioning session to assess the background contextual (CFC) and tone (TFC) fear conditioning, respectively. Inactivation of the aIC during memory consolidation did not affect fear memory for CFC or TFC. On the other hand, post-training inactivation of the pIC impaired TFC but not CFC. Our findings indicate that the pIC is a necessary part of the neural circuitry related to the consolidation of cued-fear memories.

Repurposing a digital kitchen scale for neuroscience research: a complete hardware and software cookbook for PASTA

Widely available low-cost electronics encourage the development of open-source tools for neuroscientific research. In recent years, many neuroscientists recognized the open science movement for its potential to stimulate and encourage science that is less focused on money, and more on robustness, validity, questioning and understanding. Here, we wanted to contribute to this global community by creating a research platform based on a common digital kitchen scale. This everyday ordinary kitchen tool is sometimes used in neuroscience research in various ways; however, its use is limited by sampling rate and inability to store and analyze data. To tackle this problem we developed a Platform for Acoustic STArtle or PASTA. This robust and simple platform enables users to obtain data from kitchen scale load cells at a high sampling rate, store it and analyze it. Here, we used it to analyze acoustic startle and prepulse inhibition sensorimotor gating in rats treated intracerebroventricularly with streptozotocin, but the system can be easily modified and upgraded for other purposes. In accordance with open science principles, we shared complete hardware design with instructions. Furthermore, we also disclose our software codes written for PASTA data acquisition (C++, Arduino) and acoustic startle experimental protocol (Python) and analysis (ratPASTA R package-R-based Awesome Toolbox for PASTA, and pastaWRAP-Python wrapper package for ratPASTA). To further encourage the development of our PASTA platform we demonstrate its sensitivity by using PASTA-gathered data to extract breathing patterns during rat freezing behavior in our experimental protocol.

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.

Investigation of Low Dose Cabazitaxel Potential as Microtubule Stabilizer in Experimental Model of Alzheimer's Disease: Restoring Neuronal Cytoskeleton

BACKGROUND

Neuronal Microtubule (MT) tau protein, providing cytoskeleton to neuronal cells, plays a vital role, including maintenance of cell shape, intracellular transport, and cell division. Tau hyperphosphorylation mediated MT destabilization results in axonopathy, additionally neurotransmitter deficit and ultimately causing Alzheimer's disease. Pre-clinically, streptozotocin (3mg/kg, 10μl/ unilateral, ICV) stereotaxically mimics the behavioral and neurochemical alterations similar to Alzheimer's tau pathology resulting in MT assembly defects further lead to neuropathological cascades.

OBJECTIVE

Clinically approved medications such as Donepezil (DNP), rivastigmine, and Memantine (MEM) are responsible for symptomatic care only, but there is no specific pharmacological intervention that directly interacts with the neuronal microtubule destabilization.

METHODS

The current study focused on the involvement of anti-cancer agent microtubule stabilizer cabazitaxel at a low dose (0.5 and 2 mg/kg) alone and in combination with standard drugs DNP (5 mg/kg), MEM (10 mg/kg) and microtubule stabilizer Epothilone D (EpoD) (3 mg/kg) in the prevention of intracerebroventricular streptozotocin (ICV-STZ) intoxicated microtubule-associated tau protein hyperphosphorylation.

RESULTS

Chronic treatment of CBZ at a low dose alone and in combination with standard drugs showing no side effect and significantly improve the cognitive impairment, neurochemical alterations along with reducing the level of hyperphosphorylated tau by preventing the breakdown of the neuronal cytoskeleton, respectively.

CONCLUSION

The above findings suggested that CBZ at low dose show neuroprotective effects against ICV-STZ induced microtubule-associated tau protein hyperphosphorylation in rats and may be an effective agent for the preventive treatment of AD.

N‑linoleyltyrosine protects PC12 cells against oxidative damage via autophagy: Possible involvement of CB1 receptor regulation

Oxidative stress is one of the main pathogenic factors of neurodegenerative diseases. As the ligand of cannabinoid type 1 (CB1) and 2 (CB2) receptors, anandamide (AEA) exerts benign antioxidant activities. However, the instability of AEA results in low levels in vivo, which limit its further application. Based on the structure of AEA, N‑linoleyltyrosine (NITyr) was synthesized in our laboratory and was hypothesized to possess a similar function to that of AEA. To the best of our knowledge, the present study demonstrates for the first time, the activities and mechanisms of NITyr. NITyr treatment attenuated hydrogen peroxide (H2O2)‑induced cytotoxicity, with the most promiment effect observed at 1 µmol/l. Treatment with NITyr also suppressed the H2O2‑induced elevation of reactive oxygen species (ROS) and enhanced the expression of the autophagy‑related proteins, LC3‑II, beclin‑1, ATG 5 and ATG13. The autophagic inhibitor, 3‑methyladenine, reversed the effects of NITyr on ROS levels and cellular viability. Furthermore, AM251, a CB1 receptor antagonist, but not AM630 (a CB2 receptor antagonist), diminished the effects of NITyr on cell viability, ROS generation and autophagy‑related protein expression. However, NITyr increased the protein expression of both the CB1 and CB2 receptors. Therefore, NITyr was concluded to protect PC12 cells against H2O2‑induced oxidative injury by inducing autophagy, a process which may involve the CB1 receptor.

An optimized spectrophotometric assay reveals increased activity of enzymes involved in 2-arachidonoyl glycerol turnover in the cerebral cortex of a rat model of Alzheimer's disease

The endocannabinoid system is implicated in a plethora of neuropsychiatric disorders. However, it is technically challenging to assess the turnover of 2-arachidonoyl glycerol (2-AG), the principal endocannabinoid molecule in the brain. Two recent studies showed that diacylglycerol lipase α (DAGLα), an enzyme chiefly responsible for the cerebral production of 2-AG, also accepts the surrogate chromogenic substrate 4-nitrophenyl butyrate (4-NPB). Here, we aimed to optimize this spectrophotometric assay for ex vivo brain tissue, in particular, rat cerebrocortical homogenates, to measure the activity of the major enzymes responsible for the production and degradation of 2-AG. The initial velocity of 4-NPB hydrolysis was dependent on protein, substrate, and Ca²⁺ concentrations, and was sensitive to the non-selective serine hydrolase inhibitor, methoxy arachidonyl fluorophosphonate, the DAGLα inhibitors, OMDM188, tetrahydrolipstatin, and RHC80267, as well as the monoacylglycerol lipase (MAGL) inhibitor, JZL184, respectively. Next, we tested the usefulness of this assay in ex vivo brain tissue of rat models of human health conditions known to affect cerebrocortical 2-AG production, i.e. pathological stress and sporadic Alzheimer's disease (AD). In rats submitted to chronic restraint stress, cortical CB₁ R density was significantly decreased, as assessed with radioligand binding. Nevertheless, 4-NPB hydrolysis remained at control levels. However, in rats 4 weeks after intracerebroventricular injection with streptozotocin - an established model of sporadic AD -, both CB₁ R levels and 4-NPB hydrolysis and its DAGL- and MAGL-dependent fractions were significantly increased. Altogether, we optimized a simple complementary ex vivo technique for the quantification of DAGL and MAGL activity in brain samples.

Dietary intake of polyunsaturated fatty acids alleviates cognition deficits and depression-like behaviour via cannabinoid system in sleep deprivation rats

Sleep deprivation (SD) is a common feature in modern society. Prolonged sleep deprivation causes cognition deficits and depression-like behavior in the model of animal experiments. Endocannabinoid system are key modulators of synaptic function, which were related to memory and mood. Although the underlying mechanism remains unknown, several studies indicated the benefits of polyunsaturated fatty acids (PUFAs, linolenic acid, 39.7 %; linoleic acid, 28 %; and oleic acid, 22 %) on brain function through the endocannabinoid system. The present study aimed to evaluate the influence of dietary PUFAs on cognition deficits induced by sleep deprivation in Sprague Dawley rats. The rats were sleep deprivation continuously for 7 days and fed with PUFAs at three different dosages (2, 4 and 8 μl/g body weight) at the meantime. The effect of PUFAs on cognition was investigated by object recognition test while depressive-like behavior were detected using sucrose preference test and forced swim test. The mechanism of PUFAs was elucidated by hippocampal synaptic transmission analyses. The resluts revealed that SD led to the disorder of cognition and mood which was improved by the supplement of PUFAs. SD significantly increased the mEPSC frequency, and decreased the protein level of cannabinoid type-1 receptors (CB₁R). These changes were restored by supplement of PUFAs, which showed a similar level to the control group. Behaviour tests showed that the positive effects on repairing cognition and anxiety disorders were almost completely abolished when the CB₁R receptor antagonist rimonabant was applied to the SD rats. These findings indicated that PUFAs are a factor regulating cognition deficits and depression induced by SD via cannabinoid type-1 receptors.

Intracerebral Injection of Streptozotocin to Model Alzheimer Disease in Rats

Animal models have promoted meaningful contribution to science including Alzheimer's disease (AD) research. Several animal models for AD have been used, most of them related to genetic mutations observed in familial AD. However, sporadic form of AD, also named late-onset is the most frequent form of the disease, which is multifactorial, being influenced by genetic, environmental and lifestyle factors. Here, we describe a protocol of an AD-like pathology of the sporadic form using Wistar rats by a single bilateral intracerebroventricular (icv) injection of streptozotocin (STZ, 2 mg/kg). Icv injection of STZ induces brain resistance to insulin and other pathological alterations related to those observed in AD, such as cognitive impairment and accumulation of phosphorylated tau protein and β-amyloid in the brain. Thus, icv injection of STZ is a useful tool to investigate the pathological mechanisms and the metabolic alterations involved in AD and to propose new therapeutic approaches and neuroprotective drugs.