Hippocampal Homogenates Research Articles

Glucagon-like peptide-1 analog improves neuronal and behavioral impairment and promotes neuroprotection in a rat model of aluminum-induced dementia.

Background Alzheimer's disease (AD) is a worldwide severe medical and social burden. Liraglutide (LIR) has neuroprotective effects in preclinical animal models. Aim: To explore the probable neuroprotective impact of Glucagon‐like peptide‐1 (GLP‐1) on rats' behavior and to elucidate its underlying mechanisms. Methods: A total of 24 male albino rats were assigned to control, LIR (300 µg/kg subcutaneously (s.c.)), AD only (100 mg/kg aluminum chloride (AlCl3) orally) and LIR + AD treated groups. Eight radial arm maze was performed. Serum blood glucose, proinflammatory cytokines, oxidative stress markers were measured and hippocampal tissue homogenate neurotransmitters were evaluated. Histopathological and immunofluorescent examinations were performed. Results: LIR prevents the impairment of learning and improves both working memory and reference memory through significant reduction of serum tumor necrosis factor (TNF‐α), interleukin 6 (IL‐6) and interferon‐γ (INF‐γ) and malondialdehyde (MDA) and through the increase of superoxide dismutase (SOD), dopamine, adrenaline, and noradrenaline. LIR also improves hippocampal histological features of ALCL3 administrated rats and decreases the percentage of neuronal loss. Conclusion: LIR normalizes ALCL3‐induced dementia. It improves cognitive dysfunction and ameliorates cerebral damage.

5-HT1A targeting PARCEST agent DO3AM-MPP with potential for receptor imaging: Synthesis, physico-chemical and MR studies

Contrast enhancement in MRI using magnetization or saturation transfer techniques promises better sensitivity, and faster acquisition compared to T1 or T2 contrast. This work reports the synthesis and evaluation of 5-HT1A targeted PARACEST MRI contrast agent using 1,4,7,10-tetraazacycloDOdecane-4,7,10-triacetAMide (DO3AM) as the bifunctional chelator, and 5-HT1A-antagonist methoxyphenyl piperazine (MPP) as a targeting unit. The multi-step synthesis led to the MPP conjugated DO3AM with 60% yield. CEST-related physicochemical parameters were evaluated after loading DO3AM-MPP with paramagnetic MRI active lanthanides: Gadolinium (Gd-DO3AM-MPP) and Europium (Eu-DO3AM-MPP). Luminescence lifetime measurements with Eu-DO3AM-MPP and computational DFT studies using Gd-DO3AM-MPP revealed the coordination of one water molecule (q = 1.43) with metal-water distance (rM-H2O) of 2.7 Å and water residence time (τm) of 0.23 ms. The dissociation constant of Kd 62 ± 0.02 pM as evaluated from fluorescence quenching of 5-HT1A (protein) and docking score of −4.81 in theoretical evaluation reflect the binding potential of the complex Gd-DO3AM-MPP with the receptor 5-HT1A. Insights of the docked pose reflect the importance of NH2 (amide) and aromatic ring in Gd-DO3AM-MPP while interacting with Ser 374 and Phe 370 in the antagonist binding pocket of 5-HT1A. Gd-DO3AM-MPP shows longitudinal relaxivity 5.85 mM−1s−1 with a water residence lifetime of 0.93 ms in hippocampal homogenate containing 5-HT1A. The potentiometric titration of DO3AM-MPP showed strong selectivity for Gd3+ over physiological metal ions such as Zn2+ and Cu2+. The in vitro and in vivo studies confirmed the minimal cytotoxicity and presential binding of Gd-DO3AM-MPP with 5-HT1A receptor in the hippocampus region of the mice. Summarizing, the complex Gd-DO3AM-MPP can have a potential for CEST imaging of 5-HT1A receptors.

Validation of prenatal versus postnatal valproic acid rat models of autism: A behavioral and neurobiological study

Despite the increasing prevalence of autism spectrum disorder (ASD), there is still a deficiency in understanding its exact pathophysiology and treatment, therefore validation of translational ASD animal model is warranted. Although strong evidences support the valproic acid (VPA) model of autism, yet a controversy exists regarding the best timing of exposure whether prenatal or postnatal. Accordingly, this study was designed to compare the time dependent effects of VPA exposure as regard its ability to induce autistic like changes in male Wistar rats. In this study, two different protocols of VPA exposure (prenatal and postnatal) were compared at different levels (behavioral, neurochemical and histopathological). Results of this study revealed that both prenatal and postnatal VPA exposures induced autistic-like behaviors manifested by reduced social interaction, increased repetitive stereotyped behavior and anxiety, cognitive dysfunction, lowered sensitivity to pain, and neurodevelopmental delay. Furthermore, inflammatory cytokines and oxidative/nitrosative stress markers were elevated in prefrontal cortex and hippocampal homogenates. Likewise, histopathological and immunohistochemical assessment confirmed the neurodegenerative and the apoptotic changes in prefrontal cortex, hippocampus and cerebellum exhibited by decreased viable cells number and Nissl's granules optical density, and increased caspase-3 immunoreactivity respectively. Interestingly, ASD core symptoms and histopathological changes were significantly (P < 0.05) altered in prenatal VPA model compared to postnatal VPA model. Additionally, postnatal mortality in prenatal model (4.3%) was much lower compared to the postnatal model (22.7%). In conclusion, our study overweighs the ability of prenatal VPA model over postnatal VPA model to induce behavioral and neuropathological alterations that simulate those observed in autistic individuals with a lower postnatal animal mortality, highlighting the privilege of prenatal over postnatal VPA exposure as a translational model for understanding pathophysiology and developing novel targets for management of ASD

Effects of resveratrol on alterations in cerebrum energy metabolism caused by metabolites accumulated in type I citrullinemia in rats.

We investigated the in vitro effects of citrulline (0.1, 2.5 and 5.0mM) and ammonia (0.01, 0.1 and 1.0mM), and the influence of resveratrol (0.01mM, 0.1mM and 0.5mM) on pyruvate kinase, citrate synthase, succinate dehydrogenase (SDH), complex II, and cytochrome c oxidase activities in cerebral cortex, cerebellum and hippocampus homogenates of 60-day-old male Wistar rats. Results showed that 2.5 and 5.0mM citrulline decreased pyruvate kinase activity in cerebral cortex and, at a concentration of 5.0mM, increased its activity in hippocampus. Additionally, 5.0mM citrulline increased citrate synthase activity in the cerebellum of rats. Citrulline (5.0mM) reduced complex II and cytochrome c oxidase activities in cerebral cortex and hippocampus. With regard to ammonia, at 0.1 and 1.0mM, decreased complex II activity in cerebral cortex and at 1.0mM decreased its activity in cerebellum and hippocampus. Ammonia (1.0mM) also decreased cytochrome c oxidase activity in cerebral cortex and cerebellum of rats. Resveratrol was able to prevent most of the alterations caused by these metabolites in the biomarkers of energy metabolism measured in the cerebrum of rats. Data suggest that these alterations in energy metabolism, caused by citrulline and ammonia, are probably mediated by the generation of free radicals, which can in turn be scavenged by resveratrol.

Effects of resveratrol combined with soy isoflavones on apoptosis induced by oxidative stress in hippocampus of aging model rats

To investigate the effect of resveratrol(Res) combined with soy isoflavones(SIF) on apoptosisinduced by oxidative stress in hippocampus in aging model rats. Sixty female SD rats were randomly divided into the Sham control group, aging model group, Res treatment group, SIF treatment group, Res combined with SIF treatment group and estrogen replacement therapy group(ERT group). Rats with aging were induced by bilateral ovariectomy combined with intraperitoneal injection of D-galactose. TUNEL and transmission electron microscopy were used to observe apoptosis and ultrastructural changes of mitochondrion in hippocampus, respectively. The activities of superoxide dismutase(SOD), catalase(CAT), glutathione peroxidase(GSH-Px) and content of Malonaldehyde(MDA) were detected in the hippocampal homogenate. The protein expressions of cytochrome C oxidase(COX) Ⅰ, Bcl-2 associated X protein(Bax)、B-cell leukemia/lymphoma 2(Bcl-2) and cytochrome C were detected by Western blot. Compared with the Sham control group, the number of TUNEL-positive cells and the apoptotic index(AI) in the model group increased. Marked increase of mitochondrial swelling and vacuolation, decrease of mitochondrial integrity were also observed in the model group. Additionally, the levels of SOD, CAT and GSH-Px were decreased and the level of MDA was increased in the model group in the hippocampus, Bax and cytochrome C protein expression increased, and the COX Ⅰ protein expression and the ratio of Bcl-2/Bax decreased(P&lt;0. 05). In compared with the model group, the number of TUNEL-positive cells and AI significantly decreased, mitochondrial integrity improved in all of the treatment groups, the COX Ⅰ protein expression significantly up-regulated, Bax and cytochrome C protein expression down-regulated, and the protein expression ratio of Bcl-2/Bax increased(P&lt;0. 05 or P&lt;0. 01). Compared with the Res alone and SIF alone treatment group, Res combined SIF treatment decreased the AI and Bax, cytochrome C protein expression, moreover, increased the mitochondrial integrity rate, COX Ⅰ and Bcl-2/Bax protein expression ratio(P&lt;0. 05). There was no statistically significant difference in Bcl-2 protein expression among all the groups(P&gt;0. 05). Res and SIF alone and in combination decreased apoptosisinduced by oxidative stress in hippocampus of aging model rats, and beneficial effect in the Res combined SIF treatment group is more significant than that in the alone administration. Improving the antioxidant capacity, increasing the protein expressions of COX Ⅰ andthe ratio of Bcl-2 and Bax, and inhibiting the release of cytochrome C may be the mechanisms by which Res and SIF improve apoptosis in aging rats.

Attenuation of Spatial Memory in 5xFAD Mice by Halting Cholinesterases, Oxidative Stress and Neuroinflammation Using a Cyclopentanone Derivative.

Alzheimer’s disease (AD) is an irreversible and chronic neurological disorder that gradually destroys memory and thinking skills. The research study was designed to investigate the underlying molecular signaling involved in the neuroprotective effects of cyclopentanone derivative i.e., 2-(hydroxyl-(3-nitrophenyl)methyl)cyclopentanone (3NCP) as a therapeutic agent for AD. In this study, In vivo studies were carried out on a well-known 5xFAD mice model using different behavioural test models such as open field, rotarod, Morris water maze (MWM), and Y-maze tests. Furthermore, in vitro cholinesterase inhibition activity assays were carried out. The frontal cortex (FC) and hippocampus (HC) homogenates were tested for the levels/activities of cholinesterases, glutathione (GSH), glutathione S-transferase (GST), and catalase. Furthermore, the hippocampal expression of inflammatory cytokines was observed via RT-PCR and western blot. The results of in vivo studies show an enhancement in the learning behavior. The 3NCP treatment reduced latency time in MWM and Y-maze tests, also increase spontaneous alternation indicate significant effect of 3NCP on memory. Furthermore, open field and rotarod studies revealed that 3NCP does not cause motor coordination deficit. The results of the in vitro studies revealed that the IC50 values of the 3NCP against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) were 16.17 and 20.51 µg/mL, respectively. This decline in AChE and BChE was further supported by ex vivo studies. Further, the 3NCP mitigates the GSH level, GST, and catalase activities in HC and FC. The mRNA and protein expression of inflammatory cytokines (IL-1β, IL-6, TNF-α) markedly declined in RT-PCR and western blotting. The results of the current study conclusively demonstrate that 3NCP reduces oxidative stress and mitigates neuroinflammation in 5xFAD mice, implying that 3NCP may be a potential therapeutic candidate for AD treatment in the future.

Effects of modified Xiaoyao San on TLR4/NF-κB pathway in hippocampal microglia of LPS-induced depression model rats

To investigate the effects of modified Xiaoyao San on TLR4/NF-κB pathway in hippocampal microglia of LPS-induced depression model rats, and to explore its antidepressant mechanism. SD rats were randomly divided into control, model, fluoxetine (10 mg·kg-1), low and high dose of modified Xiaoyao San (3.64, 7.28g·kg-1) group. The depression model was established by chronic LPS injection (ip, 0.5 mg·kg-1) and rats were treated by intragastric administration for 14 days. After the model was established, the depression-like behavior of rats was evaluated by open field and forced swimming test. The expression of microglia marker protein Iba-1 was detected by immunohistochemistry. The levels of TNF-α and IL-6 in hippocampal homogenate were detected by ELISA method and the expressions of TLR4 and NF-κB protein in hippocampus were detected by Western blot. Compared with control group, the depression-like behavior was significant in model group rats (P＜0.01), the microglia in the brain was activated (P＜0.01), the contents of TNF-α and IL-6 in the hippocampus were increased (P＜0.01), and the expression levels of TLR4 and NF-κB proteins were up-regulated (P＜0.01). Compared with model group, the depression-like behavior of the rats in the fluoxetine and high-dose modified Xiaoyao San group was significantly alleviated (P＜0.05), the expression of Iba-1 in microglia returned to normal (P＜0.01), the contents of TNF-α and IL-6 were decreased (P＜0.01), and the expression levels of TLR4 and NF-κB protein were decreased (P＜0.05). Compared with fluoxetine group, the high-dose modified Xiaoyao San group had no statistically significant difference in each index, suggesting that there was no significant difference in the antidepressant effect between the two groups. Modified Xiaoyao San can significantly improve the depression-like behavior in rats, and its mechanism may be related to inhibiting the TLR4/NF-κB pathway of microglia and down-regulating the expression of inflammatory factors.

Neurobehavioral, testicular and erectile impairments of chronic ketamine administration: Pathogenesis and ameliorating effect of N-acetyl cysteine

Ketamine, a dissociative anesthetic, recently has spread as a recreational drug. Its abuse lead to neurobehavioral disturbance in addition to toxic effects on other body organs. To evaluate the toxic effects of chronic administration of low ketamine doses on the memory, testicles, and erection, explore its pathophysiology through oxidative stress mechanism and examine the ameliorating effect of N-acetyl cysteine (NAC). A total of 40 male albino rats were assigned to control, vehicle, ketamine only I.P. (10 mg/kg), and ketamine (10 mg/kg) + NAC (150 mg/kg) groups. Assessment of memory affection and erectile function by Passive Avoidance, Novel Object Recognition, and copulatory tests were performed. Estimation of malondialdehyde (MDA), catalase (CAT), and total antioxidant capacity (TAC) in serum and prefrontal & hippocampal homogenate, and luteinizing hormone (LH), testosterone in serum were done. Prefrontal cortex, hippocampus, and testes were collected for histopathology. Chronic ketamine administration induced significant memory deficits (P < 0.05), reduced erectile function (P < 0.05), severe hypospermatogenesis, increased MDA, reduced CAT, TAC levels in serum, and tissue homogenate (P < 0.05) and reduction of LH, and testosterone (P < 0.05). Treatment with NAC resulted in significant improvement of memory function, improved erectile function, and decrease in oxidative injury in both serum and tissue homogenates. Testosterone and LH levels exhibited significant difference between treatment groups and controls (P < 0.05). NAC reduced the deleterious histopathological changes. These data suggest that long-term ketamine affects short and long memory, induces erectile and testicular dysfunction through oxidative stress. Co-administration with NAC ameliorates these toxic effects.

Antibodies directed to the phospho-tau peptide (residues 111-137) dissociate tau oligomers and reduce the spatial memory deficits in non-transgenic tauopathy model rats

In dementia, Alzheimer’s disease (AD) is the most common type, characterized by the deposits of neurofibrillary tangles and senile plaques with concomitant deterioration in spatial memory and other cognitive functions. Till date, although no cure is available for AD, a few treatment options offer help in reducing the symptoms. In the present study, the sequence 111-137 in the distal N-terminal charge transition region of tau, harbouring the pathologically relevant phospho-serine (pSer 113) and phospho-threonine (pThr 123) (111TPpSLEDEAAGHVpTQARMVSKSKD GTGS137)was selected as a potential immunotherapeutic peptide. Polyclonal anti-peptide antibodies raised in rabbits effectively dissociated the oligomers/aggregates of recombinant human tau in vitro. Administration of affinity purified anti-peptide antibodies to the okadaic acid induced tauopathy model rats resulted in a significant progress in spatial memory functions in Barnes maze task with concomitant reduction in p-tau levels in the hippocampal homogenates. Thus, targeting the phospho-residue sequence 111-137 in tau may be therapeutically relevant for AD and other related tauopathies. These antibodies may also have a clinical value in terms of immunosassay development for quantitation of pathology associated pSer113 and pThr 123 in AD samples.

(-)-cis-Carveol, a Natural Compound, Improves β-Amyloid-Peptide 1-42-Induced Memory Impairment and Oxidative Stress in the Rat Hippocampus.

Alzheimer's disease (AD) could be considered a multifactorial neurodegenerative disorder characterized by the accumulation of the β-amyloid-peptide (Aβ) within the brain leading to cognitive deficits, oxidative stress, and neuroinflammation. The present work was carried out to investigate the neuroprotective effect of (-)-cis-carveol (1% and 3%, for 21 days) against the β-amyloid-peptide 1-42- (Aβ1-42-) induced AD. Twenty-five rats were divided into five groups (n = 5/group): the first group—control (sham-operated); the second group—Aβ1-42 (1 mM) that received donepezil treatment (5 mg/kg, as the positive reference drug in the Y-maze and the radial arm maze tests); the third group—Aβ1-42 (1 mM); the fourth and fifth groups—Aβ1-42 (1 mM) that received (-)-cis-carveol treatment groups (1% and 3%). The results of this study demonstrated that (-)-cis-carveol improved Aβ1-42-induced memory deficits examined by using Y-maze and radial arm maze in vivo tests. Also, the biochemical analyses of the hippocampus homogenates showed that (-)-cis-carveol reduced hippocampal oxidative stress caused by Aβ1-42. Our results suggested that the use of (-)-cis-carveol may be suitable for decreasing AD-related symptoms.

The Effects of Hesperidin on Neuronal Apoptosis and Cognitive Impairment in the Sevoflurane Anesthetized Rat are Mediated Through the PI3/Akt/PTEN and Nuclear Factor-κB (NF-κB) Signaling Pathways.

BackgroundHesperidin (HPD) is a bioflavonoid found in citrus fruits. This study aimed to investigate the effects of HPD on cerebral morphology and cognitive behavior in sevoflurane anesthetized neonatal rats and the molecular mechanisms involved.Material/MethodsSixty neonatal Sprague–Dawley rats were divided into five groups, including the untreated control group, and the sevoflurane anesthesia groups untreated and treated with 25 mg/kg/day of HPD (HPD25), 50 mg/kg/day of HPD (HPD50), and 100 mg/kg/day of HPD (HPD100). The rat model was created by the administration of sevoflurane on the sixth postnatal day (P6) and for a further three days. Neonatal rats pre-treated with HPD for 19 days were given sevoflurane 30 minutes beforehand (P3 to P21). Rat hippocampal tissue specimens were investigated using the TUNEL assay for apoptosis. Hippocampal tissue homogenates underwent Western blot for the quantification of markers of neuroinflammation and oxidative stress. The neonatal rats were also investigated for behavior, learning, and memory.ResultsHPD significantly reduced sevoflurane-induced neuronal apoptosis and protein expression of cleaved caspase-3, BAD, BAX, NF-κB, TNF-α, IL-6, and IL-1β (p<0.05). HPD significantly increased the expression of Bcl-xL and Bcl-2 (p<0.05), and activated the PI3/Akt pathway. Learning and memory were significantly improved following HPD treatment (p<0.05). HPD treatment modulated the PI3/Akt/PTEN and NF-κB signaling pathways, and reduced oxidative stress (p<0.05).ConclusionsIn the sevoflurane anesthetized neonatal rat model, treatment with HPD reduced neuronal degeneration, hippocampal inflammation, and improvised memory, learning, and cognitive responses by modulating the PI3/Akt/PTEN and NF-κB signaling pathways.

Ethanol Extract of Euonymus alatus Leaf Prevents Scopolamine‐Induced Learning and Memory Impairment in Mice

Our previous in vitro study demonstrated that the ethanol extract from young leaves of Euonymus alatus (so‐called burning bush spindle tree) had antioxidant and neuroprotective activities. In the present study, we examined whether oral supplementation of the extract recovers learning and memory capabilities in a scopolamine‐induced acute hypomnesic mouse model. Behavioral tests showed that spatial learning and memory were improved by the extract treatment in scopolamine‐treated mice. Histological damage observed in the hippocampal region of the scopolamine‐treated mouse brain was attenuated by oral administration of the extract. Oxidative stress markers, including plasma 8‐hydroxy‐2′‐deoxyguanosine and hepatic malondialdehyde increased in scopolamine‐injected mice were decreased by the extract treatment. The expression levels of antioxidant proteins such as heme oxygenase‐1 and nuclear factor (erythroid‐derived 2)‐like 2 in the hippocampal tissue homogenates were decreased in group treated with scopolamine alone while the expression of those proteins was restored by the extract treatment. In addition, synaptic plasticity biomarkers such as neurotrophic factors, including postsynaptic density protein‐95, brain‐derived neurotrophic factor and N‐methyl‐D‐aspartate receptor, were enhanced in the extract‐treated mouse hippocampal tissue compared to the group exposed to scopolamine alone. These findings indicate that Euonymus alatus leaf extract could rescue learning and memory impairment caused by oxidative stress‐dependent hippocampal damage through upregulated antioxidant response and strengthened synaptic function of neuronal circuits particularly in the hippocampus.Support or Funding InformationThis study was funded by the Forest Resources Development Institute of Gyeongsanbuk‐do, Andong, Republic of Korea.

Focused Library Screening for Isoform Selective Adenylyl Cyclase 1 Inhibitors as Non‐Opioid Alternatives for Chronic and Inflammatory Pain

Due to the socioeconomic burden associated with chronic pain conditions and the fact that opioids have severe side effects, there is a need for new approaches and drug targets for the treatment of chronic pain. An increasing body of evidence suggests that inhibition of neuronal Adenylyl Cyclase 1 (AC1) may be one way to achieve this goal, as mice lacking AC1 are significantly less responsive in neuropathic and inflammatory pain models. ACs catalyze the formation of cAMP from ATP following stimulation by a variety of cellular inputs, like G protein subunits, kinases, calmodulin, and the exogenous small molecule forskolin. Here we used a recently developed cell model which lacks forskolin stimulated cAMP accumulation due to genetic ablation using CRISPR/Cas9 of AC3 and AC6, the major forskolin responsive AC isoforms in parental HEK293 cells. Following stable overexpression of recombinant human AC1, we screened over 20,000 compounds from the Eli Lilly Open Innovation Drug Discovery program against calcium‐calmodulin stimulated AC1 activity. The hit rate from the preliminary screen was less than 1%, highlighting the utility of this cell model as compared to parental HEK293 cells. Primary screen actives were retested against AC1 to confirm activity in dose‐response experiments. Counter‐screening was performed against representative AC isoforms AC2, AC5, and AC8, leading to the identification of two novel, promising scaffolds with distinct AC1 inhibition profiles. Subsequently, we evaluated the mechanism of inhibition of these lead compounds as compared to previously identified AC inhibitors in our cellular model, isolated membrane fractions, and mouse hippocampal homogenates in response to various stimuli, including GPCR‐Gαs, forskolin, and calcium‐calmodulin. Further, we have also initiated structure activity relationships for these two scaffolds, as well as begun examining their selectivity for AC1 over other unrelated neurological targets. Taken together, these scaffolds may hold promise as tool compounds for further interrogating the role of selective AC1 inhibition in pain neurobiology and for the development of AC1‐targeting therapeutics in the future.Support or Funding InformationThis work was supported by the Eli Lilly Open Innovation Drug Discovery program, Rick and Anne Borch Research Award, and Purdue University College of Pharmacy.

Profiling gene expression in the human dentate gyrus granule cell layer reveals insights into schizophrenia and its genetic risk.

Specific cell populations may have unique contributions to schizophrenia but may be missed in studies of homogenate tissue. Here laser capture microdissection followed by RNA sequencing (LCM-seq) was used to transcriptomically profile the granule cell layer of the dentate gyrus (DG-GCL) in human hippocampus and contrast these data to those obtained from bulk hippocampal homogenate. We identified widespread cell-type-enriched aging and genetic effects in the DG-GCL that were either absent or directionally discordant in bulk hippocampus data. Of the ~9 million expression quantitative trait loci identified in the DG-GCL, 15% were not detected in bulk hippocampus, including 15 schizophrenia risk variants. We created transcriptome-wide association study genetic weights from the DG-GCL, which identified many schizophrenia-associated genetic signals not found in transcriptome-wide association studies from bulk hippocampus, including GRM3 and CACNA1C. These results highlight the improved biological resolution provided by targeted sampling strategies like LCM and complement homogenate and single-nucleus approaches in human brain.

Effect of pristine fullerene on acquisition, consolidation and retrieval memory in wistar rats

The present study evaluated the effect of fullerene (C60) under in vitro conditions, in hippocampus homogenates from rats and on the induction of behavioral disabilities. Exposure to in vitro C60 led to an increase in the concentration of reactive oxygen species (ROS) and lipid peroxidation (LPO) of hippocampus treated with of fullerene and suspension. These results indicate that the oxidative stress caused by the exposure to C60 was in part related to an absence of an antioxidant response. In this sense, one-trial inhibitory avoidance task were performed and results showed that fullerene at 0.2 and 0.45 μm impaired the acquisition and consolidation of short and long-term memory. Further, enzymatic analysis in rat hippocampus were not significantly different, however, there was an increase in the content of LPO and ROS produced by fullerene. Overall, the results indicates that fullerene possess neurotoxic properties that impairs behavior and promotes oxidative stress.

Levels of Retinal Amyloid-β Correlate with Levels of Retinal IAPP and Hippocampal Amyloid-β in Neuropathologically Evaluated Individuals.

Background:Previous studies have used immunohistology to demonstrate Alzheimer’s disease (AD) characteristic accumulation of amyloid-β (Aβ) in the retina of AD patients, a finding indicating retina examination as a potential diagnostic tool for AD pathology.Objective:To further explore this idea by investigating whether levels of Aβ42 and Aβ40 in retina are associated with corresponding levels in hippocampus, neuropathological assessments, apolipoprotein E (APOE) genotype, and levels of islet amyloid polypeptide (IAPP).Methods:Levels of high molecular weight (HMW) Aβ42, Aβ40, and IAPP in ultra-centrifuged homogenates of retina and hippocampus from patients with AD, multiple sclerosis, AD with Lewy bodies, and non-demented controls were analyzed using Mesoscale Discovery electrochemiluminescence technology employing immunoassay and enzyme-linked immunosorbent assay.Results:Higher levels of retinal and hippocampal Aβ42-HMW, Aβ40-HMW, and IAPP-HMW were found in individuals with high neuropathological scores of Aβ plaques and in individuals carrying the APOE ɛ4 allele. The retinal levels of Aβ42-HMW and Aβ40-HMW correlated with corresponding levels in hippocampus as well as with neurofibrillary tangles (NFT) and Aβ scores. Retinal IAPP-HMW correlated with retinal levels of Aβ42-HMW and with NFT and Aβ scores.Conclusion:These results show that different isoforms of Aβ can be detected in the human retina and moreover support the growing number of studies indicating that AD-related pathological changes occurring in the brain could be reflected in the retina.

Zinc Transporter-3 Knockout Mice Demonstrate Age-Dependent Alterations in the Metalloproteome

Metals are critical cellular elements that are involved in a variety of cellular processes, with recent literature demonstrating that zinc, and the synaptic zinc transporter (ZnT3), are specifically involved in learning and memory and may also be key players in age-related neurodegenerative disorders such as Alzheimer’s disease. Whilst the cellular content and location of metals is critical, recent data has demonstrated that the metalation state of proteins is a determinant of protein function and potential toxicity. As we have previously reported that ZnT3 knockout (KO) mice have deficits in total zinc levels at both 3 and 6 months of age, we were interested in whether there might be changes in the metalloproteomic profile in these animals. To do this, we utilised size exclusion chromatography-inductively coupled plasma mass spectrometry (SEC-ICP-MS) and examined hippocampal homogenates from ZnT3 KO and age-matched wild-type mice at 3, 6 and 18 months of age. Our data suggest that there are alterations in specific metal binding proteins, for zinc, copper and iron all being modulated in the ZnT3 KO mice compared to wild-type (WT). These data suggest that ZnT3 KO mice may have impairments in the levels or localisation of multiple transition metals, and that copper- and iron-dependent cellular pathways may also be impacted in these mice.

Selective hyperactivation of JNK2 in an animal model of temporal lobe epilepsy

c-Jun N-terminal kinases (JNKs) are members of the mitogen-activated protein kinase (MAPK) family and are derived from three genes, Jnk1-3. These kinases are involved in cellular responses to homeostatic insults, such as inflammation and apoptosis. Furthermore, increased JNK expression and activation are associated with debilitating neurodegenerative diseases, including Alzheimer’s and Parkinson’s. We previously reported elevated levels of phosphorylated JNK (pJNK), indicative of JNK hyperactivation, in the CA1 hippocampus of chronically epileptic rats. We also showed that pharmacological inhibition of JNK activity reduced seizure frequency in a dose-dependent fashion (Tai TY et al., Neuroscience, 2017). Building on these observations, the objectives of this current study were to investigate the timeline of JNK activation during epileptogenesis, and to identify the JNK isoform(s) that undergo hyperactivation in the chronic epilepsy stage. Western blotting analysis of CA1 hippocampal homogenates showed JNK hyperactivation only during the chronic phase of epilepsy (6–9 weeks post-status epilepticus), and not in earlier stages of epileptogenesis (1 h, 1 day, and 1 week post-status epilepticus). After enrichment for pJNK by immunoprecipitation, we identified JNK2 as the only significantly hyperactivated JNK isoform, with expression of the 54 kDa pJNK2 variant elevated to a greater extent than the 46 kDa pJNK2 variant. Expression of the total amounts of both JNK2 variants (phosphorylated plus non-phosphorylated) was reduced in epilepsy, however, suggesting that activation of upstream phosphorylation pathways was responsible for JNK2 hyperactivation. Since our prior work demonstrated that pharmacological inhibition of JNK activation had an antiepileptic effect, JNK2 hyperactivation is therefore likely a pathological event that promotes seizure occurrences. This investigation provides evidence that JNK2 is selectively hyperactivated in epilepsy and thus may be a novel and selective antiepileptic target.

Corydalis edulis total alkaloids (CETA) ameliorates cognitive dysfunction in rat model of Alzheimer disease through regulation of the antioxidant stress and MAP2/NF-κB

BackgroundIn recent years, the morbidity of Alzheimer's disease in the world has become more and more serious. Therefore, it is an important means to find new drugs for treating AD from traditional medicines. It was found that Corydalis edulis Maxim. has a significant effect in the treatment of Alzheimer's disease (AD) in traditional application. In this work, we evaluated the efficacy of Corydalis edulis Maxim. total alkaloids (CETA) in AD model rats. MethodsIn this work, CETA was prepared by alkali extraction and acid precipitation, 11 alkaloids were identified by UPLC-MS/MS from CETA. AD model rats induced with D-galactose (D-gal) for 7 weeks. In modeling, the different doses of CETA (5, 20 mg/kg/Day) were continuously administered. Firstly, the change of the cognitive function, behavior, brain tissue pathology, and the activity of ROS, MDA, SOD, IL-1β, TNF-α and CAT in rat hippocampal homogenate was measurement. Finally, the protein expression of Aβ, microtubule-associated protein 2 (MAP2) and nuclear factor (κBp65) in rat brain was measurement. ResultCETA was found to have the activity in regulating AD. Compared with the normal control group, the levels of SOD and CAT in the hippocampus of the AD model group were decreased, and the level of ROS, MDA, IL-1β and TNF-α was increased. The protein expression of Aβ, and NF-κB were increased, and MAP2 were decreased. After treatment by CETA, the levels of SOD and CAT in hippocampus of AD model rats was significantly increased, ROS, MDA, IL-1β and TNF-α were significantly decreased. The protein expression of Aβ, and NF-κB were decreased, and MAP2 were increased. ConclusionCETA can improve the learning and memory ability in AD model. The mechanism may be achieved by regulating the oxidative stress and inflammatory of AD rats, inhibiting the protein expression levels of Aβ, and NF-κB, and promote the protein expression the levels of MAP2. Among them, 5 mg/kg is more effective than 20 mg/kg of CETA. Therefore, the therapeutic potential of CETA has been confirmed by our research, which may be a valuable drug for the treatment of AD.

Effect of β-asarone in normal and β-amyloid-induced Alzheimeric rats.

Introductionβ-Asarone is a major component of Acorus tatarinowii Schott. It has pharmacological effects that include antihyperlipidemic, anti-inflammatory, and antioxidant activity. In the present study, the effect of β-asarone on neurodegeneration induced by intrahippocampal administration of β-amyloid was investigated in adult male Wistar rats.Material and methodsThe rats were randomly divided into 9 groups: normal control, sham-operated control, β-asarone (12.5, 25, and 50 mg/kg intragastrically, daily) alone, Alzheimeric control rats (β-amyloid, intrahippocampal), β-asarone (12.5, 25, and 50 mg/kg intragastrically, daily) together with β-amyloid, and treatment was performed accordingly. Animals were injected with β-amyloid bilaterally. Animals received β-asarone daily using an intragastric tube for 50 days, starting from 30 days before administration of the β-amyloid. The rats were sacrificed and parameters of oxidative stress, superoxide dismutase (SOD) and glutathione peroxidase (GPX) activity were measured in hippocampus homogenate. Histopathological changes were examined by Bielschowsky staining.ResultsOur results showed that administration of β-asarone (25 and 50 mg/kg) significantly increased the levels of antioxidant enzymes, including SOD (1.09 ±0.02, 1.21 ±0.02, p < 0.001, respectively) and GPX (58.94 ±0.78, 68.92 ±3.64, p < 0.001, respectively) in comparison with Alzheimeric control rats (SOD and GPX level for Alzheimeric control group: 0.44 ±0.01, 35.09 ±1.15, respectively). Histopathological examination showed that β-asarone decreased cell loss in the cerebral cortex and hippocampus in Alzheimeric rats.ConclusionsThese results indicate that β-asarone is effective in providing protection against oxidative stress and neuronal damage induced by β-amyloid.