Search

Intracerebroventricular (icv) administration of streptozotocin (STZ) has been used as a metabolic model of sporadic Alzheimer's disease (AD). Erythropoietin (EPO) possesses neuroprotective and memory-improving effects, which might be advantageous in treating different characteristics of AD. Nevertheless, the hematopoietic effect of EPO has hindered its application as a neuroprotective agent. Previous studies have shown that a new Epo derivative called carbamylated Erythropoietin-Fc (CEPO-Fc), yield noticeable neuroprotective effects without affecting hematopoiesis. In this study, the neuroprotective effects of CEPO-Fc on icv-STZ induced memory impairment and hippocampal apoptosis were examined. Adult male Wistar rats weighing 250-300 g were used. STZ was administered on days 1 and 3 (3 mg/kg in divided doses/icv), and CEPO-Fc was administered at the dose of 5000 IU/ip/daily during days 4-14. The animals were trained in Morris water maze during days 15-17, and the memory retention test was performed on the 18th day. Following behavioral studies, the animals were sacrificed and their hippocampi isolated to determine the amounts of cleaved caspase-3 (the landmark of apoptosis). The results showed that CEPO-Fc treatment at the dose of 5000 IU/kg/ip was able to prevent the learning and memory deficit induced by icv-STZ. Western blot analysis revealed that STZ prompted the cleavage of caspase-3 in the hippocampus while pretreatment with CEPO-Fc significantly reduced the cleavage of this protein. Collectively, our findings suggest that CEPO-Fc could restore STZ-induced learning and memory impairment as well as apoptosis in the hippocampal region in a rat model of sporadic AD induced by icv-STZ., Competing Interests: Declaration of Competing Interest The authors declare that they have no conflict of interests., (Copyright © 2020 Elsevier B.V. All rights reserved.)

The tissue-protective properties of erythropoietin (EPO) have been described in several neurodegenerative diseases models, but erythrocytosis following EPO treatment may lead to deleterious effects. Carbamylated erythropoietin, an EPO derivative lacking hematopoietic side effects, has shown protective properties in some studies. However, it is not known if CEPO protects primary hippocampal cells against Aβ 25-35 toxicity. The present study aimed to investigate the effect of CEPO-Fc on biochemical alterations in Akt, GSK-3β, and ERK signaling and cell death induced by Aβ 25-35 in isolated hippocampal cell culture. The embryonic hippocampal cells were obtained from 18-19 day rat embryos. The cells were exposed with Aβ 25-35 (20 µM) in the absence or presence of CEPO-Fc (1 or 5 IU) and PI3k and ERK inhibitors. CEPO-Fc at the dose of 5 IU significantly prevented the cell loss and caspase-3 cleavage caused by Aβ 25-35 . Additionally, CEPO-Fc noticeably reversed Aβ mediated decrement of Akt and GSK-3β phosphorylation. With exposure to LY294002, PI3 kinase inhibitor, Akt phosphorylation diminished and CEPO-Fc protective effects disappeared. Furthermore, while CEPO-Fc nullified Aβ-induced increment of phospho-ERK, inhibition of ERK activity by PD98059, had no effect on Aβ 25-35 -mediated caspase-3 cleavage and cell toxicity. These results imply that protective effects of CEPO-Fc seem to be mainly exerted through the PI3K/Akt pathway rather than ERK signaling. This study suggested that CEPO-Fc prevents Aβ-induced cell toxicity as well as Akt/GSK-3β and ERK alterations in isolated hippocampal cells. These findings might provide a new perspective on CEPO-Fc protective properties as a prospective remedial factor for neurodegenerative diseases like AD.

Alzheimer's disease (AD) is a debilitating neurodegenerative disease, characterized by extracellular deposition of senile plaques, mostly amyloid β-protein (Aβ) and neuronal loss. The neuroprotective effects of erythropoietin (EPO) have been reported in some models of neurodegenerative disease, but because of its hematopoietic side effects, its derivatives lacking hematopoietic bioactivity is recommended. In this study, the neuroprotective effects of carbamylated erythropoietin-Fc (CEPO-Fc) against beta amyloid-induced memory deficit were evaluated. Adult male Wistar rats weighing 250-300 g were bilaterally cannulated into CA1. Aβ 25-35 was administered intrahippocampally for 4 consecutive days (5 μg/2.5 μL/each side/day). CEPO-Fc (500 or 5000 IU) was injected intraperitoneally during days 4-9. Learning and memory performance of rats was assessed on days 10-13 using Morris Water Maze, then hippocampi were isolated and the amount of activated forms of hippocampal MAPKs' subfamily, Akt/GSK-3β and MMP-2 were analyzed using Western blot. From the behavioral results, it was revealed that CEPO-Fc treatment in both 500 and 5000 IU significantly reversed Aβ-induced learning and memory deterioration. From the molecular analysis, an increment of MAPKs and MMP-2 activity and an imbalance in Akt/GSK-3β signaling after Aβ 25-35 administration was observed. CEPO-Fc treatment prevented the elevation of hippocampal of P38, ERK, MMP-2 activity and also Akt/GSK-3β signaling impairment induced by Aβ 25-35 but it had no effect on JNK. It seems that CEPO-Fc prevents Aβ-induced learning and memory deterioration, and also modulates hippocampal MAPKs, Akt/GSK-3β and MMP-2 activity. This study suggests that CEPO-Fc can be considered as a potential therapeutic strategy for memory deficits like AD., (Copyright © 2018 IBRO. Published by Elsevier Ltd. All rights reserved.)

Abnormal and sometimes severe behavioral and molecular symptoms are usually observed in epileptic humans and animals. To address this issue, we examined the behavioral and molecular aspects of seizure evoked by pilocarpine. Autophagy can promote both cell survival and death, but there are controversial reports about the neuroprotective or neurodegenerative effects of autophagy in seizure. Cannabidiol has anticonvulsant properties in some animal models when used as a pretreatment. In this study, we investigated alteration of seizure scores, autophagy pathway proteins, and antioxidant status in hippocampal cells during the chronic phase of pilocarpine-induced epilepsy after treatment with cannabidiol. Cannabidiol (100 ng, intracerebroventricular injection) delayed the chronic phase of epilepsy. Single administration of cannabidiol during the chronic phase of seizure significantly diminished seizure scores such as mouth clonus, head nodding, monolateral and bilateral forelimb clonus and increased the activity of catalase enzyme and reduced glutathione content. Such a protective effect in the behavioral scores of epileptic rats was also observed after repeated administrations of cannabidiol at the onset of the silent phase. Moreover, the amount of Atg7, conjugation of Atg5/12, Atg12, and LC3II/LC3I ratio increased significantly in epileptic rats treated with repeated injections of cannabidiol. In short, our results suggest that post-treatment of Cannabidiol could enhance the induction of autophagy pathway and antioxidant defense in the chronic phase of epilepsy, which could be considered as the protective mechanisms of cannabidiol in a temporal lobe epilepsy model.

It is not known if insulin prevents Aβ-induced cell death, MAPK, and Akt activity in isolated hippocampal cell culture. This study was aimed to explore the effect of insulin on Aβ-induced cell death and ERK and Akt signaling alteration in isolated hippocampal cell culture. Additionally, it was desirable to assess if there is any interaction between these two pathways. The hippocampal cells were derived from fetuses at the embryonic day 18-19. The cells were treated with different drugs, and MTT assay, morphological assessments, and Western blot were done. Insulin prevented Aβ-induced cell death and caspase-3 cleavage. Aβ-induced toxicity was aligned with decrement of the phosphorylated Akt (pAkt) which was prevented by insulin. The PI3 kinase inhibitor, LY294002, decreased pAkt and abolished the protective effect of insulin. Aβ exposure increased phosphorylated ERK (pERK) in parallel with cell death and apoptosis. Insulin-inhibited ERK activation (phosphorylation) induced by Aβ and PD98059 (as ERK inhibitor) did not affect the protective effect of insulin. One of the interesting finding of this study was the interplay of Akt and ERK in Aβ toxicity and insulin-mediated protection; meaning that there is an inverse relation between pERK and pAkt, in a way that PI3-Akt pathway inhibition leads to pERK increment while ERK inhibition causes Akt phosphorylation (activation). This study showed, for the first time, that insulin protects against Aβ toxicity in isolated hippocampal cell culture via modulating Akt and ERK phosphorylation and also revealed an interaction between those signals in Aβ toxicity and insulin-mediated protection.

One of the neuropathological hallmarks of Alzheimer's disease (AD) is the accumulation of beta-amyloid peptides (Aβ) in senile plaques. Aβ-induced oxidative stress is believed to be responsible for degeneration and apoptosis of neurons and consequent cognitive and memory deficits. Here, we investigated the possible neuroprotective effect of the heat shock protein 90 (Hsp90) inhibitor geldanamycin (GA) against amyloid pathogenesis in adult male Wistar rats. GA or vehicle was injected into the lateral cerebral ventricles of rats 24 h before injection of Aβ (1-42) in CA1 area of hippocampus. The learning and memory of the rats were assessed 7 days after injection of Aβ using passive avoidance (PA) task. As potential contributing factors in Aβ-induced memory decline, we evaluated apoptotic markers and also used terminal-transferase UTP nick end labeling (TUNEL) technique to detect apoptosis in the hippocampus of Aβ-injected rats. Our behavioral data suggest that GA pretreatment can significantly suppress memory deficits in Aβ-injected rats. There was also not only a marked increase in Hsp70 level but also upregulated 70 kDa ribosomal protein S6 kinase (p70S6K) in the hippocampus of GA-treated groups with a reduction in apoptotic factors including caspase-3, poly (ADP-ribose) polymerase, Bax/Bcl-2 ratio, and TUNEL-positive cells as well. Thus, we conclude that GA exerts its protective effects against Aβ (1-42) toxicity and memory deficits, at least in part, by upregulating of Hsp70 and P70S6K.

Anxiety-related disorders are complex illnesses that underlying molecular mechanisms of these complicated emotional disorders are poorly understood. Nuclear factor erythroid 2-related factor 2 (Nrf2) is the most important regulator of the antioxidant defense system. Its protective actions are not only limited to antioxidative transactivation, but also plays important roles in encountering various physiological and pathological stresses. In this study, we evaluated whether silencing of Nrf2 plays a role in development of anxiety-related behavior. In this regard, we exerted small interfering RNA (siRNA) targeting Nrf2 in dorsal third ventricle and subsequently examined the effect of this silencing on anxiety-related behavior along with supposed molecular mechanisms. Therefore, we evaluated apoptotic markers and mitochondrial electron transport chain (ETC) activity in three brain regions: hippocampus, amygdala, and prefrontal cortex. Based on our result, Nrf2-silenced rats exhibited greater anxiety-like behavior compared to control group. Furthermore, Nrf2 silencing increased activity of ETC complexes. Also, Bax/Bcl2 ratio of all mentioned areas of the brain and cleavage of caspase-3 in hippocampus increased in Nrf2 silenced group, however, with a distinct pattern.

Alzheimer disease (AD) is a progressive neurodegenerative disease characterized by extracellular deposits of beta amyloid (Aβ) and neuronal loss particularly in the hippocampus. Accumulating evidences have implied that insulin signaling impairment plays a key role in the pathology of AD; as much as it is considered as type 3 Diabetes. MAPKs are a group of signaling molecules which are involved in pathobiology of AD. Therefore this study was designed to investigate if intrahippocampal insulin hinders Aβ-related memory deterioration, hippocampal apoptosis and MAPKs signaling alteration induced by Aβ. Adult male Sprague-Dawely rats weighing 250-300 g were used in this study. The canules were implanted bilaterally into CA1 region. Aβ25-35 was administered during first 4 days after surgery (5 μg/2.5 μL/daily). Insulin treatment (0.5 or 6 mU) was done during days 4-9. The animal's learning and memory capability was assessed on days 10-13 using Morris water maze. After finishing of behavioral studies the hippocampi was isolated and the amount of hippocampal cleaved caspase 3 (the landmark of apoptosis) and the phosphorylated (activated) forms of P38, JNK and ERK was analyzed by western blot. The results showed that insulin in 6 but not 0.5 mU reversed the memory loss induced by Aβ25-35. Western blot analysis revealed that Aβ25-35 induced elevation of caspase-3 and all 3 MAPks subfamily activity, while insulin in 6 mu restored ERK and P38 activation but has no effect on JNK. This study disclosed that intrahippocampal insulin treatment averts not only Aβ-induced memory deterioration but also hippocampal caspase-3, ERK and P38 activation., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Alzheimer disease (AD) is characterized by accumulation of beta amyloid (Aβ) and neuronal loss, particularly in the hippocampus. Direct central administration of this peptide was suggested as a route to create an animal model of AD. Although there are some studies indicating that a single dose of Aβ induces AD-like learning and memory impairment, this model is not usually reproducible especially in rat. Then one of the aims of this study was to explore a more reliable method to trigger AD-like behavioral impairments in rat through a series of pilot studies. In other step, according to some controversies about roles of MAPKs (P38, JNK and ERK) in AD, these kinases were assayed in beta amyloid-treated rats with or without memory impairment. A series of pilot studies was done to assess if a single Aβ injection (5, 10, 15 µg/each side) induces reproducible memory impairment. Because of the failure of that set of studies, another set of experiment with repeated Aβ administration during four days was carried out. The results showed that in contrast to single treatment of beta amyloid, its repeated administration (5 µg/2.5 µl each side/day) during 4 days led to memory deterioration. Hippocampal western blot analysis revealed that behavioral impairment is in parallel with greater apoptosis and MAPKs activation. This study introduces a new method for inducing AD models by repeated intra-CA1 injection of Aβ25–35. Additionally it elucidates how caspase-3 and MAPKs activity differ between beta amyloid-treated rats with or without learning and memory impairment.

Neuroinflammation is associated with a number of neurodegenerative diseases. It is known that lipopolysaccharide (LPS) treatment induces neuroinflammation and memory deterioration. Agmatine, the metabolite of arginine by arginine decarboxylase, is suggested to be a neuroprotective agent. The aim of this study was to explore if agmatine can prevent LPS-induced spatial memory impairment and hippocampal apoptosis. Adult male Wistar rats (200-250 g) were trained in water maze for 4 days (3 days in hidden platform and the last day in visible platform task). Saline, LPS (250 microg/kg/ip) or (and) agmatine (5 or 10 mg/kg) were administered 4h before every training session. LPS treatment impaired water maze place learning while agmatine co-administration prevented it. Also western blot studies revealed that LPS induces hippocampal caspase-3 activation while agmatine treatment prevented it., (Copyright 2010 Elsevier B.V. All rights reserved.)

Corticosterone induces neuroanatomical and neurochemical changes in the hippocampus that are associated with cognitive impairments. In the present study corticosterone induced cell death in primary hippocampal neurons cultured in Neurobasal + B27 medium. Insulin prevents neuronal cell death induced in a concentration dependent manner. The neuroprotective effect of insulin was reversed by LY294002, a phosphatidylinositol 3'-kinase (PI3 kinase) inhibitor, whereas the mitogen-activated protein kinase (MAPK) inhibitor PD98059, an upstream blocker of MAPK had no effect. Western blot analyses showed that insulin induced the activation of protein kinase B (Akt). These results suggest that insulin can prevent neuronal cell death induced by corticosterone in hippocampal neurons by modulating the activity of the PI3 kinase/Akt pathway., (Copyright 2008 S. Karger AG, Basel.)

Abstract: Objectives: There are some evidences indicating that stress can affect hippocampal survival and function. During pregnancy mother is exposed to more stress and anxiety; also adrenal gland response to ACTH and glucocorticoid secretion is increased. Hence this study was done to assess the effect of restraint stress on corticosterone level, hippocampal caspase-3 and MAPK activation during pregnancy. Study design: The restraint stress was applied in day 14 or days 14–20 (single and repeated stress) of rats’ pregnancy. The hippocampi were isolated after last stress episode and western blot analysis was done to assess caspase-3 and MAPK activation. Data were analyzed by one-way ANOVA followed by Student–Newman–Keuls for multiple comparison. Results: Our study showed that single and repeated stress both increase corticosterone level compared to non-stressed pregnant rats, but do not induce hippocampal apoptosis. Single stress increases transient JNK activation but not P38 and ERK. Repeated stress activated none of the MAPKs. Conclusion: It seems that pregnancy protects mother''s hippocampus against stress-induced damages. [Copyright &y& Elsevier]