Protective role of Eugenol against the destructive effects of lead on conditioned fear memory in male rats with post-traumatic stress disorder-related behavioral traits.

Introduction: Post-traumatic stress disorder (PTSD) is a consequence of living in today's stressful society. Patients have difficulty forgetting traumatic events. lead pollution has many effects on the nervous system, one of which is memory and learning disorders. The herbal medicine Eugenol has a beneficial effect on memory. Aim: This study aims to investigate the protective effect of Eugenol on lead-induced memory impairments in stressed rats. Methods: In the first experiment, the animals were divided into three groups: SPS+Saline, SPS+Pb, and naïve. The SPS+Saline, SPS+Pb groups received normal saline and lead through gavage for 21 days, while the sham group remained untreated. Rats were subjected to the modified single prolonged stress model. Memory tests were conducted one week later, evaluating freezing levels in three consecutive tests over three days. In the second experiment, rats were divided into a SPS+Pb+Saline and three treatment groups. The SPS+Pb+Saline group received daily saline injections, while the other groups received different doses of Eugenol (25, 50, and 100 mg/kg). Memory tests similar to the first experiment were conducted. Results: The results showed significantly higher immobility levels in the SPS+Saline and SPS+Pb groups compared to the sham. Additionally, the SPS+Pb group had a significant higher immobility compared to the SPS+Saline group. In the second experiment, the SPS+Pb+EU 25 group showed a significant lower freezing compared to the SPS+Pb+Saline group. Additionally, freezing in the SPS+Pb+EU 50 and SPS+Pb+EU 100 groups was significantly higher than in the SPS+Pb+EU 25 group. The SPS+Pb+EU 50 group showed a significant higher freezing compared to the SPS+Pb+Saline group. Conclusion: lead acetate exacerbated memory impairments in stressed rats and Eugenol, particularly at a dose of 25 mg/kg, improved these impairments. Therefore, Eugenol has the potential to partially reduce the negative effects of lead on memory in individuals with PTSD.

The protective role of prenatal administration of ascorbic acid on autistic-like behavior in a rat model of autism.

Background: Autism is a complicated neurodevelopmental disorder characterized by several behavioral impairments. The pathology of autism is complex and not fully known. Several recent studies have shown alterations in the activities of antioxidant enzymes in autism. Vitamin C is a potent antioxidant that is present in high concentrations in the brain and acts as a neuromodulator. Prefrontal abnormality has been hypothesized to underlie autistic symptoms. The present study investigated the protective effect of prenatally Vitamin C on autistic-like behaviors, oxidative stress status, and histopathological change of prefrontal in valproic acid (VPA) rat model of autism. Method: The model of autism was induced by subcutaneous administration of Valproic acid (600 mg/kg) to pregnant rats at gestational day 12.5. Vitamin C was administered 600 mg/L in drinking water from the 5th day of gestaion (GD5) up to postnatal day 23 (PND23). Thirty-two rat offspring were divided into four groups: Control, Vitamin C, VPA, and Vitamin C + VPA. The offspring were tested for repetitive behaviors and cognitive ability with a Y-maze task and social interaction with a play behavior task on 31st of Postnatal days. Glutathione (GSH), superoxide dismutase (SOD) activity, and the histological change in the prefrontal lobe were assessed at the end of the study. The number of neurons from the left prefrontal lobe was counted in duplicate from slides stained with hematoxylin-eosin. Results: In the Y-maze apparatus, spontaneous alteration significantly decreased in the prenatal VPA treated rats compared to control rats showing autistic-like behavior; pre and postnatal Vitamin C treatment increased the alternation indicated benefit effect of Vitamin C. Prenatal VPA treatment impaired play behavior such as sniffing, grooming and darting. Vitamin C treatment attenuated the problems in male offspring social behavior. Histological examination showed an increase in the number of cells in the prefrontal cortex of valproic acid offspring rats compared to other groups. Moreover, prenatal VPA decreased antioxidant enzyme activities in the cortex (PFC) attenuated by Vitamin C administration. Conclusion: The present study showed that valproic acid induced oxidative stress and neural changes in the prefrontal lobe when administered prenatally which in turn may cause the development of some autistic-like behaviors, and vitamin C may reduce this symptom with its antioxidant effects.

Folic acid improved memory and learning function in a rat model of neuroinflammation induced by lipopolysaccharide.

Folic acid (FA) plays an important role in the maintenance of normal neurological functions such as memory and learning function. Neuroinflammation contributes to the progression of cognitive disorders and Alzheimer's disease. Thus, this study aimed to investigate the effect of FA supplementation on cognitive impairment, oxidative stress, and neuro-inflammation in lipopolysaccharide (LPS)-injured rats. For this purpose, the rats were given FA (5-20 mg/kg/day, oral) for 3 weeks. In the third week, LPS (1 mg/kg/day; intraperitoneal injection) was given before the Morris water maze (MWM) and passive avoidance (PA) tests. Finally, the brains were removed for biochemical assessments. In the MWM test, LPS increased the escape latency and traveled distance to find the platform compared to the control group, whereas all doses of FA decreased them compared to the LPS group. The findings of the probe trial showed that FA increased the traveling time and distance in the target area. LPS impaired the performance of the rats in the PA test. FA increased delay and light time while decreasing the frequency of entry and time in the dark region of PA. LPS increased hippocampal levels of interleukin (IL)-6 and IL-1ß. The hippocampal level of malondialdehyde was also increased but thiol content and superoxide dismutase activity were decreased in the LPS group. However, treatment with FA restored the oxidative stress markers along with a reduction in the levels of pro-inflammatory cytokines. In conclusion, FA could ameliorate the memory and learning deficits induced by LPS via normalizing the inflammatory response and oxidative stress markers in the brain.

Improving behavioral deficits induced by perinatal ethanol and stress exposure in adolescent male rat progeny via maternal melatonin treatment.

BACKGROUND AND AIM: Early-life stressful situations and binge drinking have been thus far acknowledged as two burdensome conditions that potentially give rise to negative outcomes and then synergistically affect brain development. In this context, the hippocampus, with the greatest number of glucocorticoid receptors (GCRs) in the brain, is responsible for regulating negative responses to stress. Prolonged glucocorticoid (GC) exposure can accordingly cause oxidative stress (OS), leading to cognitive and emotional dysfunction. Against this background, melatonin, as a powerful antioxidant and hypothalamus-pituitary-adrenal (HPA) axis regulator, was administered in this study to ameliorate cognitive impairments induced by perinatal ethanol and stress exposure in adolescent male rat progeny. METHODS: Wistar rat dams were exposed to ethanol (4 g/kg) and melatonin (10 mg/kg) from gestational day (GD) 6 to postnatal day (PND) 14 and then limited nesting material (LNS) from PND0 to PND14 individually or in combination. Maternal behavior was then investigated in mothers. Afterward, the plasma corticosterone (CORT) concentration, the OS marker, the corticotropin-releasing hormone receptor type 1 (CRHR1) expression, and the GCR and brain-derived neurotrophic factor (BDNF) levels were measured in the male pups. Moreover, behavioral tasks, including the elevated plus maze (EPM), the Morris water maze (MWM), the novel object recognition (NORT), and the object-location memory (OLM) tests were completed and assessed. RESULTS: The quantity and quality of maternal care significantly decreased in the mothers with dual exposure to ethanol and stress. The plasma CORT concentration in the progeny also dropped in the Ethanol + LNS group, but the risk-taking behavior elevated significantly. The ethanol and stress exposure further revealed a significant fall in the GCR and CRHR1 expression levels, compared with stress alone. The results of learning and memory tasks also indicated a significant reduction in spatial learning and memory among animals exposed to ethanol and stress. The BDNF mRNA levels correspondingly increased in the Ethanol + LNS group, compared with LNS alone. In the presence of ethanol and stress, the superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities correspondingly declined. On the other hand, the malondialdehyde (MDA) levels augmented in the hippocampus of the animals with ethanol and LNS dual exposure, as compared with the control group. Melatonin treatment (MT) thus improved nursing behaviors in dams, prevented OS, enhanced the CRHR1 and GCR expression, and reduced the BDNF levels to the similar ones in the control group. The animals in the Ethanol + LNS + MT group ultimately showed an ameliorated performance at behavioral tasks, including the memory and risk-taking behavior. CONCLUSION: It was concluded that MT could prevent stress response and memory impairments arising from dual exposure to ethanol and stress by inhibiting OS.

Intracerebroventricular Injection of MHY1485 Blocked the Beneficial Effect of Adiponectin on Aversive Memory in the STZ Model of Dementia.

BACKGROUND: The most prominent adipokine, adiponectin (APN), has an adverse relationship with the malfunction of adipose tissue. Obesity causes a decrease in plasma APN levels, which eventually results in insulin resistance and diabetes. In this study, we assessed how the effects of APN on memory are influenced by the insulin receptor substrate-1 (IRS-1) and the mammalian target of rapamycin (mTOR) pathways. METHODS: Streptozotocin (STZ) 3 mg/kg intracerebroventricular injections on days 1 and 3 following cannulation were used to create an animal model of Alzheimer's disease. The acquisition phase was preceded by injections of MHY and adiponectin. For the passive avoidance task, the stepthrough latency and total duration in the dark compartment were recorded and evaluated, and the preference index was calculated for the novel object identification test. IRS-1 protein expression in the hippocampus was assessed by western blotting. RESULTS: STZ reduced the step-through latency (STL), which rose significantly (P≤0.001) in the APN+STZ group. The memory-improving effects of APN were reversed when MHY was administered first (P≤0.001). The STZ and APN+STZ+MHY groups both had a substantial decline in the preference index (P≤0.01). Compared to the control group, the STZ group's expression of the IRS- 1 protein was dramatically reduced (P≤0.0001). In contrast to the APN+STZ group, the MHYtreated group likewise showed decreased IRS-1 protein expression (P≤0.0001), but APN+STZ was able to enhance IRS-1 expression rate (P≤0.0001). CONCLUSION: In a rat model of AD, we found that adiponectin improved aversive and cognitive memory, which is at least partially mediated by the mTOR signaling cascade.

Postnatal melatonin administration to stressed dams for ameliorating risk-taking behaviour in rat pups through maternal care improvement.

BACKGROUND AND AIM: Anxiety often occurs both concurrently and sequentially in childhood and adolescence in association with prenatal stress, which may reduce the quality of maternal care and then cause mood disorders among children in later life. Against this background, melatonin, as a powerful antioxidant, was used in the present study to ameliorate risk-taking behaviour induced by pure maternal care in rat pups. MATERIALS AND METHODS: The Wistar rat dams recruited in this study were exposed to restraint stress from gestational day (GD) 11 until delivery. They further received melatonin (10 mg/kg) during the postnatal days (PNDs) 0-7 by intraperitoneal (IP) injections at 4:00 PM. The pregnant rats were then divided into four groups, namely, control, stress, stress + melatonin and melatonin, and their maternal behaviour and corticosterone levels were measured. In the offspring, the outcomes of some behavioural tasks, including the elevated plus-maze (EPM) and open-field (OF) tests were ultimately assessed. RESULTS: The study results revealed that the quantity and quality of maternal care significantly declined and the plasma corticosterone levels compounded in the stressed dams. Melatonin treatment, however, improved their nursing behaviour and reduced their plasma corticosterone levels. The offspring performance in two tasks also showed an upward trend in risk-taking behaviour in the stress group, and melatonin administration ameliorated the effects of stress and lessened their anxiety-like behaviour. CONCLUSION: It was concluded that prenatal restraint stress could impair stress responses and quality of maternal care, whereas postnatal melatonin administration potentially contributed to the normalization of stress reaction and anxiolysis.

Lateral Hypothalamus Corticotropin-releasing Hormone Receptor-1 Inhibition and Modulating Stress-induced Anxiety Behavior.

Introduction: Stress is a reaction to unwanted events disturbing body homeostasis and its pathways and target areas. Stress affects the brain through the lateral hypothalamic area (LHA), the orexinergic system that mediates the effect of corticotropin-releasing hormone (CRH) through CRH Receptor Type 1 (CRHr1). Therefore, this study explores the outcome of stress exposure on anxiety development and the involvement of the LHA through LHA-CRHr1. Methods: Male Wistar rats (220-250 g) implanted with a cannula on either side of the LHA received acute or chronic stress. Subsequently, exploratory behavior was examined using the Open Field (OF), and anxiety was tested by Elevated Plus Maze (EPM). Before sacrifice, the cerebrospinal fluid (CSF) and the blood were sampled. Nissl stain was performed on fixed brain tissues. Results: Acute stress reduced exploration in of and increased anxiety in EPM. LHA-CRHr1 inhibition reversed the variables to increase the exploration and decrease anxiety. In contrast, chronic stress did not show any effect on anxiety-related behaviors. Chronic stress decreased the cell population in the LHA, which was prevented by the CRHr1 inhibition. However, the CRHr1 inhibition could not reverse the chronic stress-induced increase in the CSF orexin level. Furthermore, plasma corticosterone levels increased through acute or chronic stress, impeded by the inhibition of CRHr1. Conclusion: Our results recognize LHA-CRHr1 as a capable candidate that modulates acute stress-induced anxiety development and chronic stress-induced changes in the cellular population of the region. Highlights: Acute stress, increased immobility of the rat in open field and elevated plus maze.Chronic stress, increased orexin production while decreasing neuronal survival.The anxiety and immobility were not developed in presence of CRHr1.CRHr1 blocking reversed the chronic stress changes in corticosterone and orexin. Plain Language Summary: Lateral Hypothalamus (LH) is a region involved in sleep and appetite regulation and recently known to play role in stress pathophysiology. The stress mediating function of the LH is performed through Corticotropin Releasing Hormone Receptor type-1 (CRHr1). This study explored the role of LH- CRHr1 in anxiety development and orexin production. Acute and chronic stress affected the behavior and molecular changes, differently. The acute stress increased the anxiety condition, while the chronic stress could only change the molecular criteria. Although we assumed that the inability of the chronic stress to develop anxiety may be attributable to habituation, the chronic stress could increase the plasma corticosterone and orexin level. All of the stress mal-changes in behavior and molecular level prevented by antagonising CRHr1 in the LH, indicating a gating function of LH-CRHr1 for stress development.

Hippocampal orexin-1 and endocannabinoid-1 receptors underlie the kainate-induced occlusion in theta-burst long- term potentiation.

INTRODUCTION: Seizures may result from the hyperexcitable neuronal activity of the brain. Multiple neurotransmitter receptors, including orexin (OX) and endocannabinoids interfere with forming the synaptic responses linked to the seizures. Therefore, this study investigates the involvement of OX-1 (OX1R) and endocannbinoid-1 (CB1R) receptors in the kainate- induced excitability in the synaptic field responses. MATERIAL AND METHODS: Theta pattern used to stimulate Schaffer collaterals and then metal microelectrodes to record the CA1 field excitatory postsynaptic potentials (fEPSPs). Input/ output stimulation and responses and paired- pulse (PP) stimuli employed to measure the state of synaptic activity in normal and kainate- induced seizure-like hyperexcitable activities and the slope of fEPSPs used as a measure of the change in the synaptic activity. Furthermore, agonists and antagonists of OX and endocannabinoids infused to investigate the involvement of their receptors. RESULT: The results showed that kainate application increased the fEPSP slope either in input stimuli with different intensities/output synaptic responses (I/O), or test pulse stimulated baseline synaptic responses (BSR) and, hence, increased the excitability of field responses in the CA1 region. However, neither kainate nor theta burst stimulation (TBS) could alter the PP stimuli -induced synaptic responses. TBS increased the fEPSP slope of the kainate-applied I/O and BSR, however, the increase was not high enough in BSR to be classified as long-term potentiation (LTP). The single-antagonist OX1R and CB1R administration prevented TBS- induced potentiation and partially recovered the effect by adding eCB or OX agonists in kainate-injected animals. In contrast, OX or combined eCB-OX antagonist application group demonstrated nearly full recovery of LTP induction. CONCLUSION: Our study concludes that blockade of OX1 or CB1 prevents the induction of LTP, and OX infusion or both receptor blockade recovers the LTP.

The Combined Effects of Perinatal Ethanol and Early-Life Stress on Cognition and Risk-Taking Behavior through Oxidative Stress in Rats.

Both prenatal ethanol and early-life stress have been shown to induce reduced risk-taking and explorative behavior as well as cognitive dysfunction in the offspring. In this study, we examined the effect of combined exposure to ethanol and early stress on maternal care, exploratory behavior, memory performances, and oxidative stress in male offspring. Pregnant rats were exposed to ethanol (4 g/kg) from gestational day (GD) 6-to postnatal day (PND) 14 and limited nesting material (LNS) from PND0-PND14 individually or in combination. Maternal behavior was evaluated during diurnal cycle. The level of corticosterone hormone and markers of oxidative stress were evaluated in the pups. Risk-taking and explorative behavior were assessed with the elevated-plus maze (EPM) test and cognitive behavior with the Morris water maze (MWM), novel object recognition (NORT), and object location memory (OLM) tests. In the mothers, perinatal alcohol or LNS either alone or in combination decreased maternal behavior. In the offspring, the combination of the two factors significantly increased the pup's plasma corticosterone concentration in comparison with ethanol and LNS alone. Reduced risk-taking behavior was observed in the ethanol, LNS and ethanol + LNS groups compared with the control group, and this was amplified in the co-exposure of ethanol and LNS groups. The MWM, NORT, and OLM tests revealed spatial and recognition memory impairment in the ethanol and LNS groups. This impairment was more profound in the co-exposure of ethanol and LNS. Also, we observed a significant decrease in superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities and an increase in malondialdehyde (MDA) level in the hippocampus of ethanol and LNS co-exposed animals as compared with individual exposure of ethanol and LNS. While each factor independently produced similar outcomes, the results indicate that the dual exposure paradigm could significantly strengthen the outcomes.

Hippocampal orexin receptors: Localization and function.

Orexin (hypocretin) is secreted from the perifornical/lateral hypothalamus and is well known for sleep regulation. Orexin has two, orexin A and B, transcripts and two receptors, type 1 and 2 (OX1R and OX2R), located in the plasma membrane of neurons in different brain areas, including the hippocampus involved in learning, memory, seizures, and epilepsy, as physiologic and pathologic phenomena. OX1R is expressed in the dentate gyrus and CA1 and the OX2R in the CA3 areas. Orexin enhances learning and memory as well as reward, stress, seizures, and epilepsy, partly through OX1Rs, while either aggravating or alleviating those phenomena via OX2Rs. OX1Rs activation induces long-term changes of synaptic responses in the hippocampus, an age and concentration-dependent manner. Briefly, we will review the localization and functions of hippocampal orexin receptors, their role in learning, memory, stress, reward, seizures, epilepsy, and hippocampal synaptic plasticity.

Quercetin fail to protect against the neurotoxic effects of chronic homocysteine administration on motor behavior and oxidative stress in the adult rat's cerebellum.

Homocysteine (Hcy) is an excitatory amino acid that contains thiol group and derives from the methionine metabolism. It increases vulnerability of the neuronal cells to excitotoxic and oxidative damage. This study aimed to investigate the hyperhomocysteinemia (hHcy) effects on rat cerebellum and the possible protective role of quercetin administration in Hcy-treated rats, using behavioral and biochemical analyzes. To this end, the adult male rats were divided randomly into the control group that received vehicle, Hcy group received Hcy (400 µg/kg), Hcy + Que group received Hcy + quercetin (50 mg/kg), quercetin group received quercetin for 14 days. On Day 14 after the final treatment, lipid peroxidation level, the superoxide dismutase (SOD), and glutathione peroxidase (GPx) activities were evaluated in the cerebellum. After completion of treatment, the rat's performance on rotarod and locomotor activity was evaluated. The results showed that Hcy treatment elicited cerebellar lipid peroxidation, impaired locomotor activity and increased latency to fall on the rotarod. Quercetin failed to attenuate significantly motoric impairment, increased significantly the cerebellar lipid peroxidation and GPx activity in the Hcy + Que group. Our results suggest that Hcy induced cerebellar toxicity and quercetin had no significant protective effects against Hcy toxicity in the cerebellum of adult rats.

Maternal ethanol exposure induces behavioral deficits through oxidative stress and brain-derived neurotrophic factor interrelation in rat offspring.

Alcohol consumption during pregnancy damages the central nervous system of developing fetus and results in persistent physical and neurobehavioral abnormalities, including learning and memory disorders. The hippocampus which is involved in learning and memory is highly susceptible to the ethanol neurotoxic effects. Oxidative stress is one of the mechanisms in alcohol-induced disorders. Ethanol also interferes with the brain-derived neurotrophic factors (BDNF) expression. Using vitamin E as a potent antioxidant, we studied the possible interrelation between oxidative stress and BDNF on cognition. Ethanol (4 g/kg) and vitamin E (100, 200, and 400 mg/kg) were given to pregnant Wistar rats on first day of gestation (GD) until weaning (28 days). Oxidative stress marker, BDNF expression, and cyclic AMP-response binding-protein (CREB) expression levels were measured on postnatal days (PND) 28. Object location memory (OLM) was evaluated on PND 34. Our results demonstrated that ethanol exposure significantly reduced glutathione peroxidase (GPx) activity, reduced glutathione (GSH), reduced/oxidized glutathione (GSH/GSSG) ratio, and increased superoxide dismutase (SOD) activity, malondialdehyde (MDA) levels, and carbonyl protein content in the hippocampus. Total BDNF, BDNF mRNA, and CREB expression significantly reduced in the hippocampus by ethanol exposure. Also, ethanol significantly reduced the discrimination index (DI) in the OLM test. In addition, vitamin E administration could reduce oxidative stress, increase significantly BDNF and CREB levels, and improve cognitive dysfunction induced by ethanol exposure. Collectively, results suggest that probably oxidative stress can interrelate with the BDNF system for modulating cognitive function in the ethanol-exposed rat.

Bioactive Carboxymethyl Starch-Based Hydrogels Decorated with CuO Nanoparticles: Antioxidant and Antimicrobial Properties and Accelerated Wound Healing In Vivo.

In this study, nanocomposite hydrogels composed of sodium carboxymethylated starch (CMS)-containing CuO nanoparticles (CMS@CuO) were synthesized and used as experimental wound healing materials. The hydrogels were fabricated by a solution-casting technique using citric acid as a crosslinking agent. They were characterized by Fourier-transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and thermogravimetric analysis (TGA) to evaluate their physicochemical properties. In addition, swelling, antibacterial activities, antioxidant activities, cytotoxicity, and in vivo wound healing were investigated to evaluate the wound healing potential of the CMS@CuO nanocomposite hydrogels. Growth inhibition of the Gram-positive and Gram-negative pathogens, antioxidant activity, and swelling were observed in the CMS@CuO nanocomposite hydrogels containing 2 wt.% and 4 wt.% CuO nanoparticles. The hydrogel containing 2 wt.% CuO nanoparticles displayed low toxicity to human fibroblasts and exhibited good biocompatibility. Wounds created in rats and treated with the CMS@2%CuO nanocomposite hydrogel healed within 13 days, whereas wounds were still present when treated for the same time-period with CMS only. The impact of antibacterial and antioxidant activities on accelerating wound healing could be ascribed to the antibacterial and antioxidant activities of the nanocomposite hydrogel. Incorporation of CuO nanoparticles in the hydrogel improved its antibacterial properties, antioxidant activity, and degree of swelling. The present nanocomposite hydrogel has the potential to be used clinically as a novel wound healing material.

Adenosine monophosphate activated protein kinase (AMPK) is essential for the memory improving effect of adiponectin.

Adiponectin (APN) plays a major role in the regulation of insulin sensitivity and glucose homeostasis. Insulin and APN have a positive effect on memory. In this study, we examined whether the inhibition of AMPK could block the memory improving effect of APN or affect the IRS1 expression. Animal model of AD was developed by intracerebroventricular (icv) injection of 3 mg/kg streptozotocin (STZ), in 12 weeks old Wistar rats, on days 1 and 3 after cannulation. Dorsomorphin (DM) and APN (600 nM) were injected 30 and 20 min before the acquisition phase, respectively. DM was applied in 3 different doses (0.2, 2 and 20 µM). All behavioral tests were performed on days 15 and 16; the Preference Index (PI) was calculated for novel object recognition (NOR) test, while the step through latency (STL) and total time in dark compartment (TDC) were recorded and analyzed for the passive avoidance task. Relative expression of insulin receptor substrate-1 (IRS-1) protein in the hippocampus was measured by western blotting. In early retrieval test, STZ + APN treatment increased STL (P < 0.0001) and decreased TDC (P < 0.05) in comparison to STZ group, while STZ + APN + DM (2µM) caused a decrease in STL (P < 0.05) and increase in TDC (0.2µM and 2µM DM; P < 0.05). Icv injection of DM (0.2µM and 2µM) before APN decreased the PI significantly (P < 0.05) in comparison to STZ + APN group. APN treatment raised the IRS-1 expression and DM reversed this increment, significantly (P < 0.0001). It is concluded that the memory improving effect of APN is mediated, at least in part, by the AMPK pathway. APN is also able to boost insulin signaling by overexpression of IRS-1 in the hippocampus.

Vitamin E attenuates alterations in learning, memory and BDNF levels caused by perinatal ethanol exposure.

Objective: Alcohol exposure during pregnancy affects the developing fetus and causes a variety of physical and neurological abnormalities. Here we aim to study the effects of vitamin E on spatial learning and memory deficits and on changes in hippocampal brain-derived neurotrophic factor (BDNF) levels following perinatal ethanol exposure in rats.Method: Pregnant Wistar rats received ethanol (4 g/kg) and vitamin E (doses of 100, 200, and 400 mg/kg) on day 0 of gestation (GD) until weaning (28 days). On postnatal days (PND) 29, the performance of spatial learning and memory of rats were measured using the Morris water maze (MWM). The expression of BDNF protein levels in the hippocampus was assayed using BDNF ELISA kits.Results: Ethanol exposed group showed higher escape latency during training, reduced time spent in the target quadrant, higher escape location latency and average proximity in probe test. Vitamin E with doses of 100, 200 and 400 mg/kg significantly reduced escape latency during training. Also, vitamin E (400 mg/kg) significantly increased time spent in target quadrant, decreased escape location latency and average proximity in probe test. Maternal ethanol treatment significantly reduced the expression of BDNF protein in the hippocampus of offspring, whereas administration of vitamin E (400 mg/kg) significantly increased hippocampal BDNF in ethanol-treated rats.Discussion: Vitamin E administration dose-dependently ameliorate learning and memory deficits induced by perinatal ethanol exposure and increased hippocampal BDNF levels. BDNF may be implicated in the beneficial effects of vitamin E on learning and memory in the perinatal ethanol-exposed rat.

Folic Acid Protects Rat Cerebellum Against Oxidative Damage Caused by Homocysteine: the Expression of Bcl-2, Bax, and Caspase-3 Apoptotic Genes.

There is evidence that oxidative stress involves in homocysteine-induced pathogenesis. Considering the antioxidative properties of folic acid and its involvement as a cofactor for methionine synthase (MS) in the homocysteine-methionine cycle, the aim of this study was to evaluate the mechanism associated with homocysteine-induced toxicity and its prevention with folic acid supplementation. Male rat pups were divided into four groups including control, homocysteine (Hcy), Hcy + folic acid and folic acid groups. The Hcy group received Hcy 0.3-0.6 µmol/g body weight, while Hcy + folic acid group received folic acid orally as 0.011 µmol/g body weight along with Hcy on a postnatal day (PD) 4 until 25. The reduced and oxidized glutathione (GSH and GSSG) levels, GSH/GSSG ratio, protein carbonyl content, cystathionine ß synthase (CBS), and MS activities in the cerebellum were measured 25 days after birth. Levels of malondialdehyde (MDA), marker of lipid peroxidation were measured. Also, Bcl2, Bax, and caspase-3 expression levels were measured by real-time quantitative PCR. Furthermore, caspase-3 protein level assay was performed by the ELISA test. Results indicated that Hcy administration could promote both lipid and protein oxidation, which was associated with increased amounts of caspase-3 mRNA and protein levels and Bax mRNA expression level in this group. Cerebellar MS, CBS enzyme activity, GSH, GSSG, and GSH/GSH ratio did not change following Hcy administration. Folic acid significantly reduced MDA level, protein carbonyl content, Bax, the caspase-3 mRNA, and protein expression levels in the cerebellum of Hcy-treated group. Moreover, cerebellar MS, CBS enzyme activity, GSH, and GSH/GSH ratio increased following folic acid treatment. We conclude that Hcy might cause apoptosis in the cerebellum. We suggest that folic acid, in addition of having antioxidant properties, can protect cerebellum against homocysteine-mediated neurotoxicity via modulating the expression of proteins that are contributed in regulation of apoptosis in the rat's cerebellum.

Hippocampal orexin receptor blocking prevented the stress induced social learning and memory deficits.

Stress as a homeostatic challenge leads to the malfunction of learning and memory processes, namely social learning and memory. The orexin system is involved in stress responses through connections to the hypothalamic-pituitary axis (HPA). In addition, the hippocampus, a structure vulnerable to stress-induced changes, expresses orexin receptors 1 and 2 (OXr1 and OXr2) in various sub-regions. The present study is aimed at assessing the effects of hippocampal orexin receptor blockade on social learning and memory impairments and anxiety development following stress. Male Wistar rats (220-250 g) underwent cannula implantation in the hippocampus. Acute (two mild electric shocks, 5.5 mA) and chronic stresses (ten days of restraint, 6 h daily) were applied with or without injection of orexin receptor antagonists (SB-334867 or TCS OX 29). Sociability and social novelty in animals were assessed in a three-chamber social maze at the end of stress application. Anxiety and exploratory behavior of animals were then examined, with 20 min intervals, using the open field (OF) and elevated plus maze (EPM) tests, respectively. Cisterna Magna cerebro-spinal fluid (CSF) was drained, before sacrifice, for orexin (OX) assay and trunk blood was collected to measure the plasma corticosterone (CRT). Neither the acute nor the chronic stress could affect the sociability. The acute but not chronic stress prevented the animal from sniffing the familiar caged rat in the novelty session, a response which was reversed following the blockade of both OXRs. Furthermore, acute but not chronic stress, led to increased anxiety and immobility behavior which were both impeded by blocking the orexin receptor (OXR). Conversely, OX content in CSF increased due to chronic restraint stress, an effect that was reversed by orexin blockade. Finally, elevated plasma CRT was recorded in response to both acute and chronic stresses. The observed increase in plasma CRT in chronically-stressed rats was abolished following inhibition of OXRs, however a similar effect was not seen in the acute-stress group. Our results identify hippocampal OXRs as potential candidates capable of preventing acute stress-induced impairments of social novelty and anxiety behavior, and chronic stress-induced plasma CRT and CSF orexin, changes. OXR manipulation may improve adaptation to stress pathophysiology.

Postnatal Administration of Homocysteine Induces Cerebellar Damage in Rats: Protective Effect of Folic Acid.

A widely held view suggests that homocysteine (Hcy) can contribute to neurodegeneration through promotion of oxidative stress. There is evidence that homocysteine is toxic to cerebellar Purkinje neurons in vitro; however, in vivo action of Hcy on Purkinje cell has not been investigated so far. Thus, this study was designed to evaluate the Hcy effects on neonatal rat cerebellum and cerebellar oxidative stress. We also evaluated the folic acid effects on biochemical alterations elicited by hyperhomocysteinemia (hHcy) in the cerebellum. Group I received normal saline, group II received Hcy subcutaneously twice a day at 8-h intervals (0.3-0.6 µmol/g body weight), group III received Hcy + folic acid (0.011 µmol/g body weight), and group IV received folic acid on postnatal day (PD) 4 until 25. On day 25, superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities in the cerebellum and motor cortex were assayed. Malondialdehyde (MDA) levels were also evaluated as a marker of lipid peroxidation. Rotarod and locomotor activity tests were performed in PD 25-27. Our results indicated that administration of Hcy increased plasma, cortical, and cerebellar total Hcy levels; reduced GPx activity; and induced lipid peroxidation in the cerebellum. Hcy impaired performance on the rotarod in rats. However, treatment with folic acid significantly attenuated motor coordination impairment, GPx activity reduction, the lipid peroxidation process, and significantly reduced plasma total Hcy levels. Histological analysis indicated that Hcy could decrease Purkinje cell count and folic acid prevented this toxic effect. We conclude that Hcy can induce neurotoxicity and folic acid has neuroprotective effects against cerebellar Hcy toxicity.

Conditioned Medium Protects Dopaminergic Neurons in Parkinsonian Rats.

OBJECTIVE: Adipose derived stem cells (ASCs) secrete numerous neurotrophic factors and cytokines in conditioned medium (CM), which protect neurons by its antioxidative and trophic effects. This research assesses the neuroprotective effect of ASCCM on neurotrophins genes expressions and tyrosine hydroxylase positive (TH+) cell density in male Wistar rats lesioned by 6-hydroxydopamine (6-OHDA). MATERIALS AND METHODS: In this experimental study, the groups consisted of lesioned and sham rats with unilateral injections of 20 µg of 6-OHDA neurotoxin and phosphate buffered saline (PBS) into the striatum, respectively. Another groups received intravenous injections of 3×106 cells (ASCs group), 500 µl of CM (ASC-CM group) or medium [α-minimal essential medium (α-MEM) group)]. All rats underwent evaluations with the rotarod and apomorphine-induced rotation tests at 2, 4, 6, and 8 weeks post-injection. At 8 weeks we sacrificed some of the animals for real-time polymerase chain reaction (PCR) analysis, and evaluation of TH+ cell counts. RESULTS: We observed a significant decrease in contralateral turns to the lesions in the ASCs and ASC-CM groups compared to the neurotoxin lesioned or α-MEM groups at 8 weeks post transplantation. Cell and CM- injected rats showed a significant increase of staying on the rotarod compared to the lesion or α-MEM groups. Cell and CM-treated rats showed significant increases in the NGF and NT3 genes, respectively, compared with the lesion group. Both treated groups showed significant increases in BDNF gene expression and TH+ cell density. CONCLUSION: The results suggested that ASCs and ASC-CM protected dopaminergic neurons through the expressions of neurotrophin genes.

Posterior hypothalamus glutamate infusion decreases pentylenetetrazol-induced seizures of male rats through hippocampal histamine increase.

OBJECTIVES: Seizures are epileptic manifestations that are intrinsically modulated through different neurotransmitters and receptor systems. Although glutamate increases excitation and hence seizures, it activates other systems which could potentially terminate seizures. Histamine originates from neurons of the posterior hypothalamus (PH) and can mediate anticonvulsant properties, but the effect of local PH glutamate on hippocampal histamine content is unknown. Therefore, in this study, the effect of PH glutamate and the involvement of hippocampal histamine in pentylenetetrazol (PTZ) induced seizure activity was studied. MATERIALS AND METHODS: OX2R antagonist (TCS OX2 29, 40nmol/1µl, intra-PH), AMPA/Kainate receptor antagonist (CNQX, 3mM, intra-PH) and glutamate (1mM) were injected bilaterally into PH using stereotaxic surgery. The intravenous PTZ infusion model was used to generate behavioral convulsions and the amount of hippocampal histamine content was then measured using a biochemical method. RESULTS: Administration of glutamate into PH decreased both seizure stage and the duration of tonic-clonic convulsion (TCC) with increasing TCC latency and hippocampal histamine content. Blocking OX2Rs alone or coinhibition of OX2Rs and AMPA/kainate receptors reversed these effects by increasing both seizure stage and TCC duration, and by decreasing both latency and consequent histamine content. CONCLUSIONS: Our findings suggest that glutamate administration into PH may control seizures (stages and duration) through increasing the hippocampal histamine content.