Folic acid attenuated learning and memory impairment via inhibition of oxidative damage and acetylcholinesterase activity in hypothyroid rats.

Hypothyroidism has been reported to be associated with cognitive decline. Considering the role of folic acid (FA) in cognitive performance, the present study was designed to investigate the effects of FA on hypothyroidism-induced cognitive impairment, oxidative damage, and alterations in acetylcholinesterase (AChE) activity in rat model of propylthiouracil (PTU)-induced hypothyroidism. In this study, PTU (0.05% in drinking water) and FA (5, 10, and 15 mg/kg, oral gavage) were administered for the rats during 7 weeks. Then, behavioral performance was tested using Morris water maze (MWM) and passive avoidance (PA) tasks. Finally, oxidative stress indicators and AChE activity were assayed in the brain tissues. The impairing effect of hypothyroidism on cognitive performance was markedly alleviated by FA especially at higher doses. In the MWM test, FA reduced escape latency and travelled distance, compared to the non-treated hypothyroid group. In the PA test, latency to enter dark chamber was significantly enhanced by FA compared to the non-treated hypothyroid group (p < 0.05-p < 0.001). Besides, FA attenuated AChE activity and malondialdehyde level but it increased activity of superoxide dismutase enzyme and total thiol content (p < 0.05-p < 0.001). In conclusion, our findings revealed that FA could improve learning and memory ability in hypothyroid rats. The observed protective effects may have been mediated through regulation of oxidative stress and AChE activity.

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.

Systemic administrations of ß-estradiol alleviate both conditioned and sensitized fear responses in an ovariectomized rat model of post-traumatic stress disorder.

Although no single widely accepted animal model of PTSD has been established to date, the single prolonged stress (SPS) animal model has been partially validated as a model for PTSD. SPS rats mimic the pathophysiological abnormalities and behavioral characteristics of PTSD, such as enhanced fear response to the traumatic cue (conditioned fear response) and hyper arousal (the sensitized fear response). In the present study we are looking at PTSD-like symptoms in rats. We examined whether Systemic administrations of ß-estradiol could alleviate PTSD-like symptoms that are induced by SPS model. In this study, electric foot shocks (two 4s, 1mA with an interval of 30s) were given to Adult ovariectomized rats 1day after SPS procedures. Additionally, ß-estradiol (45, 90, and 180µg/kg) or sesame oil (vehicle) were injected immediately after foot shock and before Tests 2 and 3. After different incubation times, one (Test 1), two (Test 2), and three (Test 3) weeks later, the conditioned or sensitized fear responses were measured (Percent of freezing during test) by re-exposing the stressed rats to the shock chamber or a neutral tone in a novel environment. Three other groups were shock, control and sham groups. Ovariectomized rats of Shock group received shocks conducted through the procedure described below on. Animals in control (Ovariectomized rats) and Sham groups (Only submitted to surgery without removal of the ovaries), neither were exposed to the SPS procedure nor received an electrical shock. Also, these three groups were tested for fear responses three times. Findings indicated that rats who received electric shock the day after SPS exhibited both enhanced conditioned and sensitized fear responses in comparison to the control group. ß-estradiol in 45µg/kg dose could reduce both types of fear responses. ß-estradiol exert an inhibitory influence on contextual fear conditioning (hippocampal-dependent) and on sensitized fear conditioning (amygdala-dependent). Single injection of this dose is enough for CFR alleviation but at least twice injections are necessary to reduce sensitized fear response. Overall our data demonstrate that multiple injections of ß-estradiol, dose dependently, could alleviate both SPS induced conditioned and sensitized fear responses, as signs of PTSD.

Intravenous Transplantation of Adipose-Derived Mesenchymal Stem Cells Promoted The Production of Dopaminergic Neurons and Improved Spatial Memory in A Rat Model of Parkinson's Disease.

OBJECTIVE: Parkinson's disease (PD) is a neurodegenerative disorder described by the dynamic decline of dopaminergic neurons in the substantia nigra pars compacta (SNpc). Stem cell transplantation is a new therapeutic strategy in the treatment of PD. The objective of the study was to assess the impact of intravenous infusion of adipose-derived mesenchymal stem cells (AD-MSCs) on memory disorder in Parkinsonian rats. MATERIALS AND METHODS: In this experimental study, male Wistar rats were randomly divided to four groups containing sham, cell treatment, control, and lesion. The cell treatment group received intravenous injection of AD-MSCs 12 days after PD induction by bilateral injection of 6-hydroxydopamine. Four weeks after lesion formation, spatial memory was examined using the Morris water maze (MWM) assessment. The rats' brains were removed and assessed by bromodeoxyuridine (BrdU), tyrosine hydroxylase (TH), and glial fibrillary acidic protein (Gfap) immunostaining. RESULTS: Statistical analyses revealed a significant addition and reduction in time spent and escape latency in the target quadrant, respectively, in the cell group as compared to the lesion group. Also, BrdU-labeled cells were present in the substantia nigra (SN). The density of TH-positive cells was significantly increased in the AD-MSCs transplantation group as compared to the lesion group, and the density of astrocytes significantly diminished in the AD-MSCs transplantation group as compared to the lesion group. CONCLUSION: It appears that AD-MSCs treatment for Parkinson's could decrease the density of astrocytes and promote the density of TH-positive neurons. It appears that AD-MSCs could improve spatial memory impairment in PD.

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.

Pulsed electromagnetic fields accelerate wound healing in the skin of diabetic rats.

Delayed wound healing is a common complication in diabetes mellitus. From this point of view, the main purpose of the present study is to investigate the effect of extremely low frequency pulsed electromagnetic fields (ELF PEMFs) on skin wound healing in diabetic rats. In this study, diabetes was induced in male Wistar rats via a single subcutaneous injection of 65 mg/kg streptozocin (freshly dissolved in sterile saline, 0.9%). One month after the induction of diabetes, a full-thickness dermal incision (35 mm length) was made on the right side of the paravertebral region. The wound was exposed to ELF PEMF (20 Hz, 4 ms, 8 mT) for 1 h per day. Wound healing was evaluated by measuring surface area, percentage of healing, duration of healing, and wound tensile strength. Obtained results showed that the duration of wound healing in diabetic rats in comparison with the control group was significantly increased. In contrast, the rate of healing in diabetic rats receiving PEMF was significantly greater than in the diabetic control group. The wound tensile strength also was significantly greater than the control animals. In addition, the duration of wound healing in the control group receiving PEMF was less than the sham group. Based on the above-mentioned results we concluded that this study provides some evidence to support the use of ELF PEMFs to accelerate diabetic wound healing. Further research is needed to determine the PEMF mechanisms in acceleration of wound healing in diabetic rats.

Investigating the role of the amygdala orexin receptor 1 in memory acquisition and extinction in a rat model of PTSD.

Understanding the mechanisms underlying memory is essential for the treatment of post-traumatic stress disorder (PTSD). Orexin, as a lateral hypothalamic (LH) neuropeptide, interferes with the stages of memory, primarily through the orexin receptor1 (Orx1R). The aim of this study was to evaluate the effects of amygdala Orx1R in the acquisition and extinction processes of PTSD modeled in animals. In three experiments, rats were divided into three groups: control (Naïve), shock (receiving a foot shock), and PTSD (experiencing Single prolonged stress (SPS) method). The first experiment aimed to evaluate LH activity in PTSD modeled rats. The second and third experiments aimed to evaluate the effects of Orx1R in the acquisition and extinction of fear memory in PTSD modeled animals. SB334867 (SB) or its solvent was microinjected into the amygdala and the rats were subjected to conditioning thereafter. In the second group, we used a single injection after conditioning. In the third group, we used three consecutive injections (one after each memory test). Some behaviors and Orx1R expression were evaluated. The freezing response was significantly longer in the PTSD group than on the control. Similarly, anxiety and sensitized fear were also intensified. CFos expression levels in LH was higher in the PTSD group. Inhibition of Orx1R in the amygdala significantly decreased memory acquisition, diminished anxiety, and decreased the sensitized fear in the SB group. Applying SB to the amygdala after each fear memory test significantly decreased freezing. Expression of Orx1R was significantly higher following fear conditioning. These results indicate a likely involvement of the orexin and amygdalar Orx1R in memory acquisition and in extinction of PTSD.

Post-training administration of corticosterone enhances consolidation of contextual fear memory and hippocampal long-term potentiation in rats.

This study was designed to examine the effect of corticosterone on consolidation of contextual fear memory and hippocampal long-term potentiation (LTP) in rats. In Experiment 1, dose-response effects of corticosterone on consolidation of contextual fear memory were determined. Immediately after training in contextual fear conditioning task, rats received different doses of corticosterone. Testing 24 h later, it revealed that corticosterone enhanced memory consolidation in an inverted U shape as evidenced in increased freezing behavior of corticosterone-treated animals. The most effective dose was 3 mg/kg. In Experiment 2, LTP was examined in rats whose memory consolidation has been enhanced with corticosterone. The rats were trained as the above and received corticosterone (3 mg/kg) immediately after training. Immediately or up to one day after retention test, rats were anesthetized with urethane for LTP experiments. For LTP induction, three episodes of high frequency stimuli, 30 s apart, were delivered to the perforant path, each consisting of 10 stimuli at 250 Hz. LTP was assessed by measuring the increase in the initial slope of the population excitatory post-synaptic potentials and the amplitude of the population spikes. Data indicated that animals whose memory has been enhanced by corticosterone, also displayed enhanced hippocampal LTP. The above findings suggest that glucocorticoids may enhance contextual fear memory consolidation via enhancing hippocampal LTP.

Pulsed electromagnetic field attenuated PTSD-induced failure of conditioned fear extinction.

OBJECTIVES: This study aimed to determine whether exposure to pulsed electromagnetic field (PEMF) can impair behavioral failure as induced by PTSD, and also its possible effects on hippocampal neurogenesis. PEMF was used as a non-invasive therapeutic tool in psychiatry. MATERIALS AND METHODS: Male rats were divided into Control-Sham exposed, Control-PEMF, PTSD-Sham exposed, and PTSD-PEMF groups. PTSD rats were conducted by the single prolonged stress procedures and then conditioned by the contextual fear conditioning apparatus. Control rats were only conditioned. Experimental rats were submitted to daily PEMF (7 mT, 30 Hz for 16 min/day, 14 days). Sham-exposed groups were submitted to the turned off PEMF apparatus. Fear extinction, sensitized fear and anxiety, cell density in the hippocampus, and proliferation and survival rate of BrdU-labeled cells were evaluated. RESULTS: Freezing of PTSD-PEMF rats was significantly lower than PTSD-Sham exposed. In the PTSD-PEMF, center and total crossing in open field, also the percentage of open arms entry and time in the elevated plus maze, significantly increased as compared with PTSD-Sham exposed (P<0.001). Numbers of CA1, CA3, and DG cells in PTSD-PEMF and Control-Sham exposed groups were significantly more than PTSD-Sham exposed (P<0.001). There were more BrdU-positive cells in the DG of the PTSD-PEMF as compared with the PTSD-Sham exposed. Qualitative observations showed an increased number of surviving BrdU-positive cells in the PTSD-PEMF as compared with PTSD-Sham exposed. CONCLUSION: Using 14-day PEM attenuates the PTSD-induced failure of conditioned fear extinction and exaggerated sensitized fear, and this might be related to the neuroprotective effects of magnetic fields on the hippocampus.

Multiple spectroscopic studies of the interaction between a quaternary ammonium-based cationic Gemini surfactant (as a carrier) and human erythropoietin.

Erythropoietin (EPO) is a hematopoietic growth factor. This substance, as a strong cell protector, can increase cell maintenance during different damages of central nervous system. Since the brain-blood barrier prevents the entrance of large proteins similar to EPO into the brain, its systemic delivery gets limited. The aim of this study was to find an alternative approach for EPO delivery into the brain to skip the blood-brain barrier prevention. So, a new quaternary ammonium-based cationic Gemini surfactant has been used to study the interaction of the cationic Gemini surfactant (as a carrier) with EPO using various spectroscopic techniques of (fluorescence and circular dichroism (CD)) and thermal denaturation. Fluorescence spectroscopy studies show the formation of Gemini-EPO complex and also static quenching of protein upon this interaction. The binding parameters of number of binding sites, binding affinity, Gibbs free energy, enthalpy, and entropy were calculated according to fluorescence quenching studies. Also, CD results have further represented that the content of regular secondary structure of EPO did not show any significant alterations by increasing the Gemini concentration. Finally, thermal denaturation behavior of EPO results indicates decreasing the thermal stability of protein in the presence of Gemini. In conclusion, the obtained results proposed that Gemini as a cationic surfactant can bind to EPO without any significant diverse effects on the structure of this drug (EPO) which can be considered as a candidate for EPO delivery in future.

Maternal administration of melatonin prevents spatial learning and memory deficits induced by developmental ethanol and lead co-exposure.

Melatonin is a radical scavenger with the ability to remove reactive oxidant species. There is report that co-exposure to lead and ethanol during developmental stages induces learning and memory deficits and oxidative stress. Here, we studied the effect of melatonin, with strong antioxidant properties, on memory deficits induced by lead and ethanol co-exposure and oxidative stress in hippocampus. Pregnant rats in lead and ethanol co-exposure group received lead acetate of 0.2% in distilled drinking water and ethanol (4g/kg) by oral gavages once daily from the 5th day of gestation until weaning. Rats received 10mg/kg melatonin by oral gavages. On postnatal days (PD) 30, rats trained with six trials per day for 6 consecutive days in the water maze. On day 37, a probe test was done and oxidative stress markers in the hippocampus were evaluated. Results demonstrated lead and ethanol co-exposed rats exhibited higher escape latency during training trials and reduced time spent in target quadrant, higher escape location latency in probe trial test and had significantly higher malondialdehyde (MDA) levels, significantly lower superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) activities in the hippocampus. Melatonin treatment could improve memory deficits, antioxidants activity and reduced MDA levels in the hippocampus. We conclude, co-exposure to lead and ethanol impair memory and melatonin can prevent from it by oxidative stress modulation.

Effect of WIN55-212-2 and Consequences of Extinction Training on Conditioned Fear Memory in PTSD Male Rats.

INTRODUCTION: This study investigates the effects of cannabinoid agonist WIN55-212-2 on acquisition and consolidation phases of the fear memory extinction and also on anxiety and motor activity. METHODS: In this study, we used SPS & S model to induce post-traumatic stress disorder. One week after SPS, to establish a conditioned fear memory, rats received an electric foot shock within shock chamber. After 24 h, for extinction training, the rats were placed back to the chamber for 9 min, without receiving any shock. In 3 consecutive days and on days 17, 24 and 37, extinction tests were carried out and the freezing behavior was evaluated. Thirty minutes before the first three extinction tests, animals received IP injections of WIN or vehicle. Anxiety-like behavior examined with elevated plus-maze and motor activity with open field, 32 days after conditioning. RESULTS: Exaggerated and continued conditioned fear memory observed in SPS & S group compared with shock group. IP injection of a 0.25 mg/kg dose of WIN before extinction training led to reducing fear responses in animals. CONCLUSION: IP injection of WIN increased acquisition or consolidation of fear memory extinction. SPS & S caused anxiety and this effect improved by the agonist (0.25 mg/kg).

Evaluating the role of astrocytes on ß-estradiol effect on seizures of Pilocarpine epileptic model.

Epilepsy with periodic and unpredictable seizures is associated with hippocampal glutamate toxicity and tissue reorganization. Astrocytes play an important role in mediating the neuroprotective effects of estradiol and reducing seizure severity. Accordingly, the protective effects of low and high doses of estradiol on behavioral, astrocytic involvement and neuronal survival aspects of Pilocarpine-induced epilepsy were investigated. Lithium- Pilocarpine (30mg/kg) model was used to provoke epilepsy. Βeta-estradiol (2,40µg/µl) was injected subcutaneously from 48 before to 48h after seizure induction. Behavioral convulsions were then monitored and recorded on the day of induction. Four weeks later, glutamine synthetase (GS) activity and the astrocyte transporter GLT-1 expression of the hippocampus were measured. Moreover, hippocampal glutamate and GABA were evaluated to study excitability changes. Finally, neuronal counting in the hippocampus was also performed using Nissl staining. The latency for generalized clonic (GC) convulsions significantly increased while the rate of GC and death significantly reduced due to ß-estradiol treatment. GS activity and GLT-1 expression increased in the groups receiving the high dose of ß-estradiol and Pilocarpine. Furthermore, the amount of both GABA and glutamate content decreased due to high dose of estradiol, while only GABA increased in Pilocarpine treated rats. Finally, administration of ß-estradiol with low and high doses increased and improved the density of nerve cells. It is concluded that chronic administration ß-estradiol has anticonvulsant and neuroprotective properties which are plausibly linked to astrocytic activity.

The combined effects of developmental lead and ethanol exposure on hippocampus dependent spatial learning and memory in rats: Role of oxidative stress.

Either developmental lead or ethanol exposure can impair learning and memory via induction of oxidative stress, which results in neuronal damage. we examined the effect of combined exposure with lead and ethanol on spatial learning and memory in offspring and oxidative stress in hippocampus. Rats were exposed to lead (0.2% in drinking water) or ethanol (4 g/kg) either individually or in combination in 5th day gestation through weaning. On postnatal days (PD) 30, rats were trained with six trials per day for 6 consecutive days in the water maze. On day 37, a probe test was done. Also, oxidative stress markers in the hippocampus were also evaluated. Results demonstrated that lead + ethanol co-exposed rats exhibited higher escape latency during training trials and reduced time spent in target quadrant, higher escape location latency and average proximity in probe trial test. There was significant decrease in superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) activities and increase of malondialdehyde (MDA) levels in hippocampus of animals co-exposed to lead and ethanol compared with their individual exposures. We suggest that maternal consumption of ethanol during lead exposure has pronounced detrimental effects on memory, which may be mediated by oxidative stress.

Lateral hypothalamus orexinergic system modulates the stress effect on pentylenetetrazol induced seizures through corticotropin releasing hormone receptor type 1.

Stress is a trigger factor for seizure initiation which activates hypothalamic pituitary adrenal (HPA) axis as well other brain areas. In this respect, corticotropin releasing hormone (CRH) and lateral hypothalamus (LH) orexinergic system are involved in seizure occurrence. In this study, we investigated the role of LH area and orexin expression in (mediation of) stress effect on pentylenetetrazol (PTZ) -induced seizures with hippocampal involvement. Two mild foot shock stresses were applied to intact and adrenalectomized animals; with or without CRHr1 blocking (NBI 27914) in the LH area. Then, changes in orexin production were evaluated by RT-PCR. Intravenous PTZ infusion (25 mg/ml) -induced convulsions were scored upon modified Racine scale. Finally, hippocampal glutamate and GABA were evaluated to study excitability changes. We demonstrated that the duration and severity of convulsions in stress-induced as well as adrenalectomized group were increased. Plasma corticosterone (CRT) level and orexin mRNA expression were built up in the stress and/or seizure groups. Furthermore, glutamate and GABA content was increased and decreased respectively due to stress and seizures. In contrast, rats receiving CRHr1 inhibitor showed reduced severity and duration of seizures, increased GABA, decreased glutamate and corticosterone and also orexin mRNA compared to the inhibitor free rats. Stress and adrenalectomy induced augmenting effect on seizure severity and duration and the subsequent reduction due to CRHr1 blocking with parallel orexin mRNA changes, indicated the likely involvement of CRH1r induced orexin expression of the LH in gating stress effect on convulsions.

Pre-treatment by Rosemary Extract or Cell Transplantation Improves Memory Deficits of Parkinson's Disease: When Tradition Meets the Future

ABSTRACT The therapeutic effect of adipose tissue-derived stem cells (ADSCs) or RE on hippocampal neurogenesis and memory in Parkinsonian rats were investigated. Male rats were lesioned by bilateral intra-nigral injections of 6-OHDA and divided into six groups: 1. Lesion 2 and 3: RE and water groups were lesioned rats pretreated with RE or water, from 2weeks before neurotoxin injection and treated once a day for 8weeks post lesion. 4&5: Cell and α-MEM (α-minimal essential médium) received intravenous injection of BrdU-labeled ADSCs or medium, respectively from 10days post lesion until 8weeks later. 6: Sham was injected by saline instead of neurotoxin. Memory was assessed using Morris water Maze (MWM), one week before and at 1, 4 and 8weeks post 6-OHDA lesion. After the last probe, the animals were sacrificed and brain tissue obtained. Paraffin sections were stained using cresyl violet, anti-BrdU (Bromodeoxyuridine / 5-bromo-2'-deoxyuridine), anti-GFAP (Glial fibrillary acidic protein) and anti-TH antibodies. There was a significant difference of time spent in the target quadrant between groups during probe trial at 4 and 8 weeks' post- lesion. Cell and RE groups spent a significantly longer period in the target quadrant and had lower latency as compared with lesion. Treated groups have a significantly higher neuronal density in hippocampus compared to water, α-MEM and lesion groups. BrdU positive cells were presented in lesioned sites. The GFAP (Glial fibrillary acidic protein) positive cells were reduced in treated and sham groups compared to the water, α-MEM and lesion groups. Oral administration of RE (Rosemary extract) or ADSCs injection could improve memory deficit in the Parkinsonian rat by neuroprotection.

Prenatal stress decreases spatial learning and memory retrieval of the adult male offspring of rats.

INTRODUCTION: Early life or prenatal stress induces many lifelong, mostly cognitive, homeostatic alterations in the behavior of the offspring. PURPOSE: We investigated the effect of heterogeneous sequential stress (HSS) at three separate periods, before and during the first and second half of pregnancies on spatial learning and memory retrieval of adult male offspring. METHOD: HSS is composed of several stressors, each in a day, during nine consecutive days including; restraint, swimming, isolation, and water and food deprivation on Wistar rats. The offspring were studied in a Morris water maze (MWM) apparatus to explore the latency, distance, proximity and target to opposite area as measures of learning and memory. Serum corticosterone was measured as a criterion of stress application. RESULTS: HSS increased blood corticosterone in dams of PS2 (Pregnancy Stress second half), and also in adult male offspring from BPS (Before Pregnancy Stress) and PS1 (Pregnancy Stress first half) groups. The weight of the offspring decreased in the PS1 and PS2 groups. While distance traveled and latency to locate the hidden platform were increased in BPS and PS1 acquisition trials, swimming speed was unchanged during the acquisition and retrieval tests. Moreover, time to platform location was increased in BPS and PS1 during retention tests. While control rats spent more time in the target quadrant, stressed animals spent a longer duration in the opposite quadrant. Furthermore, proximity measure was increased in all stress treated rats. CONCLUSION: It is concluded that prenatal stress, around the beginning of the pregnancy, increases corticosterone in adult male offspring, which might be the basis for spatial learning and memory retrieval deficits in this study.

Unilateral Hypothalamus Inactivation Prevents PTZ Kindling Development through Hippocampal Orexin Receptor 1 Modulation.

INTRODUCTION: Epilepsy is a neural disorder in which abnormal plastic changes during short and long term periods lead to increased excitability of brain tissue. Kindling is an animal model of epileptogenesis which results in changes of synaptic plasticity due to repetitive electrical or chemical sub-convulsive stimulations of the brain. Lateral hypothalamus, as the main niche of orexin neurons with extensive projections, is involved in sleep and wakefulness and so it affects the excitability of the brain. Therefore, we investigated whether lateral hypothalamic area (LHA) inactivation or orexin-A receptor blocking could change convulsive behavior of acute and kindled PTZ treated animals and if glutamate has a role in this regard. METHODS: Kindling was induced by 40 mg/kg PTZ, every 48 hours up to 13 injections to each rat. Three consecutive stages 4 or 5 of convulsive behavior were used to ensure kindling. Lidocaine was injected stereotaxically to inactivate LHA, unilaterally. SB334867 used for orexin receptor 1 (OX1R) blocking administered in CSF. RESULTS: We demonstrated that LHA inactivation prevented PTZ kindling and hence, excitability evolution. Hippocampal glutamate content was decreased due to LHA inactivation, OX1R antagonist infusion, lidocaine injection and kindled groups. In accordance, OX1R antagonist (SB334867) and lidocaine injection decreased PTZ single dose induced convulsive behavior. While orexin-A i.c.v. infusion increased hippocampal glutamate content, it did not change PTZ induced convulsive intensity. DISCUSSION: It is concluded that LHA inactivation prevented kindling development probably through orexin receptor antagonism. CSF orexin probably acts as an inhibitory step on convulsive intensity through another unknown process.

Stress during first pregnancy increases seizure threshold in adult male offspring.

OBJECTIVE(S): Stress induces many homeostatic aberrations which are followed by lifelong allostatic responses. Epilepsy is developed or influenced by different environmental factors, i.e. prenatal stress which makes many contradictory developmental changes in seizure threshold and intensity. We investigated the potential seizure response of the rat offspring to prenatal stress; the stress which was applied to their mothers. MATERIALS AND METHODS: Nine day heterogeneous sequential stress (HSS) model was used before and during the first and before the second pregnancy. The kindling was induced using 13 IP injections of pentylenetetrazol (PTZ) every 48 hr to adult male Wistar rat's offspring. RESULTS: The results of the present study demonstrated that, before pregnancy stress decreased the rate of kindling (P<0.05) in the offspring, while stress which was applied during pregnancy completely prevented kindling (P <0.001). Further, their convulsive latency was increased and tonic clonic seizure duration was decreased. In contrast, previous pregnancy and between pregnancies stress could not change kindling process. Although maternal separation stress did not change kindling development, it could increase convulsive intensities by elongating the duration of seizures (P<0.05) and reducing convulsion latency (P <0.05). CONCLUSION: It is concluded that stress detrimental effects could be prevented by stress which was applied around first pregnancy; however this beneficial effect is weakened by before second pregnancy stress.

Riluzole Ameliorates Harmaline-induced Tremor in Rat.

INTRODUCTION: Excessive olivo-cerebellar burst-firing occurs during harmaline-induced tremor. We hypothesized that antiglutamatergic agents would suppress harmaline tremor. From this point of view, the aim of the present study was to investigate the effects of riluzole on harmaline-induced tremor in rat. METHODS: Four groups of Wistar rats weighing 80-100 g were injected with harmaline (30 mg/ kg i.p.) for inducing experimental tremors. The rats in group 1 served as control, whereas the animals in groups 2, 3 and 4 were also given riluzole intraperitonealy at doses of 2, 4 and 8 mg/ kg 30 min before and 90 min after harmaline administration. The onset latency, intensity and duration of tremor were recorded. RESULTS: The results of this study demonstrated that riluzole could significantly increase latency period, and reduce duration and intensity of tremor. DISCUSSION: It is concluded that pretreatment of riluzole can ameliorate harmaline-induced tremor in rats.