Search published articles


Showing 47 results for Hippocampus

Farshad Alizadeh Mansouri, Fereshteh Motamedi, Fereshteh Fathollahi, Nafiseh Atapour, Saeed Semnanian,
Volume 1, Issue 1 (4-1997)
Abstract

The effects of chronic morphine administration on the development of long-term potentiation (LTP) were investigated at the Schaffer collateral-CA1 pyramidal cell synapses of the rat hippocampal slices using primed-bursts tetanic stimulation. Significant enhancement of orthodromic population spike (OPS) was found for all stimulus intensities after tetanic stimulation. OPS enhancement was greatest when tested with low to mid-range stimulus intensities (25, 50 and 100 µA). There was also significant decrease in OPS delay. These responses were similar in slices from both control and morphine dependent rats. At all delivered stimulus intensities, the amount of LTP of OPS in slices from dependent rats was larger than that of control slices. However, these differences in LTP of OPS were significant at low stimulus intensities. These findings suggest that chronic morphine administration had induced changes in CA1 neurocircuitry which modulated synaptic plasticity during high frequency stimulation and appeared as augmented LTP and also inhibition of LTP decay.

Volume 1, Issue 1 (4-1997)
Abstract

  TBS (Theta Burst Stimulation) and PBs (Primed Bursts) are among effective tetanic stimulations for induction of LTP in hippocampus. Recent studies have indicated that TBS is effective in LTP induction in layer III synapses of neocortex, only if applied to layer IV. However, the possibility of neocortical LTP induction using PBs, has not yet been investigated. Sensory deprivation greatly influences the development of neocortex. Based on the effect of sensory deprivation on synaptic plasticity of developing neocortex, the induction of LTP by PBs in visual cortical slices of control and dark-reared rats, was studied. Results obtained show that application of PBs to layer IV, could effectively induce LTP. Field potential recordings consisted of two components pEPSPl and pEPSP2. In most cases PBs lead to selective potentiation of pEPSP2. Visual deprivation increased the incidence of LTP of pEPSP2 and also increased the incidence of LTD of pEPSP2. These findings show that PBs could be used as an effective tetanic stimulation to study the synaptic plasticity in neocortex. The effects of visual deprivation on LTP/LTD are consistent with its role on the development of NMDA system in neocortex.


Mirnajafizadeh, Pourgholami, Fathollahi, Behzadi,
Volume 2, Issue 2 (11-1998)
Abstract

  In this study, the effect of an experimentally increased excitability in hippocampal neurons, via hippocampal kindling, on amygdala kindling rate was investigated in rats. Animals were divided into 4 groups. In all groups, except group 2, tripolar electrodes were implanted in the amygdala and CAI region of the dorsal hippocampus. Group 2 animals were only implanted with tripolar electrodes in the amygdala. In group 1, the rats were kindled one week after surgery, first from the hippocampus, then by amygdala stimulation the next day. In groups 2 and 3, rats were kindled one week after surgery from the amygdala. Group 4 animals had a recovery period of one week plus 32 days, which was the mean of the hippocampal kindling rate in group 1, and then they were kindled from the amygdala. In group 1, the amygdala kindling rate (n number of stimulation trials that must be administered before the stage 5 motor convulsion is triggered) was significantly facilitated and seizure at day n/2 during amygdala kindling was significantly increased. There was also a significant positive correlation between hippocampal and amygdala kindling rates. Results obtained in the present study show that an increase in hippocampal excitability in group 1 could facilitate kindling from the amygdala. Thus it may be suggested that the hippocampus has an important role in the development and propagation of seizures from the amygdala.

  


Yagoob Fathollahi, Batool Rahmati, Saeed Semnanian, Mohammad Reza Vaez Mahdavi, Mahshid Shafizadeh,
Volume 7, Issue 1 (4-2003)
Abstract

The effect of ketamine (1-100 µM), which has NMDA receptor antagonist properties, on synaptic transmission and long-term potentiation (LTP) in CAl area of rat hippocampus was examined in vitro. Field potentials were recorded in pyramidal cell layer following Schaffer collateral stimulation. Primed-burst stimulation (PEs) was used for induction of LTP. The amplitude of population spiks (PS) was used as a measure of LTP induction. The results showed that ketamine (1-100 µM) affected baseline synaptic transmission in a concentration-dependent pattern. Furthennore, ketamine application at a high concentration (50-100 µM) for a period of 20-30 min markedly blocked the induction of LTP, whereas lower concentrations of ketamine (1-10 µM) failed to block LTP. However, ketamine at a concentration of 20 µM affected NMDA-mediated LTP induction in a different pattern. It is concluded that the effect of ketamine on baseline synaptic transmission and LTP induced by a l00 Hz PBs depends on ketamine concentration.
Moazedi, Hovayda, Rasekh,
Volume 7, Issue 1 (4-2003)
Abstract

Estrogen has a widespread and complex influence on brain capabilities such as learning and memory. On the other hand, hippocampus as one of the main brain structures has an important role in spatial information processing. There is some evidence on the existence of estrogen receptors in the hippocampal CA1 area. So, in this study the effect of intrahippocampal injection of estradiol benzoate on spatial learning and memory were investigated in intact and castrated adult male NMRI rats The animals were randomly divided into eight groups and bilaterally cannulated (n=7). The intact and castrated control groups (no injection) were trained in Y-maze. The castrated and intact rats received sesame oil vehicle, sham physiological saline and estradiol. Test groups received bilaterally 0.5 µl of sesame oil, 0.5 µl of physiological saline, and 1 µg/0.5 µl of estradiol benzoate respectively into the CA1 region of hippocampus immediately before training. Then, each rat was trained in 30 trials every day for a total of 5 days with Y-maze. After one month, all of the groups were again tested for memory performance. Statistical analysis of data showed that estradiol increases spatial learning in castrated and intact groups. There was also no significant difference between castrated and intact groups regarding memory performance. In conclusion, it seems that estradiol increases spatial learning task through an interaction with cholinergic system an enhancement of synaptic plasticity in CA1 region.

Volume 10, Issue 0 (9-2006)
Abstract


Fariba Zafari, Masome Sabetkasaei, Yousef Sadeghi, Mohammad Mohammad-Zade, Fateme Deljo,
Volume 11, Issue 4 (1-2008)
Abstract

Introduction: The claustrum interconnects with the allocortical and neocortical regions and also projects to the hippocampus and the amygdala. .The role of claustrum in the complex partial seizure is not clear. Thus in this study the effect of amygdala lesion on anterior claustrum kindled seizures in rat were investigated. Methods: Male Wistar rats, weighting 250-300 g, were received DC current via a bipolar electrode which is inserted in right basolateral amygdala. A tripolar electrode for stimulation and electroencephalography recording in the right anterior claustrum has been fixed. After a 10 days period of surgical recovery, animals were received kindling stimulation (60Hz, 2s, 1 ms pulse duration) daily, and kindling parameters were measured. In the control group animals did not receive DC current. In the lesion groups (2 groups) animals received DC current both before kindling stimulation and after full kindled statement respectively. Results: Our result showed that amygdala lesion, were capable of delaying claustrum kindling. The delay in kindling was due to an increase in the stimulation trials required to kindle to seizure stages. Furthermore the effect of this lesion on established kindled seizures reduced the severity of claustrum by decrease the stage 5 duration and after discharge duration. Conclusion: amygdale lesion had no effect on the expression of generalized seizures and claustrum play an important role in the propagation of epileptic seizure. Whereas the amygdala has a facilitators role in propagation claustrum kindled seizure.
Mahshid Hoseinzadeh, Iran Pouraboli, Mehdi Abbasnejad, Batool Pouraboli,
Volume 11, Issue 4 (1-2008)
Abstract

Abstract: ِIntroduction: The effect of morphine dependency on learning and spatial memory is controversial. So in this study effect of co-administeration of nitric oxide (NO) and morphine in CA3 of hippocampus on learning and spatial memory in morphine dependent rats was investigated. Methods: After anaesthetization of male rats, cannulae implanted bilaterally in CA3 of hippocampus. After recovery period (7 days), morphine dependency induced then animals divided in 6 groups that received 1μl saline (Sham), L-Arginine, L-Name and morphine individually and L-Arginine with morphine or L-Name with morphine individually. Morphine dependency was induced by subcutaneous injection of morphine(10mg/kg first day and 20mg/kg for four days). Last dose of morphine(20mg/kg) was injected daily to maintain morphine dependency during test period (5 days) in morris water maze Results: Results showed that L-Name decreased learning in morphine dependent rats although was ineffective on retention of memory. Morphine did not affect learning and spatial memory. Co-administeration of L-Arginine and morphine not only improved the effect of morphine on learning and memory but also promote the effect of L-Arginine on learning and spatial memory. Conclusion: Thus co-administeration of NO and morphine in morphine dependent rats can improve learning and spatial memory differently from using them individually.
Shirin Babri, Parham Reisi, Hojjatallah Alaei, Mohammad Reza Sharifi, Gisso Mohades,
Volume 12, Issue 1 (5-2008)
Abstract

Introduction: Previous studies indicate that exercise influences cognitive function. Nevertheless, considering that exercise in animal study can be voluntary, or forced, effects of exercise (specially forced exercise) on learning and memory abides as a matter of controversy. The present study aimed to investigate the effects of treadmill exercise on LTP in the dentate gyrus of rats. Methods: The exercise program that is used was a moderate exercise consisting of treadmill running at 17 m/min and 0-degree inclination for 40 min/day, 7 days/week, for 12 weeks. Field excitatory postsynaptic potentials (fEPSP) were recorded in dentate gyrus (DG) after stimulation (by 400 Hz titanization) of Perforant pathway. Results: The indices of responses including amplitude of population spike and slope of excitatory postsynaptic potential were significantly smaller in exercise group with respect to control group. But the stimulus-response curves in DG area measured before induction of LTP, had no significant difference between the groups. Conclusion: The present results suggest that alternative stress due to electrical shock in order to motivate the animal to run in treadmill exercise, affect synaptic transmission and impairs LTP induction in DG. Therefore, these experiments indicate that chronic treadmill exercise can decline learning and memory.
Mahmoud Aminizadeh, Mehdi Abbasnejad, Ahmad Ali Moazedi, Ahmadali Papahn,
Volume 12, Issue 1 (5-2008)
Abstract

Introduction: Previous studies have shown that vitamin A and its derivatives such as retinoid and all-trans retinoic acid have a crucial role in memory, learning and synaptic plasticity. The receptors of vitamin A are seen in different parts of the brain such as hippocampus, where vitamin A has an important role in learning. In this study, the effect of intrahippocampal (CA1) injection of all – trans retinoic acid on spatial learning was investigated in adult male rats. Methods: 49 adult male rats divided in 7 groups were used. Test groups (1 – 4) received 1μl of all – trans retinoic acid dissolved in DMSO at concentrations of 1, 2, 4 and 8 μg/μl, for 4 consecutive days, 90 minutes before training. Group 5 received DMSO and 6th and 7th groups were designated as sham operation and control (intact) group, respectively. After each injection, Morris Water Maze (MWM) was used as a method to measure learning task. Results: This study showed that all – trans retinoic acid at the concentration of 1 μg/μl improved spatial learning in Morris Water Maze (p< 0.05). Conclusion: Our findings show that all – trans retinoic acid improves spatial learning in rats via enhancing the expression of learning related proteins.
Zohreh Valizadeh, Ahmad Ali Moazedi, Gholamali Parham,
Volume 12, Issue 3 (11-2008)
Abstract

Introduction: Zinc is an essential trace element that plays an important role in synaptic plasticity and modulating the activity of CNS and involve in learning and memory. Synaptic vesicle zinc in the hippocampus area exerting modulatory effects on NMDA glutamate receptor. Method: In this experiment the effects of NMDA agonist and antagonist administration intra hippocampus on passive avoidance learning and memory in adult male rats in presence and absence of Zncl2 by step down task has been investigated. Animal divided into 10 group (n=8).Control group, second group received 0.1µg/rat NMDA in 1µlit saline for 4 days. Sham group received saline in the same volume. Forth group received 1µg/rat MK-801 in 1µlit saline 10min before training for 4 days. Sham group received saline in the same volume. Five remain groups received 30mg/kg/day zncl2 in drinking water for 2 weeks. Sixth groups only received 30mg/kg/day zncl2, but others groups (7, 8, 9, and 10) in addition consumption zncl2 received drug and saline in the same condition to 2,3,4,5 groups. Result: our experiment showed that consumption of 30mg/kg/day zncl2 impair learning and memory in adult male rats (P<0.05), while administration of NMDA improve the impairment effects on zncl2 consumption (P<0.05), but administration of MK-801 increasing the impairment effects of zncl2. Concultion: It seems that zinc impaired passive avoidance learning and memory by effects on subunits of NMDA receptor in hippocampus.
Farshad Moradpour, Nasser Naghdi, Yaghob Fathollahi,
Volume 12, Issue 3 (11-2008)
Abstract

Introduction: Sexhormones are one of most important factors in difference of learning and memory between tow sexes (male & female). High concentration of estrogen and androgen receptors and mechanism of testosterone and estrogen production in learning and memory center, especially in hippocampus show the role of this receptors, sexhormons and P450 enzymes in spatial memory. Consequently, in this study we evaluate effect of estradiol valerat and aromatase inhibitor (Anasterazole) on spatial learning and memory in Morris Water Maze. Materials and methods: Adult male rats were bilaterally connulated into CA1 region. After recovery period, control groups received DMSO 0/5µl and DMSO 0/5µl + DMSO 0/5µl. Different doses of estradiol valerat (EV) (1, 2.5, 5, 10 and 15µg / 0.5µl), anastrozole (An) (0.25, 0.5, 1µg / 0.5µl) and EV 15µg / 0.5µl +An 0.5µg / 0.5µl were microinjected all days before training. EV was injected 30-35 min before training and anastrozol was injected 25-30min before training. Result: Our results have showen EV 0.15µl / 0.5µl group increase escape latency and traveled distance. Also we have showen that anastrosole dose dependently decrease escape latency and traveled distance. Conclusion: We resulted that EV impaired acquisition of spatial learning and memory but anastrozole improved it. Anastrozole also couldn't be buffered EV – induced impairment.
Zeinab Sharifkhodaei, Nasser Naghdi, Shahrbanoo Oryan, Parichehr Yaghmaei,
Volume 12, Issue 4 (1-2009)
Abstract

Introduction: Neurohormones like testosterone and estradiol have an important role in learning and memory. The hippocampus is essentially involved in learning and memory, and is known to be a target for estradiol actions. Estrogen receptors (ERs) are highly expressed in CA1 of rat hippocampus, and mediate the effects of estrogen on learning and memory. Estradiol receptor belong to a family of transcription factors, the nuclear receptor superfamily, and has two subtypes ER and ER. The current research has been conducted to assess the effect of ER selective agonist, diarylpropionitrile (DPN), on passive avoidance of adult male rats, by using passive avoidance task.

Methods: Male adult rats were bilaterally cannulated into the CA1 area of hippocampus, and then received vehicle (dimethyl sulfoxide, DMSO) or DPN (0.2, 0.5, 1 micro-g/0.5 micro-l/side), 30 min before training on passive avoidance task.

Results: The results showed that pre-training intra-CA1 injections of DPN (0.5, 1 micro-g/0.5 micro-l/side), significantly decreased step-through latencies and increased time spent in dark on passive avoidance learning (P<0.01).

Conclusion: Our data suggest that intra-CA1 administration of DPN could impair learning and memory acquisition on passive avoidance task. 


Ali Mostafaie, Ali Pourmotabbed, Abdolrasool Khalafi, Seyed Ershad Nedaei, Hedayat Sahraei, Reza Hajihosseini,
Volume 12, Issue 4 (1-2009)
Abstract

Introduction: N-methyl-D-aspartate (NMDA) receptors play a pivotal role in the development of tolerance and physical dependence to opiates. Activation of NMDA receptors involves the induction of long term potentiation (LTP) in hippocampus. Our previous study suggested that chronic oral administration of morphine enhanced NMDA dependent LTP in the CA1 area of hippocampal slices of rats. The present study examines the expression levels of individual NMDA receptor subunits, NR1, NR2A and NR2B, in the hippocampus of morphine-dependent rats by using western blotting. Methods: Total proteins of hippocampus were extracted by Tris-HCl buffer containing anti proteases and sodium dodecyl sulfate (SDS). The extracted proteins were resolved by SDS-PAGE and transferred to polyvinylidenefloride (PVDF) membrane by tank blotting and the subunits of NMDA receptor were analyzed by immunoblotting by using specific antibodies. Results: Obtained results provide both biochemical and statistical evidence to suggest that NMDA receptor function in the hippocampus, at least in terms of expression of NR1, NR2A and NR2B protein subunits, increases in morphinedependent rats. Conclusion: Taken together, these data support several studies in the literature indicating that NMDA receptors in the hippocampus are involved in the process of opiate dependence.
Hooman Eshagh Harooni, Nasser Naghdi, Ali Haeri Rohani, Hoori Sepehri1,
Volume 13, Issue 1 (4-2009)
Abstract

Abstract: Introduction: Nitric oxide (NO) is a retrograde messenger in hippocampal synaptic plasticity which involves in learning and memory processes. Previous studies revealed that hippocampal pyramidal cells contain NO synthase (NOS) enzyme which produce NO and could be a promising target to evaluate the role of NO in brain cognitive functions. So in this study, using NOS inhibitor (L-NAME), we conducted an experiment to assess the role of NO in passive avoidance learning. Methods: For this purpose, adult male Wistar rats (200-250 gr) were bilaterally implanted into the CA1 region of hippocampus. A week after surgery animals subjected to behavioral tests. 25 min. before training, rats received different doses of L-NAME (5, 10 and 15 µg/0.5µl/side) into the CA1 of hippocampus. Retrieval tests were performed in three different stages after training as working or immediate memory (immediately after training), short-term memory (90 min. after training) and long-term memory (24 h after training). Results: Our finding showed that pre-training injection of 15 µg/0.5µl/side L-NAME significantly increased the number of step-through into dark chamber and decreased step-through latency, for immediate and short-term memory, respectively. Conclusion: These results suggested that hippocampal NOS inhibition impairs both immediate and short-term memory, but have no any significant effect on long-term memory. Thereby hippocampal NO may affect early on learning and memory in passive avoidance task.
Moslem Mohammadi, Asghar Ghasemi, Esmaeel Ghani, Ali Khoshbaten, Alireza Asgari,
Volume 13, Issue 2 (8-2009)
Abstract

Introduction: Paraoxon (the neurotoxic metabolite of organophosphorus (OP) insecticide, parathion) exerts acute toxicity by inhibition of acetylcholinesterase (AChE), leading to the accumulation of acetylcholine in cholinergic synapses and hence overstimulation of the cholinergic system. Since, reports on changes in the level of γ- amino butyric acid (GABA) during OP-induced convulsion have been controversial, in present study we used cortical and hippocampal synaptosomes from rats after paraoxon poisoning to detect changes in GABA uptake. Methods: Male Wistar rats (200-270 g) were used in this study. Animals were given a single intraperitoneal injection of corn oil (vehicle group) or one of doses of paraoxon (0.1, 0.3, or 0.7 mg/kg) and [3H]GABA uptake by cerebral cortex and hippocampal synaptosomes was measured at 30 min, 4 h, and 18 h after the exposure (n= 7 rats/group). Type of transporter involved in the uptake was also determined using β-alnine, and L-diaminobutyric acid (L-DABA), a glial and a neuronal GABA uptake inhibitor, respectively. Results: GABA uptake was significantly (p<0.001) reduced by both cerebral cortex (18-32%) and hippocampal (16-21%) synaptosomes compared with their respective control groups at all three time points after administering 0.7 of paraoxon (convulsive dose). β-alnine had no inhibitory effect on the uptake, whereas L-DABA abolished most of the transporter mediated GABA uptake. Conclusion: Since GABA uptake did not change in other two paraoxon treated groups, it may be indicating that decrement of GABA uptake is convulsion-related. The decrease in GABA uptake, presumably due to a change in the function of GABA transporters, may represent a compensatory response modulating neuronal overexcitation. Most of synaptosomal GABA uptake was blocked by L-DABA, indicating that the uptake was primarily by a neuronal GABA transporter (GAT), GAT-1.
Narges Hoseinmardi, Leila Azimi, Mohammad Javan, Naser Naghdi, Yaghoub Fathollahi,
Volume 13, Issue 2 (8-2009)
Abstract

Abstract* Introduction: Chronic morphine exposure can cause addiction and affect synaptic plasticity, but the underlying neural mechanisms of this phenomenon remain unknown. Herein we used electrophysiologic approaches in hippocampal CA1 area to examine the effect of chronic morphine administration on short-term plasticity. Methods: Experiments were carried out on hippocampal slices taken from either control animals or animals made dependent via oral chronic morphine administration. Population spikes (PSs) were recorded from stratum pyramidale of CA1 following stimulation the Schaffer collateral afferents. For examining the short-term synaptic plasticity, paired pulse stimulations with inter pulse interval (IPI) of 10, 20, 80, and 200 ms were applied and paired pulse index (PPI) was calculated. Results: Chronic morphine exposure had no effect on the baseline response. A significant increase in PPI was observed in dependent slices at 80 ms IPI as compared to the control ones. There was no significant difference in baseline response between control and dependent slices when we used long term morphine, naloxone, and both. However, long term morphine administration caused significant difference in PPI at IPI of 20 ms. This effect was eliminated in the presence of naloxone. Conclusion: These findings suggest that morphine dependence could affect short-term plasticity in hippocampal CA1 area and increase the hippocampus network excitability. Keywords: Addiction, CA1 neural networks, short-term synaptic plasticity.
Parichehr Hassanzadeh, Anna Hassanzadeh,
Volume 13, Issue 3 (11-2009)
Abstract

Introduction: Psychotropic drugs exert their effects, in part, by increasing neurotrophin levels in the brain. Nerve growth factor (NGF) protein levels after treatment with only a limited number of psychotropics have been determined. The present study was designed in order to evaluate the effects of acute and chronic administration of different psychotropic drugs on NGF protein levels in five brain regions including frontal cortex, hippocampus, amygdala, olfactory bulb, and brain stem. Methods: Adult male Sprague-Dawley rats received acute or chronic (21 days) injections of desipramine, phenelzine, fluoxetine, chlordiazepoxide (10 mg/kg, each), haloperidol (1 mg/kg), and clozapine (20 mg/kg). Twentyfour hours after the last injection, NGF protein level was quantified in the dissected brain regions by using an ELISA kit. Results: Acute administration of these drugs did not affect NGF protein levels in the brain. Chronic injections of desipramine, phenelzine, fluoxetine, haloperidol, and clozapine led to the enhancement of NGF in the frontal cortex. Desipramine, fluoxetine, phenelzine and clozapine enhanced NGF in the hippocampus. In the olfactory bulb, desipramine and fluoxetine increased NGF, whereas, phenelzine and haloperidol reduced it. NGF levels in the amygdala and brain stem were not changed by any medication. Chronic administration of chlordiazepoxide did not affect NGF protein in the brain. Conclusion: Psychotropic drugs exert dissimilar effects on NGF protein levels in the brain. This might be indicative of their therapeutic properties and differential effects on cognitive function.
Masoumeh Sabetkasaei, Amin Ataie, Abbas Haghparast, Akbar Hajizadeh Moghaddam, Ramin Ataie, Shiva Nasiraei,
Volume 13, Issue 3 (11-2009)
Abstract

Introduction: Aging is the major risk factor for neurodegenerative diseases and oxidative stress is involved in the pathophysiology of these diseases. Oxidative stress can induce neuronal damages and modulate intracellular signaling, ultimately leading to neuronal death by apoptosis or necrosis. Methods: In this study, we investigated the possible antioxidant and neuroprotective properties of the polyphenolic antioxidant compound, Curcumin against homocysteine (Hcy) neurotoxicity. Curcumin (5, 15, 45 mg/kg) was injected intraperitonealy once daily for a period of 10 days beginning 5 days prior to Hcy (0.2 μmol/μl) intracerebroventricular injection in rats. Biochemical and behavioral studies, including passive avoidance learning and locomotor activity tests were studied 24 h after the last curcumin or its vehicle injection. Also Histopathological studies and cell dencity in different regions of hippocampus was investigated. Results: Hcy could induce lipid peroxidation and increase MDA and SOA levels in rats' brain. Additionally, Hcy impaired memory retention in passive avoidance learning test. However, Curcumin treatment decreased MDA and SOA levels significantly as well as improved learning and memory in rats. Histopathological analysis also indicated that Hcy could decrease hippocampus cell count and Curcumin inhibited this toxic effect. Conclusion: These results suggest that Hcy may induce lipid peroxidation in rats' brain and decrease hippocampus cells. Also polyphenol treatment (Curcumin) has the ability to improve learning and memory deficits by protecting the nervous system against Oxidative stress. Keywords: Homocysteine, Curcumin, Lipid peroxidation, Oxidative Stress
Parvin Babaei, Leyla Jamalzadel, Keyvan Keramatee,
Volume 13, Issue 4 (1-2010)
Abstract

Introduction: S100B is a protein released from astrocytes, which controls neuroglial relationship and probably plays a role in memory and synaptic plasticity. Study of the functional relationship between astrocytes and neurons is of great importance. The present study was conducted to evaluate the effect of S100B infusion into the CA1 region of the hippocampus, on memory performance in male rats. Methods: In this study, 40 male wistar rats were used. Animals were bilaterally implanted with indwelling cannulae in the CA1 region of the hippocampus. Seven days after surgery, animals were trained in a step-down passive avoidance task (0.5 mA, 100 Hz, 5 sec). Immediately after the training, animals received 0.5 μl infusion of saline or S100B (5, 50, 500, or 5000 ng) bilaterally. Twenty four hours later step-down first latency and total time spent on platform were measured as learning and memory indices. Results: The infusion of 5 ng S100B induced a significant increase in step-down first latency (p< 0.01), and also increased the total time spent on the platform compared to the control group (p < 0.001). Surprisingly, animals which received doses of 500 and 5000 ng showed a significant decrease in both indices compared to the control group (p< 0.001). Conclusion: Our findings indicate that astrocytic S100B protein has modulatory effects on memory, in a way that in nanogram doses facilitates, but in micrograms impairs memory in passive avoidance task.

Page 1 from 3    
First
Previous
1