spatial memory

Neurodegenerative diseases such as Alzheimer's disease are the most common cause of memory impairment worldwide. No effective drug treatment has been found to improve the memory deficit and quality of life of these patients. Considering the effects of MPL on improving memory in Alzheimer's disease and hippocampal ischemia, this study investigated the effect of monophosphoryl lipid A (MPL) on the spatial memory of rats.

This study was conducted on 48 adult male Wistar rats (45-day-old) weighing 250-270 grams, which were randomly divided into two groups of “7 days” and “28 days”. Each group was divided into three subgroups (n = 8) including control, sham, and drug. The spatial learning and memory were assessed by the Morris water maze. Animals were trained to find the hidden platform in the maze for five days and 4 sessions every day. The drug was injected into the lateral cerebral ventricle at a dose of 1 µg per 5 µL per rat, 20 min after surgery. The time spent and the distance traveled in the target quadrant were assessed on the seventh and twenty-eighth days after the last day of learning.

No significant difference was found between the groups in the time spent and distance traveled in the target quadrant during the learning phase. Furthermore, there was no significant difference between groups in memory recall at both 7 days and 28 days after the training period (p > 0.05).

In our study, MPL 1 µg/5 µL/rat did not affect the spatial memory of rats.
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Pam3cys is a weak agonist of toll-like receptors type 1 and 2 and is able to inhibit learning and memory impairment in an animal model of Alzheimer's disease by inhibiting the secretion of inflammatory cytokines and increasing the secretion of anti-inflammatory cytokines. This arrangement is effective in improving memory performance. Considering the improving effect of Pam3cys on learning and memory impairment of Alzheimer's disease in an animal model, in this study, the effect of Pam3cys drug alone on the spatial memory of rats was investigated

In this experimental study, 48 male Wistar rats (age, 45-days old; weight, 220-270 g) were randomly divided into six groups (n = 8) as follows: There were two control groups of 7 and 28 days, two sham groups of 7 and 28 days, and two drug groups of 7 and 28 days. The spatial memory learning process of all mice was done using the Morris water maze for five days and four training sessions every day to find the hidden platform. At the last day of the learning period, the drug was injected intraventricularly with phosphate buffer (sham group) or Pam3cys (1 μg/5μl per mouse). 7 and 28 days after the injection, the memory of the rats was measured by measuring the time, speed and distance traveled in the target quarter of the maze.

In the learning phase, there was no significant difference between the groups in terms of the time spent and the distance traveled in the target quarter of the circle. At 7 and 28 days after the learning period, there was no significant difference between the groups in terms of memory recall between the group of animals that received Pam3cys and the group of control animals as well as sham animals without receiving the drug (p > 0.05).

Pam3cys with the dose used in this study has no effect on the spatial memory performance of rats in the short and long term. Also, due to the lack of effect on healthy rats, it can be used as a safe medicine in disease conditions.

Alzheimer's disease (AD) is a neurodegenerative disorder with severe cognitive impairments. Taking into account the role of folic acid on improving cognitive functions in some disease models, the present study aimed to examine the effect of folic acid on spatial learning and memory impairment induced by bilateral electrical lesion of nucleus basalis magnocellularis (NBM) in Alzheimer’s disease model of adult male rats.

In this experimental study, 49 adult male Wistar rats were randomly divided into seven groups: Negative control, NBM lesion (bilateral electric lesion of NBM), sham lesion (electrode entry into NBM without induction of electric current), vehicle (lesion+saline), and lesion+folic acid (FA 5, 10, 15 mg/kg). In the treated groups, intraperitoneal injection of folic acid or saline was performed for one week, 30 minutes after the NBM lesion. Then, they were trained for five days by Y-shaped maze. Twenty-five days after the training, a memory recall test was performed to evaluate long-term memory.

NBM bilateral lesion decreased learning and spatial memory compared to the negative and sham control groups (P˂0.001). There was a significant increase in learning and spatial memory in the lesion+FA 10 mg/kg (p<0.05) and lesion+FA 15 mg/kg (P<0.01) groups compared to the lesion group.

The results of this study show that folic acid improves learning and spatial memory in Alzheimer's disease models with bilateral electrical lesions of NBM in adult male rats.

Chronic fatigue caused by intense exercise can negatively affect cognitive function. Brain-Derived Neurotrophic Factor (BDNF) is essential for the processes of memory formation and learning; however, its influence on fatigue remains inadequately understood. The objective of this study was to examine the impact of intense aerobic exercise (conducted until exhaustion) on hippocampal BDNF levels, as well as on the performance of spatial and avoidance memory in male Wistar rats.

This experimental study was conducted with 16 male Wistar rats randomly divided into two groups: control (n=8) and exercise (n=8). The aerobic exercise was conducted on a treadmill over a period of 8 weeks, with three sessions each week. The intensity was maintained at 65-90% of the maximum speed required to achieve VO₂max, continuing until the rats reached a state of exhaustion during each session. At the end of the experiment, changes in BDNF protein levels and spatial and avoidance memory performance were evaluated using the Morris water maze and shuttle box tests, respectively.

The results revealed that chronic fatigue induced by aerobic exercise significantly affected hippocampal BDNF levels in the exercise group. However, the impact of fatigue on spatial memory and learning alterations did not show a significant difference when compared to the control group. Additionally, this type of exercise had a significant impact on passive avoidance memory performance.

These findings suggest that aerobic exercise, even at high intensity and duration, can improve some cognitive functions. Through appropriate exercise programming, it is possible to mitigate the effects of fatigue.

Cognition impairments are commonly  associated with pain experiences. Noopept drug leads to  impaired spatial memory improvement  by affecting the process of neuronal damage and repair in reducing and modulating pain. Therefore, in this study, changes in spatial learning and memory performance during chronic peripheral inflammatory pain and also, the effect of Noopept on these changes were investigated.

Rats were divided two into main groups (CFA and CFA+Noopept), namely CFA group which received 100 μL CFA and CFA+Noopept group which received 100 μL CFA+5mg/kg/day Noopept. After that, each group was divided into three subgroups (0, 7 and 21days) based on different time points of the study. Thermal hyperalgesia and learning and spatial memory assessed at 0, 7, 21 days of study after Persistent inflammation induction by CFA.

Our finding indicated that thermal hyperalgesia significantly increased on day 7 following CFA injection in comparison to day 0 (p<0.001) that is, administration of Noopept decreased thermal hyperalgesia on day 7(p<0.01). However, a significant decrease was observed in thermal hyperalgesia on day 21 in comparison to day 7 in CFA group (p<0.01). In addition, we indicated that CFA-induced pain impaired spatial learning and memory functions on day 7 (p<0.01). Daily administration of Noopept improved spatial memory and learning impairments on day 7(p<0.05).

It seems that acute and chronic peripheral inflammatory pain impairs spatial learning and memory. Daily administration of Noopept can improve behavioral impairments of pain, spatial learning and memory.

 Chronic immobilization stress can damage the nervous system, leading to learning and memory disorders, anxiety, and depression. Parsley (Petroselinum crispum) is known for its antioxidant, anti-diabetic, anti-inflammatory, and hepatoprotective properties. This study investigates the effects of hydroalcoholic extract of parsley on learning, spatial memory, and anxiety behavior in adult male Wistar rats subjected to chronic immobility stress.

Sixty rats were divided into six groups: control, stress, Parsley 1 (1 mg/kg), Parsley 2 (2 mg/kg), stress-parsley 1, and stress-parsley 2. For 21 consecutive days, rats were restrained for 6 hours daily to induce stress. Hydroalcoholic extracts of parsley were administered via gavage at doses of 1 and 2 mg/kg during this period. Spatial learning and memory were assessed using the Morris water maze, while anxiety behavior was evaluated with the elevated plus maze.

In the Morris water maze, stress-parsley groups 1 and 2 showed a significant reduction in the time and distance traveled to reach the hidden platform compared to the stress group (p < 0.01 and p < 0.05, respectively). In the probe test, these groups spent a greater distance and time in the target quadrant compared to the stress group (stress-parsley group 1, p < 0.05; stress-parsley group 2, p < 0.01). Additionally, the elevated plus maze results indicated that the percentage of entries into the open arm and time spent in this arm were significantly higher in the stress-parsley groups compared to the stress group (p < 0.05).

Hydroalcoholic extract of parsley improved learning and spatial memory while reducing anxiety behavior in rats exposed to chronic immobility stress, suggesting its potential therapeutic effects for stress-induced disorders.

Alzheimer's disease is a progressive disease with mild memory loss that eventually leads to the loss of the ability to conduct conversation and react to the environment. Despite the proven role of the drugs used against the obvious causes of Alzheimer's disease, it still seems impossible to achieve an effective and permanent treatment for the treatment of Alzheimer's disease. So, investigating different angles of GABAergic system signaling can be introduced as a promising target for the development of anti-Alzheimer drugs.

To induce Alzheimer's disease, the β-amyloid toxin at a dose of 5µg/µl was injected bilaterally into the hippocampus of Wistar male rats, and the rats were then treated with bilateral injection of GABA-A receptor agonist (muscimol) and antagonist (bicuculline), at a dose of 100 ng/µl/side in the hippocampus for 4 days. To assess the spatial memory of the animals, the parameters of the distance traveled by the animals, latency time to reach the hidden platform, and velocity of the animals were analyzed in Morris water maze test.

The distance traveled and the latency time to reach the hidden platform increased in the Morris water test following the injection of beta-amyloid, and the muscimol increased the amount of this memory impairment. The injection of bicuculline could not significantly change the spatial memory of the animals.

The results of this study indicate the destructive effect of beta-amyloid toxin on spatial memory, as well as the destructive role of muscimol in memory consolidation and retrieval.

Chronic immobilization is a type of stress that causes behavioral disorders such as anxiety and memory deficits by inducing oxidative stress and inflammation and changing the level of neurotransmitters in the brain. In this research, we investigated the effect of the hydroalcoholic extract of dried lemon peel (Citrus aurantifolia) on learning, spatial memory, and anxiety-like behavior in adult male rats exposed to chronic immobilization.

To induce immobilization stress, the rats were placed in the restrainer for 6 hours every day for 21 consecutive days. Lemon extract (400 mg/kg) was also treated by gavage to the animals. Spatial learning and memory were assessed using the Morris blue maze, and anxiety was studied using an elevated plus maze.

The lemon extract treatment made the animals exposed to immobilization stress swim more time and distance in the target quarter in the water maze compared with the stress group (P < 0.05). The extract increased the percentage of entry into the open arm (P < 0.01) and the percentage of time spent in the open arm (P < 0.05) of the elevated plus maze in these animals.

Dried lemon peel extract improved learning and spatial memory in animals exposed to chronic immobilization and reduced anxiety-like behavior in them. Dried lemon peel extract probably has a neuroprotective effect.

The acquisition and consolidation of new tasks into long-term memory involve the appearance of sharp-wave ripples in the temporal lobe during resting or sleep, which play a crucial role in memory consolidation. Additionally, sharp-wave ripples, high-frequency waves in the molecular layer of the hippocampus, are associated with synaptic plasticity and memory consolidation. This study aims to investigate the impact of high-frequency electrical stimulation of the hippocampal Schaffer collateral (SC) pathway on memory consolidation in behaving rats.

Stereotaxic surgery was conducted to implant stimulating electrodes in the SC pathway and recording electrodes in the CA1 region of male Wistar rats. After confirming electrophysiological recording, electrodes were secured to the skull using dental cement. Two hours following each acquisition session rats underwent stimulation of the SC pathway with a frequency of 200 Hz to assess its effect on spatial memory formation. Spatial learning was then conducted using the Morris water maze over three consecutive days. Electrical stimulation occurred two hours post-learning on each day, and spatial memory was evaluated on the fourth day.

Stimulation of the SC pathway with high frequency resulted in long-term synaptic strengthening in CA1. However, behavioral testing revealed no significant difference in learning and spatial memory between the group receiving electrical stimulation and the control group.

These findings suggest that high-frequency stimulation of the SC pathway does not enhance memory, indicating that synaptic strengthening in the CA1 region does not necessarily translate into memory improvement.

Maternal folate supplementation during pregnancy is associated with reduced risk of several fetal neurodevelopmental disorders. However, it is not well known that excess folate intake from diet and supplements can impair neurodevelopment and behavior in offspring. Therefore, the aim of this study is to investigate the effect of chronic and high doses of folic acid before and during pregnancy in female rats on learning and spatial and avoidance memory in male and female offspring.

24 female Wistar rats received doses of 0.5, 1, and 2 mg folic acid by intraperitoneal injection two weeks before and during pregnancy. The control group received normal saline. Male and female offspring were divided into 8 groups. Learning behavior and spatial memory were measured by Morris blue maze test, avoidance memory by shuttle box test. The results showed that taking a dose of 2 mg folic acid before and during pregnancy causes spatial learning deficits in male offspring.

While spatial memory is unchanged compared to the control. This dose of folic acid also causes a disturbance in avoidance memory in both male and female offspring.

Our results suggest that high doses of folic acid supplements during early life (fetal) have the potential to impair neurological functions such as memory. Although the severity of this disorder can depend on the gender of the child.