Memory Processes In Rats Research Articles

Ендогенна та екзогенна нейростероїдна модуляція пам’яті щурів з алкогольною залежністю та агресивним типом поведінки

Alcoholism and chronic stress lead to impaired cognitive functions, which are regulated, in particular, by neurosteroid hormones. Exogenous administration of progesterone is one of the ways to influence the brain system of hormonal and neurotransmitter regulation. The effect of intranasal administration of low doses of progesterone on endogenous neurosteroid modulation of working and spatial memory in male rats with alcohol dependence and aggressive behavior was investigated. Alcohol dependence in male rats was modeled by voluntary intake of bread soaked in ethanol solution at a dose of 1.2 g/kg for 30 days. Aggressiveness was determined using the sensory contact method and the “partition” test. To study memory processes in rats, neuroethological methods of testing working (recognition of new objects) and spatial (orientation in the Barnes maze) memory were used. Progesterone was administered intranasally at a dose of 80 μg per rat for 10 days. Progesterone, testosterone, and cortisol levels were measured in the frontal neocortex (FC), hippocampus, and serum using enzyme-linked immunosorbent assay kits. The stimulatory effect of alcoholization on spatial memory and impairment of working memory in male rats with aggressive behavior was found. Zoosocial conflict on the background of prolonged alcohol consumption leads to impaired object recognition and spatial orientation against the background of neurosteroid imbalance: a decrease in progesterone and testosterone content in the FC, hippocampus, serum, and an increase in cortisol levels in these structures. Intranasal administration of progesterone to rats with alcohol dependence and aggressive behavior offsets the negative effects of confrontational relationships on working memory processes, restores the acquired experience to the baseline (however, the processes of object differentiation remain weakened); leads to improved spatial memory. The favorable effects of progesterone on memory are accompanied by a decrease in the imbalance of hormonal influences in brain structures with the restoration of progesterone and testosterone concentrations in the FC, hippocampus and serum against the background of weakening of stress-induced glucocorticoid activity. Therefore, intranasal administration of low doses of progesterone improves working and spatial memory in male rats with alcohol dependence and aggressive behavior due to the tendency to restore the balance of hormones (progesterone, testosterone, cortisol) in the brain structures responsible for memory.

Study of the possibility of correcting behavioral disorders in rats with a stereotaxic model of Alzheimer's disease

Relevance. Alzheimer's disease (AD) is a neurodegenerative disease, the drug therapy of which can only slow the progression of the disease, due to the variety of existing pathogenetic processes. A possible effective approach to the correction of symptoms can be the use of compounds with a complex mechanism of action — phosphorylacetohydrazides, capable of simultaneously acting on different parts of the pathological process, the most effective representative of which is the compound 2-chloroethoxy-para-N-dimethylaminophenyl phosphorylacetohydrazide (CAPAH). Target. To study the possibility of correcting cognitive and behavioral disorders in rats with a stereotaxic model of AD using the CAPAH compound, which affects different parts of the pathological process. Methods. 24 female Wistar rats were used in the work. AD was modeled in rats by stereotaxic bilateral injection of β-amyloid into the hippocampal region in a phosphate buffer solution, then on day 11, CAPACH (10 mg/kg) was administered intraperitoneally for 10 days, after which tests were performed using the ≪Elevated Plus Maze≫, ≪Open Field≫ and ≪Morris Water Maze≫. Statistical processing was carried out in the GraphPad Prism 8.0.1 program using one-way ANOVA analysis. Results. Multiple administration of CAPAH contributed to a decrease in the level of anxiety in the ≪Elevated Plus Maze≫ method, increasing the time spent in open arms by 4.6 times (p < 0.05) compared to rats without treatment. In the ≪Morris Water Maze≫ and ≪Open Field≫ tests, normalization of memory and motor activity processes was observed, respectively, the platform search time and the number of crossed lines did not differ from those of control animals. Conclusion. CAPAH reduces anxiety and memory processes in rats with a stereotaxic model of Alzheimer's disease caused by the introduction of β-amyloid into the hippocampus.

Ex Vivo and In Vivo Study of Some Isoquinoline Precursors

This article concerns the synthesis and biological activities of some N-(1-(3,4-dimethoxyphenyl)propan-2-yl) amides as isoquinoline precursors and compounds with smooth muscle (SM) relaxant activity. Aim: find the biological activity of N-(1-(3,4-dimethoxyphenyl)propan-2-yl) amides and compare it with papaverine, an isoquinoline alkaloid that has been known as a brain and coronary vasodilator and SM relaxant. Materials and methods: In silico simulation with the PASS online program predicts SM relaxant activity for the compounds. The amides were tested on the isolated gastric SM preparations (SMPs) from rats to determine their effects on spontaneous contractile activity (CA) compared with papaverine. The in vivo effect on the learning and memory processes of rats was also assessed. Results: the data from the isometric measurements showed that one of the compounds caused ex vivo relaxation in circular SM tissues isolated from the stomach (corpus) of male Wistar rats. Conclusion: We found that the compound’s SM relaxation uses the papaverine pathway. It also has an improving effect on the cognitive functions of learning and memory processes in rats.

Effects of memantine on the passive avoidance test in young rats

Alzheimer’s disease (AD) is a long-lasting progressive neurodegenerative disease that degrades memory and cognitive function and is often complicated by disorientation and other psychiatric syndromes. At present, to improve the condition of patients with AD, for their treatment, use the drug memantine. The drug is a noncompetitive antagonist of NMDA glutamate receptors in the brain. The present experiments aimed to test the influence of memantine on the memory processes in rats. We used the passive avoidance test “Stepdown”. The latter is used to assess memory function based on the association formed between a particular environment that an animal is learning to avoid and a negative stimulus in the form of a weak electric shock to the feet. We found that memantine significantly, twice, decreased the latency time step-down from the platform in rats during their familiarization with the chamber. The rats became more determined and less afraid of the unknown environment under memantine. Memantine significantly affected the emotionality of young rats, which leads to errors in the passive avoidance test. However, it did not impair memory. It can be concluded that memantine induces a shift toward greater excitability in rats.

Effects of fluoxetine on memory processes in rats with different phenotypes of the nervous system and different levels of biogenic monoamines of the brain

Effects of fluoxetine on memory processes in rats with different phenotypes of the nervous system and different levels of biogenic monoamines of the brain

P.710 Effect of noni juice on learning and memory processes in rats with diazepam-induced amnesia

P.710 Effect of noni juice on learning and memory processes in rats with diazepam-induced amnesia

Antagonizing α7 nicotinic receptors with methyllycaconitine (MLA) potentiates receptor activity and memory acquisition

α7 nicotinic acetylcholine receptors (α7nAChRs) have been targeted to improve cognition in different neurological and psychiatric disorders. Nevertheless, no α7nAChR activating ligand has been clinically approved. Here, we investigated the effects of antagonizing α7nAChRs using the selective antagonist methyllycaconitine (MLA) on receptor activity in vitro and cognitive functioning in vivo. Picomolar concentrations of MLA significantly potentiated receptor responses in electrophysiological experiments mimicking the in vivo situation. Furthermore, microdialysis studies showed that MLA administration substantially increased hippocampal glutamate efflux which is related to memory processes. Accordingly, pre-tetanus administration of low MLA concentrations produced longer lasting potentiation (long-term potentiation, LTP) in studies examining hippocampal plasticity. Moreover, low doses of MLA improved acquisition, but not consolidation memory processes in rats. While the focus to enhance cognition by modulating α7nAChRs lies on agonists and positive modulators, antagonists at low doses should provide a novel approach to improve cognition in neurological and psychiatric disorders.

Quercetin promotes learning and memory performance concomitantly with neural stem/progenitor cell proliferation and neurogenesis in the adult rat dentate gyrus

The decline in neurogenesis is a very critical problem in Alzheimer disease. Different biological activities have been reported for medicinal application of quercetin. Herein, we investigated the neurogenesis potential of quercetin in a rat model of Alzheimer's disease induced by amyloid-beta injection. Rats were randomly divided into Control, Alzheimer + Saline and Alzheimer + Quercetin groups. Following the administration of Amyloid-beta, rats in the Alzheimer + Quercetin group received 40 mg/kg/day quercetin orally for one month. Our data demonstrated amyloid-β injection could impair learning and memory processing in rats indicated by passive avoidance test evaluation. We noted that one-month quercetin treatment alleviated the detrimental effects of amyloid-β on spatial learning and memory parameters using Morris water maze analysis. Quercetin was found to increase the number of proliferating neural stem/progenitor cells. Notably, quercetin increased the number of DCX-expressing cells, indicating the active dynamic growth of neural progenitor cells in the dentate gyrus of the hippocampus. We further observed that the quercetin improved the number of BrdU/NeuN positive cells contributed to enhanced adult neurogenesis. Based on our results, quercetin had the potential to promote the expression of BDNF, NGF, CREB, and EGR-1 genes involved in regulating neurogenesis. These data suggest that quercetin can play a valuable role in alleviating Alzheimer's disease symptoms by enhancing adult neurogenesis mechanism.

Effects of two anti-parkinsonian drugs on learning and memory processes in rats

Length of stay (LOS) after surgery for adult spinal deformity (ASD) is a critical period that allows for optimal recovery. Predictive models that estimate LOS allow for stratification of high-risk patients.A prospectively acquired multicenter database of patients with ASD was used. Patients with staged surgery or LOS >30 days were excluded. Univariable predictor importance ≥0.90, redundancy, and collinearity testing were used to identify variables for model building. A generalized linear model was constructed using a training dataset developed from a bootstrap sample; patients not randomly selected for the bootstrap sample were selected to the training dataset. LOS predictions were compared with actual LOS to calculate an accuracy percentage.Inclusion criteria were met by 653 patients. The mean LOS was 7.9 ± 4.1 days (median 7 days; range, 1–28 days). Following bootstrapping, 893 patients were modeled (653 in the training model and 240 in the testing model). Linear correlations for the training and testing datasets were 0.632 and 0.507, respectively. The prediction accuracy within 2 days of actual LOS was 75.4%.Our model successfully predicted LOS after ASD surgery with an accuracy of 75% within 2 days. Factors relating to actual LOS, such as rehabilitation bed availability and social support resources, are not captured in large prospective datasets. Predictive analytics will play an increasing role in the future of ASD surgery, and future models will seek to improve the accuracy of these tools.

Chronic treatment with the new anticonvulsant drug lacosamide impairs learning and memory processes in rats: A possible role of BDNF/TrkB ligand receptor system

Cognitive impairment is considered a frequent side effect in the drug treatment of epilepsy. The objective of the present study was to investigate the effects of lacosamide (LCM) on learning and memory processes in rats, on the serum level of brain-derived neurotrophic factor (BDNF) and BDNF/TrkB ligand receptor system expression in the hippocampal formation. Male Wistar rats underwent long-term treatment with three different doses of lacosamide – 3 mg/kg (LCM 3), 10 mg/kg (LCM 10) and 30 mg/kg (LCM 30). All rats were subjected to one active and one passive avoidance tests. The BDNF/TrkB immunohistochemical expression in the hippocampus was measured and serum BDNF was determined. The LCM-treated rats made fewer avoidance responses than controls during acquisition training and in the memory retention test. The number of escapes in the LCM 10 and LCM 30 groups decreased throughout the test, while the rats in the LCM 3 group showed fewer escapes only in the memory test in the active avoidance task. In the step-down test, the latency time of the LCM-30 treated rats was reduced as compared with the controls during the learning session and the short- and long-term memory retention tests. Lacosamide induced a dose-dependent reduction of the hippocampal expression of BDNF and its receptor TrkB. We found no significant difference between BDNF serum levels in the test animals and controls. The results of the study suggest that LCM suppresses the learning and memory processes in rats, with the inhibition of hippocampal BDNF/TrkB ligand receptor system being one of the possible mechanisms causing this effect.

Deficiency of transforming growth factor-β signaling disrupts memory processes in rats.

Cytokines, in addition to their participation in immune and inflammatory processes, play an important role in synaptic plasticity, neoneurogenesis, and cognitive functions. In our work, we aimed to clarify the role of the transforming growth factor-β (TGF-β), which is recognized as a multifunctional cytokine, in memory processes. Behavioral experiments were carried out in rats using step-through passive avoidance test. The results obtained showed that the learning of animals after treatment with SB431542, a selective inhibitor of TGF-β receptors, was impaired, which indicated a significant memory deterioration. Nevertheless, the memory of rats remained at the control level when TGF-β and SB431542 were coadministered. Thus, the role of TGF-β in memory retrieval after the passive avoidance test was revealed: memory in rats was weakened if the TGF-β signaling pathway was inhibited during learning. Evidently, successful consolidation of at least some types of memory requires a normal level of TGF-β, indicating the modulation of cognitive functions by cytokines under normal physiological conditions.

The possibility of adverse effect of Kv7-channel opener retigabine on memory processes in rats

ObjectiveRetigabine is a novel antiepileptic drug with a unique and complex mechanism of action which allows its use in many diseases associated with impaired neuronal activity. This study sought to examine the impact of retigabine on two types of memory in rats. MethodsAdult male Wistar rats were used to assess the effect of retigabine, administered p.o. as single (10mg/kg or 20mg/kg) or repeated doses, on spatial memory with the Morris water maze test (MWM) and emotional memory, associated with fear, with the passive avoidance test (PA). ResultsRetigabine administered at a high single dose transiently impairs learning processes in rats. In the MWM, these changes were delayed in time and of a lesser degree when retigabine was given at low single dose. Additionally, the drug administered repeatedly for 2weeks slowed learning processes in the MWM, but this effect occurred only after 1week of administration in the PA. ConclusionThese findings indicate that retigabine may affect memory and learning processes, especially in the first phase of administration.

ラットの受動回避学習・記憶過程におけるNMDA受容体/nNOS系の役割および神経ステロイドの修飾作用

ラットの受動回避学習・記憶過程におけるNMDA受容体/nNOS系の役割および神経ステロイドの修飾作用

Training-Associated Emotional Arousal Shapes Endocannabinoid Modulation of Spatial Memory Retrieval in Rats.

Endogenous cannabinoids play a central role in the modulation of memory for emotional events. Here we demonstrate that the endocannabinoid 2-arachidonoylglycerol in the hippocampus, a brain region crucially involved in the regulation of memory processes, selectively modulates spatial memory recall of stressful experiences. Thus, our findings provide evidence that the endocannabinoid 2-arachidonoylglycerol is a key player in mediating the impact of stress on memory retrieval. These findings can pave the way to new potential therapeutic intervention for the treatment of neuropsychiatric disorders, such as post-traumatic stress disorder, where a previous exposure to traumatic events could alter the response to traumatic memory recall leading to mental illness.

Effects of acute administration of melatonin on attentional, executive, and working memory processes in rats.

Melatonin is a potential candidate for additive therapy in cancer, neurodegenerative, and mental disorders requiring administration during the activity phase. Nevertheless, because melatonin has mostly been used as a hypnotic, less is known about its cognitive effects. In this study, we investigated the effects of acute administration of melatonin on executive, attentional, and working memory processes in rats during the activity phase. Three doses of melatonin (6, 18, or 36mg/kg) were tested and compared to a saline control group in two behavioral tests: the Attentional Set Shifting task (for attentional and executive processes assessment) and the Spontaneous Alternation test in a Y-maze (for working memory assessment). Our results revealed that, up to 36mg/kg, the acute administration dose of melatonin did not alter the attentional or executive processes, nor the working memory in rats. Consequently, this result may be encouraging for the use of melatonin in additive therapy during the activity phase.

Effects of Long-Term Treatment with Atorvastatin and Rosuaastatin on Active Avoidance Test in Intact Rats

Summary Statins are widely used for treatment of hyperlipidemia. They have been shown to possess pleiotropic effects apart from their lipid-lowering activity - anti-inflammatory, immunomodulatory, and neuroprotective. Most studies suggest that statins can protect the brain against damage but it is not clear whether they improve cognitive function in patients without neuropathy. The aim of the present study was to investigate the effect of 3-month treatment with atorvastatin and rosuvastatin on learning and memory processes in rats without brain damage. Wistar rats were treated orally for 90 days with atorvastatin and rosuvastatin at a dose of 10 mg/kg b. w. in parallel with the vehicle-treated group. After that period, learning ability and memory retention was evaluated using an active avoidance test - automatic reflex conditioner (shuttle box). The learning session was carried out on 5 consecutive days. Memory retention test was performed on day 12. The following behavioral reactions were investigated: conditioned responses (avoidance), unconditioned responses (escapes), and intertrial crossings. We found increased number of conditioned responses in groups, treated with atorvastatin 10 mg/kg b.w., and with rosuvastatin 10 mg/kg b.w. during the learning session and on the memory retention test, as compared to the same-day control group. The atorvastatin-treated group showed an increased number of unconditioned responses on days 1 and 2, as compared to the control group. In the group treated with Rosuvastatin there was an increased number of escapes on days 1,2 and 4, as compared to the vehicle-treated group. Atorvastatin and rosuvastatin at a dose of 10 mg/kg b.w. improved processes of learning and memory retention after the 3-month treatment.

P.1.d.004 Effects of Rhodiola rosea L. extract on learning and memory processes in rats using active and passive avoidance tests

To critically assess the current evidence from randomized clinical trials (RCTs) for or against the effectiveness or efficacy of Rhodiola rosea.Systematic literature searches were performed in six electronic databases: AMED (1985–July 2009), CINAHL (1982–July 2009), The Cochrane Library (search in July 2009), EMBASE (1974–July 2009), MEDLINE (1950–July 2009) and Web of Science (searched in July 2009). No language restrictions were imposed. Reference lists of all retrieved articles were searched, and experts and manufacturers were contacted for unpublished RCT.RCTs testing the efficacy or effectiveness of mono-preparations of R. rosea as sole treatment administered orally against a control intervention in any human individual suffering from any condition or healthy human volunteers were included. Studies were selected, data extracted, and quality assessed by two independent reviewers.Eleven RCTs met the inclusion criteria; all were placebo-controlled. Six trials investigated the effects of R. rosea on physical performance, four on mental performance, and two in patients diagnosed with mental health condition. The methodological quality of most trials was moderate or good. Only few mild adverse events were reported.R. rosea may have beneficial effects on physical performance, mental performance, and certain mental health conditions. There is, however, a lack of independent replications of the single different studies. Five of the 10 RCTs reached more than three points on the Jadad score (i.e., good quality). More research seems warranted.

Effect of reversible inactivation of reuniens nucleus on memory processing in passive avoidance task

The reuniens nucleus (RE) is the largest nucleus of the midline thalamic nuclei (MLN). RE has strongly connections with the amygdala and hippocampus, the structures that are involved in the learning and memory processes. In our previous report we have shown the role of RE in the spatial learning and memory using Morris water maze (MWM) task. Since RE is connected to multiple limbic structures, its involvement in the emotional learning and memory is a possibility. The present study was designed to elucidate the role of RE in acquisition, consolidation, and retrieval on the passive avoidance (PA) task which depends on a distributed network including the thalamus, amygdala, medial prefrontal cortex (mPFC) and hippocampus. For this purpose, rats were chronically implanted with a cannula aimed at the RE through which 0.5 μl tetracaine (2%) or saline were injected. Rats were trained in a PA task and their retention test was performed 24 h later. The injection of saline or tetracaine was applied 5 min before or 5, 90, and 360 min after the acquisition trial and 5 min before the retention tests. Our findings showed that inactivation of RE before training did not affect acquisition, but affected memory retention 24 h later in PA task. Moreover, inactivation of RE only 5 min after training impaired consolidation but not after 90 or 360 min. Also, inactivation of the RE, 5 min before the retrieval test impaired memory retrieval in PA task. In conclusion, it seems that RE is involved in memory processes in rats.

Neuroprotective Properties of Afobazole in Repeated Hemorrhagic Stroke Modeling in Aged Rats

Intraperitoneal administration of afobazole in a dose of 0.1 mg/kg over 2 weeks after repeated modeling of intracerebral post-traumatic hematoma reduces animal mortality, decreases motor coordination disturbances, and improves learning and memory processes in rats.

Activation of a remote (1-year old) emotional memory interferes with the retrieval of a newly formed hippocampus-dependent memory in rats

The persistent intrusion of remote traumatic memories in people with post-traumatic stress disorder (PTSD) may contribute to the impairment of their ongoing hippocampal and prefrontal cortical functioning. In the current work, we have developed a rodent analogue of the intrusive memory phenomenon. We studied the influence of the activation of a remote traumatic memory in rats on their ability to retrieve a newly formed hippocampus-dependent memory. Adult male Sprague–Dawley rats were given inhibitory avoidance (IA) training, and then 24 h or 1, 6 or 12 months later, the same rats were trained to learn, and then remember across a 30-min delay period, the location of a hidden escape platform in the radial-arm water maze (RAWM). When IA-trained rats spent the 30-min delay period in the IA apparatus, they exhibited intact remote (1-year old) memory of the shock experience. More importantly, activation of the rats' memory of the shock experience profoundly impaired their ability to retrieve the newly formed spatial memory of the hidden platform location in the RAWM. Our finding that reactivation of a remote emotional memory exerted an intrusive effect on new spatial memory processing in rats provides a novel approach toward understanding how intrusive memories of traumatic experiences interfere with ongoing cognitive processing in people with PTSD.