Effect of amitriptyline on learning and memory consolidation in the male Wistar rats with an experimental model of pentylenetetrazole-induced seizure

Abstract Amitriptyline (AMT) was developed for the treatment of chronic and neuropathic pain. There is also evidence it may be useful in the treatment of neurodegenerative disorders. In this regard, the effect of on the experimental model of seizures and memory impairment caused by seizures in rats is investigated in the present study. Seizures in Wistar rats (200-250 g) were induced by pentylenetetrazole (PTZ, 60 mg/kg, intraperitoneally (i.p.)). The anticonvulsant effect of AMT (10 and 20 mg/kg, i.p.) was evaluated in the seizure model. The effect on memory was assessed using passive avoidance (PA) learning and memory test. After behavioral tests, the animals underwent deep anesthesia and were put down painlessly. Animal serum was isolated for oxidant/antioxidant assays (malondialdehyde (MDA), and glutathione peroxidase (GPx)). Intraperitoneal injection of AMT decreased the mean number of myoclonic jerks and generalized tonic-clonic seizure (GTCS) duration and increased the mean latency of myoclonic jerk and GTCS compared to the PTZ group. Moreover, in the PA test, AMT caused a significant increase in retention latency (RL) and total time spent in the light compartment (TLC) compared to the PTZ group. Biochemical tests showed that AMT was able to significantly increase GPx serum levels and significantly reduce MDA serum levels compared to the PTZ group. Overall, this study suggests the potential neuroprotective effects of the AMT drug in a model of memory impairment caused by seizures via the mechanism of inhibition of the oxidative stress pathway.

Effects of gallic acid and physical exercise on passive avoidance memory in male rat

Learning and memory play main roles in daily life of human, and memory represents the basis of all trainings and learning. The aim of the current study is to investigate the effects of gallic acid and physical exercise on the levels of passive avoidance memory in rat. In this experimental study, 46 rats weighing 200-300 g were randomLy divided to six groups of eight each: including control group, groups treated with 10 and 20 mg/kg gallic acid, group undergoing physical exercise alone, and groups both undergoing physical exercise and treated with 10 and 20 mg/kg gallic acid. The interventions continued for 10 days. After the intervention, passive avoidance memory was measured by shuttle box, blood samples were taken, and serum and brain antioxidant capacity and malondialdehyde (MDA) levels were measured. Secondary latency in shuttle box significantly increased in groups undergoing treadmill exercise and undergoing treadmill exercise + treating 10 and 20 mg/kg gallic acid. In groups treated with 10 and 20 mg/kg gallic acid alone, secondary latency increased significantly. Results confirmed the effects of gallic acid and physical exercise, either alone or combined, in improving memory.

Effect of dopamine D1 receptor in hippocampal DG region in active avoidance learning in rats and its mechanism / 吉林大学学报(医学版)

Objective: To observe the changes of dopamine (DA) levels in the hippocampal dentate gyrus (DG) region of the rats during the establishment and extinction process of active avoidance conditioned reflex, and to investigate the effect of D1 receptor in the active avoidance learning of the rats and its mechanism. Methods: A total of 24 male SD rats were randomly divided into non-training group, training group, control group and SCH group (n= 6). The rats in training group were trained for active avoidance whereas the rats in non-training group were only put into the shuttle box without training, and then the DA levels in extracellular fluid in DG region of the rats in two groups were measured. In control and SCH groups, the saline or SCH-23390 was injected into the DG region of the rats before the active avoidance training, and then the glutamate (Glu) levels and the field excitatory postsynaptic potential (fEPSP) amplitudes in extracellular fluid in DG region of the rats in two groups were examined. The rates of active avoidance of the rats were recorded by behavioral analysis system of the shuttle box. The levels of DA and Glu in DG region of the rats were measured by microdialysis and HPLC techniques, and the amplitude of fEPSP in DG region of the rats was examined by electrophysiological recording. Results: The DA level in DG region of the rats in training group was gradually increased during the establishment process and was gradually decreased during the extinction process of conditioned reflex; compared with the 1st day, the DA level in DG region of the rats on the 5th day was markedly increased (P0. 05). In control group, the rats reached the establishment criterion on the 5th day (active avoidance rate > 65%) and reached the criterion of extinction on the 7th day (active avoidance rate 0. 05). Compared with control group, the Glu level and fEPSP amplitude of the rats in SCH group on the 5th day were markedly decreased (P<0. 05). Conclusion: DA in hippocampal DG region of the rats can facilitate the active avoidance learning via activation of D1 receptors, and its mechanism is associated with the enhancement of Glu level and synaptic transmission efficiency.

The effects of regular exercise on capsaicin-induced pulpal pain and pain-induced changes in passive avoidance learning and memory in rats

BACKGROUND: Pulpal pain is one of the most common and severe orofacial pain conditions with considerable adverse effects on physiological processes including learning and memory. Regular exercise is known to be effective on cognitive function as well as pain processing in the central nervous system. Here, the possible effects of regular exercise on pulpal pain response as well as pain-induced changes in learning and memory efficiency in rats were investigated. METHODS: Twenty-four male Wistar rats were randomly assigned to the control, capsaicin, exercise, and exercise plus capsaicin groups. Rats in exercise groups were forced to run on a treadmill with a moderate exercise protocol for 4 weeks. Capsaicin was used to induce dental pulp pain. Passive avoidance learning and memory performance was assessed by using a shuttle box apparatus. RESULTS: According to the results, regular exercise could decrease the time course of capsaicin-induced pulpal pain (P < 0.001). Moreover, in capsaicin-treated rats, passive avoidance acquisition was impaired as compared to the control (P < 0.05) and exercise (P < 0.001) groups. Additionally, regular exercise before capsaicin injection could attenuate capsaicin-induced memory impairments (P < 0.05). CONCLUSIONS: Taken together, the present data showed that regular exercise has inhibitory effects on capsaicin-induced pulpal pain as well as pain-induced cognitive dysfunction in rats.

Accuracy in dictation after improvement of reading and copying skills in a student with learning difficulties / Precisão em ditado após fortalecimento de leitura e cópia em um escolar de risco

The aim of this study was to use systematic teaching in a clinical setting using software to teach reading and writing in one boy with learning difficulties and obtain accurate performance in dictation. In the pre-test, the student showed good performance in matching-to-sample tasks (96% in matching printed words to dictated words; 88% in matching pictures to dictated words), although he obtained a low percentage of correct answers in the dictation of constructed responses (52%) and manuscripts (24%). The teaching strengthened the selection of printed words matched to dictated words and copying words. The student obtained 100% correct answers in the teaching tasks. In post-tests of dictation, he obtained 100% correct answers in constructed response and 96% correct answers in manuscripts. The results indicate that carefully teaching copying may promote accuracy in the performance of responding to minimal units in dictation tasks...

O objetivo deste trabalho foi adotar, em condições clínicas, um ensino sistemático de leitura e escrita oferecido por um software em um adolescente com características de desempenho condizentes com dificuldades de aprendizagem a fim de que ele obtivesse desempenho preciso em ditado. No pré-teste, o aluno mostrou bom desempenho em relações que envolviam a seleção de palavras impressas diante da palavra ditada (96%) e diante da figura (88%), mas registrou baixa porcentagem de acertos em ditado com construção da resposta (52%) e manuscrito (24%). O ensino fortaleceu a seleção de palavra impressa mediante ditado e cópia da palavra impressa. O aluno obteve 100% de acertos no ensino; nos pós-testes de ditado, obteve 100% de acertos com construção da resposta e 96% de acertos em manuscrito. Os resultados indicam que o ensino criterioso da cópia pode favorecer a precisão no desempenho de responder a unidades mínimas em tarefas de ditado...

Effects of single, brief exposure to an 8 mT electromagnetic field on avoidance learning in male and female mice

The present study investigated the effect of extremely low frequency (8 mT, 50 Hz) electromagnetic fields (ELF-EMF) on avoidance learning in mice and compared the effect of an ELF-EMF in adult male and female mice. Learning was evaluated using a passive avoidance learning procedure in a standard wooden box, in which, despite their instinctive tendencies, mice learn to stay on a small platform to avoidant an electric shock. Before each learning session, the animals were exposed to an 8 mT, 50 Hz ELF created by a round coil. Immediately after 60 min exposure to the ELF-EMF, the mice were subjected to avoidance learning. The animals in the sham-exposed control group were placed in the coil for 60 min but were not exposed to the EMF and were subjected to the same behavioral procedures as the experimental group. The comparison of learned behaviors in the experimental and control groups showed that exposure to an 8 mT, 50 Hz ELF for 60 min significantly affected passive avoidance learning in both male (p < .023) and female (p < .015) mice.

Effects of Combined Treatment with Fluoxetine and Choline on the Retention of Passive Avoidance Learning after Chronic Mild Stress in Rat / 신경정신의학

This study was performed to evaluate the effects of serotonin and choline on the memory function in rat model of depression. Chronic exposure to mild unpredictable stress was found to depress the consumption of sweet 1% sucrose solution in the Sprague-Dawley rats. We identified depressive behaviours in 27 Sprague-Dawley rats. Rats in experiments were stratified into 3 groups, ie, fluoxetine with choline, choline, and saline control. Memory function was evaluated by passive avoidance learning and retention tests. We evaluated how long memory retention would remain improved at training-testing intervals of 1 day, 1 week, 2 week, 3 week, and 4 week in depressive state of the Sprague-Dawley rats during 4 weeks of experimental drugs treatment. The results were as follows: 1) The fluoxetine with choline-treated group showed significant differences in the maintenance of retention from the saline control at 1, 2, 3, and 4 week training-testing interval. 2) The choline-treated group showed significant differences in the maintenance of retention from the saline control at 3 and 4 week training-testing interval. In summary, the combined treatment of fluoxetine with choline showed earlier effects on memory function compared with choline alone in the passive avoidance retention test in the animal model of depression. We suggest that there are synergistic interaction between serotonin and choline in the long term memory function in rat model of depression.

Effects of Selective Serotonin Reuptake Inhibitors on the Retention of Passive Avoidance Learning after Chronic Mild Stress in Rats

The study was designed to evaluate the significant roles of SSRI in rat of depression model. Chronic exposure to mild unpredictable stress has been found to depress the consumption of sweet 1% sucrose solutions in the Sprague-Dawley rats. We applied the variety of 11 types of stress regimens and identified depressive behavious(developed by Willner) in 70 Sprague-Dawley rats. Rats in experiments were stratified into 6 groups, i.e.; 3 kinds of SSRI(paroxetine, fluoxetine, sertraline), clomipramine, choline and saline control. Memory function was evaluated by passive avoidance learning and retention test. The authors determined how long memory retention would remain improved with 24 hour, 1 week, 2 weeks, 3 weeks, and 4 weeks at training-testing interval in depressive states of the Sprague-Dowley rats. The results were as follows; 1) There were to significant differences between the 6 groups at the 24 hour training-testing interval. 2) The paroxetine treated group showed significant differences from the control group at the 1 week and 2 weeks training-testing interval. 3) The paroxetine and the fluoxetine treated groups showed significant differences from the control group at 3 week training-testing interval. 4) The paroxetine and the choline treated groups showed significant differences from the control group 4 week training-testing interval. In summary, paroxetine had on effect on long term memory processing from 1st week to 4th week. Also, fluoxetine(or 3rd week) and choline(at 4th week) had effect on long term memory processing. Sertraline, clomipramine were ineffective on memory processing during 4 weeks observation. Possible explanations why paroxetine had early effect on memory processing than the other selective serotonin reuptake inhibitors are rapid bioavailability, which is the characteristics of pharmacokinetics of paroxetine. In clinical situation, author carefully suggest that SSRI would be beneficial to improve the memory function caused by depressive neurochemical changes.

Blockage of arginine vasopressin's effect on memory-enhancement by destruction of periaqueductal gray matter in rats / 第三军医大学学报

The effects of the destruction of the periaqueductal gray matter(PAG)on the memory-enhancement by intraperitoneal injection of arginine vasopressin(AVP)were observed in rats.Rats with either sham lesions or electrolytic destruction of the bilateral PAG were trained in a shuttle box for active avoidance response(AAR).After the rats met the criterion of 80% correctness,an intraperitoneal injection of 6?g/kg of AVP or 0.2ml of saline was given.Extinction of AAR was assessed in the rats.It was found that AVP markedly retarded the extinction of AAR in rats with sham lesion,and the extinction of the rats with destroyed PAG was significantly faster than that of the rats with sham lesion.The above mentioned findings suggest that AVP can act on the central nervous system to enhance memory mediated probably through PAG.This observation provides further support for the suggestion that certain limbic midebrain structures are involved in the memory enhancement by AVP.