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.

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.

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.