Introduction:Scopolamine, a muscarinic cholinergic receptor antagonist, is widely used to induce memory impairment in experimental animals. The present study aims to compare memory impairment and oxidative stress following single and repeated doses administration of scopolamine.Methods:A group of rats received a single shot of scopolamine in different doses (0.5, 1, or 3 mg/kg, IP) 24 hours after the passive avoidance training. Then the memory retrieval test was performed 30 minutes and 7 days after the injection. In the other experiment, rats received similar doses of scopolamine for 7 consecutive days, 24 hours after the training session. Then the memory retrieval test was performed 30 minutes and 7 days after the last injection. Acetylcholinesterase (AChE) activity and lipid peroxidation were measured in their hippocampus tissue, too.Results:Scopolamine administered in repeated doses caused more impairment in memory function compared to single dose injection based on the evaluation 30 minutes after injection. Moreover, the memory impairment persisted for 7 days only in repeated doses treated groups. Increase in acetylcholinesterase activity and lipid peroxidation in both groups was observed 30 minutes after scopolamine administration. These abnormal increases persisted for 7 days only in repeated doses treated groups. Increased AChE activity and lipid peroxidation was well correlated with behavioral deficit. Also AChE activity was well associated with lipid peroxidation.Conclusion:The results of present study showed that repeated administration of scopolamine induced results in memory impairment. This effect can be due to long-lasting oxidative stress which may damage the hippocampus tissue.
We have previously shown that infusion of the PKAII inhibitor H-89 in the CA1 area of the hippocampus impaired spatial memory retention. There is some evidence suggesting the neuroprotective effects of chronic lithium administration including its ability to attenuate a deleterious effect of chronic stress on spatial memory in rats. In the present study, we investigated whether chronic administration of lithium can improve memory as well as influence the inhibitory effect of H-89 on spatial memory retention. Male albino rats were treated systemically with lithium (600 mg/l) for 4 weeks and then trained for 4 days in the Morris water maze. Testing the animals 48 h later showed a significant reduction in escape latency (p < 0.05) and travel distance (p < 0.05) compared to the controls. In separate experiments, the rats were similarly treated with lithium for 4 weeks, followed by similar training for 4 days and then immediately infused bilaterally with vehicle or 5 µmol/l H-89 into the CA1 region of the hippocampus. Animals were then tested 48 h after H-89 infusion in order to assess their spatial memory retention. The lithium treatment caused a significant reduction in escape latency (p < 0.001) and travel distance (p < 0.001) compared to H-89-treated animals. The data suggest that lithium treatment for 4 weeks improved spatial memory retention and that lithium pretreatment prevented or reversed the H-89-induced spatial memory deficits.
Extracellular deposition of Beta-amyloid peptide (Aβ) is the main finding in the pathophysiology of Alzheimer's disease (AD), which damages cholinergic neurons through oxidative stress and reduces the cholinergic neurotransmission. Satureja bachtiarica is a medicinal plant from the Lamiaceae family which was widely used in Iranian traditional medicine. The aim of the present study was to investigate possible protective effects of S. bachtiarica methanolic extract on Aβ induced spatial memory impairment in Morris Water Maze (MWM), oxidative stress and cholinergic neuron degeneration. Pre- aggregated Aβ was injected into the hippocampus of each rat bilaterally (10 μg/rat) and MWM task was performed 14 days later to evaluate learning and memory function. Methanolic extract of S.bachtiarica (10, 50 and 100 mg/Kg) was injected intraperitoneally for 19 consecutive days, after Aβ injection. After the probe test the brain tissue were collected and lipid peroxidation, Acetylcholinesterase (AChE) activity and Cholin Acetyl Transferees (ChAT) immunorectivity were measured in the hippocampus. Intrahipocampal injection of Aβ impaired learning and memory in MWM in training days and probe trail. Methanolic extract of S. bachtiarica (50 and 100 mg/Kg) could attenuate Aβ-induced memory deficit. ChAT immunostaining revealed that cholinergic neurons were loss in Aβ- injected group and S. bachtiarica (100 mg/Kg) could ameliorate Aβ- induced ChAT reduction in the hippocampus. Also S. bachtiarica could ameliorate Aβ-induced lipid peroxidation and AChE activity increase in the hippocampus. In conclusion our study represent that S.bachtiarica methanolic extract can improve Aβ-induced memory impairment and cholinergic loss then we recommended this extract as a candidate for further investigation in treatment of AD.
Lead (Pb) is one of the most important heavy metals that possess many applications in different kinds of industrial procedures and consumer products. The adverse effects of Pb on different parts of the immune system have been reported in various studies. Although it has been shown that high concentrations of Pb have low cytotoxicity on human lymphocytes, the effects of non-cytotoxic concentrations of Pb (detected in human blood) on cellular organelles and oxidative stress factors of human lymphocytes have yet to be determined. In this study, human lymphocytes were obtained from the blood of healthy male volunteers through the use of the Ficoll standard method. The intention of this paper was to determine the effects of non-cytotoxic concentrations of Pb on human lymphocytes using the accelerated cytotoxicity mechanism screening technique. For determination of cell viability, lymphocytes were treated with 0–1 m
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