en Clinical Neuroscience Clinical Neuroscience Original Original <p align="left" ><font color="#221e1f" size="2"><font color="#221e1f" size="2"><p align="left" ><p><strong><font color="#221e1f" size="2"><font color="#221e1f" size="2">Introduction: </font></font><font color="#221e1f" face="Times New Roman,Times New Roman" size="2"><font color="#221e1f" face="Times New Roman,Times New Roman" size="2"><font color="#221e1f" face="Times New Roman,Times New Roman" size="2">Cholinergic systems are involved in learning and memory. Scopolamine, a muscarinic acetylcholine receptor antagonist, is used as a standard/ </font></font></font><font color="#221e1f" face="Times New Roman,Times New Roman" size="2"><font color="#221e1f" face="Times New Roman,Times New Roman" size="2"><font color="#221e1f" face="Times New Roman,Times New Roman" size="2">reference drug for inducing cognitive deficits in healthy humans and animals. The </font></font></font><font color="#221e1f" face="Times New Roman,Times New Roman" size="2"><font color="#221e1f" face="Times New Roman,Times New Roman" size="2"><font color="#221e1f" face="Times New Roman,Times New Roman" size="2">purpose of this study was to evaluate the effects of scopolamine on avoidance memory and number of neurons in rat’s hippocampus. . </font></font></font></strong><font color="#221e1f" size="2"><font color="#221e1f" size="2"><p align="justify"><strong>Methods: </strong></p></font></font><font color="#221e1f" face="Times New Roman,Times New Roman" size="2"><font color="#221e1f" face="Times New Roman,Times New Roman" size="2"><font color="#221e1f" face="Times New Roman,Times New Roman" size="2">Thirty five male albino Wistar rats (200 ± 20 g) were used in this study. The rats were divided randomly into five groups: control group (healthy samples), </font></font></font><font color="#221e1f" face="Times New Roman,Times New Roman" size="2"><font color="#221e1f" face="Times New Roman,Times New Roman" size="2"><font color="#221e1f" face="Times New Roman,Times New Roman" size="2">sham (saline) and 3 experimental groups 0.2, 0.5 and 1 mg/kg (intraperitoneally - single dose of Scopolamine). Animals were tested by passive avoidance method (shuttle box). After one week, a memory test was taken from rats. Finally, with dissection of the rats' brains and tissue operations, neurons were stained with cresyl violet. Photographs of the samples in hippocampal areas were prepared, and neurons were counted. </font></font></font><font color="#221e1f" size="2"><font color="#221e1f" size="2"><p align="justify"><strong>Results: </strong></p></font></font><font color="#221e1f" face="Times New Roman,Times New Roman" size="2"><font color="#221e1f" face="Times New Roman,Times New Roman" size="2"><font color="#221e1f" face="Times New Roman,Times New Roman" size="2">Our results showed that the number of neurons in all experimental groups was lower than that in the control group. The highest decrease in number of neurons was shown in response to 1 mg/kg scopolamine compared to the control group in all regions of hippocampus. Also, we found that in comparison to the saline-treated animals, the injection of scopolamine to rats after training, caused memory destruction. </font></font></font><font color="#221e1f" size="2"><font color="#221e1f" size="2"><p><strong>Discussion: </strong></p><p></p><p></p></font></font><font color="#221e1f" face="Times New Roman,Times New Roman" size="2"><font color="#221e1f" face="Times New Roman,Times New Roman" size="2"><font color="#221e1f" face="Times New Roman,Times New Roman" size="2">We concluded that memory impairment-induced by scopolamine is probably associated with neuronal loss and this decrease was dose dependent. </font></font></font></p></font></font><font color="#221e1f" face="Times New Roman,Times New Roman" size="2"><font color="#221e1f" face="Times New Roman,Times New Roman" size="2"><font color="#221e1f" face="Times New Roman,Times New Roman" size="2"><strong> </strong></font></font></font> Scopolamine,Hippocampus,Neurons,Passive Avoidance Memory 9 15 http://bcn.iums.ac.ir/browse.php?a_code=A-10-1-82&slc_lang=en&sid=1 Saba Seifhosseini 1370031947532846001461 1370031947532846001461 Yes Mehrdad Jahanshahi 1370031947532846001462 1370031947532846001462 No Ali Moghimi 1370031947532846001463 1370031947532846001463 No Nasrin-Sadat Aazami 1370031947532846001464 1370031947532846001464 No