en Cellular and molecular Neuroscience Cellular and molecular Neuroscience Original Original <p align="left" ><p><b><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">Stress is defined as any environmental change that disturbs the maintenance of brain homeostasis. Stress leads to production of pro-inflammatory </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">cytokines that provoke neurodegenerative disorders. In the present study, we investigated the effects of dalteparin on hippocampal neuronal death induced by chronic stress in rats. </font></font></font><b><font color="#221e1f" size="2"><font color="#221e1f" size="2"><p align="justify">Methods: </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">the study was carried out on 60 adult male wistar rats, weighing 200- 250 gr. The rats were randomly divided into three groups: control, stress and stress + dalteparin (SD) groups. Animals in the stress and stress + dalteparin group were exposed to chronic stress for 4 weeks. Animals in the stress + dalteparin (SD) group received dalteparin (70,100 and 140 IU/kg/days i.p.) during the stress </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">period. After the last stressor animals were sacrificed and concentration of IL-6 in </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">serum was measured using ELISA. All animals were reperfused and their brains were processed for histological analysis through Nissl analysis. </font></font></font><b><font color="#221e1f" size="2"><font color="#221e1f" size="2"><p align="justify">Results: </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 found that the serum concentration of IL-6 was significantly </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">higher in the CMS (Chronic Mild Stress) exposure group than in the control group (p<0.05). Moreover, dalteparin, dose dependently decreased IL-6 </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">concentration in the SD groups. Chronic stress also resulted in significant cell loss </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">in hippocampal CA1, CA3 and hilus. Dalteparin markedly inhibited the decreases in number of hippocamoal CA1 and CA3 (p<0.01) and hilus (p<0.05) neurons caused by chronic stress. </font></font></font><b><font color="#221e1f" size="2"><font color="#221e1f" size="2"><p>Discussion: </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">chronic stress damages hippocampal CA1, CA3 and hilus neurons, and dalteparin protects hippocampus from damage induced by chronic stress. </font></font></font></b></b></b></b></p> dalteparin, chronic stress, hippocampus, inflammation 32 37 http://bcn.iums.ac.ir/browse.php?a_code=A-10-1-107&slc_lang=en&sid=1 Fereshteh Farajdokht 1370031947532846002852 1370031947532846002852 No Arezo Nahavandi 1370031947532846002853 1370031947532846002853 Yes Mansoureh Soleimani 1370031947532846002854 1370031947532846002854 No