Study on the model for the vulnerability to stress using stress-induced c-fos mRNA expression as an index of stress response.

1.急性束缚应激和重复束缚应激对大鼠c-fos基因表达的影响：Wistar京都(WKY)大鼠和Wistar大鼠每天应激1h，连续应激1、3、7、14天。采用原位杂交技术检测应激诱导的c-fos基因在室旁核(PVN)和蓝斑(LC)中的表达。在急性束缚应激时，WKY大鼠和Wistar大鼠在PVN和LC中的c-fos基因表达水平与应激前相似，Wistar大鼠在应激第3天时，PVN和LC中的c-fos基因表达均显著降低，之后逐渐降低。WKY大鼠在反复束缚应激后，PVN和LC中c-fos基因的表达也表现出相似的下降模式。给予抗抑郁药丙咪嗪两周的重复1h束缚应激并不影响应激诱导的c-fos…表达的降低2.大鼠下丘脑HPA轴的应激反应和应激性焦虑的差异比较：在束缚应激的第1、3、6、13天，WKY大鼠和Wistar大鼠在束缚应激2小时测定血浆皮质酮(CS)水平，在急性束缚应激条件下，WKY大鼠较Wistar大鼠表现出更高的CS峰值水平。Wistar大鼠在应激后30min、60min和120min出现CS峰值和其他CS水平的下降，到第13天下降更明显，而WKY大鼠到第13天CS峰值水平没有下降，只有120min的CS水平比第3天有所下降。为了测量应激诱导的焦虑，我们测量了15分钟足底电击应激后的冻结时间。从应激第5天开始，Wistar大鼠的冰冻时间明显缩短，而WKY大鼠在应激第13天，冰冻时间并没有减少。这些结果表明WKY大鼠对应激的敏感性和脆弱性。较少

1.Strain comparison in c-fos mRNA expression induced by acute and repeated restraint stress.Wistar Kyoto (WKY) rats and Wistar rats were stressed by 1h restraint stress daily for one, three, seven and fourteen days. In these rats, stress-induced c-fos mRNA expression in paraventricle nucleus (PVN) and locus coeruleus (LC) were measured by in situ hybridization assay.To an acute restraint stress, WKY rats and Wistar rats showed similar c-fos mRNA expression in both PVN and LC.As reported before, Wistar rats showed substantial decrease in stress-induced c-fos mRNA expression in both PVN and LC on third stress day, and thereafter stress-induced c-fos mRNA expression decreased gradually. WKY rats, also, showed similar pattern of decrease in stress-induced c-fos mRNA expression in both PVN and LC by repeated restraint stress. Administration of imipramine, an antidepressant, for two weeks with repeated 1h restraint stress did not affect the decrement of stress-induced c-fos mRNA expression i … More n both PVN and LC in WKY rats.These results suggest that WKY rats are not sensitive and vulnerable to stress.2.Strain comparison in stress response of HPA axis and stress-induced anxiety.Plasma corticosterone (CS) were measured during 2h restraint stress on first, third, sixth and thirteenth stress day in WKY rats and Wistar rats.To an acute restraint stres, WKY rats showed higher peak CS level compared to Wistar rats. Wistar rats showed decrease in peak CS levels and other CS levels at 30min, 60min and 120min after the beginning of the stress from third stress day, and thereafter the decrement of CS levels were getting greater by thirteenth stress day, whereas WKY rats did not show the decrease in peak CS level by thirteenth stress day, and only CS levels at 120min after the beginning of the stress decreased from third stress day.To measure the stress-induced anxiety, we measures the freezing time after fifteen minits footshock stress. Wistar rats showed reduction of the freezing time from fifth stress day, whereas WKY rats did not show any reduction of the freezing time by thirteenth stress day.These results suggest the sensitivity and the vulnerability of WKY rats to stress. Less