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

1.急性和反复约束应激诱导c-fos mRNA表达的应变比较。Wistar Kyoto （WKY）大鼠和Wistar大鼠分别进行1、3、7、14 d的限制性应激。采用原位杂交法检测应激诱导大鼠室旁核（PVN）和蓝斑核（LC）中c-fos mRNA的表达。在急性约束应激下，WKY大鼠和Wistar大鼠PVN和LC中c-fos mRNA表达相似。如前所述，Wistar大鼠应激第3天PVN和LC中应激诱导的c-fos mRNA表达量均显著下降，此后应激诱导的c-fos mRNA表达量逐渐下降。WKY大鼠在重复约束应激下，PVN和LC中均表现出相似的应激诱导的c-fos mRNA表达下降模式。在WKY大鼠PVN和LC中，给予抗抑郁药丙咪嗪两周并重复1h约束应激，对应激诱导的c-fos mRNA表达的减少没有影响。这些结果表明，WKY大鼠对应激不敏感，易受应激影响。下丘脑轴应激反应与应激性焦虑的应变比较。测定WKY大鼠和Wistar大鼠在应激第1、3、6、13天约束应激2h时的血浆皮质酮（CS）水平。在急性约束应激下，WKY大鼠的CS峰值高于Wistar大鼠。Wistar大鼠在应激第3天开始后30min、60min和120min的CS峰值水平和其他CS水平下降，此后到应激第13天CS水平下降幅度更大，而WKY大鼠在应激第13天未出现CS峰值水平下降，仅应激第3天开始后120min CS水平下降。为了测量应激性焦虑，我们测量了脚震应激15分钟后的冻结时间。Wistar大鼠从应激第5天开始冻结时间减少，而WKY大鼠到应激第13天冻结时间没有减少。这些结果提示WKY大鼠对应激的敏感性和易感性。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