CAJ | 학술논문

探讨慢性应激对大鼠海马Akt／FKHRL1信号通路活性的影响，及其应激源特异性。将24只雄性SD大鼠随机分为心理应激组、束缚应激组和正常对照组（n=8）。用Western-blotting方法测定28天应激后海马Akt、FKHRL1蛋白含量及其磷酸化水平。结果表明，应激后三组大鼠海马磷酸化Akt、FKHRL1含量差异有统计学意义（P〈0．01；p〈0．001），束缚应激组低于正常对照组（p〈0．01）。提示慢性应激能导致海马磷酸化Akt、FKHRL1表达水平降低，但其影响程度与应激源特异性有关。
탐토만성응격대대서해마Akt／FKHRL1신호통로활성적영향，급기응격원특이성。장24지웅성SD대서수궤분위심리응격조、속박응격조화정상대조조（n=8）。용Western-blotting방법측정28천응격후해마Akt、FKHRL1단백함량급기린산화수평。결과표명，응격후삼조대서해마린산화Akt、FKHRL1함량차이유통계학의의（P〈0．01；p〈0．001），속박응격조저우정상대조조（p〈0．01）。제시만성응격능도치해마린산화Akt、FKHRL1표체수평강저，단기영향정도여응격원특이성유관。
Introduction There is now a substantial body of evidence which suggests that chronic stress can increase susceptibility to disease such as depression and posttraumatic stress disorder. Chronic stress induces neuronal atrophy and death in the cortex as well as in the hippocampus. The proto - oncogene protein kinase B （PKB）, also known as Akt, is a central player in a signaling pathway of which many components have been linked to cellular survival. Akt as well as of its downstream targets Forkhead transcription factors （forkhead homologue in rhabdomyosarcoma, FKHR） have emerged in recent years as cardinal pathway underlying cellular survival and opposing apoptosis in neurons. But the activation of Akt/FKHRL signaling pathway after chronic stress in the brain remains poorly defined. We hypothesized that repeated immobilization stress exposure may change the levels of phosphorylation of Akt （pAkt） and FKHRL1 （pFKHRL1） in the rat hippocampus. The study was designed to analyze the effect of chronic stress on activation of Akt/FKHRL1 signaling pathway in the rat hippocampus. Methods Twenty four male Sprague Downey rats （280 ±20）g were purchased from Shanghai Laboratory Animal Center, Chinese Academy Sciences and were used for all experiments. Rats were randomly divided into three groups： psychologically stressed group, immobilization stressed group, and controls. Each group contained eight rats. Animals were housed in groups of 4 under standard laboratory conditions in temperature - controlled rooms （24℃）, and maintained on a 12 h light/dark cycle （lights on at 08.00） with food pellets and water available ad libitum. Rats of the two stressed groups were subjected to immobilization stress or psychological stress one hour per day for 28 consecutive days, respectively. At the end of the experimental period, the animals were decapitated and their hippocampi were rapidly removed and kept at - 80℃ until analysis. The protein level of Akt, FKHRL1 and phosphorylation of Akt, FKHRL1 were determined by Western - blotting. The intensities of the bands corresponding to the protein of interest were quantified using scanning densitometry and compared using t tests or one - way ANOVA as appropriate. The adrenal gland and thymus gland index were also calculated at the day after 28 - day - stress modeling. Organ index = wet weight/weight of rat 100. The statistical significance was determined at p 〈 0.05. Results Totally 24 rats were involved in the analysis. The avoirdupois and the organ index of the stressed groups were significantly changed comparing to the controls. There was no significant difference in Akt and FKHRL1 levels of hippocampus among three groups. The phosphorylation of Akt and FKHRL1 had significant difference among the three groups （F = 13.75, p 〈 0.01; F =28.60, p 〈0.001, respectively）. The phosphorylation of Akt and FKHRL1 in immobilization stressed group was decreased than that in control group （p 〈 0.01 ）. In contrast, the levels of the phosphorylation of Akt and FKHRL1 show no significant deference between the psychological stressed group and controls. Conclusions These results suggest that chronic immobilization stress can induce more significant decrease of phospho- Akt and phospho - FKHRL1 level in the rat hippocampus. Activation of Akt/FKHRL1 signaling pathway may be an effective biological predictor for change of structure or function of hippocampus induced by chronic stress.