Okada Kazuyuki, Yano Masahiko, Doki Yuichiro, Azama Takashi, Iwanaga Hiroshi, Miki Hirofumi, Nakayama Mitsuo, Miyata Hiroshi, Takiguchi Shuji, Fujiwara Yoshiyuki, Yasuda Takushi, Ishida Norio, Monden Morito
Department of Surgery, Gastroenterological Surgery, Graduate School of Medicine, Osaka University, Suita, Japan.
J Surg Res. 2008 Mar;145(1):5-12. doi: 10.1016/j.jss.2007.01.010.
The biological clock regulates circadian rhythm and is important for sustaining homeostasis. Here we examined the response of biological clock genes to systemic inflammatory stimulation.
At 08:00 h (= Zeitgeber time [ZT] 01), male Wistar rats (7-wk-old) maintained on a 12:12 h light:dark cycle (light on 07:00-19:00 h) received intravenous injection of 1 mg/kg lipopolysaccharide (LPS group) or 0.3 mL saline (control group). They were then sacrificed every 4 h (09:00 h = ZT 02, 13:00 h = ZT 06, 17:00 h = ZT 10, 21:00 h = ZT 14, 01:00 h = ZT 18, 05:00 h = ZT 22) over a 2-d period, and blood, brain, and liver samples were obtained for analysis (n = 4 at each time for each group). The expression levels of clock gene, rPer2, and those of clock controlled gene, rDBP, were quantified in the suprachiasmatic nucleus by in situ hybridization, while those of rPer1, rPer2, rDBP, rPPARA, and rFKBP51 in the liver were determined by quantitative RT-PCR.
In the suprachiasmatic nucleus of control rats, rPer2 and rDBP mRNA expression levels showed robust circadian patterns with peak levels at ZT 06 and ZT 10, respectively. LPS significantly suppressed both genes on day 1 but recovery was noted on day 2. Similarly, LPS significantly suppressed rPer1, rPer2, rDBP, rPPARA, and rFKBP51 mRNA expression levels in the liver on day 1 but recovery was noted on day 2, whereas a robust circadian pattern was noted in the control group.
Our results indicate that LPS causes transient suppression of the biological clock genes and suggest that the biological clock plays an important role in the response to systemic inflammatory stimulation.
生物钟调节昼夜节律，对维持体内平衡至关重要。在此，我们研究了生物钟基因对全身炎症刺激的反应。
在上午8点（即时间geber时间[ZT]01），将维持12:12小时光照：黑暗周期（光照时间为07:00 - 19:00小时）的7周龄雄性Wistar大鼠静脉注射1mg/kg脂多糖（LPS组）或0.3mL生理盐水（对照组）。然后在2天的时间内每隔4小时（上午9点 = ZT 02，下午1点 = ZT 06，下午5点 = ZT 10，晚上9点 = ZT 14，凌晨1点 = ZT 18，凌晨5点 = ZT 22）处死大鼠，采集血液、脑和肝脏样本进行分析（每组每次时间点n = 4）。通过原位杂交定量视交叉上核中生物钟基因rPer2以及生物钟调控基因rDBP的表达水平，同时通过定量逆转录聚合酶链反应测定肝脏中rPer1、rPer2、rDBP、rPPARA和rFKBP51的表达水平。
在对照大鼠的视交叉上核中，rPer2和rDBP mRNA表达水平呈现出强烈的昼夜节律模式，峰值水平分别在ZT 06和ZT 10。LPS在第1天显著抑制了这两个基因，但在第2天观察到恢复。同样，LPS在第1天显著抑制了肝脏中rPer1、rPer2、rDBP、rPPARA和rFKBP51 mRNA表达水平，但在第2天观察到恢复，而对照组呈现出强烈的昼夜节律模式。
我们的结果表明，LPS会导致生物钟基因的短暂抑制，并提示生物钟在对全身炎症刺激的反应中起重要作用。
