Sani Mamane, Sebaï Hichem, Gadacha Wafa, Boughattas Naceur A, Reinberg Alain, Mossadok Ben Attia
Unité de Toxicométrie et Chronobiométrie, Laboratoire de Biosurveillance de l'Environnement, Faculté des Sciences de Bizerte, 7021 Zarzouna, Tunisie.
Comp Biochem Physiol B Biochem Mol Biol. 2006 Nov-Dec;145(3-4):331-7. doi: 10.1016/j.cbpb.2006.08.005. Epub 2006 Sep 3.
To protect tissues from damaging effects of reactive oxygen species (ROS), organisms possess enzymatic and non-enzymatic antioxidant systems. Cytosolic-enzyme catalase (CAT) is a component of the antioxidant defence system that reduces hydrogen peroxide (H(2)O(2)) to water (H(2)O). The aim of this study was to assess the variation of antioxidant enzyme CAT activity in brain, kidney and liver of adult male mice according to tissue-specific and temporal patterns within a 24-h period (12:12 L/D). The CAT activity was assayed at 4-h intervals. The Cosinor test programme was used to detect and confirm the best corresponding rhythm. In liver, the circadian rhythm of CAT was associated with ultradian components. The prominent circadian rhythm (with a period tau=24 h) showed a peak located at the middle of the dark phase, more precisely congruent with 17 HALO (Hours After Light Onset). In kidney, only a circadian rhythm of CAT was validated with a peak time located at congruent with 17 HALO. However, in brain, the time pattern of CAT activity showed two peak times at congruent with 1 and congruent with 17 HALO, illustrating the existence of an ultradian rhythm (with a period tau=12 h). The results showed significant organ differences with the highest activity in liver, compared with kidney (-89%) and brain (-98%). This might be related to several factors such as their respective physiological function, the risk of exposure to oxidative damage and the balance between synthesis and degradation of proteins during "normal metabolism". Moreover, CAT activity revealed differences in time-related changes across a 24-h period that were more obvious in peak levels between the three tissues.
为保护组织免受活性氧（ROS）的损伤作用，生物体拥有酶促和非酶促抗氧化系统。胞质酶过氧化氢酶（CAT）是抗氧化防御系统的一个组成部分，可将过氧化氢（H₂O₂）还原为水（H₂O）。本研究的目的是根据成年雄性小鼠在24小时周期（12:12光/暗）内的组织特异性和时间模式，评估其脑、肾和肝中抗氧化酶CAT活性的变化。每隔4小时测定一次CAT活性。使用余弦分析测试程序来检测和确认最佳对应节律。在肝脏中，CAT的昼夜节律与超日节律成分相关。显著的昼夜节律（周期τ = 24小时）显示一个峰值位于黑暗期中间，更准确地与光照开始后17小时（HALO）一致。在肾脏中，仅验证了CAT的昼夜节律，峰值时间与17 HALO一致。然而，在脑中，CAT活性的时间模式显示在与1 HALO和17 HALO一致时有两个峰值时间，表明存在超日节律（周期τ = 12小时）。结果显示器官间存在显著差异，肝脏中的活性最高，与肾脏（-89%）和脑（-98%）相比。这可能与多种因素有关，如它们各自的生理功能、暴露于氧化损伤的风险以及“正常代谢”期间蛋白质合成与降解之间的平衡。此外，CAT活性在24小时周期内显示出与时间相关变化的差异，在三个组织的峰值水平之间更为明显。
