Daily and Circadian Variations in 2‐[125I]‐Iodomelatonin Binding Sites in the Pike Brain (Esox Iucius)
Daily and Circadian Variations in 2‐[125I]‐Iodomelatonin Binding Sites in the Pike Brain (Esox Iucius)
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梭子鱼脑中 2-[125I]-碘褪黑素结合位点的每日和昼夜变化 (Esox Iucius)
DOI：
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发表时间：
1998
影响因子：
3.2
通讯作者：
J. Falcón
中科院分区：
文献类型：
--
作者：
P. Gaildrat;B. Ron;J. Falcón
鱼类松果体器官通过其24小时节律性释放褪黑激素，作为光周期的传感器，影响不同的生理功能（如繁殖、生长）。我们研究了2‐[125I]碘化褪黑素在不同光周期条件下维持24-48小时的刺鱼（Esox lucius L., teleost）的全脑膜制剂中的结合。特异性结合是稳定的，可逆的，饱和的，并且对GTP类似物的存在敏感。Scatchard分析揭示了一类结合位点。置换实验表明，在飞摩尔和纳摩尔浓度范围内存在两种亲和成分。Bmax表现为单相夜间变化，在明暗转换时值较高（34.0±4.5 fmol/mg蛋白），而在后半夜时值较低（10.0±1.0 fmol/mg蛋白）。在相同条件下，KD表现出双相变化：白天和暗相中期（约100 pM）值较低；它们在晚上开始时（大约下午225点）和结束时（大约晚上330点）都很高。这些变化在恒定光照（LL）和恒定黑暗（DD）条件下保持不变。因此，褪黑激素结合位点的数量和亲和力的变化是由昼夜节律振荡器控制的，由光周期同步。这些振子的性质尚不清楚。因此，在鱼类中，我们认为褪黑激素的光依赖性效应是由松果体及其在大脑中的结合位点产生的昼夜变化引起的。
The fish pineal organ, through its 24 h rhythmic release of melatonin, acts as a transducer of the photoperiod, influencing different physiological functions (e.g. reproduction, growth). We have investigated the binding of 2‐[125I]iodomelatonin to whole brain membrane preparations from pikes (Esox lucius L., teleost) maintained for 24–48 h under different photoperiodic conditions. Specific binding was stable, reversible, saturable and sensitive to the presence of a GTP analogue. Scatchard analysis revealed one class of binding sites. Displacement experiments suggested the presence of two components with affinities in the femtomolar and nanomolar range of concentrations, respectively. The Bmax exhibited monophasic nycthemeral variations, with higher values at the light‐to‐dark transition (34.0±4.5 fmol/mg protein) and low values during the second half of night (10.0±1.0 fmol/mg protein). Under the same conditions, the KD exhibited biphasic variations: values were low during daytime and at the middle of the dark phase (approximately 100 pM); they were high at the beginning (approximately 225 pM) and at the end (approximately 330 pM) of the night. These variations were maintained under constant light (LL) and constant darkness (DD). Thus, the variations in the number and affinity of the melatonin binding sites were controlled by circadian oscillators, synchronized by the photoperiod. The nature of these oscillators is not known. Therefore, in fish, we suggest that the photodependent effects of melatonin result from the circadian variations of both its production by the pineal and its binding sites in the brain.
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影响因子：
4.8
作者：
S. Rivkees;Vincent M. Cassone;D. Weaver;S. Reppert
通讯作者：
S. Rivkees;Vincent M. Cassone;D. Weaver;S. Reppert
DOI：
10.1073/pnas.91.13.6133
发表时间：
1994-06-21
影响因子：
11.1
作者：
EBISAWA, T;KARNE, S;REPPERT, SM
通讯作者：
REPPERT, SM
从大鼠大脑皮质膜中溶解的腺苷 Ri 受体的流体动力学特性。
DOI：
10.1042/bj2480635
发表时间：
1987
期刊：
The Biochemical journal
影响因子：
--
作者：
Yeung,SM;Perez-Reyes,E;Cooper,DM
通讯作者：
Cooper,DM
DOI：
10.1073/pnas.84.11.3916
发表时间：
1987-06-01
影响因子：
11.1
作者：
DUBOCOVICH, ML;TAKAHASHI, JS
通讯作者：
TAKAHASHI, JS
蜥蜴大脑中褪黑激素受体的溶解和纯化。
影响因子：
4.8
作者：
Rivkees,SA;ConronJr,RW;Reppert,SM
通讯作者：
Reppert,SM