Midline thalamic paraventricular nucleus neurons display diurnal variation in resting membrane potentials, conductances, and firing patterns in vitro
Midline thalamic paraventricular nucleus neurons display diurnal variation in resting membrane potentials, conductances, and firing patterns in vitro
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DOI：
10.1152/jn.00974.2011
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发表时间：
2012-04-01
影响因子：
2.5
通讯作者：
Renaud, Leo P.
中科院分区：
文献类型：
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作者：
Kolaj, Miloslav;Zhang, Li;Renaud, Leo P.
张立，李文.中线丘脑室旁核神经元显示昼夜变化的静息膜电位，电导，和放电模式在体外。J Neurophysiol 107：1835-1844，2012.首次发表于2012年1月4日; doi：10.1152/jn.00974.2011。啮齿类动物中线丘脑室旁核（PVT）的神经元接受脑干和下丘脑已知参与睡眠-觉醒和昼夜节律的网站的输入。为了评估其兴奋性的可能的昼夜变化，我们使用膜片钳技术记录和检查在Zeitgeber时间（ZT）2-6与ZT 14-18制备的冠状大鼠脑切片中前部PVT（aPVT）神经元的特性，并记录在ZT 8.4 +/- 0.2（白天）与ZT 21.2 +/- 0.2（夜晚），主观安静与唤醒状态，分别与在白天记录的神经元相比，从夜间的神经元显着更去极化，并表现出较低的膜电导，部分反映了钾介导的电导损失。此外，这些神经元也明显更加活跃，具有强直性和爆发性放电模式。从每个ZT期的神经元进行了评估的幅度的两个电导已知有助于爆裂行为，即。例如，低阈值激活的Ca ~（2+）电流（I-T）和超极化激活的阳离子电流（I-h）。数据显示，I-T和I-h的振幅在夜间显著较大。此外，来自夜间的活检样本显示Ca（v）3.1和Ca（v）3.3低阈值Ca 2+通道亚型的mRNA显著增加。从夜间记录的神经元也显示出在约-60 mV的膜电位下的自发爆发和超极化诱导的低阈值电流和去极化诱导的电流脉冲引起的爆发放电的相对增强。这些新的体外观察表明，中线丘脑神经元经历昼夜变化，在他们的I-T，I-H，和未定义的钾电导。其基本机制仍有待确定。
Kolaj M, Zhang L, Ronnekleiv OK, Renaud LP. Midline thalamic paraventricular nucleus neurons display diurnal variation in resting membrane potentials, conductances, and firing patterns in vitro. J Neurophysiol 107: 1835-1844, 2012. First published January 4, 2012; doi: 10.1152/jn.00974.2011.-Neurons in the rodent midline thalamic paraventricular nucleus (PVT) receive inputs from brain stem and hypothalamic sites known to participate in sleep-wake and circadian rhythms. To evaluate possible diurnal changes in their excitability, we used patch-clamp techniques to record and examine the properties of neurons in anterior PVT (aPVT) in coronal rat brain slices prepared at zeitgeber time (ZT) 2-6 vs. ZT 14-18 and recorded at ZT 8.4 +/- 0.2 (day) vs. ZT 21.2 +/- 0.2 (night), the subjective quiet vs. aroused states, respectively. Compared with neurons recorded during the day, neurons from the night period were significantly more depolarized and exhibited a lower membrane conductance that in part reflected loss of a potassium-mediated conductance. Furthermore, these neurons were also significantly more active, with tonic and burst firing patterns. Neurons from each ZT period were assessed for amplitudes of two conductances known to contribute to bursting behavior, i. e., low-threshold-activated Ca2+ currents (I-T) and hyperpolarization- activated cation currents (I-h). Data revealed that amplitudes of both I-T and I-h were significantly larger during the night period. In addition, biopsy samples from the night period revealed a significant increase in mRNA for Ca(v)3.1 and Ca(v)3.3 low-threshold Ca2+ channel subtypes. Neurons recorded from the night period also displayed a comparative enhancement in spontaneous bursting at membrane potentials of approximately -60 mV and in burst firing consequent to hyperpolarization-induced low-threshold currents and depolarization-induced current pulses. These novel in vitro observations reveal that midline thalamic neurons undergo diurnal changes in their I-T, I-h, and undefined potassium conductances. The underlying mechanisms remain to be characterized.