Alam N, Szymusiak R, McGinty D
Research Service (151A3), Department of Veterans Affairs Medical Center, Sepulveda, CA 91343, USA.
Brain Res. 1995 Oct 23;696(1-2):221-30. doi: 10.1016/0006-8993(95)00884-s.
Local warming of the medial preoptic/anterior hypothalamus (POAH) promotes sleep, enhances EEG slow-wave activity during sleep, and suppresses arousal-related discharge in neurons of the midbrain reticular formation (MRF) and the posterior lateral hypothalamic area (PLHa). Another important site of sleep and arousal regulation, and a potential site of POAH thermal modulation, is the magnocellular basal forebrain (BF). We examined the ability of local POAH warming during wakefulness to influence the spontaneous and evoked discharge of neurons recorded in the BF of unanesthetized, unrestrained cats. Seventy of 174 BF neurons responded to 60-90 s periods of POAH warming with either increases or decreases in discharge rate. Forty-one of the 70 responsive cells displayed suppression of waking discharge during warming. Discharge rate in these cells declined by an average of 26.04 +/- 2.76%/degrees C of POAH temperature increase. The majority of warming-suppressed BF cells (73%) displayed higher rates of discharge during periods of wakefulness compared to periods of sleep. Twenty-nine of 70 responsive cells responded to POAH warming with an average increase in discharge rate of 43.81 +/- 6.26%/degrees C. A majority of these neurons (62%) exhibited higher spontaneous discharge rates during sleep compared to waking. Orthodromic excitatory responses were evoked in 29 BF cells by electrical stimulation of the MRF or PLHa. Thirteen of 29 cells displayed a waking-related discharge pattern, and responded to POAH warming with a significant suppression of evoked excitation. For a group of 15 behavioral state-indifferent cells (i.e., cells displaying no modulation of spontaneous discharge rate across the sleep-waking cycle), POAH warming had no effect on evoked excitatory responses. These results support the hypothesis that thermosensitive neurons of the POAH exert control of sleep-waking state, in part, via modulation of arousal- and sleep-regulating cell types within the magnocellular BF.
内侧视前区/下丘脑前部（POAH）的局部升温可促进睡眠，增强睡眠期间的脑电图慢波活动，并抑制中脑网状结构（MRF）和下丘脑后外侧区（PLHa）神经元的觉醒相关放电。另一个睡眠和觉醒调节的重要部位，也是POAH温度调节的潜在部位，是大细胞基底前脑（BF）。我们研究了清醒状态下POAH局部升温对未麻醉、未束缚猫BF中记录的神经元自发和诱发放电的影响。174个BF神经元中有70个对POAH升温60 - 90秒的反应是放电率增加或减少。70个反应性细胞中有41个在升温期间显示出觉醒放电受到抑制。这些细胞的放电率随着POAH温度每升高1℃平均下降26.04 +/- 2.76%。与睡眠期间相比，大多数升温抑制的BF细胞（73%）在清醒期间放电率更高。70个反应性细胞中有29个对POAH升温的反应是放电率平均增加43.81 +/- 6.26%/℃。这些神经元中的大多数（62%）与清醒相比，在睡眠期间表现出更高的自发放电率。通过对MRF或PLHa进行电刺激，在29个BF细胞中诱发了顺向兴奋性反应。29个细胞中有13个表现出与觉醒相关的放电模式，并对POAH升温有明显的诱发兴奋抑制反应。对于一组15个行为状态无差异的细胞（即，在睡眠 - 觉醒周期中自发放电率无调节的细胞），POAH升温对诱发的兴奋性反应没有影响。这些结果支持了这样的假设，即POAH的热敏神经元部分地通过调节大细胞BF内的觉醒和睡眠调节细胞类型来控制睡眠 - 觉醒状态。
