快速眼动睡眠剥夺大鼠中缝背核内galanin阳性神经元表达及抑郁行为的研究

目的:研究不同时间快速眼动睡眠剥夺大鼠中缝背核内galanin阳性神经元的表达,抑郁行为的变化以及两者间的相互关系。方法:SD大鼠,雄性,采用完全随机对照分组:正常对照组,24h快速眼动睡眠剥夺组,48h快速眼动睡眠剥夺组,72h快速眼动睡眠剥夺组。用小平台水环境法建立快速眼动睡眠剥夺大鼠模型,正常对照组大鼠常规饲养。分别对各组大鼠进行强迫游泳实验,悬尾实验,记录抑郁行为得分;然后对各组大鼠脑片进行免疫荧光组化染色,检测中缝背核内galanin阳性神经元的表达。结果:各快速眼动睡眠剥夺组大鼠抑郁行为的得分较正常对照组均增高,尤以72h快速眼动睡眠剥夺组的得分较高,同时,各快速眼动睡眠剥夺组大鼠中缝背核内galanin阳性神经元的数量较正常对照组均增多,尤其以72h快速眼动睡眠剥夺组阳性神经元的表达增多显著。结论:galanin参与快速眼动睡眠剥夺发生后的生物学效应,中缝背核内galanin阳性神经元的表达上调可能与快速眼动睡眠剥夺大鼠抑郁行为的变化有关。     

5-羟色胺3A受体在成年小鼠海马中间神经元中的分布

目的:利用成年5-HT3AR-BACEGFP转基因小鼠,研究5-羟色胺3A受体(5-HT3AR)在海马中间神经元中的分布情况。方法:成年5-HT3AR-BACEGFP转基因小鼠经心脏灌注固定后,利用免疫荧光双标记方法,并结合激光共焦显微镜扫描技术,观察5-HT3AR在成年5-HT3AR-BACEGFP转基因小鼠海马中不同中间神经元内的表达和分布情况。结果:5-HT3AR在成年小鼠整个海马中都有分布,且主要在CA1区、CA2/CA3区和齿状回有大量5-HT3AR免疫阳性细胞;激光共聚焦显微镜下观察到5-HT3AR阳性产物在细胞核、细胞浆和树突上均有表达;免疫荧光双标实验结果表明5-HT3AR阳性产物在CB(calbindin),CR(calretinin),Reelin,Som(somatostatin),NPY(neuropeptide Y)和VIP(vasoactive intestinal peptide)免疫阳性神经元中表达,但在PV(parvalbumin)免疫阳性神经元中不表达。定量结果显示:几乎所有的VIP阳性神经元均表达5-HT3AR阳性,约3/4的CR阳性神经元表达5-HT3AR,约1/2的CB、Reelin、NPY和Som阳性神经元表达5-HT3AR阳性;约1/4的5-HT3AR阳性神经元中表达Reelin,1/5的表达Som,5-HT3AR/CB和5-HT3AR/CR双标神经元各占5-HT3AR阳性神经元的1/10左右。结论:5-HT3AR-BACEGFP转基因小鼠能够作为研究海马中5-HT3AR功能及其在中间神经元中的作用机制研究的工具鼠。     

5-HT1A受体亚型与P物质、Ⅰ型囊泡膜谷氨酸转运体和甘丙肽在大鼠背根神经节神经元中的共表达

为探讨5-HT1A受体亚型参与感觉信息调控的机制,本文利用免疫荧光组织化学双重染色技术观察了该受体亚型与P物质(SP)、I型囊泡膜谷氨酸转运体(VGLUT1)和甘丙肽(Gal)在大鼠背根神经节(DRG)神经元内的共存状况。结果表明:5-HT1A受体亚型阳性神经元占DRG神经元总数的46.2%,阳性神经元以大型及小型神经元为主。在DRG内观察到了5-HT1A/SP、5-HT1A/VGLUT1以及5-HT1A/Gal双标神经元。其中5-HT1A/SP双标神经元占5-HT1A受体亚型阳性神经元的34.6%,占SP阳性神经元的72.0%;5-HT1A/VGLUT1双标神经元占5-HT1A受体亚型阳性神经元的24.1%,占VGLUT1阳性神经元的18.5%;5-HT1A/Gal双标神经元占5-HT1A免疫阳性神经元的17.6%,占Gal免疫阳性神经元的63.8%。5-HT1A/SP和5-HT1A/Gal双标神经元主要为DRG的小型神经元,而5-HT1A/VGLUT1双标神经元主要为大、中型神经元。上述结果提示,5-HT1A受体亚型可能通过调节SP、谷氨酸以及Gal在初级传入终末及外周神经末稍的释放发挥其感觉信息的调节作用。     

阻断Notch信号通路降低1-甲基-4苯基-1,2,3,6-四氢吡啶诱导的多巴胺能神经元损伤

目的探讨Notch信号通路的缺失对1-甲基-4苯基-1,2,3,6-四氢吡啶(MPTP)诱导的中脑多巴胺能神经元损伤的影响。方法选用5月龄TH-Cre Rbpj基因敲除小鼠及野生型小鼠共48只,腹腔注射MPTP建立帕金森病(PD)模型,通过行为学、免疫组织化学和Western blotting等方法研究阻断Notch信号通路对MPTP诱导的中脑黑质多巴胺能神经元损伤的影响。结果 MPTP处理的Rbpj CKO小鼠运动能力强于MPTP处理的野生型小鼠;Rbpj CKO小鼠黑质致密部神经元数目较野生型小鼠减少;MPTP处理后,野生型小鼠多巴胺能神经元数目明显下降,而Rbpj CKO小鼠多巴胺能神经元数目无明显改变;Western blotting结果显示,MPTP处理后Rbpj CKO小鼠和野生型小鼠Notch-1胞内结构域(NICD-1)的表达均明显增加,且Rbpj CKO小鼠表达量增加更为显著。结论Notch信号通路缺失导致多巴胺能神经元数量减少,阻断Notch信号通路可以降低MPTP诱导的多巴胺能神经元损伤。     

大鼠中缝背核向缰核投射的5-羟色胺能神经元对躯体伤害性刺激的fos表达

用WGA-HRP逆行追踪与抗FOS和抗5-羟色胺免疫组化的三重标记方法,观察向大鼠一侧有前跖部皮下注射8%福尔马林50μl后,中缝背核至缰核5-羟色胺能神经元的FOS表达.光镜下发现中缝背核内有七种阳性神经元.即HRP、FOS、5-HT单标细胞;FOS/HRP、FOS/5-HT、HRP/5-HT双标细胞;FOS/HRP/5-HT三标细胞.结果表明中缝背核至缰核的5-HT能投射神经元对躯体伤害性刺激起反应.     

GAD67-GFP基因敲入小鼠三叉上核内向三叉神经运动核投射的GFP阳性神经元表达c-fos的研究

本文综合应用逆行束路追踪(将四甲基罗达明-TMR注入一侧三叉神经运动核)和免疫荧光组织化学三重标记技术,在激光共聚焦显微镜下对谷氨酸脱羧酶67-绿色荧光蛋白(GAD67-GFP)基因敲入小鼠在口周部给予伤害性刺激时,三叉上核(Vsup)内向对侧三叉神经运动核(Vmo)投射的呈GFP阳性的GABA能神经元表达c-fos的情况进行了研究。结果显示:(1)Vsup内可观察到许多GFP阳性神经元,细胞较小;(2)也可观察到许多TMR或c-fos单标神经元较密集地分布于Vsup内,其中c-fos阳性产物只见于神经元的胞核,在胞浆内未见表达;(3)在激光共聚焦显微镜下可进一步观察到部分神经元同时呈GFP/TMR、TMR/c-fos、GFP/c-fos双重标记或GFP/TMR/c-fos三重标记。其中GFP/TMR双标神经元分别占GFP或TMR阳性神经元的17.8%和19.2%;TMR/c-fos双标神经元分别占TMR或c-fos阳性神经元的34.9%和31.3%;GFP/c-fos双标神经元分别占GFP或c-fos阳性神经元的21.2%和20.5%;而GFP/TMR/c-fos三标神经元分别占GFP、TMR或c-fos阳性神经元的11.1%、12%和10.8%。以上结果表明小鼠Vsup内部分GABA能神经元可接受来自同侧的口面部伤害性信息,并对这些信息进行整合后,直接发出投射纤维至Vmo;故Vsup内部分GABA能运动前神经元可能参与口面部伤害性反射局部环路的构成。     

Wnt/β-catenin信号介导的小鼠海马神经元发生参与睡眠剥夺引起的学习记忆下降

目的:研究睡眠剥夺对小鼠行为及海马神经元发生的影响。从Wnt/β-catenin信号的角度探索其相关的分子机制,以及干预Wnt/β-catenin信号的改善作用。方法:采用改良多平台水环境法制作小鼠睡眠剥夺模型(SD)。利用Brd U/DCX免疫荧光双标研究海马神经元发生;采用Wnt信号报告基因Topgal小鼠研究Wnt信号的改变;利用Nestin/ROSA/EX3基因修饰小鼠研究激活Wnt信号对睡眠剥夺小鼠海马神经元发生及学习记忆的影响;采用高架十字迷宫和旷场实验评估小鼠的焦虑情绪;运用Morris水迷宫评估小鼠的空间学习记忆能力。结果:与正常小鼠相比,SD处理组小鼠无焦虑样行为,但空间学习记忆能力显著下降。Brd U/DCX免疫荧光双标染色显示SD 5 d后小鼠海马神经元发生明显减弱。Wnt信号报告基因β-gal在海马神经干细胞表达降低。在Nestin/ROSA/EX3基因修饰小鼠激活Wnt信号后,可显著促进海马神经元发生,并改善SD小鼠的空间记忆能力。结论:Wnt/β-catenin信号参与睡眠剥夺引起的小鼠海马神经元发生减弱,增强Wnt信号可改善SD小鼠海马的神经元发生及其学习记忆能力。     

大小鼠睡眠剥夺动物模型建立及其进展

正常的睡眠保障了人体的发育并维持了人的生理功能,然而现实生活中由于不同的生活压力或不良的睡眠习惯,越来越多的人出现了睡眠不足和睡眠质量下降的表现。不良睡眠会影响心血管健康、心理健康,引起认知和记忆巩固障碍、免疫力下降。研究睡眠不足影响的常用方法是睡眠剥夺。经典的睡眠剥夺方法包括完全睡眠剥夺和快速眼动睡眠剥夺。除了经典的睡眠剥夺方法,目前有研究人员通过调节睡眠-觉醒环路来实现睡眠剥夺,也有不少研究人员观察疼痛模型中睡眠-觉醒周期的变化。本文综述了睡眠剥夺大、小鼠模型建立及其进展。     

睡眠剥夺促进大鼠海马神经元凋亡及相关基因表达

探讨睡眠剥夺引起的神经元凋亡与相关基因表达的变化。采用TUNEL染色观察了快眼动睡眠剥夺大鼠海马神经元形态学变化,应用原位杂交、Western blot法检测了快眼动睡眠剥夺大鼠海马bcl-2,bax mRNA,MAPKs表达的变化。结果表明：快眼动睡眠剥夺大鼠海马CAl,CA3区神经元阳性凋亡细胞数明显增多,bcl-2,bax mRNA表达明显增强,ERK活性降低,JNK蛋白表达量较对照组明显增高。提示睡眠剥夺可引起大鼠海马神经元凋亡。与凋亡相关的bcl-2,bax mRNA基因表达及MAPKs活性的变化可能涉及神经元的凋亡机制。     

大鼠前庭神经核复合体内5-HT能终末与表达5-HT1A受体的前庭-臂旁核投射神经元之间的联系

目的 观察大鼠前庭神经核复合体(VNC)内5-羟色胺(5-HT)样阳性终末与表达5-HT1A受体(5-HT1A R)的前庭-臂旁核投射神经元之间的联系.方法 运用逆行束路追踪和免疫荧光组织化学染色相结合的双重标记技术,在激光共焦显微镜下观察.结果 将四甲基罗达明(TMR)注入臂旁核后,在双侧VNC的各个核团内均可观察到许多TMR逆标神经元,但以同侧为主.免疫荧光组织化学染色结果显示,在前庭内侧核(MVe)、前庭下核(SpVe)、前庭上核(SuVe)、前庭外侧核(LVe)、X核以及Y核的一些区域内,许多神经元表达5-HT1A R样免疫阳性,并可观察到大量5-HT样阳性纤维和终末.激光共焦显微镜下可进一步观察到一些TMR逆标神经元同时呈5-HT1A R样免疫阳性,且有部分5-HT样阳性终末与TMR/5-HT1A R双标神经元的胞体或树突形成密切接触.结论 提示5-HT可能通过5-HT1A R对前庭神经核复合体-臂旁核间的信息传递发挥调控作用.     

Orexin Neurons Are Necessary for the Circadian Control of REM Sleep

Study Objectives:

The orexin-producing neurons are hypothesized to be essential for the circadian control of sleep/wake behavior, but it remains unknown whether these rhythms are mediated by the orexin peptides or by other signaling molecules released by these neurons such as glutamate or dynorphin. To determine the roles of these neurotransmitters, we examined the circadian rhythms of sleep/wake behavior in mice lacking the orexin neurons (ataxin-3 [Atx] mice) and mice lacking just the orexin neuropeptides (orexin knockout [KO] mice).

Design:

We instrumented mice for recordings of sleep-wake behavior, locomotor activity (LMA), and body temperature (T_b) and recorded behavior after 6 days in constant darkness.

Results:

The amplitude of the rapid eye movement (REM) sleep rhythm was substantially reduced in Atx mice but preserved in orexin KO mice. This blunted rhythm in Atx mice was caused by an increase in the amount of REM sleep during the subjective night (active period) due to more transitions into REM sleep and longer REM sleep episodes. In contrast, the circadian variations of T_b, LMA, Wake, non-REM sleep, and cataplexy were normal, suggesting that the circadian timekeeping system and other output pathways are intact in both Atx and KO mice.

Conclusions:

These results indicate that the orexin neurons are necessary for the circadian suppression of REM sleep. Blunting of the REM sleep rhythm in Atx mice but not in orexin KO mice suggests that other signaling molecules such as dynorphin or glutamate may act in concert with orexins to suppress REM sleep during the active period.

Citation:

Kantor S; Mochizuki T; Janisiewicz AM; Clark E; Nishino S; Scammell TE. Orexin neurons are necessary for the circadian control of REM sleep. SLEEP 2009;32(9):1127-1134.     

High‐amplitude theta wave bursts characterizing narcoleptic mice and patients are also produced by histamine deficiency in mice

Histamine and orexins are wake promoters released by hypothalamic neurons. The activity of histamine neurons is increased by orexin neurons. Recently, it has been shown that orexin deficiency entails high‐amplitude theta wave bursts during rapid eye movement sleep and cataplexy in narcoleptic mice. The primary aim of this study was to assess whether histamine system is involved in high‐amplitude theta wave burst generation during rapid eye movement sleep. The secondary aim was to assess the effects of combined histamine and orexin deficiency on high‐amplitude theta wave bursts during rapid eye movement sleep in mice. Twelve histidine‐decarboxylase knockout mice with congenital histamine deficiency, seven double mutant mice with combined deficiency of orexin neurons and histamine, and 11 wild‐type control mice were studied with electrodes for sleep recordings and a telemetric blood pressure transducer. High‐amplitude theta wave bursts during rapid eye movement sleep were detected in each of the histidine‐decarboxylase knockout and double mutant mice, whereas only one burst was found in a wild‐type control mouse. High‐amplitude theta wave bursts occurred significantly more often and were significantly longer in double mutant than in histidine‐decarboxylase knockout mice. In conclusion, it was demonstrated that, similarly to orexin, the chronic impairment of histamine entailed high‐amplitude theta wave bursts during rapid eye movement sleep. The current data also suggested a synergistic role of orexin and histamine signalling on high‐amplitude theta wave bursts during rapid eye movement sleep in mice.     

Modafinil more effectively induces wakefulness in orexin-null mice than in wild-type littermates

Narcolepsy—cataplexy, a disorder of excessive sleepiness and abnormalities of rapid eye movement (REM) sleep, results from deficiency of the hypothalamic orexin (hypocretin) neuropeptides. Modafinil, an atypical wakefulness-promoting agent with an unknown mechanism of action, is used to treat hypersomnolence in these patients. Fos protein immunohistochemistry has previously demonstrated that orexin neurons are activated after modafinil administration, and it has been hypothesized that the wakefulness-promoting properties of modafinil might therefore be mediated by the neuropeptide. Here we tested this hypothesis by immunohistochemical, electroencephalographic, and behavioral methods using modafinil at doses of 0, 10, 30 and 100 mg/kg i.p. in orexin^−/− mice and their wild-type littermates. We found that modafinil produced similar patterns of neuronal activation, as indicated by Fos immunohistochemistry, in both genotypes. Surprisingly, modafinil more effectively increased wakefulness time in orexin^−/− mice than in the wild-type mice. This may reflect compensatory facilitation of components of central arousal in the absence of orexin in the null mice. In contrast, the compound did not suppress direct transitions from wakefulness to REM sleep, a sign of narcolepsy–cataplexy in mice. Spectral analysis of the electroencephalogram in awake orexin^−/− mice under baseline conditions revealed reduced power in the θ band frequencies (8–9 Hz), an index of alertness or attention during wakefulness in the rodent. Modafinil administration only partly compensated for this attention deficit in the orexin null mice. We conclude that the presence of orexin is not required for the wakefulness-prolonging action of modafinil, but orexin may mediate some of the alerting effects of the compound.     

Running promotes wakefulness and increases cataplexy in orexin knockout mice

STUDY OBJECTIVE: People with narcolepsy and mice lacking orexin/hypocretin have disrupted sleep/wake behavior and reduced physical activity. Our objective was to identify physiologic mechanisms through which orexin deficiency reduces locomotor activity. DESIGN: We examined spontaneous wheel running activity and its relationship to sleep/wake behavior in wild type (WT) and orexin knockout (KO) mice. Additionally, given that physical activity promotes alertness, we also studied whether orexin deficiency reduces the wake-promoting effects of exercise. MEASUREMENTS AND RESULTS: Orexin KO mice ran 42% less than WT mice. Their ability to run appeared normal as they initiated running as often as WT mice and ran at normal speeds. However, their running bouts were considerably shorter, and they often had cataplexy or quick transitions into sleep after running. Wheel running increased the total amount of wakefulness in WT and orexin KO mice similarly, however, KO mice continued to have moderately fragmented sleep/wake behavior. Wheel running also doubled the amount of cataplexy by increasing the probability of transitioning into cataplexy. CONCLUSIONS: Orexin KO mice run significantly less than normal, likely due to sleepiness, imminent cataplexy, or a reduced motivation to run. Orexin is not required for the wake-promoting effects of wheel running given that both WT and KO mice had similar increases in wakefulness with running wheels. In addition, the clear increase in cataplexy with wheel running suggests the possibility that positive emotions or reward can trigger murine cataplexy, similar to that seen in people and dogs with narcolepsy.     

A critical role of hypocretin deficiency in pregnancy

Hypocretin/orexin peptides are known for their role in the control of the wake–sleep cycle and narcolepsy–cataplexy pathophysiology. Recent studies suggested that hypocretin peptides also have a role in pregnancy. We tested this hypothesis by conducting a retrospective analysis on pregnancy complications in two different mouse models of hypocretin deficiency. We recorded 85 pregnancies of mice lacking either hypocretin peptides (knockout) or hypocretin‐releasing neurons (transgenic) and their wild‐type controls. Pregnancy was associated with unexplained dam death before delivery in 3/15 pregnancies in knockout mice, and in 3/23 pregnancies in transgenic mice. No casualties occurred in wild‐type pregnant dams (P < 0.007 versus hypocretin‐deficient mice as a whole). Hypocretin deficiency did not impact either on litter size or the number of weaned pups per litter. These data provide preliminary evidence of a critical role of hypocretin deficiency in pregnancy.     

The effects of 1 week of REM sleep deprivation on parvalbumin and calbindin immunoreactive neurons in central visual pathways of kittens

Many maturational processes in the brain are at high levels prenatally as well as neonatally before eye-opening, when extrinsic sensory stimulation is limited. During these periods of rapid brain development, a large percentage of time is spent in rapid eye movement (REM) sleep, a state characterized by high levels of endogenously produced brain activity. The abundance of REM sleep in early life and its ensuing decline to lower levels in adulthood strongly suggest that REM sleep constitutes an integral part of the activity-dependent processes that enable normal physiological and structural brain development. We examined the effect of REM sleep deprivation during the critical period for visual development on the development of two calcium-binding proteins that are associated with developmental synaptic plasticity and are found in the lateral geniculate nucleus (LGN) and visual cortex. In this study, REM sleep deprivation was carried out utilizing a computer-controlled, cage-shaking apparatus that successfully suppressed REM sleep. Body weight data suggested that this method of REM sleep deprivation produced less stress than the classical multiple-platform-over-water method. In REM sleep-deprived animals with normal binocular vision, the number of parvalbumin-immunoreactive (PV) neurons in LGN was found to be lower compared with control animals but was not affected in visual cortex. The pattern of calbindin-immunoreactivity (CaB) was unchanged at either site after REM sleep deprivation. Parvalbumin-immunoreactivity develops later than calbindin-immunoreactivity in the LGN, and the REM sleep deprivation that we applied from postnatal day 42-49 delayed this essential step in the development of the kitten's visual system. These data suggest that in early postnatal brain development, REM sleep facilitates the usual time course of the expression of PV-immunoreactivity in LGN neurons.     

The role of active zone protein Rab3 interacting molecule 1 alpha in the regulation of norepinephrine release, response to novelty, and sleep

Sleep mechanisms and synaptic plasticity are thought to interact to regulate homeostasis and memory formation. However, the influences of molecules that mediate synaptic plasticity on sleep are not well understood. In this study we demonstrate that mice lacking Rab3 interacting molecule 1 alpha (RIM1 alpha) (Rim1 alpha KO), a protein of the synaptic active zone required for certain types of synaptic plasticity and learning, had 53+/-5% less baseline rapid eye movement (REM) sleep compared with their wild type littermates. Also, compared with wild type littermates, exposure of the mice to an open field or to a novel object induced more robust and longer lasting locomotion suggesting altered habituation. This difference in exploratory behavior correlated with genotype specific changes in REM and deregulated release of norepinephrine in the cortex and basal amygdala of the Rim1 alpha KO mice. Also, moderate sleep deprivation (4 h), a test of the homeostatic sleep response, induced REM sleep rebound with different time course in Rim1 alpha KO and their wild type littermates. As norepinephrine plays an important role in regulating arousal and REM sleep, our data suggest that noradrenergic deficiency in Rim1 alpha KO animals impacts exploratory behavior and sleep regulation and contributes to impairments in learning.     

Disruptive effects of rapid eye movement sleep deprivation on long-term memory

The fact that sleep is associated with very active endogenous neural (chemical and electrical) processes, suggests that these processes may be involved in the maintenance of long-term memory storage. The present experiments were designed to examine the hypothesis that rapid eye movement (REM) sleep deprivation will produce impairment of long-term memory. Mice deprived of REM sleep for 3, 5 or 7 continuous days, during the interval between a one-trial inhibitory avoidance training experience and a subsequent retention test, displayed a temporary retrograde amnesia when tested 30 min or three hr following termination of REM deprivation. The mice did not recover from the amnesia if electroconvulsive shock was administered immediately following the interval of REM sleep deprivation. In a further study, the generality of these findings was obtained by depriving mice of REM sleep during the interval between a discrimination training experiment in a black-white T-maze and the subsequent retention test.     

Prepro-hypocretin (prepro-orexin) expression is unaffected by short-term sleep deprivation in rats and mice

The hypocretin/orexin ligand-receptor system has recently been implicated in the sleep disorder narcolepsy. During the dark (active) period, null mutants of the prepro-orexin (prepro-hypocretin) gene have cataplectic attacks and increased levels of both rapid eye movement (REM) and non-REM (NREM) sleep. Intracerebroventricular injection of one of the encoded neuropeptides, orexin-A, early in the light period increases wakefulness and reduces REM sleep in the rat, suggesting that this system may be involved in the normal regulation of sleep and wakefulness. To further test this hypothesis, we measured hypocretin (hcrt) mRNA levels by both Northern hybridization and Taqman analysis in mouse and rat hypothalamus after short-term (6 h) sleep deprivation (SD) and 2-4 hours after recovery from SD. Although our SD procedures effectively induced a sleep debt and increased c-fos mRNA expression in the cortex and hypothalamus as described by other investigators, we found that hcrt mRNA levels were not significantly changed in either species either after SD or after recovery from SD. If the hcrt system is involved in normal regulation of sleep and wakefulness, longer periods of SD may be necessary to affect hcrt mRNA levels or changes may occur at the protein rather than mRNA level. Alternatively, this system may also be involved in another function that counterbalances any SD-induced changes in hcrt mRNA levels.     

Increased apoptosis in rat brain after rapid eye movement sleep loss

Rapid eye movement (REM) sleep loss impairs several physiological, behavioral and cellular processes; however, the mechanism of action was unknown. To understand the effects of REM sleep deprivation on neuronal damage and apoptosis, studies were conducted using multiple apoptosis markers in control and experimental rat brain neurons located in areas either related to or unrelated to REM sleep regulation. Furthermore, the effects of REM sleep deprivation were also studied on neuronal cytoskeletal proteins, actin and tubulin. It was observed that after REM sleep deprivation a significantly increased number of neurons in the rat brain were positive to apoptotic markers, which however, tended to recover after the rats were allowed to undergo REM sleep; the control rats were not affected. Further, it was also observed that REM sleep deprivation decreased amounts of actin and tubulin in neurons confirming our previous reports of changes in neuronal size and shape after such deprivation. These findings suggest that one of the possible functions of REM sleep is to protect neurons from damage and apoptosis.