5-HT_(1A)和5-HT_2受体功能与觉醒、睡眠成分关系的研究

目的　观察 5 HT1A受体激动剂 8 OH DPAT和HT2受体拮抗剂利坦色林 (ritanserin)对大鼠清醒和睡眠成分的影响 ,给予 5 HT1A受体激动剂和剥夺REM睡眠后皮层 5 HT2 受体结合能力的变化 ,进一步分析两种 5 HT受体亚型之间的关系以及 5 HT2 受体在睡眠中的作用。方法　利用大鼠睡眠自动分析系统定量分析清醒和睡眠成分的变化 ,注射PCPA制作剥夺睡眠的大鼠模型 ,水上平台法制作剥夺REM睡眠的大鼠模型 ,利用放射配体结合实验研究配体与受体结合力的变化。结果　 8 OH DPAT小剂量 (0 0 1mg·kg-1,sc)可以增加深睡眠和浅睡眠 ,减少觉醒 ;大剂量(0 375mg·kg-1,sc)则增加觉醒 ,减少全部睡眠成分。 5 HT2 受体拮抗剂ritanserin可以明显增加深睡眠 ,减少觉醒和REM睡眠。而 8 OH DPAT低剂量与ritanserin联合用药则使深浅睡眠明显增加 ,清醒和REM睡眠明显减少 ,具有协同作用。对于PCPA化使 3种睡眠成分均明显减少 ,觉醒比例明显增加的大鼠 ,ritanserin仅使浅睡眠增加其它成分不变。用 [3 H] ritanserin放射性配基结合显示 ,剥夺大鼠REM睡眠后皮层 5 HT2 受体Bmax值明显增加但Kd 值无变化 ;给予 5 HT1A激动剂 8 OH DPAT后皮层 5 HT2 受体Kd 和Bmax均降低。结论　 5 HT1A受体和 5 HT2 受体与睡眠有密切关系     

中缝背核投射到基底外侧杏仁核的5-羟色胺能纤维对睡眠的调节作用

目的　观察大鼠中缝背核 (DRN)到基底外侧杏仁核(BLA)的 5 HT能纤维投射在睡眠 -觉醒调节中的作用。方法　采用脑立体定位 ,核团微量注射和多导睡眠描记 (PSG)方法。结果　DRN内微量注射L Glu ,可使觉醒 (W )增加 ,慢波睡眠 (SWS)和异相睡眠 (PS)明显减少。在双侧BLA微量注射非选择性 5 HT受体阻断剂麦角新碱 (MS)可以逆转DRN内微量注射L Glu的效应 ,SWS增加 ,W减少 ,但PS没有变化 ;DRN内微量注射PCPA ,导致SWS增加 ,W减少 ,但当在DRN内微量注射PCPA后 ,双侧BLA内微量注射 5 HTP可以逆转PCPA所引起的睡眠增加效应 ,使SWS减少 ,W增加 ,但PS没有变化。结论　DRN对睡眠 -觉醒的调节作用部分通过DRN到BLA的 5 HT能纤维投射介导的     

腹外侧视前区5-羟色胺对大鼠睡眠-觉醒周期的作用

目的　通过腹外侧视前区 (VLPO)微量注射 5 羟色胺酸 (5 HTP)、非特异性 5 HT受体阻断剂麦角新碱 (MS)和5 HT再摄取抑制剂氟西汀观察 5 HT在VLPO对大鼠睡眠-觉醒周期的影响。方法　采用脑立体定位、核团微量注射和多导睡眠描记技术。结果　VLPO双侧分别微量注射小剂量 5 HTP(0 5μg ,0 1 μl)对大鼠睡眠 -觉醒周期无明显影响 ;而双侧注射大剂量 5 HTP(1 0 μg ,0 1 μl)使大鼠睡眠减少 ,觉醒增加 ;VLPO双侧注射 5 HT再摄取抑制剂氟西汀(6 0 μg ,0 1 μl)可产生与大剂量 5 HTP类似的作用 ;而VLPO双侧微量注射非特异性 5 HT受体阻断剂麦角新碱(MS ,1 0 μg ,0 1 μl)使大鼠睡眠增加 ,觉醒减少。大剂量 5 HTP和MS对觉醒 ,睡眠成分改变具有明显的时间相关性。结论　 5 HT在VLPO参与睡眠 -觉醒周期调节且有促觉醒作用 ,其促觉醒作用可能与突触后物质表达有关     

5-HT_(1A)受体激动剂乌拉地尔对吗啡依赖大鼠前列腺组织的病理学影响

目的··:观察5-HT1A 受体激动剂乌拉地尔对吗啡依赖大鼠前列腺的组织学影响。方法··:皮下注射(sc)5d吗啡 ,建立吗啡依赖大鼠模型 ;实验组分别进行侧脑室注射 (icv)乌拉地尔和继续sc吗啡。实验后将前列腺组织作HE染色后在光镜下观察。结果··:吗啡依赖大鼠的前列腺组织有轻度萎缩 ,吗啡依赖大鼠自然戒断后前列腺有明显增生 ,icv乌拉地尔可抑制吗啡戒断大鼠的前列腺组织增生。结论··:乌拉地尔可抑制吗啡戒断大鼠前列腺组织的增生     

5-HT_(1P)受体介导的交感神经节慢突触传递

目的　在豚鼠肠系膜下神经节 (IMG)细胞上观察不同 5 羟色胺 (5 HT)受体亚型拮抗剂对非胆碱能迟慢兴奋性突触后电位 (LS EPSP)的作用。方法　应用离体细胞内记录技术。结果　赛庚啶 (cyproheptadine ,5 HT1/ 2 受体拮抗剂 )及BRL 2 492 4(5 HT1P受体拮抗剂 )可逆的阻抑 5 HT敏感细胞的LS EPSP ,而mianserin(5 HT2 受体拮抗剂 ) ,MDL72 2 2 2 (5 HT3 受体拮抗剂 ) ,spiperone(5 HT1A受体拮抗剂 )对LS EPSP无显著影响 ;用MCPP(5 HT1P受体激动剂 )持续灌流IMG使 5 HT敏感细胞脱敏后可逆的阻抑LS EPSP的发生。结论　 5 HT敏感细胞的LS EPSP是由 5 HT1P受体介导的。     

5—HT2C受体：设计抗肥胖药物和抗癫痫药物的潜在治疗靶标

5－羟色胺（5－HT）是一种重要的神经递质，在哺乳动物的中枢神经系统中至少有14种不同的5－HT受体亚型，研究发现其中5－HT2C受体对食物摄取和癫症的发作有调节作用。5－HT2C受体激动剂可能是通过增加饱食感来减少对食物的提取，许多高选择性的5－HT2C受体激动剂正进行临床前及临床评价，5－HT2C受体有可能成为抗肥胖和抗癫痫药物的新靶标。     

孤束核微注射5-羟色胺系统药物对大鼠睡眠-觉醒的影响及机制

目的:探讨孤束核(NST)微注射5-羟色胺(5-HT)系统药物对大鼠睡眠-觉醒的影响及其机制.方法:选用雄性SD大鼠,分7组,孤束核分别微注射5-羟基色氨酸(5-HTP)、非特异性5-HT受体阻断剂麦角新碱(MS)、5-羟色胺1A受体(5-HT1AR)激动剂8-OH-DPAT、5-HT1AR拮抗剂spiperone、cAMP、cAMP依赖的蛋白激酶A(PKA)拮抗剂H89和生理盐水(NS)后,采用光电脑电机记录脑电和肌电;采用免疫组化ABC法检测NST处5-HT1AR及5-HT表达情况.结果:与处理前相比,NS组和MS组大鼠睡眠-觉醒各期差异均无统计学意义,5-HTP组、8-OH-DPAT组和H89组给药后均显示觉醒期(W)缩短,异相睡眠(PS)延长(P<0.05或P<0.01),8-OH-DPAT组和H89组慢波睡眠(SWS)延长(P<0.01或P<0.05);spiperone组和cAMP组W延长(P<0.01或P<0.05),SWS缩短(P<0.01或P<0.05),spiperone组PS缩短(P<0.05).免疫组化结果显示,与NS组相比,5-HTP组的5-H T1AR阳性细胞数较多,5-HT能神经纤维末梢5-HT表达增强,MS组则结果相反.结论:作为睡眠诱发区,孤束核很可能是通过5一羟色胺作用于5-HT1AR,使cAMP生成减少,PKA磷酸化减少而发挥使觉醒减少、睡眠增加的生物学效应.     

基于GABA信号通路探究柏子养心汤对失眠大鼠睡眠时相的影响

目的 基于γ-氨基丁酸(GABA)信号通路探究柏子养心汤对氯苯丙氨酸(PCPA)致失眠大鼠睡眠时相的影响。方法 将SD大鼠分为对照组、模型组、柏子养心汤低剂量、中剂量、高剂量组(5.625 g/kg、11.25 g/kg、22.5 g/kg),每组24只。通过腹腔注射PCPA建立失眠大鼠模型。给予相应剂量的药物连续灌胃7 d后,观察大鼠一般活动状态及体重变化,通过动物睡眠生物解析系统记录脑电图(EEG)和肌电图(EMG)信号,分析大鼠夜晚和白天觉醒(Wake)总量和非快速眼动(NREM)睡眠、快速眼动(REM)睡眠总量;酶联免疫吸附法(ELISA)检测大鼠下丘脑5-羟色胺(5-HT)、谷氨酸(Glu)与GABA含量;免疫组织化学法(IHC)检测大鼠下丘脑谷氨酸脱羧酶67(GAD67)表达;Western blot和RT-qPCR检测大鼠下丘脑组织中γ-氨基丁酸A型(GABAA)受体α1(GABRA1)、β2(GABRB2)和γ2(GABRG2)亚基的mRNA和蛋白表达。结果 与对照组相比,模型组大鼠精神状态较差,昼夜节律消失,体重、NREM睡眠和REM睡眠总量、下丘脑5-HT、GABA...     

莫达非尼对REM睡眠剥夺后大鼠认知功能及突触可塑性的影响*

目的：探讨新型中枢性兴奋剂莫达非尼对不同程度快速动眼（REM）睡眠剥夺与睡眠恢复后大鼠认知功能和大鼠海马突触可塑性的影响。方法：成年雄性SD大鼠随机分为莫达非尼组与对照组,每组分5个不同的REM睡眠剥夺和恢复时间点（SD1d,SD3d,SD5d,SD5d/RS6h,SD5d/RS12h）,采用改良多平台水环境REM睡眠剥夺法进行REM睡眠剥夺,利用Y迷宫测定大鼠学习记忆能力,运用蛋白质免疫印记（Western Blot）技术对大鼠海马突触素（SynapsinⅠ）蛋白作选择性半定量分析,免疫组织化学和电镜观察的方法分析大鼠海马CA3区SynapsinⅠ的表达,观察突触可塑性变化。结果：莫达非尼组的错误反应次数（EN）在REM睡眠剥夺后小于对照组,差异有统计学意义（P〈0.05）,睡眠恢复后两组EN比较,差异无统计学意义（P〉0.05）,总反应时间（TRT）两组比较,差异也无统计学意义（P〉0.05）。Western Blot结果显示SD1d,SD3d,SD5d/RS6h和SD5d/RS12h时莫达非尼组Syn- apsinⅠ表达比对照组增多（P〈0.05）,SD5d时两组SynapsinⅠ表达无显著差异（P〉0.05）,免疫组化结果与其一致;电镜下观察SD1d时莫达非尼组的突触联系、突触前膜囊泡数量均较对照组增加。结论：REM睡眠剥夺会引起大鼠认知功能下降,大鼠海马CA3区SynapsinⅠ表达降低,而莫达非尼可以抑制睡眠剥夺后SynapsinⅠ的表达减少,诱导大鼠海马突触可塑性变化,可改善REM睡眠剥夺后的认知行为。     

阻塞性睡眠呼吸暂停低通气综合征与认知障碍

阻塞性睡眠呼吸暂停低通气综合征(obstructive sleep apnea-hypopnea syndrome,OSAHS)是一种严重的睡眠呼吸疾病,以反复发作的睡眠呼吸暂停和低氧血症为主要临床特征,常出现睡眠结构紊乱,表现为浅睡眠和觉醒增加,快速眼动睡眠(rapid eye movement sleep,REMS)和深睡眠时间减少,并引起白天困倦嗜睡。一般人群OSAHS的发病率为2%～5%,60     

Role of spinal 5-HT receptors in cutaneous hypersensitivity induced by REM sleep deprivation

Previous studies indicate that rapid eye movement (REM) sleep deprivation facilitates pain sensitivity. Since serotoninergic raphe neurons are involved both in regulation of sleep and descending pain modulation, we studied whether spinal 5-HT receptors have a role in sleep deprivation-induced facilitation of pain-related behavior. REM sleep deprivation of 48h was induced by the flower pot method in the rat. The pain modulatory influence of various serotoninergic compounds administered intrathecally was assessed by determining limb withdrawal response to monofilaments. REM sleep deprivation produced a marked hypersensitivity. Sleep deprivation-induced hypersensitivity and normal sensitivity in controls were reduced both by a 5-HT(1A) receptor antagonist (WAY-100635) and a 5-HT(2C) receptor antagonist (RS-102221). An antagonist of the 5-HT(3) receptor (LY-278584) failed to modulate hypersensitivity in sleep-deprived or control animals. Paradoxically, sensitivity in sleep-deprived and control animals was reduced not only by a 5-HT(1A) receptor antagonist but also by a 5-HT(1A) receptor agonist (8-OHDPAT). The results indicate that serotoninergic receptors in the spinal cord have a complex role in the control of sleep-deprivation induced cutaneous hypersensitivity as well as baseline sensitivity in control conditions. While endogenous serotonin acting on 5-HT(1A) and 5-HT(2C) receptors may facilitate mechanical sensitivity in animals with a sleep deprivation-induced hypersensitivity as well as in controls, increased activation of spinal 5-HT(1A) receptors by an exogenous agonist leads to suppression of mechanical sensitivity in both conditions. Spinal 5-HT(3) receptors do not contribute to cutaneous hypersensitivity induced by sleep deprivation.     

Effects of serotonin antagonists on motion sickness and its suppression by 8-OH-DPAT in cats

This investigation evaluated the antagonist properties of (-)propranolol, (+)propranolol, metergoline and BMY 7378 on the known effect of 8-OH-DPAT (DPAT) to decrease motion sickness in cats. (-)Propranolol produced a greater decrease in the antiemetic effect of DPAT than did (+)propranolol. Although metergoline produced a decrease in the antiemetic effect of DPAT, the decrease could not be clearly attributed to interactions with 5-HT1A receptors because metergoline alone slightly enhanced motion sickness. Depletion of 5-HT with PCPA produced a weaker, nonsignificant enhancement of motion sickness, while mesulergine had no effect. As neither nonspecific 5-HT receptor blockade with metergoline nor depletion of 5-HT mimicked the antiemetic effect of DPAT, it was concluded that DPAT acts on postsynaptic 5-HT1A receptors to prevent emesis. BMY 7378 alone decreased the incidence of motion sickness. A dose just below this agonist range did not decrease the effects of DPAT.     

Inhibition of REM sleep by ipsapirone,A 5HT1A agonist,in normal volunteers

In order to test the hypothesis that serotonergic mechanisms inhibit REM sleep via a 5HT1_A receptor, we administered placebo and ipsapirone (10 and 20 mg by mouth 15 min before bedtime) to ten normal volunteers in a double blind fashion. Ipsapirone is a relatively selective 5HT1_A receptor agonist. As predicted, ipsapirone prolonged REM latency and Mean Latency to Eye Movements (M-LEM), a measure of time between onset of REM sleep and the first eye movement of the REM period, and REM% at both doses compared with placebo. It also reduced sleep efficiency and total REM sleep time at the highest dose. These results support the hypothesis that systemic stimulation of 5HT1_A receptors prolong REM latency and inhibit REM sleep.Supported in part by a grant from the General Clinical Research Centers Program, MO1 RR00827, of the National Center for Research Resources, National Institutes of Health; UCSD Mental Health Clinical Research Center (MH30914), San Diego Veterans A¤airs Medical Center Research Service and UCSD Fellowship in Clinical Psychopharmacology and Psychobiology (MH18399), and a Travel Award from the Upjohn Company to W.J.     

Hypnotic action of flunitrazepam in the rat: Does 5-HT mechanism play a role?

This study examined whether pharmacological manipulation of serotonergic (5-HT) systems would affect the hypnotic action of flunitrazepam in rats. Flunitrazepam, a potent hypnotic, was used alone or combined with parachlorophenylalanine (pCPA), an inhibitor of the synthesis of 5-HT, 8-OH-DPAT, a 5-HT_1A receptor agonist and fluvoxamine, an inhibitor of the reuptake of 5-HT. Flunitrazepam increased the amount of orthodox sleep, the latency of rapid eye movement (REM) sleep and decreased the amount of REM sleep. The drug pCPA decreased the total sleep time and the amount of orthodox and REM sleep. Administration of flunitrazepam to pCPA-pretreated rats induced orthodox sleep in an identical way to that found in the controls. The drug 8-OH-DPAT increased wakefulness and the latency of REM sleep. The association of flunitrazepam with 8-OH-DPAT abolished the increase in waking seen after 8-OH-DPAT alone. In contrast, the combined treatment with flunitrazepam and 8-OH-DPAT resulted in a lengthening of the latency of REM sleep significantly greater than that observed with the same dose of each drug alone. Fluvoxamine increased the latency and decreased the amount of REM sleep. The association of fluvoxamine with flunitrazepam induced a decrease in REM sleep, equal to the sum of the effects of the two drugs alone. Fluvoxamine did not modify the other effects of flunitrazepam. The present experiments demonstrate that the association of pCPA, 8-OH-DPAT and fluvoxamine, did not alter the hypnogenic effect of flunitrazepam. The possibility of an involvement of 5-HT mechanisms in the effect of flunitrazepam on the phasic events in sleep is questionable.     

Counteraction of the Rapid Tolerance to 8‐Hydroxy‐2‐(di‐n‐propylamino)tetralin‐Induced Hypothermia in Rats by Activation of the GABAA Receptor‐Chloride Channel Complex

Abstract: The effects of compounds that open the GABA_A receptor‐chloride channel complex on the rapidly developed tolerance to the 8‐hydroxy‐2‐(di‐n‐propylamino)tetralin hydrobromide(8‐OH‐DPAT)‐induced hypothermia in rats were examined. The test compound was injected 15 min. before 1 mg/kg subcutaneous 8‐OH‐DPAT or saline and 24 hr later a challenge dose of 0.1 mg/kg subcutaneous 8‐OH‐DPAT was given. The rectal temperature was measured before the challenge dose and 30, 60, 90 and 120 min. thereafter. The hypothermic effect was calculated as the area under the curve. It was found that all the GABAergic compounds examined significantly counteracted the 8‐OH‐DPAT‐induced tolerance to the hypothermic response: muscimol at 3 mg/kg subcutaneous, diazepam at 1 – 3 mg/kg subcutaneous, pentobarbitone sodium at 20 mg/kg subcutaneous, and chlormethiazole at 40 mg/kg subcutaneous. Combined treatment of the rats with the GABA_A receptor antagonist, bicucculine, or the GABA_A receptor‐chloride channel blocker, picrotoxin and diazepam, pentoparbitone sodium or chlormethiazole significantly antagonised this counteraction of the 8‐OH‐DPAT‐induced tolerance. Depletion of 5‐HT by pretreatment of the rats with the tryptophan hydroxylase inhibitor p‐chlorophenylalanine did not counteract the 8‐OH‐DPAT‐induced tolerance to the hypothermic response. Pretreatment of the rats with dexamethazone did not change the development of the tolerance to 8‐OH‐DPAT‐induced hypothermic effect which seems to exclude the involvement of the hypothalamo‐pituitary‐adrenocortical axis in the tolerance development. It is concluded that the results support the hypothesis that GABA neurones beyond the 5‐HT neurones are involved in the mechanism causing tolerance to the 5‐HT_1A receptor‐mediated hypothermia in rats.     

Effects of N-cyclopentyladenosine and caffeine on sleep regulation in the rat

To study the role of adenosine in sleep regulation, the adenosine A₁ receptor agonist N⁶-cyclopentyladenosine (CPA) and the antagonist caffeine were administered to rats. Intraperitoneal (i.p.) CPA 1 mg/kg but not 0.1 mg/kg, suppressed rapid-eye-movement (REM) sleep and enhanced electroencephalographic (EEG) slow-wave activity (power density 0.75–4.0 Hz) in non-REM sleep. The latter effect was remarkably similar to the response to 6-h sleep deprivation. The effects persisted when CPA-induced hypothermia was prevented. Caffeine (10 and 15 mg/kg i.p.) elicited a dose-dependent increase in waking followed by a prolonged increase of slow-wave activity in non-REM sleep. The combination of caffeine (15 mg/kg) and sleep deprivation caused less increase in slow-wave activity than sleep deprivation alone, indicating that caffeine may reduce the buildup of sleep pressure during waking. The results are consistent with the involvement of adenosine in the regulation of non-REM sleep.     

Stress-induced insomnia: opioid-dopamine interactions

REM sleep deprivation induced by means of the platform technique (72 h) was followed by a period of latency to sleep characterized by a marked excitement in rats. The administration of naloxone at the end of the REM deprivation period reduced this latency to sleep while morphine, beta-endorphin and DADLE prolonged it. The dopamine D1 receptor antagonist SCH 23390 was extremely potent (0.003 mg/kg) to reduce the latency to sleep and the excitement while the D1 agonist SKF 38393 induced an opposite effect. The dopamine D2 receptor antagonist L-sulpiride was inactive up to a dose of 25 mg/kg. These data suggest that hyperactivity of the opioid and dopamine systems (specifically mediated through D1 receptors) is involved in such behaviour.     

Effects of biperiden on sleep at baseline and after 72 h of REM sleep deprivation in the cat

We examined the effects of the muscarinic M1 antagonist biperiden in cats. In the first experiment a dose-response analysis was performed with intraventricular injection (IV ventricle) of biperiden. In the second experiment after REM sleep deprivation cats were injected with either biperiden (0.1 mg/kg) or saline. Biperiden produced a reduction in REM sleep percentage and an increase in REM sleep latency with these high doses. The 0.1 mg/kg biperiden dose, which did not suppress REM sleep at baseline, did reduce the REM sleep rebound. The present study suggests a modulatory role of biperiden on REM sleep regulatory processes. The fact that an effect of biperiden is noted only at the high doses suggests that at these doses the drug is influencing non-M1 receptors. Changes in the sensitivity of these receptors as a result of REM sleep deprivation might explain why a dose of biperiden will reduce REM sleep rebound, while being ineffective in suppressing REM sleep at baseline.     

Depletion of brain serotonin by 5,7-DHT: effects on the 8-OH-DPAT-induced changes of sleep and waking in the rat

The effect of 5-HT_1A receptor agonist 8-OH-DPAT on sleep and wakefulness was studied in rats with selective serotonin depletion after ICV administration of the neurotoxin 5,7-dihydroxytryptamine (5,7-DHT). Injection of 8-OH-DPAT to vehicle-treated animals induced biphasic effects, such that low doses (0.010 mg/kg) which act perferentially on the somatodendritic autoreceptor decreased wakefulness (W) and increased slow wave sleep (SWS), while higher doses (0.375 mg/kg) which stimulate postsynaptic receptors caused opposite effects. REM sleep was suppressed irrespective of the dosage given. Injection of the 0.010 mg/kg dose in the 5,7-DHT-treated rats did not result in significant changes in sleep or W. On the other hand, the 0.375 mg/kg dose produced changes in sleep variables which were similar to those described in the vehicle-treated animals. Our findings tend to indicate that increased SWS after low doses of 8-OH-DPAT depends upon the activation of inhibitory somatodendritic 5-HT_1A receptors, while increased W after higher doses of the compound is related to stimulation of postsynaptic receptors.     

Differential EEG effects of the anxiolytic drugs, deramciclane (EGIS-3886), ritanserin and chlordiazepoxide in rats

The influence of serotonergic and benzodiazepine type anxiolytic drugs on the cortical activation and sleep-wakefulness cycle were compared by evaluating the effects of ritanserin and deramciclane (EGIS-3886), two 5-HT₂ receptor antagonists, and chlordiazepoxide on the electroencephalogram (EEG) in freely moving rats. Following drug administration (1, 3, and 10 mg/kg, PO for all drugs), EEG was continuously sampled for 6 h and power spectra were calculated for every 5 s to assess changes in slow wave activity and sleep phases. In a separate test, anticonvulsant effects of the drugs were examined in mice. Both deramciclane and ritanserin slightly increased total time spent in deep sleep (DS) and lengthened sleep episodes. In contrast, chlordiazepoxide had a strong inhibitory action on DS, sleep time being shifted to more superficial light sleep (LS). The incidence and length of the high voltage spindle (HVS) episodes characteristic for the motionless, awake rat were increased at the highest dose of both deramciclane and ritanserin, while it was decreased by chlordiazepoxide. In mice, chlordiazepoxide had a marked anticonvulsant effect, while deramciclane was moderately effective and ritanserin ineffective. In conclusion, the 5-HT₂ receptor antagonist anxiolytic drugs seem to be superior compared to the benzodiazepine type anxiolytic drug, chlordiazepoxide, as ritanserin and deramciclane improved sleep quality by increasing sleep episode length and time spent in DS, while chlordiazepoxide enhanced sleep fragmentation and decreased DS. Received: 1 July 1998/Final version: 4 September 1998