Increased NREM Sleep Research Articles

NHBA isolated from Gastrodia elata exerts sedative and hypnotic effects in sodium pentobarbital-treated mice

The rhizomes of Gastrodia elata have been used for the treatment of insomnia in oriental countries. N6-(4-hydroxybenzyl) adenine riboside (NHBA) was originally isolated from G. elata. For the first time we report a detailed study on the effects and mechanisms of NHBA on its sedative and hypnotic activity. Adenosine, an endogenous sleep factor, regulates sleep–wake cycle via interacting with adenosine A1/A2A receptors. Using radioligand binding studies and cAMP accumulation assays, our results show that NHBA may be a functional ligand for the adenosine A1 and A2A receptors. NHBA significantly decreases spontaneous locomotor activity and potentiates the hypnotic effect of sodium pentobarbital in mice. Sleep architecture analyses reveal that NHBA significantly decreases wakefulness time and increases NREM sleep times. However, NHBA does not affect the amount of REM sleep. Pretreatment with the adenosine A1 receptor antagonist DPCPX or the A2A receptor antagonist SCH 58261 significantly reverses the increase in sleeping time induced by NHBA in sodium pentobarbital treated mice. Immunohistochemical studies show that NHBA increases c-Fos expression in GABAergic neurons of the ventrolateral preoptic area (VLPO), which suggests that NHBA activates the sleep center in the anterior hypothalamus. Altogether, these results indicate that NHBA produces significant sedative and hypnotic effects. Such effects might be mediated by the activation of adenosine A1/A2A receptors and stimulation of the sleep center VLPO.

Microdialysis (MD) of atropine into the Kölliker‐Fuse Nucleus (KFN) alters breathing of awake and sleeping goats

We MD atropine, a muscarinic receptor antagonist, at sites in the rostral pons of awake and sleeping goats to test the hypothesis that cholinergic mechanisms have site‐ and state‐dependent effects on the control of breathing. Cannula were bilaterally implanted into either rostral pontine tegmental nuclei (n = 3), the lateral (n = 3) or medial (n = 4) parabrachial nuclei, or the KFN (n = 6). After >2 weeks recovery from surgery, the goats were studied during a 45 minute period of MD with mock cerebrospinal fluid, followed by 30 minutes of recovery and 45 minutes of MD with atropine. Unilateral and bilateral MD of atropine into the KFN at night decreased pulmonary ventilation and breathing frequency and increased inspiratory and expiratory time by 12 to 14% during both wakefulness and NREM sleep. However, during daytime studies, MD of atropine into the KFN had no affect on these variables but increased the variation of genioglossus muscle activity. Nighttime unilateral and bilateral MD of atropine into the KFN increased NREM sleep by 63% (p > 0.05) and 365% (p < 0.01), respectively. MD during the day or at night into the other 3 pontine sites had only minimal effects on any variable studied. Finally, bilateral MD of atropine decreased levels of acetylcholine and choline in the effluent dialysate. Our data support the concept that the KFN is a significant contributor to cholinergically modulated control of breathing and sleep.

Adenosine in the tuberomammillary nucleus inhibits the histaminergic system via A1 receptors and promotes non-rapid eye movement sleep.

Adenosine has been proposed to promote sleep through A(1) receptors (A(1)R's) and/or A(2A) receptors in the brain. We previously reported that A(2A) receptors mediate the sleep-promoting effect of prostaglandin D(2), an endogenous sleep-inducing substance, and that activation of these receptors induces sleep and blockade of them by caffeine results in wakefulness. On the other hand, A(1)R has been suggested to increase sleep by inhibition of the cholinergic region of the basal forebrain. However, the role and target sites of A(1)R in sleep-wake regulation remained controversial. In this study, immunohistochemistry revealed that A(1)R was expressed in histaminergic neurons of the rat tuberomammillary nucleus (TMN). In vivo microdialysis showed that the histamine release in the frontal cortex was decreased by microinjection into the TMN of N(6)-cyclopentyladenosine (CPA), an A(1)R agonist, adenosine or coformycin, an inhibitor of adenosine deaminase, which catabolizes adenosine to inosine. Bilateral injection of CPA into the rat TMN significantly increased the amount and the delta power density of non-rapid eye movement (non-REM; NREM) sleep but did not affect REM sleep. CPA-promoted sleep was observed in WT mice but not in KO mice for A(1)R or histamine H(1) receptor, indicating that the NREM sleep promoted by A(1)R-specific agonist depended on the histaminergic system. Furthermore, the bilateral injection of adenosine or coformycin into the rat TMN increased NREM sleep, which was completely abolished by coadministration of 1,3-dimethyl-8-cyclopenthylxanthine, a selective A(1)R antagonist. These results indicate that endogenous adenosine in the TMN suppresses the histaminergic system via A(1)R to promote NREM sleep.

Opioidergic projections to sleep-active neurons in the ventrolateral preoptic nucleus

Although opioids are known to influence sleep–wake regulation, the neuroanatomic substrate(s) mediating these effects remain unresolved. We hypothesized that the influence of opiates on sleep may be mediated, at least in part, by the ventrolateral preoptic nucleus (VLPO), a key cell group for producing behavioral sleep. By combining in situ hybridization for kappa and mu receptor mRNA with immunostaining of Fos expressed by VLPO cells during sleep we show that > 85% of sleep-active VLPO neurons contain mRNA for either or both opioid receptors. Microinfusions of a kappa receptor agonist into the VLPO region increased NREM sleep by 51% during the subjective night, whereas a mu receptor agonist increased wakefulness by 60% during the subjective day. The sleep- and wake-promoting effects of the kappa and mu agonists were blocked by prior administration of their respective antagonist. Combining retrograde tracing from the VLPO with immunohistochemistry for dynorphin (Dyn, the endogenous kappa receptor agonist) or endomorphin 1 (EM1, the endogenous mu receptor agonist) we show that the central lateral parabrachial subnucleus (PBcl) provides Dyn inputs to the VLPO, whereas hypothalamic histaminergic neurons provide EM1 inputs to the VLPO. In summary, results from the present study suggest that central opioid inputs to the VLPO may play a role in sleep–wake regulation and that the VLPO likely mediates the hypnotic response to high levels of opioid analgesics.

Effects of Eszopiclone and Zolpidem on Sleep and Waking States in the Adult Guinea Pig

The present study was designed to compare and contrast the effects of eszopiclone and zolpidem on the states of sleep and wakefulness in chronically instrumented, unanesthetized adult guinea pigs. Adult guinea pigs were implanted with electrodes to record sleep and waking states and to perform a frequency analysis of the EEG. Eszopiclone (1 and 3 mg/kg) and zolpidem (1 and 3 mg/kg) were administered intraperitoneally. The administration of eszopiclone (1 and 3 mg/kg) resulted in a significant dose-dependent increase in NREM sleep. Zolpidem produced a significant increase in NREM sleep, but only at a dose of 3 mg/kg. The following changes in NREM and REM sleep, as well as in the power spectra, were all significant when the effects of 1 and 3 mg/kg of eszopiclone were compared with responses induced with 1 and 3 mg/kg of zolpidem, respectively: The increase in NREM sleep produced by eszopiclone was greater than that following the administration of zolpidem. The mean latency to NREM sleep following the administration of eszopiclone was significantly shorter than zolpidem. Eszopiclone significantly increased the latency to REM sleep. The mean duration of episodes of NREM sleep was increased by eszopiclone, but not by zolpidem. The EEG power increased in the delta band and decreased in the theta band during NREM sleep following the administration of eszopiclone. No significant changes occurred in any of the frequency bands analyzed following zolpidem administration. The differences in the effects of eszopiclone and zolpidem on sleep and waking states and the power spectra of the EEG likely reflect the fact that eszopiclone and zolpidem bind to different subunits of the GABAA receptor complex.

Selective 5HT2A and 5HT6 Receptor Antagonists Promote Sleep in Rats

Serotonin (5-HT) has long been implicated in the control of sleep and wakefulness. This study evaluated the hypnotic efficacy of the 5-HT6 antagonist RO4368554 (RO) and the 5-HT2A receptor antagonist MDL100907 (MDL) relative to zolpidem. A randomized, repeated-measures design was utilized in which Wistar rats received intraperitoneal injections of RO (1.0, 3.0, and 10 mg/kg), MDL (0.1, 1.0 and 3.0 mg/kg), zolpidem (10 mg/kg), or vehicle in the middle of the dark (active) period. Electroencephalogram, electromyogram, body temperature (Tb) and locomotor activity were analyzed for 6 hours after injection. RO, MDL, and zolpidem all produced significant increases in sleep and decreases in waking, compared with vehicle control. All 3 doses of MDL produced more consolidated sleep, increased non-rapid eye movement sleep (NREM) sleep, and increased electroencephalographic delta power during NREM sleep. The highest dose of RO (10.0 mg/kg) produced significant increases in sleep and decreases in waking during hour 2 following dosing. These increases in sleep duration were associated with greater delta power during NREM sleep. ZO Zolpidem induced sleep with the shortest latency and significantly increased NREM sleep and delta power but also suppressed rapid eye movement sleep sleep; in contrast, neither RO nor MDL affected rapid eye movement sleep. Whereas RO did not affect Tb, both zolpidem and MDL reduced Tb relative to vehicle-injected controls. These results support a role for 5-HT2A receptor modulation in NREM sleep and suggest a previously unrecognized role for 5-HT6 receptors in sleep-wake regulation.

Adenosinergic Regulation of Sleep: Multiple Sites of Action in the Brain

Adenosinergic Regulation of Sleep: Multiple Sites of Action in the Brain

Monoaminergic system lesions increase post-sigh respiratory pattern disturbance during sleep in rats

Monoamines are important regulators of behavioral state and respiratory pattern, and the impact of monoaminergic control during sleep is of particular interest for the stability of breathing regulation. The aim of this study was to test the effects of systemically induced chemical lesions to noradrenergic and serotonergic efferent systems, on the expression of sleep–wake states, pontine wave activity, and sleep-related respiratory pattern and its variability. In chronically instrumented male adult Sprague–Dawley rats we lesioned noradrenergic terminal axonal branches by a single intraperitoneal dose of DSP-4 ( N-(2-chloroethyl)- N-ethyl-2-brombenzilamine; 50 mg/kg, i.p.), and serotonergic axonal terminals by two intraperitoneal doses, 24 h apart, of PCA ( p-chloroamphetamine; 6 mg/kg, i.p.). In each animal, we recorded sleep, pontine waves (P-waves) and breathing at baseline, following sham injection, and every week for 5 weeks following injection of either systemic neurotoxin. Distinct responses were observed to the two lesions. DSP-4 lesions were associated with a trend toward increased NREM sleep ( p < 0.06), decreased wakefulness ( p < 0.05) and increased respiratory tidal volume during NREM ( p = 0.0002) and REM ( p = 0.0001) sleep with respect to baseline. None of these effects, however, were observed during the first 14 days after injection. No significant changes were observed in the frequency of apneas or sighs, nor in the coupling between these two, at any time after DSP-4 injection. Conversely, selective serotonergic lesion by PCA produced no change in the baseline respiratory frequency or tidal volume during sleep or wakefulness, nor was the expression of Wake, NREM or REM sleep affected. Instead, PCA injection resulted in a sustained increase in the frequency and duration of post-sigh apneas (PS) during NREM sleep ( p = 0.002). This reflected increased coupling between sighs and apneas, because neither the frequency nor the amplitude of spontaneous sighs was altered by PCA.

Sleep changes vary by odor perception in young adults

Peppermint, a stimulating odor, increases alertness while awake and therefore may inhibit sleep. This study examined peppermint's effects on polysomnographic (PSG) sleep, alertness, and mood when presented before bedtime. Twenty-one healthy sleepers (mean age ± S.D., 20.1 ± 2.0 years) completed three consecutive laboratory sessions (adaptation, control, and stimulus nights). Peppermint reduced fatigue and improved mood and was rated as more pleasant, intense, stimulating, and elating than water. These perceptual qualities associated with sleep measures: subjects rating peppermint as very intense had more total sleep than those rating it as moderately intense, and also showed more slow-wave sleep (SWS) in the peppermint than control session. Furthermore, subjects who found peppermint stimulating showed more NREM and less REM sleep while those rating it as sedating took longer to reach SWS. Peppermint did not affect PSG sleep, however, when these perceptual qualities were not considered. Peppermint also produced gender-differentiated responses: it increased NREM sleep in women, but not men, and alertness in men, but not women, compared with the control. Thus, psychological factors, including individual differences in odor perception play an important role in physiological sleep and self-rated mood and alertness changes.

A novel melatonin derivative modulates sleep–wake cycle in rats

The aim of this study was to evaluate, in comparison with melatonin (MLT), the effects of a novel 2-melatonin derivative, having a 2-trifluoromethyl group (MLTD) on the sleep–wake cycle in freely behaving rats. Doses of MLTD (100, 300 and 500 nmol/100 μl saline) or MLT (500 nmol/100 μl saline) replaced the i.c.v. infusion of saline during the diurnal infusion period (7:00–17:00). Diurnal infusion of MLTD significantly ( P<0.05) increased NREM sleep at doses of 300 and 500 nmol during the second 4-h time interval of the light period and the lowest dose showed delayed effects on NREM sleep in the third 4-h time interval. However, REM sleep was only increased significantly at the dose of 500 nmol. The infusion of MLT did not have effects on REM sleep but significantly increased NREM sleep. These findings support the notion that MLTD diurnal infusion into the third ventricle produces soporific effects dose-dependently and more potently than MLT. Thus, MLTD may play an important role in studies of sleep.

Melatonin microinjection into the medial preoptic area increases sleep in the rat

A wide variety of hypnotic compounds including triazolam, pentobarbital, ethanol and adenosine have been reported to enhance sleep when microinjected into the medial preoptic area (MPA) of the anterior hypothalamus of the rat. It is uncertain whether the pineal hormone melatonin, which may alter sleep/wake physiology in mammals, acts at this site. A previous report has indicated that a more widespread injection of melatonin into the hypothalamus of the cat induces sleep. In the present study we have examined the possibility that the MPA may mediate this effect. Nine adult rats were microinjected with melatonin 1 and 50 ug and vehicle into the MPA during the daytime in a repeated measures design study. It was found that melatonin increased total sleep time in a dose-dependent manner, primarily by increasing NREM sleep, and that wake time after sleep onset was significantly reduced. These data add melatonin to the growing list of compounds that increase total sleep after administration into the MPA, and suggest that the MPA may be a common site of action for such agents from a variety of pharmacologic classes. Based on previous studies, the possibility is raised that this sleep enhancement results from an alteration in function of the GABA A-benzodiazepine receptor complex.

Effects of pinealectomy on baseline sleep and response to sleep deprivation.

We have previously reported that older (24 mo.) Fischer rats manifest a diminished post-sleep deprivation increase in NREM and REM sleep. In order to examine whether this decline reflects an age-related change in pineal function, we are now reporting on baseline and recovery sleep parameters in pinealectomized 3-, 12-, and 24-month old rats following 24 hours of sleep deprivation using the disk-over-water method. Three independent age groups; within each group there were sequential measures of sleep under baseline conditions and during recovery from sleep deprivation. The Sleep Research Laboratory at the University of Chicago 56 male Fisher (F344) rats 24 hours of total sleep deprivation using the disk-over-water method Sleep staging of EEG and EMG, and power spectral analysis of the EEG RESULTS: Pinealectomized (pinex) rats did not differ from sham-operated (sham) rats in total sleep, REM sleep, super-modal high-amplitude NREM sleep (HS2), a measure of NREM EEG delta power, or circadian rhythm amplitude. In the pinex rats, there was a modest (2.5%) age-independent increase in NREM sleep (p<0.02). The pinex rats of all ages failed to manifest the increase in NREM sleep during recovery seen in the sham-operated animals (p<0.04). We found no evidence that altered pineal function is responsible for age-related changes in baseline sleep in the rat. These data also suggest that, independent of age, normal pineal function may be relevant to the ability to generate increased NREM sleep in response to prior sleep deprivation.

Effects of aging on sleep in the golden hamster.

The golden hamster (Mesocricetus auratus) has been a model organism for the study of circadian rhythmicity and, in particular, the effects of age on the circadian system. Surprisingly, nothing is known about the effects of advanced age on sleep in this species. As a first step in determining the effects of aging on sleep in the golden hamster, we recorded sleep for 24 hours in 12 young (3 months) and 18 old (17-18 months) golden hamsters entrained to a 14:10 light:dark (LD) cycle. Aged hamsters exhibited small but significant increases in overall NREM sleep time, primarily due to an increase in time the old animals spent in the NREM sleep state during the dark period relative to the young hamsters. There were no significant differences in REM sleep, median sleep episode length, or the number of arousals. The most striking differences between the sleep of young and old hamsters was in NREM delta (0.5-4 Hz) power per epoch. Old hamsters showed approximately 27% less (p=0.0004) delta power per NREM epoch than young hamsters. It is possible that increased NREM sleep time in the old hamsters may be a failed attempt to maintain cumulative delta power; ie, old hamsters may have more NREM sleep in order to make up for the lower intensity of their sleep. This decline in delta power with age parallels earlier findings in cats and humans, although has it not been previously reported in rodents.

Effects of Parenterally Administered Triazolam on Sleep in Rats With Lesions of the Preoptic Area

In previous work we have reported that microinjections of triazolam or pentobarbital into the medial preoptic area of the anterior hypothalamus produce a hypnotic effect. This finding raised the possibility that the sleep-enhancing actions after systemic administration of these compounds might be mediated by hypnogenic mechanisms in the preoptic area. The current study examined whether sleep enhancement by triazolam requires the anatomic integrity of the preoptic area. Nine rats with histologically confirmed lesions of the preoptic area induced by ibotenic acid (2.5 μg/μl in 0.4 μl), and 10 rats that had undergone a sham lesion procedure, had 2-h sleep studies that confirmed that by day 5 measures of total sleep time and sleep latency had returned to preintervention values. Rats were then given triazolam 0.8 mg/kg or vehicle intraperitoneally in counterbalanced order, on days 7 and 9 postlesion, in an environment with an ambient temperature of 25°C. Following injections at 1000 h, in conditions in which lights were on from 0800–2000 h, 2-h sleep studies were performed. In the lesioned rats, triazolam significantly decreased sleep latency and increased total sleep time, primarily by increasing NREM sleep, whereas injections of vehicle did not. In summary, parenterally administered triazolam was found to have hypnotic effects in rats who were 1 week post-preoptic area lesion. These data are interpreted in light of previous evidence of redundancy of sleep-regulating mechanisms in the nervous system.

Sleep and EEG power spectrum effects of the 5-HT 1A antagonist NAN-190 alone and in combination with citalopram

The sleep and waking and EEG power spectrum effects of the putative 5-HT 1A antagonist NAN-190 (0.5 mg/kg, i.p.) were studied alone and in co-administration with the selective serotonin re-uptake inhibitor citalopram (5.0 mg/kg, i.p.) in the rat. Citalopram, as in a prior dose-response study, reduced REM sleep. In addition, a slight increase in NREM sleep was observed. Citalopram reduced NREM fronto-parietal (FP) EEG power density in the 5–20 Hz range. When administered alone, NAN-190 suppressed REM sleep in the first 2 h, and reduced SWS-2 in the first 4 h after administration. NAN-190 also suppressed selectively NREM sleep slow-wave activity in both fronto-frontal (FF) and FP EEG power spectrum. When administrated in combination with citalopram, an attenuation of the power density reduction in the 7–15 Hz range in the FF EEG of citalopram alone, was observed. However, the EEG power spectral density and REM sleep suppressive effects of NAN-190 were both augmented. The results are compatible with the notion that serotonin is involved in the modulation of the slow wave activity in the EEG during NREM sleep. The results are cordant with other data suggesting that postsynaptic 5-HT 1A stimulation might increase slow wave activity in the NREM EEG, and that serotonergic stimulation of other receptor subtypes (possibly 5-HT 2) may decrease slow wave activity in the NREM EEG.

Effects of some DSIP peptide analogs on rat sleep for intraventricular infusion

Peptide [D-AIa2]DSIP markedly increases the representation of NREM and REM sleep delayed by several hours from the onset of infusion and lasting after the infusion till the end of the 12-hour night period in a chamber. Peptide [D-Tyr1]DSIP increases NREM sleep during hours IV and XI of recordings. Analogs of these peptides have no noticeable effects.

Fluoxetine decreases brain temperature and REM sleep in Syrian hamsters.

The antidepressant drug, fluoxetine (FLX), a selective serotonin reuptake inhibitor, was administered to Syrian hamsters, and its acute and chronic effects on EEG sleep and hypothalamic temperature were recorded. Acute fluoxetine treatment at doses of 5, 10, 20 and 40 mg/kg decreased REM sleep and hypothalamic temperature in a dose-dependent manner. It increased NREM sleep, and, at doses of 20 and 40 mg/kg, it increased wakefulness. At 40 mg/kg, it decreased motor activity. During chronic treatment, tolerance developed to FLX's REM sleep-inhibiting effects, but tolerance did not develop to FLX's hypothalamic temperature-decreasing effects. Chronic FLX treatment produced circadian phase-dependent decreases in temperature beyond those that were observed during acute treatment. The apparent dissociation during chronic treatment between FLX's temperature-lowering effects and its REM-decreasing effects might be related to long-term changes in 5HT receptor function or FLX pharmacokinetics.

Developmental phases of sleep and motor behaviour in a cat mother-infant system: A time-lapse video approach.

The evolution of sleep patterns in developing kittens was studied using time-lapse video technology and direct observation. The duration, frequency, and onset of the behavioural states and interactions of the cats were analyzed and then organized into phases that represent major changes in developmental structure during the first 6 weeks of kitten life. We have demonstrated that the kittens began exhibiting adult bi-cyclic sleep patterns on approximately Day 30 of development. During the 10-day period that preceded this consolidation of sleep pattern, REM sleep decreased by half, with a reciprocal increase in NREM sleep. These changes were coincident with an increase in kitten patterned motor behaviour and an increase in stimulation of the kittens by the mother during her bi-cyclic active periods.

969 SLEEP STATE AND MATURATION OF CO2 SENSITIVITY IN THE PREMATURE PRIMATE

Sleep apnea and altered CO2 sensitivity have been implicated in the pathophysiology of SIDS. To investigate the hypothesis that sleep state and postnatal maturation influence minute ventilation and steady state CO2 sensitivity, 7 healthy premature M. nemestrina were studied serially in the first 3 weeks of life. VE/Kg in room air, 2,3,4, and 5% CO2 was measured via nasal wrongs and hot wire anemometer and arterial gases were sampled in 3 animals after a steady state was attained. Sleep state was assessed from EEG, EOG, EMG and respiratory pattern. Baseline VE/Kg and VT/Kg increased and f decreased in REM and NREM sleep with increasing postnatal age (p<.05), but there were no differences in VE/Kg between the 2 states at each age. VE/Kg increased following inhalation of CO2 in each state at each postnatal age, but there were no significant differences in CO2 sensitivity between NREM and REM sleep. In NREM sleep CO2 sensitivity increased progressively with increasing postnatal age (p<.025) whereas in REM sleep this maturational increase in slope was not observed (p>.4). The CO2 ventilatory response curve shifted to the left in both states with increasing age. These results suggest that there is a sleep state specific difference in postnatal maturation of CO2 sensitivity - a progressive increase in NREM sleep and no significant change in REM sleep. Failure of this normal maturational increase in NREM sleep may be important to the pathophysiology of SIDS.

Comparison of the effects of cyclazocine and imipramine on the circadian sleep-waking cycle of the cat.

The effects of both acute and chronic oral doses of , imipramine and a combination of these two agents Cyclazocine (acute) were determined on sleep-wake patterning in the cat. Acute cyclazocine (0.5 mg/kg), imipramine (2.5 mg/kg) and the combination (0.25 mg/kg cyclazocine plus 1.25 mg/kg imipramine) REM rebound significantly depressed REM sleep on the administration day, but in no case was any observed on the post-drug days. Cyclazocine depressed while imipramine and the combination increased NREM sleep. The combination induced marked behavioral changes and had a longer duration of action than either drug alone. Chronic, oral cyclazocine or imipramine (14 days) resulted in complete tolerance to the initial effects. The abrupt withdrawal of either agent resulted in a significant REM rebound that for imipramine reached a peak on the first post-drug day, but for cyclazocine did not peak until the third post-drug day.