Decreased muscarinic receptor binding in rat brain after paradoxical sleep deprivation: an autoradiographic study

Crosstalk between the subiculum and sleep-wake regulation: A review

The circuitry underlying the initiation, maintenance, and coordination of wakefulness, rapid eye movement sleep, and non-rapid eye movement sleep is not thoroughly understood. Sleep is thought to arise due to decreased activity in the ascending reticular arousal system, which originates in the brainstem and awakens the thalamus and cortex during wakefulness. Despite the conventional association of sleep-wake states with hippocampal rhythms, the mutual influence of the hippocampal formation in regulating vigilance states has been largely neglected. Here, we focus on the subiculum, the main output region of the hippocampal formation. The subiculum, particulary the ventral part, sends extensive monosynaptic projections to crucial regions implicated in sleep-wake regulation, including the thalamus, lateral hypothalamus, tuberomammillary nucleus, basal forebrain, ventrolateral preoptic nucleus, ventrolateral tegmental area, and suprachiasmatic nucleus. Additionally, second-order projections from the subiculum are received by the laterodorsal tegmental nucleus, locus coeruleus, and median raphe nucleus, suggesting the potential involvement of the subiculum in the regulation of the sleep-wake cycle. We also discuss alterations in the subiculum observed in individuals with sleep disorders and in sleep-deprived mice, underscoring the significance of investigating neuronal communication between the subiculum and pathways promoting both sleep and wakefulness.

The stress of losing sleep: Sex-specific neurobiological outcomes

Sleep is a vital and evolutionarily conserved process, critical to daily functioning and homeostatic balance. Losing sleep is inherently stressful and leads to numerous detrimental physiological outcomes. Despite sleep disturbances affecting everyone, women and female rodents are often excluded or underrepresented in clinical and pre-clinical studies. Advancing our understanding of the role of biological sex in the responses to sleep loss stands to greatly improve our ability to understand and treat health consequences of insufficient sleep. As such, this review discusses sex differences in response to sleep deprivation, with a focus on the sympathetic nervous system stress response and activation of the hypothalamic-pituitary-adrenal (HPA) axis. We review sex differences in several stress-related consequences of sleep loss, including inflammation, learning and memory deficits, and mood related changes. Focusing on women's health, we discuss the effects of sleep deprivation during the peripartum period. In closing, we present neurobiological mechanisms, including the contribution of sex hormones, orexins, circadian timing systems, and astrocytic neuromodulation, that may underlie potential sex differences in sleep deprivation responses.

Animal Models for Elucidation of the Mechanisms of Neuropsychiatric Disorders Induced by Sleep and Dietary Habits

Numerous changes in human lifestyle in modern life increase the risk of disease. Especially, modern sleep and dietary habits are crucial factors affecting lifestyle disease. In terms of sleep, decreases in total sleep time and in rapid eye movement sleep time have been observed in attention-deficit/hyperactivity disorder (ADHD) patients. From a dietary perspective, mastication during eating has several good effects on systemic, mental, and physical functions of the body. However, few animal experiments have addressed the influence of this decline in sleep duration or of long-term powdered diet feeding on parameters reflecting systemic health. In our studies, we examined both the influence of intermittent sleep deprivation (SD) treatment and long-term powdered diet feeding on emotional behavior in mice, and focused on the mechanisms underlying these impaired behaviors. Our findings were as follows: SD treatment induced hypernoradrenergic and hypodopaminergic states within the frontal cortex. Furthermore, hyperactivity and an explosive number of jumps were observed. Both the hypernoradrenergic state and the jumps were improved by treatment with ADHD therapeutic drugs. On the other hand, long-term powdered diet feeding increased social interaction behaviors. The feeding affected the dopaminergic function of the frontal cortex. In addition, the long-term powdered diet fed mice presented systemic illness signs, such as elevations of blood glucose, and hypertension. This review, describing the SD mice and long-term powdered diet fed mice can be a useful model for elucidation of the mechanism of neuropsychiatric disorders or the discovery of new therapeutic targets in combatting effects of the modern lifestyle.

Short-term sleep deprivation disrupts the molecular composition of ionotropic glutamate receptors in entorhinal cortex and impairs the rat spatial reference memory

Numerous studies reported that sleep deprivation (SD) causes impairment in spatial cognitive performance. However, the molecular mechanisms affected by SD underlying this behavioral phenomenon remain elusive. Here, we focused on the entorhinal cortex (EC), the gateway of the hippocampus, and investigated how SD affected the subunit expression of AMPARs and NMDARs, the main ionotropic glutamategic receptors serving a pivotal role in spatial cognition. In EC, we found 4h SD remarkably reduced surface expression of GluA1, while there was an increase in the surface expression of GluA2 and GluA3. As for NMDARs, SD with short duration significantly reduced the surface expression levels of GluN1 and GluN2B without effect on the GluN2A. In parallel with the alterations in AMPARs and NMDARs, we found the 4h SD impaired rat spatial reference memory as assessed by Morris water maze task. Overall, these data indicate that brief SD differently affects the AMPAR and NMDAR subunit expressions in EC and might consequently disrupt the composition and functional properties of these receptors.

The EEG as an index of neuromodulator balance in memory and mental illness

There is a strong correlation between signature EEG frequency patterns and the relative levels of distinct neuromodulators. These associations become particularly evident during the sleep-wake cycle. The monoamine-acetylcholine balance hypothesis is a theory of neurophysiological markers of the EEG and a detailed description of the findings that support this proposal are presented in this paper. According to this model alpha rhythm reflects the relative predominance of cholinergic muscarinic signals and delta rhythm that of monoaminergic receptor effects. Both high voltage synchronized rhythms are likely mediated by inhibitory Gαi/o-mediated transduction of inhibitory interneurons. Cognitively, alpha and delta EEG measures are proposed to indicate automatic and flexible strategies, respectively. Sleep is associated with marked changes in relative neuromodulator levels corresponding to EEG markers of distinct stages. Sleep studies on memory consolidation present some of the strongest evidence yet for the respective roles of monoaminergic and cholinergic projections in declarative and non-declarative memory processes, a key theoretical premise for understanding the data. Affective dysregulation is reflected in altered EEG patterns during sleep.

Paradoxical sleep deprivation potentiates epilepsy induced by homocysteine thiolactone in adult rats

There is an intriguing and still poorly understood relationship between sleep deprivation and epilepsy. It has recently been shown that paradoxical sleep deprivation decreases levels of homocysteine, an amino acid involved together with its thiolactone metabolite in epileptogenesis. The aim of the present study was to investigate the effects of paradoxical sleep deprivation on homocysteine thiolactone (H)-induced seizures in rats, a model of generalized seizures. Selective deprivation of paradoxical sleep in adult male Wistar rats was achieved by the platform method. Animals with implanted electrodes for electroencephalogram (EEG) registration were assigned to appropriate experimental conditions (dry cage for control, large platform for stress control and small platform for paradoxical sleep deprivation) and 72 h later were intraperitoneally treated with either H (5.5 mmol/kg) or saline (0.9% NaCl). This study showed that paradoxical sleep deprivation increased the incidence and number of H-induced seizure episodes, shortened latency time to seizures and led to significant rates of lethality after H administration, but without effect on the seizure severity. Paradoxical sleep deprivation increased the number and duration of spikes-and-wave discharges, while decreased latency to its appearance in EEG. Judging by the behavioral and EEG findings, it could be concluded that paradoxical sleep deprivation can provoke the expression of factors that can potentiate H-induced seizures in adult rats.

Association of methamidophos and sleep loss on reproductive toxicity of male mice

This study investigated the effects of organophosphate exposure on the male reproductive system of mice submitted to chronic sleep loss condition. Adult Swiss mice were distributed into 4 groups: control; methamidophos (MTP); sleep restriction (SR); and MTP+SR. The dose of methamidophos was 0.002 mgkg(-1)day(-1) (half of the Acceptable Daily Intake). Sleep restriction condition was 21 h day(-1) during 15 days. In relation to control group, MTP treatment induced a significant reduction of 12% on morphologically normal spermatozoa in both MTP and MTP+SR groups. In addition, the absolute and relative weights of the seminal vesicles were decreased (MTP, -34%; MTP+SR, -45%). Epididymal fat was reduced in SR groups (SR, -64%; MTP+SR, -58%). Plasma testosterone levels were significantly decreased in MTP and SR groups, and progesterone levels were increased 8 times in MTP+SR in comparison with the control group. The corticosterone levels were unaffected by MTP or SR conditions. Thus, low dose MTP exposure resulted in deleterious effects on the male reproductive system. Sleep loss associated with MTP potentiated the effect on steroidogenesis, mainly in terms of progesterone levels.

Paradoxical sleep deprivation: neurochemical, hormonal and behavioral alterations. Evidence from 30 years of research

Sleep comprises approximately one-third of a person's lifetime, but its impact on health and medical conditions remains partially unrecognized. The prevalence of sleep disorders is increasing in modern societies, with significant repercussions on people's well-being. This article reviews past and current literature on the paradoxical sleep deprivation method as well as data on its consequences to animals, ranging from behavioral changes to alterations in the gene expression. More specifically, we highlight relevant experimental studies and our group's contribution over the last three decades.

Privação de sono e exercício físico

A privação do sono é a remoção ou supressão parcial do sono, e esta condição pode causar diversas alterações: endócrinas, metabólicas, físicas, cognitivas, neurais e modificações na arquitetura do sono, que em conjunto comprometem a saúde e a qualidade de vida do sujeito nestas condições. Já o exercício físico praticado regularmente promove benefícios como melhora do aparato cardiovascular, respiratório, endócrino, muscular e humoral, além disso, pode melhorar a qualidade do sono. Entretanto, a associação desses dois parâmetros não tem sido bem explorada, em parte pela dificuldade conseguir voluntários que se submetam a essa condição principalmente sem nenhum tipo de compensação financeira. A maioria dos estudos que investigaram o binômio exercício físico e privação de sono focou os efeitos no desempenho aeróbio. Embora ainda haja controvérsias, os estudos apontam para pequena ou nenhuma alteração desse parâmetro quando as duas situações se fazem presentes. Em relação à potência anaeróbia e força não tem sido encontrados alterações significativas, mas para eventos prolongados, parece haver uma interação entre a privação de sono e o exercício físico, o que sugere um mecanismo de proteção. Entretanto, é importante considerar que uma das alterações mais importantes causadas pela privação do sono é o aumento na percepção subjetiva, que por si só já representa um fator para diminuição e comprometimento do desempenho físico e pode representar um elemento de "mascaramento" dos efeitos deletérios da privação. Assim, o objetivo da presente revisão é o de discutir os diferentes aspectos da relação entre o exercício físico e a privação de sono, evidenciando seus efeitos e reflexos no desempenho físico.

Carbachol induction of REM sleep in the rat is more effective at lights-out than lights-on

Long-lasting increases in REM sleep are induced in the rat following injection of small amounts of muscarinic receptor agonists into the caudal oral pontine reticular formation. By injecting carbachol at the beginning of the light period or beginning of the dark period, we sought to determine whether the muscarinic, REM sleep induction is influenced by the time of day it is initiated. We found that carbachol is more effective at increasing REM sleep when administered at the beginning of the dark in 87% of the cases. Of these cases, 43% showed evidence of a decreased potency of carbachol by a shift in the dose-response curve to the right. The lack of agreement in efficacy and potency to increase REM sleep supports a conclusion that alterations in local muscarinic receptors are not mediating the effect of time of day. REM sleep control mechanisms down stream of the muscarinic receptors may be the responsible factors.

Differential effects of chronic partial sleep deprivation and stress on serotonin-1A and muscarinic acetylcholine receptor sensitivity

Disrupted sleep and stress are often linked to each other, and considered as predisposing factors for psychopathologies such as depression. The depressed brain is associated with reduced serotonergic and enhanced cholinergic neurotransmission. In an earlier study, we showed that chronic sleep restriction by forced locomotion caused a gradual decrease in postsynaptic serotonin-1A receptor sensitivity, whilst chronic forced activity alone, with sufficient sleep time, did not affect receptor sensitivity. The first aim of the present study was to examine whether the sleep loss-induced change in receptor sensitivity is mediated by adrenal stress hormones. The results show that the serotonin-1A receptor desensitization is independent of adrenal hormones as it still occurs in adrenalectomized rats. The second aim of the study was to establish the effects of sleep restriction on cholinergic muscarinic receptor sensitivity. While sleep restriction affected muscarinic receptor sensitivity only slightly, forced activity significantly hypersensitized the muscarinic receptors. This hypersensitization is because of the stressful nature of the forced activity protocol as it did not occur in adrenalectomized rats. Taken together, these data confirm that sleep restriction may desensitize the serotonin-1A receptor system. This is not a generalized effect as sleep restriction did not affect the sensitivity of the muscarinic cholinergic receptor system, but the latter was hypersensitized by stress. Thus, chronic stress and sleep loss may, partly via different pathways, change the brain into a direction as it is seen in mood disorders.

Cholinergic mechanisms in cocaine-induced genital reflexes in paradoxical sleep-deprived male rats

In view of the fact that paradoxical sleep deprivation (PSD) modifies cocaine-induced genital reflexes (penile erection [PE] and ejaculation [EJ]), the aim of this study was to address the interaction of cholinergic agents with the action of cocaine on the genital reflexes of PSD male rats. After a 4-day period of PSD, each group was administered with cholinergic drugs 1 h prior to cocaine and was placed in observation cages. The administration of nicotine (0.12, 0.25, 0.5 and 1 mg/kg sc) reduced the frequency and number of animals displaying PE and increased PE latency. Pretreatment with mecamylamine (1.25, 5, 10 and 20 mg/kg sc) also significantly reduced PE frequency for all doses used. The percentage of rats showing EJ was significantly reduced in the group pretreated with 1 mg/kg of nicotine compared with the saline group. The administration of pilocarpine (1.25, 2.5, 5 and 10 mg/kg sc) and atropine (1.25, 5, 10 and 20 mg/kg sc) led to a reduction in the frequency of PE displayed by the rats. These data show that agonist and antagonist cholinergic drugs inhibit genital reflexes in PSD male rats injected with cocaine. The data also suggest that the stimulating action of cocaine in potentiating the sexual effects in PSD rats does not override the effects of the cholinergic mechanisms of sexual behavior.

Deficits in avoidance responding after paradoxical sleep deprivation are not associated with altered [3H]pirenzepine binding to M1 muscarinic receptors in rat brain

Previous work had indicated that animals that were sleep-deprived and then trained on a passive avoidance task show poor retention of the task 24 h later after being allowed to sleep freely again. Cholinergic involvement is suggested by the fact that this effect is prevented by treatment with the muscarinic agonist pilocarpine during sleep deprivation. The observation that similar deficits are observed in non-deprived rats after treatment with M1-selective antagonist compounds such as dicyclomine or pirenzepine cause similar impairments, and gave rise to the hypothesis that sleep deprivation might induce significant reductions in M1 binding in brain areas involved in learning and memory processes. Rats were deprived of sleep for 96 h and then either immediately killed, or allowed to recover sleep for 24 h before being killed. [3H]pirenzepine binding to M1 sites was examined by quantitative autoradiography in 39 different brain areas in cage controls, sleep-deprived and sleep-recovered animals (N=8 per group). No significant differences among groups were found in any brain region. A separate group of animals was subjected to the sleep deprivation procedure and then trained in a simple avoidance task. Animals were then allowed to sleep and retested 24 h later. This group showed a significant impairment in the avoidance task compared to cage controls, in agreement with previous observations. These data suggest that proactive learning/memory deficits induced by sleep deprivation cannot be attributed to altered M1 binding either immediately after deprivation (when avoidance training occurs) or after sleep has recovered (when acquisition/retention are tested). The possibility remains that alterations in M1 function occur at post-membrane second messenger systems.

Social stress does not interact with paradoxical sleep deprivation-induced memory impairment

Extensive evidence has linked both paradoxical sleep (PS) and stress to memory processing. The purpose of the present study was to examine the effect of social instability stress on memory and to verify whether this stress interferes with the amnesic effect of PS deprivation using the modified multiple platform method. In addition to the PS-deprived group (put onto narrow platforms inside the deprivation tanks) two control groups were used: one of them remained in its home-cages and the other was placed inside the deprivation tanks, onto a grid that contained large platforms on it. All groups were subdivided in socially stable and unstable conditions. Immediately after 96 h of sleep deprivation, the animals were trained in three different memory tasks: inhibitory avoidance, classical fear conditioning to a discrete stimulus and contextual fear conditioning. Twenty-four hours after training, the animals were tested in order to assess task acquisition. The results showed that social instability did not impair the performance of animals nor interacted with PS deprivation in any of the tasks. Grid control animals presented a selective impairment in the inhibitory avoidance task and contextual, but not in the classical, fear conditioning task, compared to cage control rats. This finding could be due to the stress to which grid control animals were exposed (humidity and luminosity) during the manipulation period. PS-deprived animals exhibited poorer performance than the other groups in all tasks. As they also showed an increased threshold to shock-induced vocalisation, but not to flinch response, it is not possible to completely rule out a decreased response to noxious stimulation as a contributing factor for the present results with PS deprivation.

Distribution of G-protein-coupled receptor kinase (GRK) isoforms 2, 3, 5 and 6 mRNA in the rat brain

There is limited knowledge about the distribution of the different G-protein-coupled receptor kinases (GRKs) in the rat brain, especially for the recently cloned isoforms GRK5 and GRK6. In this work an overview will be given of the mRNA expression patterns of four G-protein-coupled receptor kinases, GRK2 (betaARK1), GRK3 (betaARK2), GRK5 and GRK6 in the rat brain. As now shown by us and recently by others GRK2 and GRK3 are widely distributed in rat brain with nearly the same expression pattern. But GRK3, in general, appeared to be weaker expressed than GRK2 in most brain areas. Exceptions were the islands of Calleja, the compact part of the substantia nigra and the locus coeruleus. GRK3 mRNA was very low expressed or absent in the striatum and in some hypothalamic and thalamic nuclei. The expression pattern of GRK6 was also similar to GRK2. In the caudate putamen GRK6 yielded the strongest hybridization signal of all GRK types. GRK5 took a special position. The message for this form was not expressed ubiquitously in the brain but was mainly localized in limbic brain regions with a very prominent expression in the lateral septal area. GRK5 may therefore be involved in reward and addiction. Accordingly, a higher expression level of GRK5 mRNA was found in the lateral septum of cocaine-sensitized rats as compared to controls.

Cholinergic modulation of inhibitory avoidance impairment induced by paradoxical sleep deprivation

1. Male Wistar rats were submitted to paradoxical sleep deprivation for 96 hr by a modified multiple platform technique. 2. Training of step-through inhibitory avoidance was performed immediately after the last day of paradoxical sleep deprivation. Twenty-four hr after training the animals were submitted to the retention test. 3. In Experiment 1, pilocarpine (4 mg/kg, i.p.) or atropine (4 mg/kg, i.p.) were administered daily during the paradoxical sleep deprivation period. Pilocarpine, but not atropine, reversed the impairment induced by PS deprivation. 4. In Experiment 2, pilocarpine (4, 8 and 12 mg/kg, i.p.) was injected 1 hr before training in order to verify if the reversal of memory impairment was an effect secondary to residual enhanced blood levels of pilocarpine during training. Acute treatment with pilocarpine, in any dose, did not reverse the impairment produced by paradoxical sleep deprivation 5. Activation of the cholinergic system during the period of deprivation is able to prevent memory deficits induced by paradoxical sleep deprivation.

Differences in gene expression during sleep and wakefulness

Compared with our understanding of the electrophysiological correlates of sleep and wakefulness, the search for correlates at the molecular level is still in its infancy. However, the evidence obtained so far supports the hypothesis that reliable molecular correlates do exist. As will be summarized in this review, levels of receptor binding, second messengers and protein phosphorylation differ between sleep and wakefulness. Moreover, compelling data obtained in different animal species suggest that the transition between sleep and wakefulness is accompanied by significant changes in gene expression. Many immediate early genes, transcription factors, plasticity-related genes and mitochondrial genes are expressed at higher levels in wakefulness than in sleep, while a few still unknown genes are up-regulated during sleep. The ongoing systematic screening of gene expression across behavioural states should prove crucial in elucidating the regulatory mechanisms of sleep homeostasis and the functions of sleep.

Rapid eye movement sleep induction by vasoactive intestinal peptide infused into the oral pontine tegmentum of the rat may involve muscarinic receptors

In rats, rapid eye movement sleep can be induced by microinjection of either the cholinergic agonist carbachol or the neuropeptide vasoactive intestinal peptide into the oral pontine reticular nucleus. Possible involvement of cholinergic mechanisms in the effect of vasoactive intestinal peptide was investigated using muscarinic receptor ligands. Sleep-waking cycles were analysed after infusion into the oral pontine reticular nucleus of vasoactive intestinal peptide (10 ng in 0.1 microl), carbachol (20 ng), atropine (200 ng) and pirenzepine (50, 100 ng), performed separately or in combination at 15-min intervals. The increase in rapid eye movement sleep due to the combined infusion of vasoactive intestinal peptide and carbachol (+58.7+/-4.6% for 8 h, P<0.05) was not significantly different from that induced by each compound separately. The enhancement of rapid eye movement sleep by vasoactive intestinal peptide was totally prevented by infusion of atropine, but not pirenzepine, a relatively selective M1 antagonist. On their own, none of the latter two compounds affected the sleep-waking cycle. Quantitative autoradiographic studies using [3H]quinuclidinyl benzylate (1 nM) and pirenzepine (0.5 microM) indicated that muscarinic receptors correspond to pirenzepine-insensitive binding sites in the oral pontine reticular nucleus. In vitro, vasoactive intestinal peptide (1-100 nM) significantly increased (+30-40%) the specific binding of [3H]quinuclidinyl benzylate to the oral pontine reticular nucleus in rat brain sections. This effect appeared to be due to an increased density, with no change in affinity, of pirenzepine-insensitive binding sites in this area. These data suggest that pirenzepine-insensitive muscarinic binding sites are involved in the induction of rapid eye movement sleep by vasoactive intestinal peptide at the pontine level in the rat.

Rapid eye movement (REM) sleep deprivation reduces rat frontal cortex acetylcholinesterase (EC 3.1.1.7) activity

Rapid eye movement (REM) sleep deprivation induces several behavioral changes. Among these, a decrease in yawning behavior produced by low doses of cholinergic agonists is observed which indicates a change in brain cholinergic neurotransmission after REM sleep deprivation. Acetylcholinesterase (Achase) controls acetylcholine (Ach) availability in the synaptic cleft. Therefore, altered Achase activity may lead to a change in Ach availability at the receptor level which, in turn, may result in modification of cholinergic neurotransmission. To determine if REM sleep deprivation would change the activity of Achase, male Wistar rats, 3 months old, weighing 250-300 g, were deprived of REM sleep for 96 h by the flower-pot technique (N = 12). Two additional groups, a home-cage control (N = 6) and a large platform control (N = 6), were also used. Achase was measured in the frontal cortex using two different methods to obtain the enzyme activity. One method consisted of the obtention of total (900 g supernatant), membrane-bound (100,000 g pellet) and soluble (100,000 g supernatant) Achase, and the other method consisted of the obtention of a fraction (40,000 g pellet) enriched in synaptic membrane-bound enzyme. In both preparations, REM sleep deprivation induced a significant decrease in rat frontal cortex Achase activity when compared to both home-cage and large platform controls. REM sleep deprivation induced a significant decrease of 16% in the membrane-bound Achase activity (nmol thiocholine formed min-1 mg protein-1) in the 100,000 g pellet enzyme preparation (home-cage group 152.1 +/- 5.7, large platform group 152.7 +/- 24.9 and REM sleep-deprived group 127.9 +/- 13.8). There was no difference in the soluble enzyme activity. REM sleep deprivation also induced a significant decrease of 20% in the enriched synaptic membrane-bound Achase activity (home-cage group 126.4 +/- 21.5, large platform group 127.8 +/- 20.4, REM sleep-deprived group 102.8 +/- 14.2). Our results suggest that REM sleep deprivation changes Ach availability at the level of its receptors through a decrease in Achase activity.

Stress-induced sleep deprivation modifies corticotropin releasing factor (CRF) levels and CRF binding in rat brain and pituitary

Electroencephalographic (EEG) studies have shown that corticotropin-releasing factor (CRF) administration induces EEG activation, decreases sleep time both in rats and humans and modifies the sleep pattern in sleep deprived rats. In the present study we have investigated whether CRF neuronal activity could be altered in a situation of disrupted sleep-wake cycle. Sleep deprivation (SD) was induced by keeping the rat for 72 h on a small platform (7 cm) surrounded by water. Immediately after the SD period rats were killed and CRF levels and CRF receptor binding were evaluated in different brain areas. A marked increase in CRF levels was present in the striatum (+224%), limbic areas (+144%) and pituitary (+42%) whereas the hypothalamic CRF content was reduced (-57%). A significant decrease in CRF binding was found in the striatum (-33%) and pituitary (-38%) of sleep deprived rats. These results indicate that CRF neuronal activity is stimulated by SD, suggesting that CRF might play an important role in the physiological regulation of the sleep-wake cycle and that an altered CRF neuronal activity might be involved in behavioral modifications related to sleep disturbances.

Effect of sleep deprivation on the growth hormone response to the alpha-3 adrenergic receptor agonist, clonidine, in normal subjects

One night's sleep deprivation (SD) increased the growth hormone (GH) response to clonidine (20 ug/kg i.v.) in 11 normal men ( p < 0.005). This finding may indicate that SD enhances alpha-2 adrenergic receptor function or that the GH response to GH releasing factor in increased by SD.