Diazepam and midazolam increase light slow-wave sleep (SWS1) and decrease wakefulness in rats

Network pharmacology and pharmacological evaluation for deciphering novel indication of Sishen Wan in insomnia treatment

BACKGROUND

Insomnia is the most frequent sleep disorder worldwide and is a prominent risk factor for mental and physical health deterioration. The clinical application of common pharmacological treatments for insomnia is far from satisfactory due to their various adverse effects. In recent years, drugs developed from natural herbs have become potential alternative therapies for insomnia. Sishen Wan (SSW), a traditional Chinese medicine (TCM) used for centuries to treat diarrheal disease, consists of multiple neurologically active herbs with sleep-regulating potential that may have therapeutic effects on insomnia. However, its hypnotic and sleep-regulating effects have not been evaluated in clinical practice or laboratory experiments.

PURPOSE

To investigate the anti-insomnia effects of SSW and explore its possible mechanisms using preclinical models.

STUDY DESIGN AND METHODS

The sedative effect of the SSW formula was investigated using network pharmacology analysis that was validated using various pharmacological approaches, including the evaluation of locomotor activity (LMA), pentobarbital-induced sleep time, and electroencephalography/electromyogram (EEG/EMG)-based sleep profiling in normal rats. Several animal models of insomnia, including sleep deprivation, serotonin depletion, and cage-changing models, have been used to further assess the anti-insomnia effects of SSW. Furthermore, the potential underlying mechanisms of action of SSW were predicted using bioinformatics methods and verified using in vivo and in silico experiments.

RESULTS

The results showed that SSW reduced LMA and prolonged pentobarbital-induced sleep time in a dose-dependent manner, which was consistent with the increase in non-rapid eye movement (NREM) sleep in normal rats, indicating a solid sedative effect. In animal models of insomnia, SSW alleviated sleep disturbance by increasing NREM sleep time, shortening NREM sleep latency, and inhibiting sleep fragmentation, suggesting a possible curative effect of SSW on insomnia. Finally, through functional enrichment analysis and in vivo and in silico experiments, 5-HT_1A was identified as the key target of the anti-insomnia effect of SSW. Moreover, (S)-propranolol, nuciferine, zizyphusine, and N,N-dimethyl-5-methoxytryptamine may be the active compounds of SSW responsible for its anti-insomnia effect.

CONCLUSION

This study extended the possible indication scope for SSW, which provides a potential therapeutic TCM that may be used for insomnia treatment, as well as a reference scheme for the discovery of novel indications of TCM.

Hydroalcoholic Extract of Ashwagandha Improves Sleep by Modulating GABA/Histamine Receptors and EEG Slow-Wave Pattern in In Vitro - In Vivo Experimental Models

Withania somnifera (ashwagandha) has been used traditionally as a remedy for insomnia and to enhance cognitive function. The effects of ashwagandha extract (AE, 35% withanolide glycosides, Shoden^Ⓡ) on the expression levels of γ-aminobutyric acid (GABA)_Aρ1 and histamine H3 receptors in Rattus norvegicus glioblastoma (C6) cell lines were studied using semiquantitative reverse transcriptase-polymerase chain reactions. The effects of AE on sleep onset and duration were studied in Swiss albino mice using the pentobarbital-induced sleep model. Furthermore, the effects on nonrapid eye movement (NREM) and rapid eye movement sleep patterns were studied in Wistar rats with electroencephalogram (EEG) to support the improvement in sleep quality. There was an increase in gene expression levels of GABA_Aρ1 receptor (1.38 and 1.94 folds) and histamine H3 (1.14 and 1.29 folds) receptors induced by AE at doses of 15 and 30 μg/mL compared to control. AE at doses of 10, 25, and 50 mg/kg body weight showed a significant decrease in time to sleep onset and increased total sleep duration in the pentobarbital-induced sleep model. At 50 mg/kg body weight dosage level, a 34% decrease (P<0.0001) in sleep onset time and 47% increase (P<0.0001) in sleep duration was observed. The EEG study showed significant improvement in alpha, beta, theta, delta, and gamma bands at doses of 10, 25, and 50 mg/kg body weight with delta waves showing increases of 30%, 46% (P<0.05), and 34%, respectively. The induction of sleep, GABA-mimetic action, NREM sleep, and the effects on slow-wave cycles support the calming property of AE in improving the quality of sleep.

Modification of brain waves and sleep parameters by Citrus reticulata Blanco. cv. Sai-Nam-Phueng essential oil

Background

Citrus essential oil (EO) has been used for mood elevation and sedative hypnotic purposes. However, scientific proofs of its central nervous system (CNS) action remained largely unexplored. This study investigated chemotypes, electrical brain waves and sleep-wake effects of the essential oil from Citrus reticulata in rat model.

Methods

Chemical contents of citrus EO were analyzed using gas chromatography-mass spectrometry (GC–MS). Male Wistar rats implanted with electrodes on the frontal and parietal skulls were used for electroencephalographic (EEG) recording while inhaling the citrus EO (200 μl on cotton wool). Diazepam (10 mg/kg, p.o.) was used as a standard anxiolytic drug. EEG frequency analyses were performed by using Fast Fourier transform. All data were statistical analyzed using One-way ANOVA followed by Tukey's test.

Results

GC–MS analysis revealed d-limonene (95.7%) as a major constituent of citrus EO. The EEG results showed that overall EEG patterns of citrus EO effects were relatively similar to that of diazepam. However, significant differences between treatments were seen from sleep-wake analyses. Diazepam significantly increased episode numbers of awake and non-rapid eye movement (REM) sleep and reduced averaged episode duration. On the other hand, the citrus EO significantly decreased REM sleep latency and increased total time and episode numbers of REM sleep.

Conclusion

These findings demonstrated unique CNS effects of C. reticulata EO with EEG fingerprints and sleep-wake profiles. The data might be useful for citrus essential oil sub-classification and clinical application.

Global slowing of network oscillations in mouse neocortex by diazepam

Benzodiazepines have a broad spectrum of clinical applications including sedation, anti-anxiety, and anticonvulsive therapy. At the cellular level, benzodiazepines are allosteric modulators of GABA(A) receptors; they increase the efficacy of inhibition in neuronal networks by prolonging the duration of inhibitory postsynaptic potentials. This mechanism of action predicts that benzodiazepines reduce the frequency of inhibition-driven network oscillations, consistent with observations from human and animal EEG. However, most of existing data are restricted to frequency bands below ∼30 Hz. Recent data suggest that faster cortical network rhythms are critically involved in several behavioral and cognitive tasks. We therefore analyzed diazepam effects on a large range of cortical network oscillations in freely moving mice, including theta (4-12 Hz), gamma (40-100 Hz) and fast gamma (120-160 Hz) oscillations. We also investigated diazepam effects over the coupling between theta phase and the amplitude fast oscillations. We report that diazepam causes a global slowing of oscillatory activity in all frequency domains. Oscillation power was changed differently for each frequency domain, with characteristic differences between active wakefulness, slow-wave sleep and REM sleep. Cross-frequency coupling strength, in contrast, was mostly unaffected by diazepam. Such state- and frequency-dependent actions of benzodiazepines on cortical network oscillations may be relevant for their specific cognitive effects. They also underline the strong interaction between local network oscillations and global brain states.

Power spectral analysis of recovery sleep of sleep deprivation and hypnotic drug induced sleep

Hypnotic drugs induced sleep is usually different from physiological sleep in restoring body energy. The cause of the differences is not clear. To investigate the differences between these two types of sleep, in this study, hypnotic drug diazepam (DZP) induced sleep was compared with the recovery sleep following sleep deprivation. Power spectral analysis was used to reveal the different EEG features of these two types of sleep. EEGs were recorded in rat occipital cortex with implanted electrodes under three vigilance states of waking, slow wave sleep (SWS) and rapid eye movement (REM) sleep. Spectral powers of the EEG segments were evaluated in sub-bands of delta (0.5 - 4.0 Hz), theta (4.25 - 8.0 Hz), alpha (8.25 - 16.0 Hz), beta (16.25 - 25.0 Hz) and for total frequency range of 0.5 - 25.0 Hz. The data showed that both hypnotic drug DZP and sleep deprivation increased the time of SWS and REM sleep; however, DZP decreased low-frequency activity in SWS sleep, while sleep deprivation increased low-frequency activity in SWS sleep during recovery sleep. The decrease of low-frequency activity in DZP induced SWS sleep could result from the DZP inhibitory effects. The results suggest that increases of sleep evoked by different factors can have different features and the method of power spectral analysis is useful in revealing deep features of different types of sleep.

An integrative analysis to sleep functions

Various studies suggest that some sleep functions, especially some slow wave sleep functions, are indispensable in mammals and related to brain regulation. It has been proposed that two of these functions are the adjustment of emotional balance and the processing of acquired emotional memories. During waking, the gradual accumulation of various randomly learned emotional memories in the limbic structures would inevitably imbalance and disorganize emotional behaviors. Although the emotional balance can be restored during waking by the ascending NA, DA, ACh and 5-HT systems, their roles in memory retention and emotional regulation may sometimes be dissociated and their adjustment of the emotional balance can only be a transient effect. On the other hand, the function of slow wave sleep for emotional adjustment can be long-lasting and is in agreement with its function on the processing of emotional memories. As a result, these sleep functions become indispensable in preventing the emotional imbalance inevitably caused by the accumulation of emotional memories. The effects of rapid eye movement sleep on memory and emotional regulation are just opposite to those of slow wave sleep. Low vigilance is required as premise for sleep to accomplish these indispensable functions.

Triazolam-induced sleep in the rat: influence of prior sleep, circadian time, and light/dark cycles

Rats entrained to 12-h on /12-h off light schedule and injected with triazolam 0.4 mg/kg at the mid-point of their activity phase (6 h after lights out: circadian time = CT-18) had a stronger hypnotic response than animals free-running in constant dark injected at the equivalent circadian time. In contrast, entrained rats injected 5 h after lights on (CT-5) showed increased wake after injection relative to baseline, largely due to REM sleep inhibition. Hypnotic efficacy was found to be inversely related to prior accumulated sleep. During the 6 h before injection, entrained rats injected at CT-18 slept significantly less than the free-running rats, which in turn slept significantly less than entrained rats injected at CT-5. Taken together, the results suggest that the amount of prior sleep was a more important influence on the response to triazolam than either light/dark per se or circadian phase. Methodologically, automated sleep scoring was found to be an efficient method for examining drug effects, particularly when corroborated by concurrent independent physiological variables and spectral analysis.

Effects of diazepam and two beta-carbolines on epileptic activity and on EEG and behavior in rats with absence seizures

In the present series of experiments, effects of a full benzodiazepine receptor agonist (diazepam) are described and compared with those of a partial benzodiazepine receptor agonist (ZK 91296) and an inverse partial benzodiazepine receptor agonist (FG 7142), both compounds of the beta-carboline family. In a rat model for generalized absence epilepsy, the anticonvulsant, the hypnotic and the myorelaxant properties were investigated, as well as effects on on-going behavior and effects on the electroencephalogram (EEG). While diazepam showed all behavioral and electrophysiological changes characteristic for the benzodiazepines, the partial agonist ZK 91296 reduced seizure activity without inducing any signs of sedation, sleepiness, myorelaxation and changes in behavior or EEG spectral content. The partial inverse agonist FG 7142 aggrevated epileptic activity, with slightly enhanced immobile behavior, suggesting some anxiogenic properties. The results not only demonstrate that the multiple effects of the benzodiazepines could be separated by these compounds, but also that the anticonvulsant activity is not related to changes in spectral content of the EEG. Because of its selective activity, ZK 91296 appears to be more suitable than diazepam in reducing seizure activity. Finally, FG 7142 seems a genuine partial inverse agonist which has some, but not all, of the inverse effects of a full agonist.

Desensitization of adenosine A2 receptors in the striatum of the rat following chronic treatment with diazepam

Following prolonged treatment (7 days) with diazepam (10 mg/kg/day, using ALZET mini-osmotic pumps) in rats, the function of adenosine receptors was assessed in specific structures of the brain, using both agonist ligand binding and adenylate cyclase assays. Binding to A1 receptors was quantified using [3H]N6-[(R)-1-methyl-2-phenylethyl] adenosine, a selective ligand at A1 receptors. Differences in the binding of this ligand and that of [3H]5'-N-ethylcarboxamide adenosine, which binds to both A1 and A2 subtypes of receptors with similar affinities, were used to quantify A2 receptors. Treatment with diazepam failed to alter the binding of [3H]N6-[(R)-1-methyl-2-phenylethyl] adenosine in all areas of the brain studied. However, the binding of A2 receptors and A2 receptor-mediated stimulation of adenylate-cyclase were significantly attenuated in striatal membranes from diazepam-treated rats. Thus, the present study indicated that functional adenosine A2 receptors were desensitized after prolonged treatment with diazepam, since decreased agonist binding to A2 receptors paralleled an attenuation in the stimulation by adenosine of the activity of adenylate cyclase, an effect mediated by the A2 receptor. These results further indicate that the changes in adenosine A2 receptors correlated with significant short-lasting alterations in the sleep-wake cycle during the withdrawal of diazepam. The alterations in sleep-wakefulness did not correlate with the effect of diazepam on benzodiazepine receptors since no changes were observed in the binding of benzodiazepine receptors.