Orexin receptor antagonists in the pathophysiology and treatment of sleep disorders and epilepsy

At least 150 min per week of Tai chi practice improves sleep quality in the older people: evidence from a meta-analysis

OBJECTIVE

To conduct a meta-analysis to explore the optimal dosage of Tai chi exercise that positively influences the sleep quality of the older people.

METHODS

A literature search was conducted from 2004 to October 2024 in PubMed, Embase, Web of Science, Google Scholar, Cochrane Library, and Chinese databases (CNKI and Wanfang) for randomised controlled trials in Chinese and English on Tai chi improving sleep quality in the older people. Data extraction and verification were performed by two independent researchers. Additionally, a meta-analysis of the mean difference (MD) and 95% confidence interval (CI) was conducted using RevMan 5.4.

RESULTS

A total of nine randomised controlled trials involving 1,166 older participants were included. Compared with the control group, Tai chi significantly reduced the total Pittsburgh Sleep Quality Index (PSQI) scores in the older people [MD =  - 1.53, 95% CI (- 2.18, - 0.89), p < 0.001], with heterogeneity results Q = 53.63, df = 12, and I2 of 78% (p < 0.001); Total weekly duration of Tai chi exercise: Less than 150 min reduced PSQI scores, but the difference was not statistically significant [MD =  - 1.47, 95% CI (- 3.89, 0.95), p = 0.23]. Between 150-300 min significantly reduced PSQI scores [MD =  - 1.54, 95% CI (- 2.00, - 1.08), p < 0.001]; Duration of Tai chi exercise programme: 8-12 weeks significantly reduced PSQI scores [MD =  - 1.93, 95% CI (- 2.60, - 1.25), p < 0.001]; 16-24 weeks significantly reduced PSQI scores [MD =  - 1.27, 95% CI (- 2.27, - 0.26), p = 0.01]; Single session duration of Tai chi exercise: 60 min significantly reduced PSQI scores [MD =  - 2.17, 95% CI (- 3.15, - 1.18), p < 0.001]; Less than 60 min (25-45 min) significantly reduced PSQI scores [MD =  - 0.92, 95% CI (- 1.63, - 0.20), p = 0.01].

CONCLUSION

Older individuals engaging in at least 150 min per week of Tai chi practice can improve sleep quality. Beyond this threshold, extending the duration of individual practice sessions or the exercise programme does not yield additional benefits for sleep quality.

Mechanisms, consequences and role of interventions for sleep deprivation: Focus on mild cognitive impairment and Alzheimer's disease in elderly

Sleep is established as an essential physiological need that impacts physical, emotional, and cognitive functions profoundly. Physiologically, inadequate sleep weakens immune function, heightening susceptibility to infections and chronic illnesses such as obesity, diabetes, and cardiovascular diseases. Hormonal disruptions due to sleep loss further exacerbate metabolic dysregulation, contributing to weight gain and other health complications. Emotionally, sleep deprivation leads to mood disturbances, including increased irritability, heightened stress responses, and a greater likelihood of mood disorders like depression and anxiety. These effects are compounded by cognitive impairments such as reduced alertness, impaired memory consolidation, and compromised decision-making abilities, akin to the impairments caused by alcohol consumption. Motor skills and coordination also suffer, elevating the risk of accidents, particularly in high-stress environments. For older adults, sleep quality is closely linked to cognitive function and overall longevity. Optimal sleep patterns are associated with slower brain aging and improved health outcomes. However, sleep disorders exacerbate existing conditions such as epilepsy and asthma, necessitating interventions like cognitive behavioral therapy (CBT) and medications such as melatonin to mitigate their impact. Education emerges as a crucial tool in promoting healthier sleep habits across all age groups. Addressing misconceptions about sleep and integrating sleep health into public health policies are essential steps toward improving overall well-being. Additionally, lifestyle factors such as diet and physical activity play significant roles in regulating sleep patterns, further emphasizing the interconnectedness of sleep with broader health outcomes. In summary, the articles underscore the intricate mechanisms through which sleep influences physiological functions and advocate for comprehensive approaches to enhance sleep hygiene and mitigate the adverse effects of sleep deprivation on human health.

Role of hippocampal and prefrontal cortical cholinergic transmission in combination therapy valproate and cannabidiol in memory consolidation in rats: involvement of CREB- BDNF signaling pathways

PURPOSE

Cognitive disorders are associated with valproate and drugs used to treat neuropsychological diseases. Cannabidiol (CBD) has beneficial effects on cognitive function. This study examined the effects of co-administration of CBD and valproate on memory consolidation, cholinergic transmission, and cyclic AMP response element-binding protein (CREB)-brain-derived neurotrophic factor (BDNF) signaling pathway in the prefrontal cortex (PFC) and hippocampus (HPC).

METHODS

One-trial, step-through inhibitory test was used to evaluate memory consolidation in rats. The intra-CA1 injection of physostigmine and atropine was performed to assess the role of cholinergic transmission in this co-administration. Phosphorylated CREB (p-CREB)/CREB ratio and BDNF levels in the PFC and HPC were evaluated.

RESULTS

Post-training intraperitoneal (i.p.) valproate injection reduced memory consolidation; however, post-training co-administration of CBD with valproate ameliorated memory impairment induced by valproate. Post-training intra-CA1 injection of physostigmine at the ineffective doses in memory consolidation (0.5 and 1 µg/rat), plus injection of 10 mg/kg of CBD as an ineffective dose, improved memory loss induced by valproate, which was associated with BDNF and p-CREB level enhancement in the PFC and HPC. Conversely, post-training intra-CA1 injection of ineffective doses of atropine (1 and 2 µg/rat) reduced the positive effects of injection of CBD at a dose of 20 mg/kg on valproate-induced memory loss associated with BDNF and p-CREB level reduction in the PFC and HPC.

CONCLUSION

The results indicated a beneficial interplay between valproate and CBD in the process of memory consolidation, which probably creates this interaction through the BDNF-CREB signaling pathways in the cholinergic transmission of the PFC and HPC regions.

Anti-inflammatory and protective effects of Aripiprazole on TNBS-Induced colitis and associated depression in rats: Role of kynurenine pathway

BACKGROUND

The prevalence of depression is higher in patients with inflammatory bowel disease (IBD) than in the general population. Inflammatory cytokines and the kynurenine pathway (KP) play important roles in IBD and associated depression. Aripiprazole (ARP), an atypical antipsychotic, shows various anti-inflammatory properties and may be useful in treating major depressive disorder. This study aimed to evaluate the protective effects of ARP on TNBS-induced colitis and subsequent depression in rats, highlighting the role of the KP.

MATERIAL AND METHODS

Fifty-six male Wistar rats were used, and all groups except for the normal and sham groups received a single dose of intra-rectal TNBS. Three different doses of ARP and dexamethasone were injected intraperitoneally for two weeks in treatment groups. On the 15th day, behavioral tests were performed to evaluate depressive-like behaviors. Colon ulcer index and histological changes were assessed. The tissue levels of inflammatory cytokines, KP markers, lipopolysaccharide (LPS), nuclear factor-kappa-B (NF-κB), and zonula occludens (ZO-1) were evaluated in the colon and hippocampus.

RESULTS

TNBS effectively induced intestinal damages and subsequent depressive-like symptoms in rats. TNBS treatment significantly elevated the intestinal content of inflammatory cytokines and NF-κB expression, dysregulated the KP markers balance in both colon and hippocampus tissues, and increased the serum levels of LPS. However, treatment with ARP for 14 days successfully reversed these alterations, particularly at higher doses.

CONCLUSION

ARP could alleviate IBD-induced colon damage and associated depressive-like behaviors mainly via suppressing inflammatory cytokines activity, serum LPS concentration, and affecting the NF-κB/kynurenine pathway.

Orexin B protects dopaminergic neurons from 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced neurotoxicity associated with reduced extracellular signal-regulated kinase phosphorylation

BACKGROUND

The loss of dopaminergic (DA) neurons in the substantia nigra pars compacta (SNpc) is a major pathological hallmark of Parkinson's disease (PD). Orexin B (OXB) has been reported to promote the growth of DA neurons. However, the roles of OXB in the degeneration of DA neurons still remained not fully clear.

METHODS

An in vivo PD model was constructed by administrating 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in mice. Pole test was performed to investigate the motor function of mice and the number of DA neurons was detected by immunofluorescence (IF). A PD cell model was established by treating SH-SY5Y cells with 1-methyl-4-phenylpyridinium (MPP+). OXB was added to the culture medium 2 h after MPP + treatment. Microscopic analysis was carried out to investigate the function of OXB in the cell model of PD 24 h after MPP + challenge. RNA-Seq analysis of the PD cell model was performed to explore the possible mechanisms. Western blot was used to detect the phosphorylation levels of extracellular signal-regulated kinase (ERK).

RESULTS

OXB significantly decreased the DA neurons death caused by MPTP, alleviated MPP+-induced neurotoxicity in SH-SY5Y cells, and robustly enhanced the weight and motor ability of PD mice. Besides, RNA-Seq analysis demonstrated that the mitogen-activated protein kinase (MAPK) pathway was involved in the pathology of PD. Furthermore, MPP + led to increased levels of phosphorylation of ERK (p-ERK), OXB treatment significantly decreased the levels of p-ERK in MPP+-treated SH-SY5Y cells.

CONCLUSIONS

This study demonstrated that OXB exerts a neuroprotective role associated with reduced ERK phosphorylation in the PD model. This suggests that OXB may have therapeutic potential for treatment of PD.

Ameliorative Effect of Cannabidiol on Topiramate-Induced Memory Loss: The Role of Hippocampal and Prefrontal Cortical NMDA Receptors and CREB/BDNF Signaling Pathways in Rats

Cannabidiol (CBD) is a promising neurological agent with potential beneficial effects on memory and cognitive function. The combination of CBD and topiramate in the treatment of some neurological diseases has been of great interest. Since Topiramate-induced memory loss is a major drawback of its clinical application and the overall effect of the combination of CBD and topiramate on memory is still unclear, here we investigated the effect of CBD on topiramate-induced memory loss and the underlying molecular mechanisms. A one trial step-through inhibitory test was used to evaluate memory consolidation in rats. Moreover, the role of N-methyl-D-aspartate receptors (NMDARs) in the combination of CBD and topiramate in memory consolidation was evaluated through the intra-CA1 administration of MK-801 and NMDA. Western blot analysis was used to evaluate variations in brain-derived neurotrophic factor (BDNF) and phosphorylated cyclic AMP response element-binding protein (pCREB)/CREB ratio in the prefrontal cortex (PFC) and hippocampus (HPC). While the intraperitoneal (i.p.) administration of topiramate (50, 75, and 100 mg/kg) significantly reduced inhibitory time latency, the i.p. administration of CBD (20 and 40 mg/kg) could effectively reverse these effects. Similarly, the sub-effective doses of NMDA plus CBD (10 mg/kg) could improve the topiramate-induced memory loss along with an enhancement in BDNF and pCREB expression in the PFC and HPC. Contrarily, the administration of sub-effective doses of the NMDAR antagonist (MK-801) diminished the protective effects of CBD (20 mg/kg) on topiramate-induced memory loss associated with decreased BDNF and pCREB levels in the PFC and HPC. These findings suggest that CBD can improve topiramate-induced memory impairment, partially by the NMDARs of the PFC and HPC, possibly regulated by the CREB/BDNF signaling pathway.

Sulfonamide Compounds as Orexin Receptor Agonists for Treating Sleep Disorders, Namely, Narcolepsy and Hypersomnia

Provided herein are novel sulfonamide compounds as orexin receptor agonists, their pharmaceutical compositions, the use of such compounds in treating sleep disorders, namely, narcolepsy and hypersomnia, and processes for preparing such compounds.

Comparison of neuroprotective effects of a topiramate-loaded biocomposite based on mesoporous silica nanoparticles with pure topiramate against methylphenidate-induced neurodegeneration

BACKGROUND

Methylphenidate (MPH) abuse has been criticized for its role in neurodegeneration. Also, a high risk of seizure was reported in the first month of MPH treatment. Topiramate, a broad-spectrum Antiepileptic Drug (AED), has been used as a neuroprotective agent in both aforementioned complications. Nanotechnology is introduced to increase desirable neurological treatment with minimum side effects. We aimed to investigate the potential neuroprotective activity of topiramate loaded on nanoparticles.

METHODS AND RESULTS

MTT assay was performed to evaluate the cellular cytotoxicity of Mesoporous Silica Nanoparticles (MSN). Male rats were randomly divided into eight groups. Rats received an intraperitoneal (i.p) MPH (10 mg/kg) injection and a daily oral dose of topiramate (TPM, 30 mg/kg), MSN with Zn core (10 and 30 mg/kg), and MSN with Cu core (10 and 30 mg/kg) for three weeks. On day 21, a seizure was induced by a single injection of pentylenetetrazole (PTZ) to evaluate the protective effects of TPM-loaded nanoparticles on seizure latency and duration following MPH-induced neurotoxicity. Moreover, the hippocampal content of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), malondialdehyde (MDA), and the anti-oxidant enzymes (SOD, GPx, and GR) activities were assessed. Also, BAX and Bcl-2 as two main apoptotic markers were evaluated.

RESULTS

MPH neurotoxicity was observed as a raised duration and reduced latency in PTZ-induced seizure. However, TPM-loaded MSN with Zn species (NE) treatment reduced the duration and improved the latency time. Also, NE and, somewhat, TPM-loaded MSN with Cu species (NM) administration reduced inflammatory cytokines, MDA, and Bax levels and increased activities in the rat hippocampus.

CONCLUSION

TPM-loaded nanoparticles could be used as neuroprotective agents against MPH-induced neurodegeneration by improving seizure parameters and reducing inflammatory, oxidant, and apoptotic factors.

Cross state-dependent memory retrieval between tramadol and ethanol: involvement of dorsal hippocampal GABAA receptors

RATIONALE

Tramadol and ethanol, as psychoactive agents, are often abused. Discovering the molecular pathways of drug-induced memory creation may contribute to preventing drug addiction and relapse.

OBJECTIVE

The tramadol- and ethanol-induced state-dependent memory (SDM) and cross-SDM retrieval between tramadol and ethanol were examined in this study. Moreover, because of the confirmed involvement of GABAA receptors and GABAergic neurotransmission in memory retrieval impairment, we assessed cross-SDM retrieval between tramadol and ethanol with a specific emphasis on the role of the GABAA receptors. The first hypothesis of this study was the presence of cross-SDM between tramadol and ethanol, and the second hypothesis was related to possible role of GABAA receptors in memory retrieval impairment within the dorsal hippocampus. The cannulae were inserted into the hippocampal CA1 area of NMRI mice, and a step-down inhibitory avoidance test was used to evaluate state dependence and memory recovery.

RESULTS

The post-training and/or pre-test administration of tramadol (2.5 and 5 mg/kg, i.p.) and/or ethanol (0.5 and 1 g/kg, i.p.) induced amnesia, which was restored after the administration of the drugs 24 h later during the pre-test period, proposing ethanol and tramadol SDM. The pre-test injection of ethanol (0.25 and 0.5 g/kg, i.p.) with tramadol at an ineffective dose (1.25 mg/kg) enhanced tramadol SDM. Moreover, tramadol injection (1.25 and 2.5 mg/kg) with ethanol at the ineffective dose (0.25 g/kg) promoted ethanol SDM. Furthermore, the pre-test intra-CA1 injection of bicuculline (0.0625, 0.125, and 0.25 μg/mouse), a GABAA receptor antagonist, 5 min before the injection of tramadol (5 mg/kg) or ethanol (1 g/kg) inhibited tramadol- and ethanol-induced SDM dose-dependently.

CONCLUSION

The findings strongly confirmed cross-SDM between tramadol and ethanol and the critical role of dorsal hippocampal GABAA receptors in the cross-SDM between tramadol and ethanol.

Ameliorative effects of Albizia adianthifolia aqueous extract against pentylenetetrazole-induced epilepsy and associated memory loss in mice: Role of GABAergic, antioxidant defense and anti-inflammatory systems

Albizia adianthifolia (Schumach.) (Fabaceae) is a medicinal herb used for the treatment of epilepsy and memory impairment. This study aims to investigate the anticonvulsant effects of Albizia adianthifolia aqueous extract against pentylenetetrazole (PTZ)-induced spontaneous convulsions in mice; and determine whether the extract could mitigate memory impairment, oxidative/nitrergic stress, GABA depletion and neuroinflammation. Ultra-high performance liquid chromatography/mass spectrometry analysis was done to identify active compounds from the extract. Mice were injected with PTZ once every 48 h until kindling was developed. Animals received distilled water for the normal group and negative control groups, doses of extract (40, 80, or 160 mg/kg) for the test groups and sodium valproate (300 mg/kg) for the positive control group. Memory was measured using Y maze, novel object recognition (NOR) and open field paradigms, while the oxidative/nitrosative stresses (MDA, GSH, CAT, SOD and NO), GABAergic transmission (GABA, GABA-T and GAD) and neuro-inflammation (TNF-α, IFN-γ, IL- 1β, and IL-6) were determined. Brain photomicrograph was also studied. Apigenin, murrayanine and safranal were identified in the extract. The extract (80-160 mg/kg) significantly protected mice against seizures and mortality induced by PTZ. The extract significantly increased the spontaneous alternation and the discrimination index in the Y maze and NOR tests, respectively. PTZ kindling induced oxidative/nitrosative stress, GABA depletion, neuroinflammation and neuronal cells death was strongly reversed by the extract. The results suggest that the anticonvulsant activity of Albizia adianthifolia extract is accompanied by its anti-amnesic property, and may be supported by the amelioration of oxidative stress, GABAergic transmission and neuroinflammation.

Daridorexant, an Orexin Receptor Antagonist for the Management of Insomnia

BACKGROUND

Insomnia is a common sleep disorder that is diagnosed primarily by patients' subjective reported symptoms. Daridorexant is a new dual orexin receptor antagonist that was recently approved by Food and Drug Administration for insomnia characterized by difficulty falling asleep and/or maintaining sleep.

MECHANISM OF ACTION, PHARMACODYNAMICS, AND PHARMACOKINETICS

The orexin neuropeptide signaling system plays a role in wakefulness, and blocking the wake-promoting neuropeptides results in diminished wake signaling, thus exerting a sedative effect using an entirely different mechanism of action than the classical sleep promoting agents. The drug has quick onset of action, high volume of distribution, and high protein binding. Pharmacokinetics and pharmacodynamic parameters were similar in patients of different sex and age and were not significantly affected by race, body size, or mild-to-moderate kidney impairment. Dose limitation to 25 mg in moderate liver impairment and no use in severe liver impairment are recommended. The drug undergoes hepatic CYP3A4 metabolism; thus, caution with strong CYP3A4 inhibitors and inducers is warranted.

CLINICAL TRIALS

The drug was approved based on phase 3 trials involving study 1 and study 2. Study 1 noted daridorexant at doses of 25 and 50 mg demonstrated a statistically significant improvement in wake time after sleep onset, latency to persistent sleep, and self-reported total sleep time against placebo at months 1 and 3. Similarly in study 2, compared with placebo, the 25 mg dose demonstrated statistically significant improvement in wake time after sleep onset, latency to persistent sleep, and self-reported total sleep time at months 1 and 3. Treatment-emergent adverse events were similar for daridorexant and placebo, with nasopharyngitis and headache most frequently reported.

THERAPEUTIC ADVANCE

Daridorexant is a novel agent with demonstrated efficacy in sleep onset and maintenance and decrease in daytime sedation. Preliminary results from a 1-year extension study note similar incidences of mild-to-moderate side effects as noted in previous trials. Further studies are needed to establish its place in the pharmacological treatment of insomnia.

Several neuropeptides involved in parkinsonian neuroprotection modulate the firing properties of nigral dopaminergic neurons

Parkinson's disease is characterized by progressive degeneration of dopaminergic neurons in the substantia nigra pars compacta. The surviving nigral dopaminergic neurons display altered spontaneous firing activity in Parkinson's disease. The firing rate of nigral dopaminergic neurons decreases long before complete neuronal death and the appearance of parkinsonian symptoms. A mild stimulation could rescue dopaminergic neurons from death and in turn play neuroprotective effects. Several neuropeptides, including cholecystokinin (CCK), ghrelin, neurotensin, orexin, tachykinins and apelin, within the substantia nigra pars compacta play important roles in the modulation of spontaneous firing activity of dopaminergic neurons and therefore involve motor control and motor disorders. Here, we review neuropeptide-induced modulation of the firing properties of nigral dopaminergic neurons. This review may provide a background to guide further investigations into the involvement of neuropeptides in movement control by modulating firing activity of nigral dopaminergic neurons in Parkinson's disease.