Losing sleep with age

Mechanism of action of Panax ginseng alcohol extract based on orexin-mediated autophagy in the treatment of sleep and cognition in aged sleep-deprived rats

ETHNOPHARMACOLOGICAL RELEVANCE

Panax ginseng (P. ginseng) C. A. Meyer. has been used extensively globally as a medicine. It has a therapeutic effect on sleep and is an attractive alternative for patients with insomnia. The United States Patent of Invention has approved the use of P. ginseng alcohol extract (GAE) in nutraceuticals or food to improve sleep. It has shown promise as an effective therapeutic agent for improving sleep and cognition. However, its mechanism of action is not yet fully understood.

AIM OF THE STUDY

To investigate the therapeutic benefits of GAE on sleep and cognition and its underlying mechanism in aged sleep-deprived rats, with a focus on orexin-mediated autophagy function.

MATERIALS AND METHODS

We conducted in vivo tests in an aged sleep-deprivation rat model produced using p-chlorophenylalanine (PCPA) coupled with modified multi-platform method to examine the therapeutic effects and mechanisms of GAE. A pentobarbital sodium-induced sleep test and water maze were used to assess sleep and cognitive performance, respectively. An enzyme-linked immunosorbent assay was used to determine orexin levels and aging and sleep markers in serum and hypothalamic tissues. Hematoxylin-eosin staining and Nissl staining were used to assess histopathological changes, and autophagy levels were assessed using transmission electron microscopy, immunofluorescence. Western blot and immunohistochemical staining were performed to detect the levels of orexin, orexin-receptor proteins, and autophagy-associated proteins to study the effects of GAE on hippocampal neurons, and the underlying mechanisms.

RESULTS

In aged sleep-deprived rats, GAE treatment prolonged sleep duration, improved cognitive function, prevented hippocampal neuronal damage, increased the number of Nissl bodies, improved aging and sleep markers, and enhanced the LC3A/B expression in autophagosomes and neurons. The amount of orexin in serum and hypothalamic tissue and OX1R, OX2R, and phosphatidylinositol-3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) proteins also reduced, which resulted in the inhibition of the PI3K/Akt/mTOR pathway and activation of the autophagy process.

CONCLUSIONS

GAE may reduce hypothalamic orexin secretion and interact with orexin receptors to inhibit the PI3K/Akt/mTOR signalling network and activate autophagy. This may be a potential mechanism of action of GAE in regulating sleep-related cognitive function.

Effect of dexmedetomidine infusion on postoperative sleep disturbances in women with breast cancer: A monocentric randomized-controlled double-blind trial

BACKGROUND

Most women with breast cancer are prone to postoperative sleep disturbances (POSD). Little is known about the differences between sevoflurane and propofol combined with dexmedetomidine on POSD in the same context. We investigated the effect of intra-operative sevoflurane or propofol combined with intravenous dexmedetomidine on the incidence of POSD and postoperative sleep structures.

METHODS

A monocentric, randomized-controlled, double-blind trial. Female patients undergoing radical surgery for breast cancer were randomly assigned to receive sevoflurane and placebo, sevoflurane and dexmedetomidine, propofol and placebo, or propofol and dexmedetomidine. Dexmedetomidine was administered at 1.0 μg kg-1 infusion 15 min before induction, then infused at 0.4 μg kg-1 h-1 until the surgical drain started to be placed. The primary outcome was the incidence of POSD within the postoperative first three days (defined as an Athens Insomnia Scale score ≥ 6 points on at least one day of postoperative first three days). The secondary outcome was the duration of sleep structures, collected from the Fitbit Charge 2® smart bracelet (Fitbit, Inc., San Francisco, CA, USA).

RESULTS

There were 188 women analyzed with the modified intention-to-treat method. The incidences of POSD in the dexmedetomidine and placebo groups were similar (p = 0.649). In the sevoflurane sedation strategy, dexmedetomidine decreased nocturnal wakefulness on postoperative first day (p = 0.001). In the propofol sedation strategy, dexmedetomidine increased nocturnal deep sleep on postoperative first (p < 0.001) and third (p < 0.001) days.

CONCLUSION

Intra-operative infusion of dexmedetomidine had no significant effect on POSD but decreased nocturnal wakefulness in the sevoflurane group and increased nocturnal deep sleep in the propofol group.

TRIAL REGISTRATION

Registered at www.chictr.org.cn (ChiCTR2300070136).

Orexin Receptor Antagonism: Normalizing Sleep Architecture in Old Age and Disease

Sleep is essential for human well-being, yet the quality and quantity of sleep reduce as age advances. Older persons (>65 years old) are more at risk of disorders accompanied and/or exacerbated by poor sleep. Furthermore, evidence supports a bidirectional relationship between disrupted sleep and Alzheimer's disease (AD) or related dementias. Orexin/hypocretin neuropeptides stabilize wakefulness, and several orexin receptor antagonists (ORAs) are approved for the treatment of insomnia in adults. Dysregulation of the orexin system occurs in aging and AD, positioning ORAs as advantageous for these populations. Indeed, several clinical studies indicate that ORAs are efficacious hypnotics in older persons and dementia patients and, as in adults, are generally well tolerated. ORAs are likely to be more effective when administered early in sleep/wake dysregulation to reestablish good sleep/wake-related behaviors and reduce the accumulation of dementia-associated proteinopathic substrates. Improving sleep in aging and dementia represents a tremendous opportunity to benefit patients, caregivers, and health systems.

Association between circadian rhythm and sleep quality among nursing interns: A latent profile and moderation analysis

Background

Disturbances in circadian rhythms are common among night-shift workers and result in poor sleep quality. Nevertheless, the heterogeneity of circadian rhythms and their relationship with sleep quality is less explored in nursing interns. Therefore, we aimed to identify the latent subtypes of circadian rhythm, explore their relationship with sleep quality, and evaluate their moderating role between perceived stress and sleep quality in nursing interns.

Materials and methods

In all, 452 nursing interns were recruited between October 2020 and January 2021 from Be Resilient to Nursing Career (BRNC), which is a multicenter, prospective cohort of a career growth program for nursing students. They were assessed using the 10-item Chinese Perceived Stress Scale, Circadian Type Inventory, and Pittsburgh Sleep Quality Index. Latent profile analysis and moderation analysis were performed.

Results

Overall, 72.3% of the nursing interns reported poor sleep quality. We identified three latent subtypes of circadian rhythms, namely, Vigorousness (40.1%), Inadaptability (18.6%), and Flexibility (41.1%). Females (OR = 1.97, 95% Cl: 1.01-3.83, P = 0.047) with normal body mass index (OR = 1.62, 95% CI: 0.95-2.76, P = 0.078) were prone to Flexibility. Circadian rhythm types significantly moderated the association between perceived stress and sleep quality (P < 0.05).

Conclusion

Nursing interns suffer from poor sleep. There exists heterogeneity of circadian rhythm subtypes in nursing interns, and attention should be paid to those with Inadaptability type. The association between perceived stress and sleep quality is significantly moderated by circadian rhythm subtypes.