Nobiletin Attenuates Anesthesia/Surgery-Induced Neurocognitive Decline by Preserving the Expression of Clock Genes in Mice

Agonists, inverse agonists, and antagonists as therapeutic approaches to manipulate retinoic acid-related orphan receptors

Retinoic acid-related orphan receptors (RORs) serve as transcription factors that play a pivotal role in a myriad of physiological processes within the body. Their involvement extends to critical biological processes that confer protective effects in the heart, immune system, and nervous system, as well as contributing to the mitigation of several aggressive cancer types. These protective functions are attributed to ROR's regulation of key proteins and the management of various cellular processes, including autophagy, mitophagy, inflammation, oxidative stress, and glucose metabolism, highlighting the emerging need for pharmacological approaches to modulate ROR expression. Thus, the modulation of RORs is a rapidly growing area of research aimed not only at comprehending these receptors, but also at manipulating them to attain the desired physiological response. Despite the presence of natural ROR ligands, the development of synthetic agonists with high selectivity for these receptors holds substantial therapeutic potential. The exploration and advancement of such compounds can effectively target diseases associated with ROR dysregulation, thereby providing avenues for therapeutic interventions. Herein, we provide a comprehensive examination of the multifaceted role of ROR in diverse physiological and pathophysiological conditions, accompanied by an in-depth exploration of a spectrum of ROR agonists, inverse agonists, and antagonists.

A review on recent advances on nobiletin in central and peripheral nervous system diseases

In recent years, the role of nobiletin in neuronal disorders has received extensive attention. However, the study of nobiletin in the peripheral nervous system is limited. Nobiletin, as a compound with high fat solubility, high bioavailability and low toxicity, has been extensively studied. Accumulating scientific evidence has shown that nobiletin has a variety of biological functions in the nervous system, such as inhibiting the expression of inflammatory factors, reducing the neurotoxic response, improving the antioxidant capacity, promoting the survival of nerve cells, promoting axon growth, reducing blood‒brain barrier permeability, reducing brain oedema, promoting cAMP response element binding protein expression, improving memory, and promoting mild depolarization of nerve cell mitochondria to improve antioxidative stress capacity. Accumulating studies have shown that nobiletin also protects enteric nervous system, spinal cord and sciatic nerve. To explore the new therapeutic potential of nobiletin in the nervous system, recent and relevant research progress is reviewed in this article. This will provide a new research idea for nobiletin in the nervous system.

Neuroinflammation: The central enabler of postoperative cognitive dysfunction

The proportion of advanced age patients undergoing surgical procedures is on the rise owing to advancements in surgical and anesthesia technologies as well as an overall aging population. As a complication of anesthesia and surgery, older patients frequently suffer from postoperative cognitive dysfunction (POCD), which may persist for weeks, months or even longer. POCD is a complex pathological process involving multiple pathogenic factors, and its mechanism is yet unclear. Potential theories include inflammation, deposition of pathogenic proteins, imbalance of neurotransmitters, and chronic stress. The identification, prevention, and treatment of POCD are still in the exploratory stages owing to the absence of standardized diagnostic criteria. Undoubtedly, comprehending the development of POCD remains crucial in overcoming the illness. Neuroinflammation is the leading hypothesis and a crucial component of the pathological network of POCD and may have complex interactions with other mechanisms. In this review, we discuss the possible ways in which surgery and anesthesia cause neuroinflammation and investigate the connection between neuroinflammation and the development of POCD. Understanding these mechanisms may likely ensure that future treatment options of POCD are more effective.

Chrysin Attenuates Oxidative Stress to Alleviate Sevoflurane-Induced Cognitive Impairments in Aged Rats

OBJECTIVE

Anesthesia-induced cognitive impairments are common for elder patients after surgery. Oxidative stress is the predominant factor contributing to the impairments. This study was to assess the therapeutic potential of an anti-oxidative naturally occurring flavonoid, chrysin, in attenuating sevoflurane-induced cognitive impairments in rat models.

METHODS

Rat models of cognitive impairments were constructed by exposing aged rats (18 months old) to sevoflurane for 2 h. Chrysin was administered via oral gavage at the dose of 25, 50, and 100 mg/kg/day for seven days. The elevated plus maze test was used to assess anxiety and explorative behaviors. Spatial memory tests were performed using novel object recognition test, object location memory task, and water maze experiments. Oxidative stress was evaluated by measuring levels of malondialdehyde, nicotinamide adenine dinucleotide phosphate, 4-hydroxynonenal, and glutathione using colorimetric assays. Quantitative real-time polymerase chain reaction and Western blot were used to analyze how chrysin affects nuclear factor E2-related factor (Nrf) signaling.

RESULTS

While sevoflurane anesthesia led to significant decline in cognitive performance in object recognition test, object location memory task, and water maze test, chrysin exerted significant effects in alleviating the impairments. Oxidative stress was also reduced in the hippocampus tissue of rats after chrysin intake. Nrf signaling was activated by chrysin treatment in sevoflurane-induced cognitive impairment models.

CONCLUSION

Chrysin was effective in alleviating cognitive impairments induced by sevoflurane anesthesia, which was at least in part facilitated by its effects in reducing oxidative stress via activating Nrf signaling.

Effect of the Citrus Flavone Nobiletin on Circadian Rhythms and Metabolic Syndrome

The importance of the circadian clock in maintaining human health is now widely acknowledged. Dysregulated and dampened clocks may be a common cause of age-related diseases and metabolic syndrome Thus, circadian clocks should be considered as therapeutic targets to mitigate disease symptoms. This review highlights a number of dietary compounds that positively affect the maintenance of the circadian clock. Notably the polymethoxyflavone nobiletin has shown some encouraging results in pre-clinical experiments. Although many more experiments are needed to fully elucidate its exact mechanism of action, it is a promising candidate with potential as a chronotherapeutic agent.