Pterostilbene Improves Cognitive Performance in Aged Rats: An in Vivo Study

Pterostilbene Ameliorates Cognitive Impairment in Polycystic Ovary Syndrome Rat Model through Improving Insulin Resistance via the IRS-1/PI3K/Akt/GSK-3β Pathway: A Comparative Study with Metformin

Polycystic ovary syndrome (PCOS) is an intricate endocrine disorder that targets millions of women globally. Recent research has drawn attention to its association with cognitive impairment and Alzheimer's disease (AD) risk, yet the exact mechanism remains elusive. This study aimed to explore the potential role of PCOS-associated insulin resistance (IR) and inflammation in linking PCOS to AD pathogenesis. It additionally investigated the therapeutic merits of pterostilbene (PTS) in ameliorating PCOS and associated cognitive deficits in comparison to metformin (MET). Rats were divided into five groups; vehicle group, PTS group [30 mg/kg, per os (p.o.) for 13 days], and the remaining three groups received letrozole (1 mg/kg, p.o. for 21 days) to represent the PCOS, PCOS + MET (300 mg/kg, p.o. for 13 days), and PCOS + PTS groups, respectively. Behavioral tests were conducted, along with a histopathological investigation of brains and ovaries. Assessment of serum hormonal profile and hippocampal IRS-1/PI3K/AKT/GSK-3β insulin signaling pathway components were performed. PTS rats exhibited improved insulin sensitivity and hormonal profile, besides enhanced neurobehavioral tests performance and histopathological findings. These effects may be attributed to modulation of the IRS-1/PI3K/AKT/GSK-3β pathway, reducing GSK-3β activity, and mitigating Tau hyperphosphorylation and Aβ accumulation in the brain. Likewise, PTS attenuated nuclear factor kappa B-mediated inflammation and reversed AChE elevation, suggesting multifaceted neuroprotective effects. Comparatively, PTS showed outcomes similar to those of MET in most parameters. The obtained findings validated that dysregulated insulin signaling in PCOS rats detrimentally affects cognitive function, which is halted by PTS, unveiling the potential of PTS as a novel therapy for PCOS and related cognitive deficits.

Chronic and postprandial effect of blueberries on cognitive function, alertness, and mood in participants with metabolic syndrome - results from a six-month, double-blind, randomized controlled trial

BACKGROUND

Anthocyanin and blueberry intakes positively associated with cognitive function in population-based studies and cognitive benefits in randomized controlled trials of adults with self-perceived or clinical cognitive dysfunction. To date, adults with metabolic syndrome (MetS) but without cognitive dysfunction are understudied.

OBJECTIVES

Cognitive function, mood, alertness, and sleep quality were assessed as secondary end points in MetS participants, postprandially (>24 h) and following 6-mo blueberry intake.

METHODS

A double-blind, randomized controlled trial was conducted, assessing the primary effect of consuming freeze-dried blueberry powder, compared against an isocaloric placebo, on cardiometabolic health >6 mo and a 24 h postprandial period (at baseline). In this secondary analysis of the main study, data from those completing mood, alertness, cognition, and sleep assessments are presented (i.e., n = 115 in the 6 mo study, n = 33 in the postprandial study), using the following: 1) Bond-Lader self-rated scores, 2) electronic cognitive battery (i.e., testing attention, working memory, episodic memory, speed of memory retrieval, executive function, and picture recognition), and 3) the Leeds Sleep Evaluation Questionnaire. Urinary and serum anthocyanin metabolites were quantified, and apolipoprotein E genotype status was determined.

RESULTS

Postprandial self-rated calmness significantly improved after 1 cup of blueberries (P = 0.01; q = 0.04; with an 11.6% improvement compared with baseline between 0 and 24 h for the 1 cup group), but all other mood, sleep, and cognitive function parameters were unaffected after postprandial and 6-mo blueberries. Across the ½ and 1 cup groups, microbial metabolites of anthocyanins and chlorogenic acid (i.e., hydroxycinnamic acids, benzoic acids, phenylalanine derivatives, and hippuric acids) and catechin were associated with favorable chronic and postprandial memory, attention, executive function, and calmness.

CONCLUSIONS

Although self-rated calmness improved postprandially, and significant cognition-metabolite associations were identified, our data did not support strong cognitive, mood, alertness, or sleep quality improvements in MetS participants after blueberry intervention. This trial was registered at clinicaltrials.gov as NCT02035592.

Alzheimer, Parkinson, dementia, and phytochemicals: insight review

Alzheimer's, Parkinson's, and dementia are the leading neurodegenerative diseases that threaten the world with the aging population. Although the pathophysiology of each disease is unique, the steps to be taken to prevent diseases are similar. One of the changes that a person can make alone is to gain the habit of an antioxidant-rich diet. Phytochemicals known for their antioxidant properties have been reported to prevent neurodegenerative diseases in various studies. Phytochemicals with similar chemical structures are grouped. Accordingly, there are two main groups of phytochemicals, flavonoid and non-flavonoid. Various in vitro and in vivo studies on phytochemicals have proven neuroprotective effects by increasing cognitive function with their anti-inflammatory and antioxidant mechanisms. The purpose of this review is to summarize the in vitro and in vivo studies on phytochemicals with neuroprotective effects and to provide insight.

Unlocking the therapeutic potential of natural stilbene: Exploring pterostilbene as a powerful ally against aging and cognitive decline

The therapeutic potential of natural stilbenes, with a particular focus on pterostilbene (PTE), has emerged as a promising avenue of research targeting age-associated conditions encompassing cardiovascular diseases (CVD), diabetes mellitus (DM), and cognitive decline. This comprehensive investigation delves into the intricate mechanisms through which PTE, a polyphenolic compound abundant in grapes and blueberries, exerts its advantageous effects as an anti-aging agent. Central to its action is the modulation of hallmark aging processes, including oxidative damage, inflammatory responses, telomere attrition, and cellular senescence. PTE's ability to effectively penetrate the blood-brain barrier amplifies its potential for safeguarding neural health, thereby facilitating the regulation of neuronal signalling cascades, synaptic plasticity, and mitochondrial functionality. Through engagement with sirtuin proteins, it orchestrates cellular resilience, longevity, and metabolic equilibrium. Encouraging findings from preclinical studies portray PTE as a robust candidate for counteracting age-linked cognitive decline, augmenting memory consolidation, and potentially ameliorating neurodegenerative maladies such as Alzheimer's disease (AD). The synthesis of current scientific insights accentuates the promising translational prospects of PTE as a potent, naturally derived therapeutic agent against cognitive impairments associated with aging. Consequently, these collective findings lay a solid groundwork for forthcoming clinical inquiries and innovative therapeutic interventions in this realm.

Pterostilbene as a Therapeutic Alternative for Central Nervous System Disorders: A Review of the Current Status and Perspectives

Neurological disorders are diverse, have complex causes, and often result in disability; yet, effective treatments remain scarce. The resveratrol derivative pterostilbene possesses numerous physiological activities that hold promise as a novel therapy for the central nervous system (CNS) disorders. This review aimed to summarize the protective mechanisms of pterostilbene in in vitro and in vivo models of CNS disorders and the pharmacokinetics and safety to assess its possible effects on CNS disorders. Available evidence supports the protective effects of pterostilbene in CNS disorders involving mechanisms such as antioxidant and anti-inflammatory activity, regulation of lipid metabolism and vascular smooth muscle cell proliferation, improvement of synaptic function and neurogenesis, induction of glioma cell cycle arrest, and inhibition of glioma cell migration and invasion. Studies have identified possible molecular targets and pathways for the protective actions of pterostilbene in CNS disorders including the AMPK/STAT3, Akt, NF-κB, MAPK, and ERK signaling pathways. The possible pharmacological effects and molecular pathways of pterostilbene in CNS disorders are critically discussed in this review. Future studies should aim to increase our understanding of pterostilbene in animal models and humans to further evaluate its role in CNS disorders and the detailed mechanisms.

Pharmacological Approaches to Decelerate Aging: A Promising Path

Biological aging or senescence is a course in which cellular function decreases over a period of time and is a consequence of altered signaling mechanisms that are triggered in stressed cells leading to cell damage. Aging is among the principal risk factors for many chronic illnesses such as cancer, cardiovascular disorders, and neurodegenerative diseases. Taking this into account, targeting fundamental aging mechanisms therapeutically may effectively impact numerous chronic illnesses. Selecting ideal therapeutic options in order to hinder the process of aging and decelerate the progression of age-related diseases is valuable. Along therapeutic options, life style modifications may well render the process of aging. The process of aging is affected by alteration in many cellular and signaling pathways amid which mTOR, SIRT1, and AMPK pathways are the most emphasized. Herein, we have discussed the mechanisms of aging focusing mainly on the mentioned pathways as well as the role of inflammation and autophagy in aging. Moreover, drugs and natural products with antiaging properties are discussed in detail.

Stilbenes: Source plants, chemistry, biosynthesis, pharmacology, application and problems related to their clinical Application-A comprehensive review

Stilbenes are some of the important phenolic compounds originating from plant families like Vitaceae, Leguminaceae, Gnetaceae, and Dipterocarpaceae. Structurally, they have a C6-C2-C6 skeleton, usually with two isomeric forms. Stilbenes are biosynthesized due to biotic and abiotic stresses such as microbial infections, high temperatures, and oxidation. This review aims to provide a comprehensive overview of stilbenes' botanical sources, chemistry, biosynthetic pathways, pharmacology, and clinical applications and challenges based on up-to-date data. All included studies were collected from PubMed, ScienceDirect, Google Scholar, and CNKI, and the presented data from these indexed studies were analyzed and summarized. A total of 459 natural stilbene compounds from 45 plant families and 196 plant species were identified. Pharmacological studies also show that stilbenes have various activities such as anticancer, antimicrobial, antioxidant, anti-inflammatory, anti-degenerative diseases, anti-diabetic, neuroprotective, anti-aging, and cardioprotective effects. Stilbene synthase (STS) is the key enzyme involved in stilbene biosynthetic pathways. Studies on the therapeutic application of stilbenes pinpoint that challenges such as low bioavailability and isomerization are the major bottlenecks for their development as therapeutic drugs. Although the medicinal uses of several stilbenes have been demonstrated in vivo and in vitro, studies on the development of stilbenes deserve more attention in the future.

Multiple Mechanisms Converging on Transcription Factor EB Activation by the Natural Phenol Pterostilbene

Pterostilbene (Pt) is a potentially beneficial plant phenol. In contrast to many other natural compounds (including the more celebrated resveratrol), Pt concentrations producing significant effects in vitro can also be reached with relative ease in vivo. Here we focus on some of the mechanisms underlying its activity, those involved in the activation of transcription factor EB (TFEB). A set of processes leading to this outcome starts with the generation of ROS, attributed to the interaction of Pt with complex I of the mitochondrial respiratory chain, and spreads to involve Ca²⁺ mobilization from the ER/mitochondria pool, activation of CREB and AMPK, and inhibition of mTORC1. TFEB migration to the nucleus results in the upregulation of autophagy and lysosomal and mitochondrial biogenesis. Cells exposed to several μM levels of Pt experience a mitochondrial crisis, an indication for using low doses in therapeutic or nutraceutical applications. Pt afforded significant functional improvements in a zebrafish embryo model of ColVI-related myopathy, a pathology which also involves defective autophagy. Furthermore, long-term supplementation with Pt reduced body weight gain and increased transcription levels of Ppargc1a and Tfeb in a mouse model of diet-induced obesity. These in vivo findings strengthen the in vitro observations and highlight the therapeutic potential of this natural compound.

Co-treatment of vitamin D supplementation with enriched environment improves synaptic plasticity and spatial learning and memory in aged rats

RATIONALE AND OBJECTIVE

Environmental enrichment (EE) has been shown in old rats to improve learning and memory. Vitamin D (VitD) has also been shown to modulate age-related, cognitive dysfunction. As both EE and VitD could work to improve cognition via enhancement of neurotrophic factors, their effects might occlude one another. Therefore, a clinically relevant question is whether noted cognition-promoting effects of EE and VitD can co-occur.

METHODS

Aged rats were housed for 6 weeks in one of three housing conditions: environmentally enriched (EE), socially enriched (SE), or standard condition (SC). Further, a 4th group was co-treated with VitD supplementation (400 IU kg^-1 daily, 6 weeks) under EE conditions (EE + VitD).

RESULTS

Treatment with VitD and EE housing were associated with higher score on measures of learning and memory and exhibited lower anxiety scores compared to EE alone, SE or SC as assayed in the elevated plus maze, Morris water maze, passive avoidance, and open field tasks. Additionally, in the EE + VitD group, mRNA expression levels of NGF, TrkA, BDNF, Nrf2, and IGF-1 were significantly higher compared to expression seen in the EE group. Furthermore, field potential recordings showed that EE + VitD resulted in a greater enhancement of hippocampal LTP and neuronal excitability when compared to EE alone.

CONCLUSIONS

These findings demonstrate that in aged rats exposure to EE and VitD results in effects on hippocampal cognitive dysfunction and molecular mechanisms which are greater than effects of EE alone, suggesting potential for synergistic therapeutic effects for management of age-related cognitive decline.

The rodent object-in-context task: A systematic review and meta-analysis of important variables

Environmental information plays an important role in remembering events. Information about stable aspects of the environment (here referred to as 'context') and the event are combined by the hippocampal system and stored as context-dependent memory. In rodents (such as rats and mice), context-dependent memory is often investigated with the object-in-context task. However, the implementation and interpretation of this task varies considerably across studies. This variation hampers the comparison between studies and-for those who design a new experiment or carry out pilot experiments-the estimation of whether observed behavior is within the expected range. Also, it is currently unclear which of the variables critically influence the outcome of the task. To address these issues, we carried out a preregistered systematic review (PROSPERO CRD42020191340) and provide an up-to-date overview of the animal-, task-, and protocol-related variations in the object-in-context task for rodents. Using a data-driven explorative meta-analysis we next identified critical factors influencing the outcome of this task, such as sex, testbox size and the delay between the learning trials. Based on these observations we provide recommendations on sex, strain, prior arousal, context (size, walls, shape, etc.) and timing (habituation, learning, and memory phase) to create more consensus in the set-up, procedure, and interpretation of the object-in-context task for rodents. This could contribute to a more robust and evidence-based design in future animal experiments.

Pterostilbene Improves Stress-Related Behaviors and Partially Reverses Underlying Neuroinflammatory and Hormonal Changes in Stress-Challenged Mice

Pterostilbene is a natural compound contained in various dietary sources that has received tremendous attention due to its antioxidant properties with promising benefits in cancers and vascular diseases. Currently, little is known about pterostilbene-associated neuroimmune endocrine effects. We aimed to examine the efficacy of pterostilbene for improving stress-related behaviors, neuroinflammation, and hormonal changes in a mouse stress model. To evaluate the efficacy of oral administration of pterostilbene or vehicle for 16 days for improving behavior, inflammation, and hypothalamic-pituitary-adrenal (HPA) axis hyperactivity, mice were divided into a normal control group or one of five restraint stress groups-the vehicle group; the 20, 40, or 80 mg/[kg·day] pterostilbene treatment group; or the 20 mg/[kg·day] resveratrol treatment group. Open field and forced swimming tests were conducted. Hippocampal brain-derived neurotrophic factor (BDNF) levels, endocrine hormone levels, oxidative stress parameters, and histopathological features were assessed. Oral pterostilbene administration significantly increased the measured times in the open field and forced swimming tests, elevated the BDNF levels, decreased the inducible nitric oxide synthase and superoxide dismutase levels in the brain, and reduced the plasma adrenocorticotropic hormone and corticosterone levels. Compared with vehicle treatment, pterostilbene dose dependently increased the numbers of neurons and decreased the numbers of glial and tumor necrosis factor alpha-immunolabeled cells in the hypothalamus. These findings suggest that pterostilbene may effectively modulate stress-related abnormal behaviors, neuroinflammation, and HPA axis hyperactivity.

Evidence of Polyphenols Efficacy against Dry Eye Disease

Dry eye disease is a multifactorial pathology compromising the quality of life of patients, resulting in significant damage of the ocular surface and discomfort. The current therapeutical strategies are not able to definitively resolve the underlying causes and stop the symptoms. Polyphenols are promising natural molecules that are receiving increasing attention for their activity/effects in counteracting the main pathologic mechanisms of dry eye disease and reducing its symptoms. In the present review, a deep literature search focusing on the main polyphenols tested against dry eye disease was conducted, analyzing related in vitro, in vivo, and clinical studies to provide a comprehensive and current review on the state of the art. Polyphenols present multiple effects against dry eye diseases-related ocular surface injury. In particular, the observed beneficial effects of polyphenols on corneal cells are the reduction of the pathological processes of inflammation, oxidative stress, and apoptosis and modulation of the tear film. Due to numerous studies reporting that polyphenols are effective and safe for treating the pathological mechanisms of this ocular surface disease, we believe that future studies should confirm and extend the evidence of polyphenols efficacy in clinical practice against dry eye disease and help to develop new ophthalmic drug(s).

Apoptosis inhibition is involved in improvement of sevoflurane-induced cognitive impairment following normobaric hyperoxia preconditioning in aged rats

Sevoflurane, a commonly used anesthetic agent has been confirmed to induce cognitive impairment in aged rats. Normobaric hyperoxia preconditioning has been demonstrated to induce neuroprotection in rats. The present study aimed to determine whether normobaric hyperoxia preconditioning could ameliorate cognitive deficit induced by sevoflurane and the possible mechanism by which it may exert its effect. A total of 66, 20-month-old male Sprague-Dawley rats were randomly divided into 3 groups (n=22 each): Rats in the control (C) and sevoflurane anesthesia (S) groups received no normobaric hyperoxia preconditioning before sevoflurane exposure, rats in the normobaric hyperoxia pretreatment (HO) group received normobaric hyperoxia preconditioning before sevoflurane exposure (95% oxygen for 4 continuous h daily for 6 consecutive days). The anesthesia rats (S and HO groups), were exposed to 2.5% sevoflurane for 5 h, while the sham anesthesia rats (C group) were exposed to no sevoflurane. The neurobehavioral assessment was performed using a Morris water maze test, the expressions of the apoptosis proteins were determined using western blot analysis, and the apoptosis rate and cytosolic calcium concentration were measured by flow cytometry. Normobaric hyperoxia preconditioning improved prolonged escape latency and raised the number of platform crossings induced by sevoflurane in the Morris water maze test, increased the level of bcl-2 protein, and decreased the level of bax and active caspase-3 protein, the apoptosis rate and cytosolic calcium concentration in the hippocampus 24 h after sevoflurane exposure. The findings of the present study may imply that normobaric hyperoxia preconditioning attenuates sevoflurane-induced spatial learning and memory impairment, and this effect may be partly related to apoptosis inhibition in the hippocampus. In conclusion, normobaric hyperoxia preconditioning may be a promising strategy against sevoflurane-induced cognitive impairment by inhibiting the hippocampal neuron apoptosis.

Anticonvulsant effect of pterostilbene and its influence on the anxiety- and depression-like behavior in the pentetrazol-kindled mice: behavioral, biochemical, and molecular studies

RATIONALE

Pterostilbene is the 3,5-dimethoxy derivative of resveratrol with numerous beneficial effects including neuroprotective properties. Experimental studies revealed its anticonvulsant action in the acute seizure tests.

OBJECTIVES

The purpose of the present study was to evaluate the effect of pterostilbene in the pentetrazol (PTZ)-induced kindling model of epilepsy in mice as well as to assess some possible mechanisms of its anticonvulsant action in this model.

METHODS

Mice were repeatedly treated with pterostilbene (50-200 mg/kg) and its effect on the development of seizure activity in the PTZ kindling was estimated. Influence of pterostilbene on the locomotor activity and anxiety- and depression-like behavior in the PTZ-kindled mice was also assessed. To understand the possible mechanisms of anticonvulsant activity of pterostilbene, γ-aminobutyric acid (GABA) and glutamate concentrations in the prefrontal cortex and hippocampus of the PTZ-kindled mice were measured using LC-MS/MS method. Moreover, mRNA expression of BDNF, TNF-α, IL-1β, IL-6, GABRA1A, and GRIN2B was determined by RT-qPCR technique.

RESULTS

We found that pterostilbene at a dose of 200 mg/kg considerably reduced seizure activity but did not influence the locomotor activity and depression- and anxiety-like behavior in the PTZ-kindled mice. In the prefrontal cortex and hippocampus, pterostilbene reversed the kindling-induced decrease of GABA concentration. Neither in the prefrontal cortex nor hippocampus pterostilbene affected mRNA expression of IL-1β, IL-6, GABRA1A, and GRIN2B augmented by PTZ kindling. Pterostilbene at a dose of 100 mg/kg significantly decreased BDNF and TNF-α mRNA expression in the hippocampus of the PTZ-kindled mice.

CONCLUSIONS

Although further studies are necessary to understand the mechanism of anticonvulsant properties of pterostilbene, our findings suggest that it might be considered a candidate for a new antiseizure drug.

The Epigenetic Link between Polyphenols, Aging and Age-Related Diseases

Aging is a complex process mainly categorized by a decline in tissue, cells and organ function and an increased risk of mortality. Recent studies have provided evidence that suggests a strong association between epigenetic mechanisms throughout an organism’s lifespan and age-related disease progression. Epigenetics is considered an evolving field and regulates the genetic code at several levels. Among these are DNA changes, which include modifications to DNA methylation state, histone changes, which include modifications of methylation, acetylation, ubiquitination and phosphorylation of histones, and non-coding RNA changes. As a result, these epigenetic modifications are vital targets for potential therapeutic interventions against age-related deterioration and disease progression. Dietary polyphenols play a key role in modulating these modifications thereby delaying aging and extending longevity. In this review, we summarize recent advancements linking epigenetics, polyphenols and aging as well as critical findings related to the various dietary polyphenols in different fruits and vegetables. In addition, we cover studies that relate polyphenols and their epigenetic effects to various aging-related diseases such as cardiovascular diseases, neurodegenerative diseases, autoimmune disorders, diabetes, osteoporosis and cancer.

Characterization of Effectiveness in Concerted Ih Inhibition and IK(Ca) Stimulation by Pterostilbene (Trans-3,5-dimethoxy-4'-hydroxystilbene), a Stilbenoid

Pterostilbene (PTER), a natural dimethylated analog of resveratrol, has been demonstrated to produce anti-neoplastic or neuroprotective actions. However, how and whether this compound can entail any perturbations on ionic currents in electrically excitable cells remains unknown. In whole-cell current recordings, addition of PTER decreased the amplitude of macroscopic I_h during long-lasting hyperpolarization in GH₃ cells in a concentration-dependent manner, with an effective IC₅₀ value of 0.84 μM. Its presence also shifted the activation curve of I_h along the voltage axis to a more hyperpolarized potential, by 11 mV. PTER at a concentration greater than 10 μM could also suppress l-type Ca²⁺ and transient outward K⁺ currents in GH₃ cells. With the addition of PTER, I_K(Ca) amplitude was increased, with an EC₅₀ value of 2.23 μM. This increase in I_K(Ca) amplitude was attenuated by further addition of verruculogen, but not by tolbutamide or TRAM-39. Neither atropine nor nicotine, in the continued presence of PTER, modified the PTER-stimulated I_K(Ca). PTER (10 μM) slightly suppressed the amplitude of l-type Ca²⁺ current and transient outward K⁺ current. The presence of PTER (3 μM) was also effective at increasing the open-state probability of large-conductance Ca²⁺-activated K⁺ (BK_Ca) channels identified in hippocampal mHippoE-14 neurons; however, its inability to alter single-channel conductance was detected. Our study highlights evidence to show that PTER has the propensity to perturb ionic currents (e.g., I_h and I_K(Ca)), thereby influencing the functional activities of neurons, and neuroendocrine or endocrine cells.