Age-related learning and memory deficits in rats: role of altered brain neurotransmitters, acetylcholinesterase activity and changes in antioxidant defense system

Vanillylacetone attenuates cadmium chloride-induced hippocampal damage and memory loss through up-regulation of nuclear factor erythroid 2-related factor 2 gene and protein expression

JOURNAL/nrgr/04.03/01300535-202412000-00030/figure1/v/2024-04-08T165401Z/r/image-tiff Memory loss and dementia are major public health concerns with a substantial economic burden. Oxidative stress has been shown to play a crucial role in the pathophysiology of hippocampal damage-induced memory impairment. To investigate whether the antioxidant and anti-inflammatory compound vanillylacetone (zingerone) can protect against hippocampal damage and memory loss induced by cadmium chloride (CdCl2) administration in rats, we explored the potential involvement of the nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway, which is known to modulate oxidative stress and inflammation. Sixty healthy male Wistar rats were divided into five groups: vehicle-treated (control), vanillylacetone, CdCl2, vanillylacetone + CdCl2, vanillylacetone + CdCl2 + brusatol (a selective pharmacological Nrf2 inhibitor) groups. Vanillylacetone effectively attenuated CdCl2-induced damage in the dental gyrus of the hippocampus and improved the memory function assessed by the Morris Water Maze test. Additionally, vanillylacetone markedly decreased the hippocampal tissue levels of inflammatory biomarkers (interleukin-6, tumor necrosis factor-α, intracellular cell adhesive molecules) and apoptosis biomarkers (Bax and cleaved caspase-3). The control and CdCl2-treated groups treated with vanillylacetone showed reduced generation of reactive oxygen species, decreased malondialdehyde levels, and increased superoxide dismutase and glutathione activities, along with significant elevation of nuclear Nrf2 mRNA and protein expression in hippocampal tissue. All the protective effects of vanillylacetone were substantially blocked by the co-administration of brusatol (a selective Nrf2 inhibitor). Vanillylacetone mitigated hippocampal damage and memory loss induced by CdCl2, at least in part, by activating the nuclear transcription factor Nrf2. Additionally, vanillylacetone exerted its potent antioxidant and anti-inflammatory actions.

Age-Related Effects of AT1 Receptor Antagonist Losartan on Cognitive Decline in Spontaneously Hypertensive Rats

Both hypertension and aging are known to increase the vulnerability of the brain to neurovascular damage, resulting in cognitive impairment. The present study investigated the efficacy of the antihypertensive drug losartan on age- and hypertension-associated cognitive decline and the possible mechanism underlying its effect in spontaneously hypertensive rats (SHRs). Losartan was administered (10 mg/kg, i.p. for 19 days) to 3- and 14-month-old SHRs. Age-matched Wistar rats were used as controls. Working memory, short-term object recognition, and spatial memory were assessed using the Y-maze, object recognition test (ORT) and radial arm maze (RAM) test. The expression of markers associated with aging, oxidative stress, and memory-related signaling was assessed in the frontal cortex (FC) and hippocampus. Motor activity measured over 24 h was not different between groups. Middle-aged vehicle-treated SHRs showed poorer performance in spontaneous alternation behavior (SAB) and activity in the first Y-maze test than their younger counterparts, suggesting age-related reduced "decision making" and reactivity in a novel environment. Losartan improved the age- and hypertension-induced decline in short-term recognition and spatial memory measured in the ORT and the second Y-maze test, particularly in the middle-aged rats, but was ineffective in the young adult rats. Changes in memory and age-related markers such as cAMP response element-binding protein (CREB) and amyloid-β1-42 (Aβ1-42) and increased oxidative stress were observed in the hippocampus but not in the FC between young adult and middle-aged vehicle-treated SHRs. Losartan increased CREB expression while reducing Aβ1-42 levels and concomitant oxidative stress in middle-aged SHRs compared with vehicle-treated SHRs. In conclusion, our study highlights the complex interplay between hypertension, aging, and cognitive impairment. It suggests that there is a critical time window for therapeutic intervention with angiotensin II type 1 receptor blockers.

Effects of Ocimum basilicum L. Extract on Hippocampal Oxidative Stress, Inflammation, and BDNF Expression in Amnesic Aged Rats

The present study was conducted to investigate the effects of Ocimum basilicum L. (OB) extract on learning and memory impairment in aged rats. Male rats were divided into the following experimental groups: Group 1 (control): including 2 months old rats, Group 2 (aged) including 2 years old rats, Groups 3-5 (aged-OB): including 2 years old rats received 50, 100, and 150 mg/kg OB for 8 weeks by oral gavage. Aging increased the delay to find the platform but, however, decreased the time spent in the target quadrant when tested by Morris water maze (MWM). Aging also reduced the latency to enter the dark chamber in the passive avoidance (PA) test compared to the control group. Moreover, interleukin-6 (IL-6) and malondialdehyde (MDA) levels were raised in the hippocampus and cortex of aged rats. In contrast, thiol levels and enzymatic activity of superoxide dismutase (SOD) and catalase (CAT) significantly reduced. In addition, aging significantly reduced BDNF expression. Finally, OB administration reversed the mentioned effects. The current research showed that OB administration improves learning/memory impairment induced by aging. It also found that this plant extract protects the brain tissues from oxidative damage and neuroinflammation.

Neuroprotective effect of Withania somnifera leaves extract nanoemulsion against penconazole-induced neurotoxicity in albino rats via modulating TGF-β1/Smad2 signaling pathway

Penconazole (PEN) is a systemic triazole fungicide used to control various fungal diseases on grapes, stone fruits, cucurbits, and strawberries. Still, it leaves residues on treated crops after collection with many hazardous effects on population including neurotoxicity. Withania somnifera leaves extract (WSLE) is known for its memory and brain function enhancing ability. To evoke such action efficiently, WSLE bioactive metabolites are needed to cross the blood-brain barrier, that could limit the availability of such compounds to be localized within the brain. Therefore, in the present study, the association between PEN exposure and neurotoxicity was evaluated, and formulated WSLE nanoemulsion was investigated for improving the permeability of the plant extract across the blood-brain barrier. The rats were divided into five groups (n = 6). The control group was administered distilled water, group II was treated with W. somnifera leaves extract nanoemulsion (WSLE NE), group III received PEN, group IV received PEN and WSLE, and group V received PEN and WSLE NE. All rats were gavaged daily for 6 weeks. Characterization of compounds in WSLE using LC-MS/MS analysis was estimated. Neurobehavioral disorders were evaluated in all groups. Oxidative stress biomarkers, antioxidant enzyme activities, and inflammatory cytokines were measured in brain tissue. Furthermore, the gene expression patterns of GFAP, APP, vimentin, TGF-β1, Smad2 and Bax were measured. Histopathological changes and immunohistochemical expression in the peripheral sciatic nerve and cerebral cortex were evaluated. A total of 91 compounds of different chemo-types were detected and identified in WSLE in both ionization modes. Our data showed behavioral impairment in the PEN-treated group, with significant elevation of oxidative stress biomarkers, proinflammatory cytokines, neuronal damage, and apoptosis. In contrast, the PEN-treated group with WSLE NE showed marked improvement in behavioral performance and histopathological alteration with a significant increase in antioxidant enzyme activity and anti-inflammatory cytokines compared to the group administered WSLE alone. The PEN-treated group with WSLE NE in turn significantly downregulated the expression levels of GFAP, APP, vimentin, TGF-β1, Smad2 and Bax in brain tissue. In conclusion, WSLE NE markedly enhanced the permeability of plant extract constituents through the blood brain barrier to boost its neuroprotective effect against PEN-induced neurotoxicity.

Curcumin attenuates brain aging by reducing apoptosis and oxidative stress

Brain aging is a physiological event, and oxidative stress and apoptosis are involved in the natural aging process of the brain. Curcumin is a natural antioxidant with potent anti-aging and neuroprotective properties. Therefore, we investigated the protective effects of curcumin on brain apoptosis and oxidative stress, brain-derived neurotrophic factor (BDNF), and vascular endothelial growth factor (VEGF) in aged rats. Old female Wistar rats were randomly divided into three groups (n = 7); as follows: (1) control; (2); saline and (3) curcumin (received 30 mg/kg of curcumin, 5 days/week for 8 weeks, intraperitoneally). Our results indicated that treatment with curcumin in aged rats attenuates brain lipid peroxidation, which was accompanied by a significant increase in the BDNF, VEGF, superoxide dismutase (SOD) activity, and anti-apoptotic protein BCl-2. No significant change in brain anti-apoptotic Bax protein levels was observed after curcumin treatment. The study indicates that curcumin could alleviate brain aging which may be due to attenuating oxidative stress, inhibiting apoptosis, and up-regulating SOD activity, which in turn enhances VEGF and BDNF. Therefore, curcumin has potential therapeutic value in the treatment of neurological apoptosis, neurogenesis, and angiogenesis changes caused by brain aging.

Centella asiatica improves memory and executive function in middle-aged rats by controlling oxidative stress and cholinergic transmission

ETHNOPHARMACOLOGICAL RELEVANCE

Centella asiatica (L.) Urban, is a medicinal herb with rich history of traditional use in Indian subcontinent. This herb has been valued for its diverse range of medicinal properties including memory booster, and also as a folk treatment for skin diseases, wound healing and mild diuretic.

AIM OF STUDY

Aging is a gradual and continuous process of natural decay in the biological systems, including the brain. This work aims to evaluate the effectiveness of ethanolic extract of Centella asiatica (CAE) on age-associated cognitive impairments in rats, as well as the underlying mechanism.

MATERIAL AND METHODS

Rats were allocated into five distinct groups of 5 animals each: Young rats (3 months old rats), middle-aged (m-aged) rats (13-14 months old), and the remaining three groups were comprised of m-aged rats treated with different concentrations of CAE, viz., 150, 300, and 450 mg/kg b. w., orally for 42 days. Y-maze, open field, novel object recognition, and elevated plus maze tests were used to assess animal behavior. The malondialdehyde (MDA), superoxide dismutase (SOD), and acetylcholinesterase (AChE) assays; and H&E staining were done in the rat brain to assess the biochemical and structural changes. CAE was also subjected to HPLC analysis, in vitro antioxidant and anti-cholinergic activity. The active compounds of CAE were docked with AChE and BuChE in molecular docking study.

RESULTS

The results showed that CAE treatment improves behavioral performance; attenuates the age-associated increase in MDA content, SOD, and AChE activity; and reduces neuronal loss. In vitro study showed that CAE has concentration-dependent antioxidant and anti-AChE activity. Furthermore, the presence of Asiatic acid and Madecassic acid in CAE and their good binding with cholinergic enzymes (in silico) also suggest the anticholinergic effect of CAE.

CONCLUSION

The findings of the current study show that the anticholinergic and antioxidant effects of CAE are attributable to the presence of Asiatic acid and Madecassic acid, which not only provide neuroprotection against age-associated cognitive decline but also reverse it.

Western diet consumption impairs memory function via dysregulated hippocampus acetylcholine signaling

Western diet (WD) consumption during early life developmental periods is associated with impaired memory function, particularly for hippocampus (HPC)-dependent processes. We developed an early life WD rodent model associated with long-lasting HPC dysfunction to investigate the neurobiological mechanisms mediating these effects. Rats received either a cafeteria-style WD (ad libitum access to various high-fat/high-sugar foods; CAF) or standard healthy chow (CTL) during the juvenile and adolescent stages (postnatal days 26-56). Behavioral and metabolic assessments were performed both before and after a healthy diet intervention period beginning at early adulthood. Results revealed HPC-dependent contextual episodic memory impairments in CAF rats that persisted despite the healthy diet intervention. Given that dysregulated HPC acetylcholine (ACh) signaling is associated with memory impairments in humans and animal models, we examined protein markers of ACh tone in the dorsal HPC (HPCd) in CAF and CTL rats. Results revealed significantly lower protein levels of vesicular ACh transporter in the HPCd of CAF vs. CTL rats, indicating chronically reduced ACh tone. Using intensity-based ACh sensing fluorescent reporter (iAChSnFr) in vivo fiber photometry targeting the HPCd, we next revealed that ACh release during object-contextual novelty recognition was highly predictive of memory performance and was disrupted in CAF vs. CTL rats. Neuropharmacological results showed that alpha 7 nicotinic ACh receptor agonist infusion in the HPCd during training rescued memory deficits in CAF rats. Overall, these findings reveal a functional connection linking early life WD intake with long-lasting dysregulation of HPC ACh signaling, thereby identifying an underlying mechanism for WD-associated memory impairments.

Cognition and Behavior in the Aging Brain Following TBI: Surveying the Preclinical Evidence

Elderly individuals (65 years and older) represent the fastest-growing demographic of new clinical traumatic brain injury (TBI) cases, yet there is a paucity of preclinical research in aged animals. The limited preclinical work available aligns with the clinical literature in that there appear to be significant differences in pathophysiology, recovery potential, and response to medications between animals at different points across the age spectrum. The aim of this review is to discuss the limited studies and highlight critical age-related differences in affective, cognitive, and neurobehavioral deficits, to discuss factors that influence functional outcomes, and to identify targets for future research. The consensus is that aged rodents face challenges related to dysregulated inflammation, reduced neuroplasticity, and age-related cellular changes, which hinder their recovery after TBI. The most successful intervention studies in animal models to date, of the limited array available, have explored interventions targeting inflammatory downregulation. Current standards of neuropsychopharmacology for post-TBI neurocognitive recovery have not been investigated in a significant capacity. In addition, currently available animal models do not sufficiently account for important age-related comorbidities, dual insults, or differences in TBI mechanism of injury in elderly individuals. TBI in the aged population is more likely to lead to additional neurodegenerative diseases that further complicate recovery. The findings underscore the need for tailored therapeutic interventions to improve outcomes in both adult and elderly populations.

Effect of hydro-alcoholic extract of Nigella sativa on cisplatin-induced memory impairment and brain oxidative stress status in male rats

Objective

Studies have shown the complications of chemotherapy on learning and memory. Empirical evidence suggests that Nigella sativa (NS) has neuroprotective activities. Therefore, the aim of our study was to investigate the effects of NS on cisplatin-induced memory impairment.

Materials and Methods

This study was conducted on 40 male rats grouped as: control (saline: 2 ml/kg, intraperitoneally (IP), once weekly/2 weeks), cisplatin (Cis, 2 mg/kg, IP, once weekly/2 weeks), NS (200 mg/kg, IP, once weekly/2 weeks), Cis +NS 200 (2 mg/kg Cis + 200 mg/kg NS, IP, once weekly/2 weeks), and Cis +NS 400 (2 mg/kg Cis + 400 mg/kg NS, IP, once weekly/2 weeks). Morris water maze (MWM) test was used to assess spatial learning and memory. In addition, superoxide dismutase (SOD) activity, and thiol and malondialdehyde (MDA) levels were evaluated in the brain.

Results

Cis significantly enhanced the traveled distance and time spent in the target quadrant in the MWM test. Additionally, MDA levels increased in the Cis group, while thiol and SOD decreased in this group. As a result of treatment with NS, behavioral results were reversed in the groups receiving NS compared to the Cis group. Also, NS reduced MDA level but improved SOD and thiol levels in brain tissue samples.

Conclusion

NS could improve memory impairment and oxidative stress in animals receiving Cis. Therefore, NS could be used as a potential food supplement to prevent neurotoxicity in patients undergoing chemotherapy.

An Overview of Chemistry, Kinetics, Toxicity and Therapeutic Potential of Boldine in Neurological Disorders

Boldine is an alkaloid obtained from the medicinal herb Peumus boldus (Mol.) (Chilean boldo tree; boldo) and belongs to the family Monimiaceae. It exhibits a wide range of pharmacological effects such as antioxidant, anticancer, hepatoprotective, neuroprotective, and anti-diabetic properties. There is a dearth of information regarding its pharmacokinetics and toxicity in addition to its potential pharmacological activity. Boldine belongs to the aporphine alkaloid class and possesses lipophilic properties which enable its efficient absorption and distribution throughout the body, including the central nervous system. It exhibits potent free radical scavenging activity, thereby reducing oxidative stress and preventing neuronal damage. Through a variety of neuroprotective mechanisms, including suppression of AChE and BuChE activity, blocking of connexin-43 hemichannels, pannexin 1 channel, reduction of NF-κβ mediated interleukin release, and glutamate excitotoxicity which successfully reduces neuronal damage. These results point to its probable application in reducing neuroinflammation and oxidative stress in epilepsy, Alzheimer's disease (AD), and Parkinson's disease (PD). Moreover, its effects on serotonergic, dopaminergic, opioid, and cholinergic receptors were further investigated in order to determine its applicability for neurobehavioral dysfunctions. The article investigates the pharmacokinetics of boldine and reveals that it has a low oral bioavailability and a short half-life, requiring regular dosage to maintain therapeutic levels. The review studies boldine's potential therapeutic uses and mode of action while summarizing its neuroprotective benefits.  Given the favorable results for boldine as a potential neurotherapeutic drug in laboratory animals, more research is required. However, in order to optimise its therapeutic potential, it must be more bioavailable with fewer detrimental side effects.

Long-Term Acetylcholinesterase Depletion Alters the Levels of Key Synaptic Proteins while Maintaining Neuronal Markers in the Aging Zebrafish (Danio rerio) Brain

INTRODUCTION

Interventions targeting cholinergic neurotransmission like acetylcholinesterase (AChE) inhibition distinguish potential mechanisms to delay age-related impairments and attenuate deficits related to neurodegenerative diseases. However, the chronic effects of these interventions are not well described.

METHODS

In the current study, global levels of cholinergic, cellular, synaptic, and inflammation-mediating proteins were assessed within the context of aging and chronic reduction of AChE activity. Long-term depletion of AChE activity was induced by using a mutant zebrafish line, and they were compared with the wildtype group at young and old ages.

RESULTS

Results demonstrated that AChE activity was lower in both young and old mutants, and this decrease coincided with a reduction in ACh content. Additionally, an overall age-related reduction in AChE activity and the AChE/ACh ratio was observed, and this decline was more prominent in wildtype groups. The levels of an immature neuronal marker were upregulated in mutants, while a glial marker showed an overall reduction. Mutants had preserved levels of inhibitory and presynaptic elements with aging, whereas glutamate receptor subunit levels declined.

CONCLUSION

Long-term AChE activity depletion induces synaptic and cellular alterations. These data provide further insights into molecular targets and adaptive responses following the long-term reduction of AChE activity that was also targeted pharmacologically to treat neurodegenerative diseases in human subjects.

Enhancement of hippocampal-dependent spatial memory by Ashwagandha (Withania somnifera) characterized by activation of NMDA receptors against monosodium glutamate-induced neurotoxicity in rats

BACKGROUND AND AIM

Monosodium glutamate (MSG) is used in food-additives, and the Food and Drug Administration has placed it under intense scrutiny following several reports that it causes glutamate neurotoxicity. Ashwagandha (ASH) roots are traditionally used for memory enhancement. This study aimed to evaluate the nootropic activity of ASH as well as its therapeutic anti-amnesic activity against MSG-induced hippocampal-dependent spatial memory impairment and hippocampal-NMDAR modulation.

METHOD

A total of 36 rats were divided equally into six groups (n = 6 in each group); the rats in the normal and negative groups were administered daily doses of normal saline and MSG (300 mg/kg), respectively, for 21 days. Two nootropic groups were administered ASH at 300 and 500 mg/kg o.p., respectively, for 21 days. Two other treatment groups were administered daily doses of MSG 300 mg/kg o.p. as well as 300 mg/kg and 500 mg/kg o.p. of ASH for 21 days. The rats' spatial memory was assessed for five days using the MWM. Additionally, NMDAR were measured quantitatively by immunohistochemistry.

RESULTS

We found that the rats in the nootropic groups showed significantly enhanced nootropic activity characterized by improved hippocampal-dependent spatial memory, as well as increases in the level of NMDAR in the Cornu Ammonis 1 region of their hippocampus. Moreover, we elucidated the therapeutic potential of ASH to protect against the depression of spatial memory caused by MSG-induced neurotoxicity.

CONCLUSION

Further, we elucidated a strong correlation between NMDAR-positive cells in the hippocampus and enhancement of spatial learning induced by long-term administration of ASH as well as a strong correlation between NMDAR positive cells in the hippocampus and depression of spatial learning induced by long-term administration of ASH and MSG.

Association of Selenium Levels with Neurodegenerative Disease: A Systemic Review and Meta-Analysis

BACKGROUND

Neurodegenerative diseases (NDs) have posed significant challenges to public health, and it is crucial to understand their mechanisms in order to develop effective therapeutic strategies. Recent studies have highlighted the potential role of selenium in ND pathogenesis, as it plays a vital role in maintaining cellular homeostasis and preventing oxidative damage. However, a comprehensive analysis of the association between selenium and NDs is still lacking.

METHOD

Five public databases, namely PubMed, Web of Science, EMBASE, Cochrane and Clinical Trials, were searched in our research. Random model effects were chosen, and Higgins inconsistency analyses (I2), Cochrane's Q test and Tau2 were calculated to evaluate the heterogeneity.

RESULT

The association of selenium in ND patients with Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS) and Huntington's disease (HD) was studied. A statistically significant relationship was only found for AD patients (SMD = -0.41, 95% CI (-0.64, -0.17), p < 0.001), especially for erythrocytes. However, no significant relationship was observed in the analysis of the other four diseases.

CONCLUSION

Generally, this meta-analysis indicated that AD patients are strongly associated with lower selenium concentrations compared with healthy people, which may provide a clinical reference in the future. However, more studies are urgently needed for further study and treatment of neurodegenerative diseases.

Western diet consumption impairs memory function via dysregulated hippocampus acetylcholine signaling

Western diet (WD) consumption during development yields long-lasting memory impairments, yet the underlying neurobiological mechanisms remain elusive. Here we developed an early life WD rodent model to evaluate whether dysregulated hippocampus (HPC) acetylcholine (ACh) signaling, a pathology associated with memory impairment in human dementia, is causally-related to WD-induced cognitive impairment. Rats received a cafeteria-style WD (access to various high-fat/high-sugar foods; CAF) or healthy chow (CTL) during the juvenile and adolescent periods (postnatal days 26-56). Behavioral, metabolic, and microbiome assessments were performed both before and after a 30-day healthy diet intervention beginning at early adulthood. Results revealed CAF-induced HPC-dependent contextual episodic memory impairments that persisted despite healthy diet intervention, whereas CAF was not associated with long-term changes in body weight, body composition, glucose tolerance, anxiety-like behavior, or gut microbiome. HPC immunoblot analyses after the healthy diet intervention identified reduced levels of vesicular ACh transporter in CAF vs. CTL rats, indicative of chronically reduced HPC ACh tone. To determine whether these changes were functionally related to memory impairments, we evaluated temporal HPC ACh binding via ACh-sensing fluorescent reporter in vivo fiber photometry during memory testing, as well as whether the memory impairments could be rescued pharmacologically. Results revealed dynamic HPC ACh binding during object-contextual novelty recognition was highly predictive of memory performance and was disrupted in CAF vs. CTL rats. Further, HPC alpha-7 nicotinic receptor agonist infusion during consolidation rescued memory deficits in CAF rats. Overall, these findings identify dysregulated HPC ACh signaling as a mechanism underlying early life WD-associated memory impairments.

NXP032 ameliorates cognitive impairment by alleviating the neurovascular aging process in aged mouse brain

Vascular aging is well known to be associated with the breakdown of the neurovascular unit (NVU), which is essential for maintaining brain homeostasis and linked to higher cognitive dysfunction. Oxidative stress is believed to be a significant cause of the vascular aging process. Vitamin C is easily oxidized under physiological conditions, so it loses its potent antioxidant activity. We developed a DNA aptamer that enhances the function of vitamin C. NXP032 is the binding form of the aptamer and vitamin C. In this study, we investigated the effect of NXP032 on neurovascular stabilization through the changes of PECAM-1, PDGFR-β, ZO-1, laminin, and glial cells involved in maintaining the integrity of the blood-brain barrier (BBB) in aged mice. NXP032 was orally administered daily for 8 weeks. Compared to young mice and NXP032-treated mice, 20-month-old mice displayed cognitive impairments in Y-maze and passive avoidance tests. NXP032 treatment contributed to reducing the BBB damage by attenuating the fragmentation of microvessels and reducing PDGFR-β, ZO-1, and laminin expression, thereby mitigating astrocytes and microglia activation during normal aging. Based on the results, we suggest that NXP032 reduces vascular aging and may be a novel intervention for aging-induced cognitive impairment.

Rosmarinus officinalis and Mentha piperita Oils Supplementation Enhances Memory in a Rat Model of Scopolamine-Induced Alzheimer's Disease-like Condition

Alzheimer's disease is regarded as a common neurodegenerative disease that may lead to dementia and the loss of memory. We report here the nootropic and anti-amnesic effects of both peppermint and rosemary oils using a rat model of scopolamine-induced amnesia-like AD. Rats were administered orally with two doses (50 and 100 mg/kg) of each single oil and combined oils. The positive group used donepezil (1 mg/kg). In the therapeutic phase, rats were administered scopolamine (1 mg/kg) through the oral administration of oils. During the nootropic phase, both oils showed a significant (p < 0.05) decrease in radial arm maze latency times, working memory, and reference memory errors compared with the normal group, along with significant (p < 0.05) enhancements of long-term memory during the passive avoidance test. Therapeutic phase results revealed significant enhancements of memory processing compared with the positive groups. In the hippocampus, oils exhibited an elevation of BDNF levels in a dose-dependent manner. Immunohistochemistry findings showed increased hippocampal neurogenesis suppressed by scopolamine in the sub-granular zone, and the anti-amnesic activity of single oil was enhanced when the two oils combined. Gas chromatography-mass spectrometry (GCMS) of the two oils revealed sufficient compounds (1,8-Cineole, α-Pinene, menthol and menthone) with potential efficacy in the memory process and cognitive defects. Our work suggests that both oils could enhance the performance of working and spatial memory, and when combined, more anti-amnesic activity was produced. A potential enhancement of hippocampal growth and neural plasticity was apparent with possible therapeutic activity to boost memory in AD patients.

Astaxanthin as a King of Ketocarotenoids: Structure, Synthesis, Accumulation, Bioavailability and Antioxidant Properties

Astaxanthin (3,3-dihydroxy-β, β-carotene-4,4-dione) is a ketocarotenoid synthesized by Haematococcus pluvialis/lacustris, Chromochloris zofingiensis, Chlorococcum, Bracteacoccus aggregatus, Coelastrella rubescence, Phaffia rhodozyma, some bacteria (Paracoccus carotinifaciens), yeasts, and lobsters, among others However, it is majorly synthesized by Haematococcus lacustris alone (about 4%). The richness of natural astaxanthin over synthetic astaxanthin has drawn the attention of industrialists to cultivate and extract it via two stage cultivation process. However, the cultivation in photobioreactors is expensive, and converting it in soluble form so that it can be easily assimilated by our digestive system requires downstream processing techniques which are not cost-effective. This has made the cost of astaxanthin expensive, prompting pharmaceutical and nutraceutical companies to switch over to synthetic astaxanthin. This review discusses the chemical character of astaxanthin, more inexpensive cultivating techniques, and its bioavailability. Additionally, the antioxidant character of this microalgal product against many diseases is discussed, which can make this natural compound an excellent drug to minimize inflammation and its consequences.

Cellular mechanisms in brain aging: Focus on physiological and pathological aging

Aging is a natural phenomenon characterized by accumulation of cellular damage and debris. Oxidative stress, cellular senescence, sustained inflammation, and DNA damage are the main cellular processes characteristic of aging associated with morphological and functional decline. These effects tend to be more pronounced in tissues with high metabolic rates such as the brain, mainly in regions such as the prefrontal cortex, hippocampus, and amygdala. These regions are highly related to cognitive behavior, and therefore their atrophy usually leads to decline in processes such as memory and learning. These cognitive declines can occur in physiological aging and are exacerbated in pathological aging. In this article, we review the cellular processes that underlie the triggers of aging and how they relate to one another, causing the atrophy of nerve tissue that is typical of aging. The main topic of this review to determine the central factor that triggers all the cellular processes that lead to cellular aging and discriminate between normal and pathological aging. Finally, we review how the use of supplements with antioxidant and anti-inflammatory properties reduces the cognitive decline typical of aging, which reinforces the hypothesis of oxidative stress and cellular damage as contributors of physiological atrophy of aging. Moreover, cumulative evidence suggests their possible use as therapies, which improve the aging population's quality of life.

Intranasal Lipid Nanoparticles Containing Bioactive Compounds Obtained from Marine Sources to Manage Neurodegenerative Diseases

Marine sources contain several bioactive compounds with high therapeutic potential, such as remarkable antioxidant activity that can reduce oxidative stress related to the pathogenesis of neurodegenerative diseases. Indeed, there has been a growing interest in these natural sources, especially those resulting from the processing of marine organisms (i.e., marine bio-waste), to obtain natural antioxidants as an alternative to synthetic antioxidants in a sustainable approach to promote circularity by recovering and creating value from these bio-wastes. However, despite their expected potential to prevent, delay, or treat neurodegenerative diseases, antioxidant compounds may have difficulty reaching the brain due to the need to cross the blood–brain barrier (BBB). In this regard, alternative delivery systems administered by different routes have been proposed, including intranasal administration of lipid nanoparticles, such as solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC), which have shown promising results. Intranasal administration shows several advantages, including the fact that molecules do not need to cross the BBB to reach the central nervous system (CNS), as they can be transported directly from the nasal cavity to the brain (i.e., nose-to-brain transport). The benefits of using SLN and NLC for intranasal delivery of natural bioactive compounds for the treatment of neurodegenerative diseases have shown relevant outcomes through in vitro and in vivo studies. Noteworthy, for bioactive compounds obtained from marine bio-waste, few studies have been reported, showing the open potential of this research area. This review updates the state of the art of using SLN and NLC to transport bioactive compounds from different sources, in particular, those obtained from marine bio-waste, and their potential application in the treatment of neurodegenerative diseases.

Neuroprotective effect of piracetam-loaded magnetic chitosan nanoparticles against thiacloprid-induced neurotoxicity in albino rats

Thiacloprid (TH) is a neurotoxic agricultural insecticide and potential food contaminant. The purpose of this study was to investigate the relationship between TH exposure and memory dysfunction in rats, as well as the potential protective effect of piracetam and piracetam-loaded magnetic chitosan nanoparticles (PMC NPs). Rats were divided into five equal groups (six rats/group). The control group received saline. Group II was treated with PMC NPs at a dose level of 200 mg/kg body weight (Bwt); Group III was treated with 1/10 LD₅₀ of TH (65 mg/kg Bwt); Group IV was treated with TH (65 mg/kg Bwt) and piracetam (200 mg/kg Bwt); Group V was co-treated with TH (65 mg/kg Bwt) and PMC NPs (200 mg/kg Bwt). All animal groups were dosed daily for 6 weeks by oral gavage. Footprint analysis, hanging wire test, open field test, and Y-maze test were employed to assess behavioral deficits. Animals were euthanized, and brain tissues were analyzed for oxidative stress biomarkers, proinflammatory cytokines, and gene expression levels of glial fibrillary acidic protein (GFAP), amyloid-beta precursor protein (APP), B-cell lymphoma 2 (Bcl-2), and caspase-3. Brain and sciatic nerve tissues were used for the evaluation of histopathological changes and immunohistochemical expression of tau protein and nuclear factor kappa B (NF-κB), respectively. The results revealed that TH-treated rats suffered from oxidative damage and inflammatory effect on the central and peripheral nerves. The administration of PMC NPs considerably protected against TH-induced neuronal damage, increased antioxidant enzyme activity, decreased inflammatory markers, and improved behavioral performance than the group treated with piracetam. The neuroprotective effect of PMC NPs was mediated through the inhibition of GFAP, APP, caspase-3, Tau, and NF-κB gene expression with induction of Bcl-2 expression. In conclusion, TH could induce oxidative stress, inflammatory and neurobehavior impairment in rats. However, PMC NPs administration markedly mitigated TH-induced brain toxicity, possibly via oxidative and inflammatory modulation rather than using piracetam alone.

Memory Enhancing and Neurogenesis Activity of Honey Bee Venom in the Symptoms of Amnesia: Using Rats with Amnesia-like Alzheimer's Disease as a Model

BACKGROUND/OBJECTIVE

Alzheimer's disease (AD) is mainly characterized by amnesia that affects millions of people worldwide. This study aims to explore the effectiveness capacities of bee venom (BV) for the enhancement of the memory process in a rat model with amnesia-like AD.

METHODS

The study protocol contains two successive phases, nootropic and therapeutic, in which two BV doses (D1; 0.25 and D2: 0.5 mg/kg i.p.) were used. In the nootropic phase, treatment groups were compared statistically with a normal group. Meanwhile, in the therapeutic phase, BV was administered to scopolamine (1mg/kg) to induce amnesia-like AD in a rat model in which therapeutic groups were compared with a positive group (donepezil; 1mg/kg i.p.). Behavioral analysis was performed after each phase by Working Memory (WM) and Long-Term Memory (LTM) assessments using radial arm maze (RAM) and passive avoidance tests (PAT). Neurogenic factors; Brain-derived neurotrophic factor (BDNF), and Doublecortin (DCX) were measured in plasma using ELISA and Immunohistochemistry analysis of hippocampal tissues, respectively.

RESULTS

During the nootropic phase, treatment groups demonstrated a significant (P < 0.05) reduction in RAM latency times, spatial WM errors, and spatial reference errors compared with the normal group. In addition, the PA test revealed a significant (P < 0.05) enhancement of LTM after 72 hours in both treatment groups; D1 and D2. In the therapeutic phase, treatment groups reflected a significant (P < 0.05) potent enhancement in the memory process compared with the positive group; less spatial WM errors, spatial reference errors, and latency time during the RAM test, and more latency time after 72 hours in the light room. Moreover, results presented a marked increase in the plasma level of BDNF, as well as increased hippocampal DCX-positive data in the sub-granular zone within the D1 and D2 groups compared with the negative group (P < 0.05) in a dose-dependent manner.

CONCLUSION

This study revealed that injecting BV enhances and increases the performance of both WM and LTM. Conclusively, BV has a potential nootropic and therapeutic activity that enhances hippocampal growth and plasticity, which in turn improves WM and LTM. Given that this research was conducted using scopolamine-induced amnesia-like AD in rats, it suggests that BV has a potential therapeutic activity for the enhancement of memory in AD patients in a dose-dependent manner but further investigations are needed.

Vitamin D Mitigates Hyperglycemia-Induced Cognition Decline in Danio rerio (Zebrafish) through the Activation of Antioxidant Mechanisms

Hyperglycemia contributes to the development of cognition impairment and related disorders, induces oxidative stress in neuronal cells; thereby, impairs normal signaling mechanisms involved in cognition processes. Studies have shown a significant decrease in the vitamin D in individuals with hyperglycemia and cognition impairment. But whether supplementing vitamin D has any beneficiary impact on mitigating hyperglycemia-induced cognition impairment is unknown. We have first tested the impact of hyperglycemia on the induction of cognition deficiency in a zebrafish model. Next, the molecular mechanisms related to oxidative stress, which are deregulated in hyperglycemic zebrafish brains, have been explored. Subsequently, the impact of supplementing the water with vitamin D and a known activator of nuclear factor erythroid-2 related factor 2 (Nrf2) i.e., sulforaphane (SFN) on learning and memory functions were assessed. We showed a significant increase in the oxidative stress in the brain tissue of zebrafish residing in hyperglycemic water (111 mM glucose). Addition of vitamin D and SFN increased Nrf2, but differentially modulated its target genes (NQO1, SOD, GPx etc) activity in zebrafish and neuronal cell lines thereby improved the hyperglycemia-induced decline of cognition impairment. Mechanistically, vitamin D binds to the Keap1 protein; thereby, interfering with its binding to Nrf2, which leads to the activation of antioxidant mechanisms in the cells. In summary, reducing the oxidative stress through vitamin D treatment is a possible option for controlling the cognition impairment in diabetic population, but studies testing this possibility in clinical trials are currently needed.

Exploring the Role of Lipid-Binding Proteins and Oxidative Stress in Neurodegenerative Disorders: A Focus on the Neuroprotective Effects of Nutraceutical Supplementation and Physical Exercise

The human brain is primarily composed of lipids, and their homeostasis is crucial to carry on normal neuronal functions. In order to provide an adequate amount of lipid transport in and out of the central nervous system, organisms need a set of proteins able to bind them. Therefore, alterations in the structure or function of lipid-binding proteins negatively affect brain homeostasis, as well as increase inflammation and oxidative stress with the consequent risk of neurodegeneration. In this regard, lifestyle changes seem to be protective against neurodegenerative processes. Nutraceutical supplementation with antioxidant molecules has proven to be useful in proving cognitive functions. Additionally, regular physical activity seems to protect neuronal vitality and increases antioxidant defenses. The aim of the present review was to investigate mechanisms that link lipid-binding protein dysfunction and oxidative stress to cognitive decline, also underlining the neuroprotective effects of diet and exercise.

Diphenyl diselenide modulate antioxidant status, inflammatory and redox-sensitive genes in diesel exhaust particle-induced neurotoxicity

This study seeks to determine the influence of diphenyl diselenide (DPDSe) on redox status, inflammatory and redox-sensitive genes in diesel exhaust particle (DEP)-induced neurotoxicity in male albino rats. Male Wistar albino rats were administered nasally with DEP (30 and 60 μg/kg) and treated with intraperitoneal administration of 10 mg/kg DPDSe. Non-enzymatic (lipid peroxidation and conjugated diene concentrations) and enzymatic (catalase, superoxide dismutase, glutathione peroxidase) antioxidant indices and activity of acetylcholinesterase enzyme were evaluated in brain tissues of the rats. Furthermore, the expression of genes linked to oxidative stress (HO-1, Nrf2), pro-inflammatory (NF-KB, IL-8, TNF-α) anti-inflammatory (IL-10) and brain-specific (GFAP, ENO-2) genes were also determined. The results indicated that DPDSe caused a notable reduction in the high levels of thiobarbituric acid reactive substances and conjugated diene observed in the brain of DEP-administered rats. DPDSe also reversed the observed reduction in catalase, superoxide dismutase and glutathione peroxidase enzyme activities in the brain of DEP-administered rats. Lastly, the downregulation of genes associated with redox homeostasis, anti-inflammatory and brain-specific genes and upregulation of pro-inflammatory genes observed in the DEP-treated groups were ameliorated by DPDSe. The immediate restoration of altered biochemical conditions and molecular expression in the brain of DEP-treated rats by DPDSe further validates its use as a promising therapeutic candidate for restoring neurotoxicity linked with DEP-induced oxidative stress.

Kynurenine and oxidative stress in children having learning disorder with and without attention deficit hyperactivity disorder: possible role and involvement

Background

The etiological and pathophysiological factors of learning disorder (LD) and attention deficit hyperactivity disorder (ADHD) are currently not well understood. These disorders disrupt some cognitive abilities. Identifying biomarkers for these disorders is a cornerstone to their proper management. Kynurenine (KYN) and oxidative stress markers have been reported to influence some cognitive abilities. Therefore, the aim was to measure the level of KYN and some oxidative stress indicators in children with LD with and without ADHD and to investigate their correlations with the abilities of children with LD.

Methods

The study included 154 participants who were divided into 3 groups: one for children who have LD (N = 69); another for children with LD and ADHD (N = 31); and a group for neurotypical (NT) children (N = 54). IQ testing, reading, writing, and other ability performance evaluation was performed for children with LD. Measuring plasma levels of KYN, malondialdehyde, glutathione peroxidase, and superoxide dismutase by enzyme-linked immunosorbent assay was performed for all participants.

Results

Some IQ measures and learning skills differed between the first two groups. The biochemical measures differed between children with LD (with and without ADHD) and NT children (p < 0.001). However, the biochemical measures did not show a significant statistical difference between the first two groups. KYN and glutathione peroxidase levels were correlated with one-minute writing and at-risk quotient, respectively (p = 0.03;0.04). KYN and malondialdehyde showed the highest sensitivity and specificity values.

Conclusion

These biochemical measures could be involved or have a role in the abilities’ performance of children with specific learning disorder.

mGluR5 ablation leads to age-related synaptic plasticity impairments and does not improve Huntington’s disease phenotype

Glutamate receptors, including mGluR5, are involved in learning and memory impairments triggered by aging and neurological diseases. However, each condition involves distinct molecular mechanisms. It is still unclear whether the mGluR5 cell signaling pathways involved in normal brain aging differ from those altered due to neurodegenerative disorders. Here, we employed wild type (WT), mGluR5^−/−, BACHD, which is a mouse model of Huntington’s Disease (HD), and mGluR5^−/−/BACHD mice, at the ages of 2, 6 and 12 months, to distinguish the mGluR5-dependent cell signaling pathways involved in aging and neurodegenerative diseases. We demonstrated that the memory impairment exhibited by mGluR5^−/− mice is accompanied by massive neuronal loss and decreased dendritic spine density in the hippocampus, similarly to BACHD and BACHD/mGluR5^−/− mice. Moreover, mGluR5 ablation worsens some of the HD-related alterations. We also show that mGluR5^−/− and BACHD/mGluR5^−/− mice have decreased levels of PSD95, BDNF, and Arc/Arg3.1, whereas BACHD mice are mostly spared. PSD95 expression was affected exclusively by mGluR5 ablation in the aging context, making it a potential target to treat age-related alterations. Taken together, we reaffirm the relevance of mGluR5 for memory and distinguish the mGluR5 cell signaling pathways involved in normal brain aging from those implicated in HD.

Does ( -)-epigallocatechin-3-gallate protect the neurotoxicity induced by bisphenol A in vivo?

Bisphenol A (BPA) is one of the chemicals that is firmly accompanied by hippocampal neuronal injury. As oxidative stress appears to be a major contributor to neurotoxicity induced by BPA, antioxidants with remarkable neuroprotective effects can play a valuable protective role. Around the world, ( -)-epigallocatechin-3-gallate (EGCG) was one of the most popular antioxidants that could exert a beneficial neuroprotective role. Here, we examined the potential efficiency of EGCG against neurotoxicity induced by BPA in the hippocampal CA3 region of the rat model. This study revealed that EGCG was unable to abrogate the significant decrease in circulating adiponectin level and hippocampal superoxide dismutase activity as well as an increase in hippocampal levels of nitric oxide and malondialdehyde. Notably, EGCG failed to antagonize the oxidative inhibitory effect of BPA on hippocampal neurotransmission and its associated cognitive deficits. In addition, the histopathological examination with immunohistochemical detection of caspase-3 and NF-kB/p65 emphasized that EGCG failed to protect hippocampal CA3 neurons from apoptotic and necrotic effects induced by BPA. Our study revealed that EGCG showed no protective role against the neurotoxic effect caused by BPA, which may be attributed to its failure to counteract the BPA-induced oxidative stress in vivo. The controversial effect is probably related to EGCG's ability to impede BPA glucuronidation and thus, its detoxification. That inference requires further additional experimental and clinical studies.

SHEDDING LIGHT ON THE TOXICITY OF SARS-CoV-2-DERIVED PEPTIDE IN NON-TARGET COVID-19 ORGANISMS: A STUDY INVOLVING INBRED AND OUTBRED MICE

Despite advances in research on the vaccine and therapeutic strategies of COVID-19, little attention has been paid to the possible (eco)toxicological impacts of the dispersion of SARS-CoV-2 particles in natural environments. Thus, in this study, we aimed to evaluate the behavioral and biochemical consequences of the short exposure of outbred and inbred mice (male Swiss and C57Bl/6 J mice, respectively) to PSPD-2002 (peptide fragments of the Spike protein of SARS-CoV-2) synthesized in the laboratory. Our data demonstrated that after 24 h of intraperitoneal administration of PSPD-2002 (at 580 μg/kg) the animals did not present alterations in their locomotor, anxiolytic-like, or anxiety-like behavior (in the open field test), nor antidepressant-like or depressive behavior in the forced swimming test. However, the C57Bl/6 J mice exposed to PSPD-2002 showed memory deficit in the novel object recognition task, which was associated with higher production of thiobarbituric acid reactive substances, as well as the increased suppression of acetylcholinesterase brain activity, compared to Swiss mice also exposed to peptide fragments. In Swiss mice the reduction in the activity of superoxide dismutase and catalase in the brain was not associated with increased oxidative stress biomarkers (hydrogen peroxide), suggesting that other antioxidant mechanisms may have been activated by exposure to PSPD-2002 to maintain the animals' brain redox homeostasis. Finally, the results of all biomarkers evaluated were applied into the "Integrated Biomarker Response Index" (IBRv2) and the principal component analysis (PCA), and greater sensitivity of C57Bl/6 J mice to PSPD-2002 was revealed. Therefore, our study provides pioneering evidence of mammalian exposure-induced toxicity (non-target SARS-CoV-2 infection) to PSPD-2002, as well as “sheds light” on the influence of genetic profile on susceptibility/resistance to the effects of viral peptide fragments.

Roflumilast Reduces Pathological Symptoms of Sporadic Alzheimer's Disease in Rats Produced by Intracerebroventricular Streptozotocin by Inhibiting NF-κB/BACE-1 Mediated Aβ Production in the Hippocampus and Activating the cAMP/BDNF Signalling Pathway

Alzheimer's disease (AD) is a neurological disease that gradually causes memory loss and cognitive impairment. The intracellular secondary messenger cyclic nucleotide cAMP helps in memory acquisition and consolidation. In several models of AD, increasing their levels using phosphodiesterase (PDE) inhibitors improved cognitive performance and prevent memory loss. Thus, the current investigation was undertaken to investigate the therapeutic potential of the PDE-4 inhibitor roflumilast (RFM) against intracerebroventricular (ICV) streptozotocin (STZ)-induced sporadic AD in rats. STZ (3 mg/kg) was given to rats via the ICV route on the stereotaxic apparatus, followed by RFM (0.51 mg/kg/oral) treatment for 15 days, and donepezil (5 mg/kg/oral) was employed as a reference standard drug. Subsequently, we observed that RFM dramatically increased rats learning and memory capacities as measured by the Morris water maze and a novel object recognition task. RFM enhanced the levels of cAMP and brain-derived neurotrophic factors (BDNFs) while decreasing the expression of nuclear factor kappa B (NF-κB) and glial fibrillary acidic protein (GFAP) in the hippocampus of ICV-STZ-infused rats. RFM was found to significantly reduce ICV-STZ-induced neuroinflammation, amyloidogenesis, oxidative stress cholinergic impairments, GSK-3β, and phosphorylated tau levels in the rat hippocampus. Supporting these, histopathological study using Cresyl violet and Congo red demonstrated that RFM reduced neuronal alterations and Aβ deposition in the hippocampus of AD rats. These findings suggest that RFM could be a promising candidate for the management of AD by inhibiting NF-κB/BACE-1 mediated Aβ production in the hippocampus and activating the cAMP/BDNF signalling pathway.

Synergistic alleviation effects of anchovy hydrolysates-catechin on scopolamine-induced mice memory deficits: the exploration of the potential relationship among gut-brain-axis

Anchovy protein hydrolysates (APH) and catechin (CA) have proved to be effective in memory improvement. However, the enhancing effects of APH-CA conjugates on the memory are little investigated. The underlying mechanism and synergic effects remain unclear. Herein, relationships among memory enhancement, gut microbiota, fecal metabolites, and neurotransmitters of mice regulated by APH-CA were investigated. APH, APH-CA, and CA decreased MDA, IL-1β, and TNF-α in liver, altered levels of GPx, LDH, IL-1β, and TNF-α in serum, re-structured gut microbiota, regulated fecal metabolites, and regulated neurotransmitters in the brain. The alleviation effects of APH-CA were partially better than those of APH and CA. The 16s rRNA results illustrated that Bacteroidetes and Firmicutes were altered. Notably, memory-related metabolites and neurotransmitters were significantly up-regulated by the administration of samples. Moreover, possible connections are observed among the gut microbiota, fecal metabolites, and brain neurotransmitters. Together, the regulation of the microbiota-metabolites-brain-neurotransmitters axis may be one of the mechanisms for APH-CA against scopolamine-induced cognitive deficits. In addition, the synergic effects of APH and CA were partially confirmed.

Fisetin, a potential caloric restriction mimetic, modulates ionic homeostasis in senescence induced and naturally aged rats

CONTEXT

Fisetin as a caloric restriction mimetic (CRM) exerts numerous beneficial effects on different aging model systems. The effect of fisetin on erythrocyte membrane functions against induced aging is not very clear.

OBJECTIVES

The potential role of fisetin in the modulation of erythrocytes membrane-bound transporters during natural and induced aging in rats was assessed.

MATERIALS AND METHODS

Male Wistar rats were used for natural and D-galactose (D-gal) induced aging model. After supplementation with fisetin, the activities of different membrane transporters and biomarkers of oxidative stress were evaluated.

RESULTS

Fisetin modulated membrane transporters such as calcium-ATPase, sodium potassium-ATPase and sodium hydrogen exchanger during senescence-induced as well as in natural aging. Fisetin also protected oxidative modifications in rat aging.

DISCUSSION AND CONCLUSION

Fisetin supplementation improves the ionic homeostasis, a factor that is involved in the aetiology of several age-associated diseases, in naturally old as well as D-gal induced aged rats.

Differential effects of voluntary and forced exercise trainings on spatial learning ability and hippocampal biomarkers in aged female rats

This study aimed to compare the effects of voluntary and forced exercise trainings on cognitive functions and to evaluate their relationship with hippocampal synaptic proteins, neurotrophic factors and markers of oxidative damage in aged female rats. Aged female rats were randomly assigned to control, voluntary exercise training and forced exercise training groups. Voluntary or forced exercise trainings were performed for 12 weeks. At the end of the training period, cognitive functions of the animals were assessed with Morris water maze (MWM) test. After the behavioral test, hippocampus tissues were taken for the analysis of synaptophysin, acetylcholinesterase (AChE), brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), malondialdehyde (MDA), protein carbonyl (PC), glutathione (GSH) and superoxide dismutase (SOD). During the MWM test, the number of platform crossings was higher in the voluntary exercise group than in the control group (P < 0.05). In the hippocampus tissue, levels of the synaptophysin, BDNF, NGF and SOD were higher, but MDA levels were lower in the voluntary exercise group than in the control group (P < 0.05). Additionally, hippocampal AChE concentration was higher, but PC levels were lower in the both voluntary and forced exercise groups than in the control group (P < 0.05). In conclusion, voluntary exercise was more effective intervention to improve spatial learning ability in aging process. Increased neurotrophic factors, synaptic proteins, and improved oxidative damage may play a role in these positive effects.

Dunalialla salina microalgea and its isolated zeaxanthin mitigate age-related dementia in rats: Modulation of neurotransmission and amyloid-β protein

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D. salina as well as its isolated zeaxanthin showed marked recovery of the D-gal-induced effect on the escape latency time.

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D. salina exerted an amelioration in the brain Aβ contents and an increase in the brain 5-HT, NE and DOP levels.

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These effects were confirmed by histopathological increase in number of viable neurons in both cerebral cortex and hippocampus.

Age-related deterioration of sensorimotor and cognitive abilities suggests that the brain undergoes regressive alterations with aging that compromise its function. Thus, the present study was designed to assess the efficacy of Dunaliella salina in counteracting D-galactose (D-gal)-induced dementia brain aging and its modulatory role in attenuating amyloid β (Aβ) protein and neurotransmitters. Aging associated dementia was generated by injection of D-gal (200 mg/kg; i.p) of rats for 8 weeks. D. salina biomass (250 mg/kg), polar (30 mg/kg), its carotenoid (30 mg/kg) fractions as well as the isolated zeaxanthin (250 μg/kg) were given orally simultaneously with D-gal for additional two weeks. Twenty-four hours after the last treatment dose; behavioral, biochemical and histopathological assessment were performed. Results showed that oral treatment of motor deficit rats with D. salina biomass and its isolated polar and carotenoid fractions showed amelioration in the motor coordination assessed by the rotarod test and in the memory and learning capabilities evaluated by Morris water maze test. D. salina also showed a reduction in brain levels of inflammatory indicators viz. interlekin-1β and inducible nitric oxide synthetase as well as brain contents of Aβ protein and myelin base protein. Likewise, oral treatment with D. salina biomass and its isolated polar and carotenoid fractions exhibited an increase in the rats’ brain neurotransmitters and their metabolites. Furthermore, histopathological investigations have confirmed all of these results. Our findings suggest that D. salina overcomes brain aging and thereby repairs age-related dementia, both for its modulating function in attenuating the Aβ protein and neurotransmitters.

Quercetin exhibits potent antioxidant activity, restores motor and non-motor deficits induced by rotenone toxicity

The rotenone-induced animal model of Parkinson's disease (PD) has been used to investigate the pathogenesis of PD. Oxidative stress is one of the main contributors of neurodegeneration in PD. Flavonoids have the potential to modulate neuronal function and combat various neurodegenerative diseases. The pre- and post-supplementation of quercetin (50 mg/kg, p.o) was done in rats injected with rotenone (1.5 mg/kg, s.c). After the treatment, behavioral activities were monitored for motor activity, depression-like behavior, and cognitive changes. Rats were decapitated after behavioral analysis and the brain samples were dissected out for neurochemical and biochemical estimation. Results showed that supplementation of quercetin significantly (p<0.01) restored rotenone-induced motor and non-motor deficits (depression and cognitive impairments), enhanced antioxidant enzyme activities (p<0.01), and attenuated neurotransmitter alterations (p<0.01). It is suggested that quercetin supplementation improves neurotransmitter levels by mitigating oxidative stress via increasing antioxidant enzyme activity and hence improves motor activity, cognitive functions, and reduces depressive behavior. The results of the present study showed that quercetin pre-supplementation produced more significant results as compared to post-supplementation. These findings show that quercetin can be a potential therapeutic agent to reduce the risk and progression of PD.

The neuroprotective potential of carotenoids in vitro and in vivo

BACKGROUND

Despite advances in research on neurodegenerative diseases, the pathogenesis and treatment response of neurodegenerative diseases remain unclear. Recent studies revealed a significant role of carotenoids to treat neurodegenerative diseases. The aim of this study was to systematically review the neuroprotective potential of carotenoids in vivo and in vitro and the molecular mechanisms and pathological factors contributing to major neurodegenerative diseases (Alzheimer's disease, Huntington's disease, Parkinson's disease, amyotrophic lateral sclerosis, and stroke).

HYPOTHESIS

Carotenoids as therapeutic molecules to target neurodegenerative diseases.

RESULTS

Aggregation of toxic proteins, mitochondrial dysfunction, oxidative stress, the excitotoxic pathway, and neuroinflammation were the major pathological factors contributing to the progression of neurodegenerative diseases. Furthermore, in vitro and in vivo studies supported the beneficiary role of carotenoids, namely lycopene, β-carotene, crocin, crocetin, lutein, fucoxanthin and astaxanthin in alleviating disease progression. These carotenoids provide neuroprotection by inhibition of neuro-inflammation, microglial activation, excitotoxic pathway, modulation of autophagy, attenuation of oxidative damage and activation of defensive antioxidant enzymes. Additionally, studies conducted on humans also demonstrated that dietary intake of carotenoids lowers the risk of neurodegenerative diseases.

CONCLUSION

Carotenoids may be used as drugs to prevent and treat neurodegenerative diseases. Although, the in vitro and in vivo results are encouraging, further well conducted clinical studies on humans are required to conclude about the full potential of neurodegenerative diseases.

Protective effects of vitamin D on neurophysiologic alterations in brain aging: role of brain-derived neurotrophic factor (BDNF)

Background/aim: Vitamin D has been hypothesized to be main regulator of the aging rate, alongside evidences support its role in neuroprotection. However, data about the protective role of vitamin D against neurophysiologic alterations associated with brain aging is limited. This study investigated the possible protective effects that vitamin D has on brain-derived neurotrophic factor (BDNF), cholinergic function, oxidative stress and apoptosis in aging rat brain.Methods: Male Wister albino rats aged 5 months (young), 12 months (middle aged) and 24 months (old) (n = 20 each) were used. Each age group subdivided to either vitamin D3 supplementation (500 IU/kg/day orally for 5 weeks) or no supplementation (control) group (n = 10 each). Serum 25-hydroxyvitamin D [25(OH)D], brain BDNF and malondialdehyde levels and activities of acetylcholinesterase (AChE), antioxidant enzymes (glutathione reductase, glutathione peroxidase and superoxide dismutase) and caspase-3 were quantified.Results: Vitamin D supplementation significantly mitigated the observed aging-related reduction in brain BDNF level and activities of AChE and antioxidant enzymes and elevation in malondialdehyde level and caspase-3 activity compared to control groups. Brain BDNF level correlated positively with serum 25(OH) D level and brain AChE activity and negatively with brain malondialdehyde level and caspase-3 activity in supplemented groups.Conclusion: Restoring vitamin D levels may, therefore, represent a useful strategy for healthy brain aging. Augmenting brain BDNF seems to be a key mechanism through which vitamin D counteracts age-related brain dysfunction.

Therapeutic potential of astaxanthin and superoxide dismutase in Alzheimer's disease

Oxidative stress, the imbalance of the antioxidant system, results in an accumulation of neurotoxic proteins in Alzheimer's disease (AD). The antioxidant system is composed of exogenous and endogenous antioxidants to maintain homeostasis. Superoxide dismutase (SOD) is an endogenous enzymatic antioxidant that converts superoxide ions to hydrogen peroxide in cells. SOD supplementation in mice prevented cognitive decline in stress-induced cells by reducing lipid peroxidation and maintaining neurogenesis in the hippocampus. Furthermore, SOD decreased expression of BACE1 while reducing plaque burden in the brain. Additionally, Astaxanthin (AST), a potent exogenous carotenoid, scavenges superoxide anion radicals. Mice treated with AST showed slower memory decline and decreased depositions of amyloid-beta (Aβ) and tau protein. Currently, the neuroprotective potential of these supplements has only been examined separately in studies. However, a single antioxidant cannot sufficiently resist oxidative damage to the brain, therefore, a combinatory approach is proposed as a relevant therapy for ameliorating pathological changes in AD.

Protective effects of krill oil on high fat diet-induced cognitive impairment by regulation of oxidative stress

Consumption of high fat diet (HFD) increases risk of cognitive impairment and memory deficit by elevation of oxidative stress in the brain. In this study, we investigated the protective effects of krill oil (KO) against HFD-induced cognitive impairment in mice. The mice were fed with HFD for 10 weeks, and then KO was orally administered at doses of 100, 200, or 500 mg/kg/d for 4 weeks. To evaluate the cognitive abilities, we carried out the behavior tests, such as T-maze, novel object recognition test, and Morris water maze test. The HFD-induced cognitive impairment mice showed impairments in both spatial memory and novel object cognitive abilities. However, administration of KO at doses of 100, 200, or 500 mg/kg/d improved spatial memory ability and novel object cognition by increase of the exploration of new route and novel object. In addition, KO-administered group improved learning and memory abilities, showing shorter latency to reach hidden platform compared with control group. Furthermore, levels of reactive oxygen species (ROS), lipid peroxidation, and nitric oxide (NO) were significantly elevated by consumption of HFD, indicating that consumption of HFD induces oxidative stress in the brain. However, administration of KO attenuated oxidative stress by decrease of the ROS levels, lipid peroxidation, and NO. This study suggests that KO improves HFD-induced cognitive impairment by attenuation of oxidative stress in the brain. Therefore, KO may play as a promising agent in treatment and prevention of HFD-induced cognitive impairment.

Behavioural tagging: Effect of novelty exploration on plasticity related molecular signatures

Learning and memory are one of those frontier areas of neurobiology which attract us to investigate the intricacy of this process. Here, we aimed to investigate the general mechanism of "Behavioural Tagging and Capture" in long term memory (LTM) formation and to find the key factors playing role in consolidation of LTM. In this study, we've shown that not only plasticity related proteins (PRPs) but neurotransmitters and immediate early genes (IEGs) also play an important role in memory formation process. It's very well evident that memory traces can last longer if close in time novelty is introduced around memory encoding. Here our results point out that this novelty exploration acts as a modulator in memory consolidation by providing PRPs such as brain-derived neurotrophic factor (BDNF), cAMP response element-binding protein (CREB), enhancing neurotransmitters (Dopamine), IEGs (cFos) and some enzymes such as acetylcholinesterase (AChE), monoamine oxidase (MAO), sodium-potassium ATPase (Na⁺K⁺-ATPase). Therefore, by using a Novel Object Recognition task (NOR) in combination with novel task exposure, we evaluated the role of molecular markers in memory consolidation employing a behavioural tagging model. The purpose of the current study was first to evaluate the effect of novelty exposure around a single trail of NOR task in a critical time window on memory consolidation in rats after 24 h and second to determine the expression of BDNF, CREB, c-fos, AChE, MAO, Na⁺K⁺-ATPase as potential markers in the medial prefrontal cortex (mPFC) during memory formation. In the present study, to identify and validate the role of these molecular signatures in memory consolidation, infusion of the protein synthesis inhibitor Anisomycin (Ani) was done around the training session that causes a deficit in the formation of LTM when tested 24 h after weak encoding. Altogether, here we are providing the first comprehensive set of evidences indicating that BDNF, CREB, dopamine, some enzymes and c-fos role in modulating LTM by employing behavioural tagging model.

Hydrogen Sulfide Ameliorates Lipopolysaccharide-Induced Memory Impairment in Mice by Reducing Apoptosis, Oxidative, and Inflammatory Effects

Hydrogen sulfide (H₂S) is reported to have a neuroprotective activity; however, the role of H₂S in neuroinflammation-induced neuronal damage is ambiguous. Here, we aimed to evaluate the underlying mechanisms for the neuroprotective effect of NaHS, a known H₂S donor, against lipopolysaccharide (LPS)-induced memory impairment (MI). All the treatments were administered for 28 days, and LPS (0.25 mg/kg i.p.) was co-administered intermittently for 7 days from days 15 to 21. Morris water maze (MWM) and Y-maze tests were performed to evaluate MI. Neurodegeneration was histopathologically examined, and the brain homogenates were characterized for reduced glutathione (GSH), superoxide dismutase (SOD), malondialdehyde (MDA), tumor necrosis factor (TNF)-α, interleukin (IL)-6, caspase-3, c-Jun, and acetylcholinesterase (AChE) by biochemical analysis. H₂S administration significantly improved spatial and working memory in MWM and Y-maze tasks, respectively. Exogenous H₂S significantly reversed LPS-induced oxidative stress as evidenced by improved GSH, MDA, and SOD levels. H₂S pretreatment significantly attenuated LPS-induced apoptosis and inflammation by decreasing c-Jun and caspase-3 levels and inhibiting TNF-α and IL-6, respectively. The decrease in these markers was supported by H&E and Nissl staining, which confirmed the anti-necrotic activity of H₂S. However, there was no significant improvement in LPS-induced increase in AChE activity. These results indicate that chronic systemic inflammation leads to neurodegeneration and MI and H₂S exerts its neuroprotective effect due to its anti-oxidative, anti-inflammatory, and anti-apoptotic potential via modulation of JNK and extrinsic apoptosis pathways.

Environmental enrichment applied with sensory components prevents age-related decline in synaptic dynamics: Evidence from the zebrafish model organism

Progression of cognitive decline with or without neurodegeneration varies among elderly subjects. The main aim of the current study was to illuminate the molecular mechanisms that promote and retain successful aging in the context of factors such as environment and gender, both of which alter the resilience of the aging brain. Environmental enrichment (EE) is one intervention that may lead to the maintenance of cognitive processing at older ages in both humans and animal subjects. EE is easily applied to different model organisms, including zebrafish, which show similar age-related molecular and behavioral changes as humans. Global changes in cellular and synaptic markers with respect to age, gender and 4-weeks of EE applied with sensory stimulation were investigated using the zebrafish model organism. Results indicated that EE increases brain weight in an age-dependent manner without affecting general body parameters like body mass index (BMI). Age-related declines in the presynaptic protein synaptophysin, AMPA-type glutamate receptor subunits and a post-mitotic neuronal marker were observed and short-term EE prevents these changes in aged animals, as well as elevates levels of the inhibitory scaffolding protein, gephyrin. Gender-driven alterations were observed in the levels of the glutamate receptor subunits. Oxidative stress markers were significantly increased in the old animals, while exposure to EE did not alter this pattern. These data suggest that EE with sensory stimulation exerts its effects mainly on age-related changes in synaptic dynamics, which likely increase brain resilience through specific cellular mechanisms.

Near-infrared fluorescent probe for evaluating the acetylcholinesterase effect in the aging process and dietary restriction via fluorescence imaging

Dietary restriction (DR), as a natural intervention, not only benefits the neuroendocrine system, but also has an antiaging action. Acetylcholinesterase (AChE) is one of the most important bioactive substances and plays a major part in choline changes in the aging process. Thus, we aim to evaluate the effect of DR on AChE in the brains of aging animals. In this study, we synthesize a NIR fluorescent probe BD-AChE for the real-time and in situ monitoring of AChE level changes in living cells and living mice, notably in brains. In situ visualization with BD-AChE verified a decrease in the AchE level in the brains of mice aging models. Evidently, the prepared probe has the excellent capability of measuring AChE variation in the brains of aging mice with DR via NIR fluorescence bioimaging, indicating that long-term DR can effectively affect AChE levels in the brain. The attenuation of AChE level in the brain of aging mice after DR could be helpful in infering the advantageous impact of DR on age-related neurodegenerative disease, as a better treatment alternative in the future.

Impaired GABAergic and glutamatergic neurometabolic activity in aged mice brain as measured by 1 H-[13 C]-NMR spectroscopy

Healthy aging is associated with a decline in cognitive function, and is a major risk factor for many neurodegenerative diseases. Although, there are several evidence that brain mitochondrial function is altered with aging its significance at the cellular level is elusive. In this study, we have investigated mitochondrial TCA cycle and neurotransmitter cycle fluxes associated with glutamatergic, GABAergic neurons and astroglia in the cerebral cortex and hippocampus of young (6 months) and aged (24 months) C57BL6 mice by using ¹ H-[¹³ C]-NMR spectroscopy together with timed infusion of ¹³ C-labeled glucose and acetate. The ratio V_Cyc /V_TCA was determined from a steady-state [2-¹³ C]acetate experiment. Metabolic fluxes were obtained by fitting a three-compartment metabolic model to ¹³ C turnover of amino acids from glucose. Levels of glutamate, aspartate and taurine were reduced in the cerebral cortex, while glutamine and choline were elevated in the hippocampus of aged mice. Interestingly, the rate of acetate oxidation increased in the cerebral cortex, while the flux of mitochondrial TCA cycle of glutamatergic neurons decreased in the cerebral cortex (P < .0001) and hippocampus (P = .025) of aged mice. The glutamate-glutamine neurotransmitter cycle flux was reduced in the cerebral cortex (P < .0001). The GABAergic TCA cycle flux was reduced in the cerebral cortex (P = .0008), while GABA-glutamine neurotransmitter cycling flux was also reduced in the cerebral cortex (P = .011) and hippocampus (P = .042) of aged brain. In conclusion, the reduction in excitatory and inhibitory neurotransmitter activity of glutamatergic and GABAergic neurons in the cerebral cortex and hippocampus correlates qualitatively with declined cognitive function in aged mice.

The protective effect of Indian Catechu methanolic extract against aluminum chloride-induced neurotoxicity, A rodent model of Alzheimer's disease

Alzheimer's disease (AD) is the commonest neurodegenerative disorder with a wide array of manifestations, courses, and contributing causes. Despite being clinically characterized a long time ago; no treatment has been developed that could improve the pathology or slow down the disease manifestation- so far. Indian Catechu methanolic extract (ICME) has proved to have multiple beneficial effects that support its use in several disorders- especially those with complex etiology. In the present study, we evaluated the neuroprotective effect of ICME in a rat model of AD using Aluminum Chloride (AlCl3). The results showed that ICME could have a positive impact on the course of AD through its anticholinesterase effect and significant antioxidant effect which was reflected on the animals both on behavioral tests as well as hallmark pathological findings.

Screening of Synthetic Isoxazolone Derivative Role in Alzheimer's Disease: Computational and Pharmacological Approach

Alzheimer's disease (AD) is age-dependent neurological disorder with progressive loss of cognition and memory. This multifactorial disease is characterized by intracellular neurofibrillary tangles, beta amyloid plaques, neuroinflammation, and increased oxidative stress. The increased cellular manifestations of these markers play a critical role in neurodegeneration and pathogenesis of AD. Therefore, reducing neurodegeneration by decreasing one or more of these markers may provide a potential therapeutic roadmap for the treatment of AD. AD causes a devastating loss of cognition with no conclusive and effective treatment. Many synthetic compound containing isoxazolone nucleus have been reported as neuroprotective agents. The aim of this study was to explore the anti-Alzheimer's potential of a newly synthesized 3,4,5-trimethoxy isoxazolone derivative (TMI) that attenuated the beta amyloid (Aβ1-42) and tau protein levels in streptozotocin (STZ) induced Alzheimer's disease mouse model. Molecular analysis revealed increased beta amyloid (Aβ1-42) protein levels, increased tau protein levels, increased cellular oxidative stress and reduced antioxidant enzymes in STZ exposed mice brains. Furthermore, ELISA and PCR were used to validate the expression of Aβ1-42. Pre-treatment with TMI significantly improved the memory and cognitive behavior along with ameliorated levels of Aβ1-42 proteins. TMI treated mice further showed marked increase in GSH, CAT, SOD levels while decreased levels of acetylcholinesterase inhibitors (AChEI's) and MDA intermediate. The multidimensional nature of isoxazolone derivatives and its versatile affinity towards various targets highpoint its multistep targeting nature. These results indicated the neuroprotective potential of TMI which may be considered for the treatment of neurodegenerative disease specifically in AD.

Cognitive and Neurochemical Changes Following Polyphenol-Enriched Diet in Rats

Dietary recommendations are frequently developed based on nutrient deficiency or prevention of disease, but less attention has been paid to the dietary guidelines to promote brain health. Active and healthy aging is a prerequisite for improving quality of life as people age, and evidence is establishing a relationship between diet and brain health. This work studied the effect of a diet based on foods rich in antioxidants, especially polyphenols, in rats, three days a week for 20 months starting at 14 months. Behavioral analysis testing working memory, spatial and episodic memory, as well as brain monoaminergic neurotransmitters involved in these processes but also in general brain health were analyzed. In addition, hippocampal SIRT1 protein which has an important role in regulating normal brain function was evaluated. The results show that long-term intake of polyphenol-enriched diet improves memory and learning, correlating with restoration of brain monoaminergic neurotransmitters and hippocampal SIRT1 levels in aged rats. These results agree with reports revealing a neuroprotective effect of different polyphenolic compounds on age-related brain decline, based on its antioxidant and anti-inflammatory properties; and demonstrate that consumption of antioxidant-rich foods, a few days a week, gives good long-term results in terms of brain health.

Effects of different LED light spectra on rainbow trout (Oncorhynchus mykiss): in vivo evaluation of the antioxidant status

Rainbow trout (Oncorhynchus mykiss) farming is one of the major aquacultures in Turkey. Some conditions in fish farming can induce oxidative stress leading to the deterioration in properties such as appearance/color, texture, and flavor in fish meat. This situation may cause the consumer not to prefer edible fish. Although there are some studies on the impacts of light intensity on fish welfare, the changes in the antioxidant enzyme activities have not been elucidated. In the current study, it was intended to examine in rainbow trout how cultivating under different wavelengths affects the antioxidant enzymes and acetylcholine esterase (AChE) activity, because its activity is associated with oxidative stress, and also the determination of which light is suitable for fish welfare was aimed. Rainbow trout larvae were grown under four lights with different wavelengths: natural sunlight and incandescent long-wave (red light), medium-wave (green light), and short-wave (blue light) LED light. The experiment lasted for 64 days. Biochemical assays were carried on in the brain, gill, and liver of rainbow trout. Antioxidant enzymes and AChE activity, which play an important role in the central nervous system, were assayed. In gill tissues, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glucose 6 phosphate dehydrogenase (G6PD), glutathione reductase (GR), glutathione S-transferase (GST), and AChE activities increased under all three light wavelengths. In the liver, while activities of antioxidant enzymes and AChE decreased in red light, all of them increased in blue and green light. In the brain, GPx, GST, G6PD, and SOD activities were reduced but AChE activity did not alter under all three light sources. In conclusion, light sources with different spectral structures caused important changes in the activities of antioxidant enzymes in rainbow trout. On this basis, it may be thought that this may be a response to the changing redox status of a cell. Based on our results, blue light sources may be suggested for fish welfare in rainbow trout culture, and providing fish welfare by changing light sources can be easy and cheap in fish farming.