Intermittent fasting enhances long-term memory consolidation, adult hippocampal neurogenesis, and expression of longevity gene Klotho

Sex-dependent changes in AMPAR expression and Na, K-ATPase activity in the cerebellum and hippocampus of α-Klotho-Hypomorphic mice

Aging is characterized by a functional decline in several physiological systems. α-Klotho-hypomorphic mice (Kl-/-) exhibit accelerated aging and cognitive decline. We evaluated whether male and female α-Klotho-hypomorphic mice show changes in the expression of synaptic proteins, N-methyl-d-aspartate receptor (NMDAR) and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) subunits, postsynaptic density protein 95 (PSD-95), synaptophysin and synapsin, and the activity of Na+, K+-ATPase (NaK) isoforms in the cerebellum and hippocampus. In this study, we demonstrated that in the cerebellum, Kl-/- male mice have reduced expression of GluA1 (AMPA) compared to wild-type (Kl+/+) males and Kl-/- females. Also, Kl-/- male and female mice show reduced ɑ2/ɑ3-NaK and Mg2+-ATPase activities in the cerebellum, respectively, and sex-based differences in NaK and Mg2+-ATPase activities in both the regions. Our findings suggest that α-Klotho could influence the expression of AMPAR and the activity of NaK isoforms in the cerebellum in a sex-dependent manner, and these changes may contribute, in part, to cognitive decline.

Sex-specific effects of intermittent fasting on hippocampal neurogenesis via the gut-brain axis

Intermittent fasting (IF) is a widely used dietary strategy that has shown several advantageous impacts on general health and aging. IF has recently been linked to the control of neurogenesis, a crucial process for emotional control, memory, and learning, in the hippocampus. Nevertheless, there is little knowledge about the sex-specific impacts of IF on hippocampal neurogenesis and the related mechanisms, which were investigated in this study among both male and female rats, together with analyzing the involvement of the flora-gut-brain axis in facilitating these effects. Our findings show that IF favorably affects hippocampus neurogenesis in female mice relative to male mice, suggesting a sex-specific mechanism. In addition, IF influenced the diversity of the gut microbiota and decreased the synthesis of fructose-1-phosphate (F-1-P), which is believed together with fructose metabolism to be linked to neurological damage and cognitive decline. Collectively, these data indicate that the connection between the flora-gut-brain axis and hippocampus neurogenesis is significant.

Intermittent fasting alleviates postoperative cognitive dysfunction by reducing neuroinflammation in aged mice

Elderly individuals undergoing surgical procedures are often confronted with the peril of experiencing postoperative cognitive dysfunction (POCD). Prior research has demonstrated the exacerbating effect of sevoflurane anesthesia on neuroinflammation, which can further deteriorate the condition of POCD in elderly patients. Intermittent fasting (IF) restricts food consumption to a specific time window and has been demonstrated to ameliorate cognitive dysfunction induced by neuropathic inflammation. We subjected 18-month-old male mice to 16 hours of fasting and 8 hours of unrestricted eating over a 24-hour period for 0, 1, 2, and 4 weeks, followed by abdominal exploration under sevoflurane anesthesia. In this study, we aim to explore the potential impact of IF on postoperative cognitive function in aged mice undergoing sevoflurane surgery through the preoperative implementation of IF measures. The findings indicate two weeks of IF leads to a significant enhancement of learning and memory capabilities in mice following surgery. The cognitive performance, as determined by the novel object recognition and Morris water maze tests, as well as the synaptic plasticity, as measured by in vivo electrophysiological recordings, has demonstrated marked improvements. Furthermore, the administration of IF markedly enhances the expression of synaptic-associated proteins in hippocampal neurons, concomitant with a decreasing expression of pro-inflammatory factors and a reduced density of microglial cells within the hippocampal brain region. To summarize, the results of this study indicate that IF may mitigate inflammation in the hippocampal area of the brain. Furthermore, IF appears to provide a safeguard against cognitive impairment and synaptic plasticity impairment brought on by sevoflurane anesthesia.

Health Benefits of Intermittent Fasting

We propose that intermittent fasting (time-restricted eating), in agreement with the conclusions of other biologists, as revealed in recent publications, promotes the achievement of numerous health benefits including the extension of human and animal lifespans. Background: There is evidence, obtained both with animal model systems and with humans, that intermittent fasting has health benefits. These benefits include extended longevity, weight loss, and counteracting various disease conditions. Such procedures positively influence the benefits of human tissue-specific microbiomes and minimize the consequences of organellar apoptosis. Key Messages: In this review, we attempt to summarize the predominant evidence, published in the scientific literature, relevant to the conclusions that in general, and in many specific instances, intermittent fasting has long-term benefits to animals, including humans, with respect to overall and specific organismal health and longevity.

Association between serum magnesium levels and cognitive function in patients undergoing hemodialysis

BACKGROUND

The relationship between chronic kidney disease-mineral and bone disorder (CKD-MBD) and cognitive function remains largely unknown. This cross-sectional study aimed to explore the association between CKD-MBD and cognitive function in patients on hemodialysis.

METHODS

Hemodialysis patients aged ≥ 65 years without diagnosed dementia were included. Cognitive function was assessed using the Montreal Cognitive Assessment (MoCA) and Mini-Mental State Examination (MMSE). CKD-MBD markers, serum magnesium, intact parathyroid hormone (PTH), 25-hydroxyvitamin D (25-OHD), fibroblast growth factor (FGF)-23, and soluble α-klotho were measured.

RESULTS

Overall, 390 patients with a median age of 74 (interquartile range, 70-80) years, mean serum magnesium level of 2.4 ± 0.3 mg/dL, and median MoCA and MMSE scores of 25 (22-26) and 28 (26-29), respectively, were analyzed. MoCA and MMSE scores were significantly higher (preserved cognitive function) in the high-magnesium group than in the low-magnesium group according to the unadjusted linear regression analysis (β coefficient [95% confidence interval (CI)] 1.05 [0.19, 1.92], P = 0.017 for MoCA; 1.2 [0.46, 1.94], P = 0.002 for MMSE) and adjusted multivariate analysis with risk factors for dementia (β coefficient [95% CI] 1.12 [0.22, 2.02], P = 0.015 for MoCA; 0.92 [0.19, 1.65], P = 0.014 for MMSE).

CONCLUSIONS

Higher serum magnesium levels might be associated with preserved cognitive function in hemodialysis patients. Conversely, significant associations were not observed between cognitive function and intact PTH, 25-OHD, FGF-23, or soluble α-klotho levels.

Intermittent Metabolic Switching and Vascular Cognitive Impairment

Intermittent fasting (IF), a dietary pattern alternating between eating and fasting periods within a 24-hour cycle, has garnered recognition for its potential to enhance both healthspan and lifespan in animal models and humans. It also shows promise in alleviating age-related diseases, including neurodegeneration. Vascular cognitive impairment (VCI) spans a severity range from mild cognitive deficits to severe cognitive deficits and loss of function in vascular dementia. Chronic cerebral hypoperfusion has emerged as a significant contributor to VCI, instigating vascular pathologies such as microbleeds, blood-brain barrier dysfunction, neuronal loss, and white matter lesions. Preclinical studies in rodents strongly suggest that IF has the potential to attenuate pathological mechanisms, including excitotoxicity, oxidative stress, inflammation, and cell death pathways in VCI models. Hence, this supports evaluating IF in clinical trials for both existing and at-risk VCI patients. This review compiles existing data supporting IF's potential in treating VCI-related vascular and neuronal pathologies, emphasizing the mechanisms by which IF may mitigate these issues. Hence providing a comprehensive overview of the available data supporting IF's potential in treating VCI by emphasizing the underlying mechanisms that make IF a promising intervention for VCI.

Mechanisms Underlying Memory Impairment Induced by Fructose

Fructose consumption has increased over the years, especially in adolescents living in urban areas. Growing evidence indicates that daily fructose consumption leads to some pathological conditions, including memory impairment. This review summarizes relevant data describing cognitive deficits after fructose intake and analyzes the underlying neurobiological mechanisms. Preclinical experiments show sex-related deficits in spatial memory; that is, while males exhibit significant imbalances in spatial processing, females seem unaffected by dietary supplementation with fructose. Recognition memory has also been evaluated; however, only female rodents show a significant decline in the novel object recognition test performance. According to mechanistic evidence, fructose intake induces neuroinflammation, mitochondrial dysfunction, and oxidative stress in the short term. Subsequently, these mechanisms can trigger other long-term effects, such as inhibition of neurogenesis, downregulation of trophic factors and receptors, weakening of synaptic plasticity, and long-term potentiation decay. Integrating all these neurobiological mechanisms will help us understand the cellular and molecular processes that trigger the memory impairment induced by fructose.

Lancao decoction alleviates cognitive dysfunction: A new therapeutic drug and its therapeutic mechanism

BACKGROUND

Cognitive dysfunction (CD) is a neurodegenerative disease characterized primarily by the decline of learning and memory abilities. The physiological and pathological mechanisms of CD are very complex, which is mainly related to normal function of the hippocampus. Lancao decoction (LC) is a Chinese medicine formula, which has been used to treat neurodegenerative disorders. However, the potential of LC for the treatment of CD, as well as its underlying mechanisms, is unclear.

PURPOSE

In the study, we aimed to reveal the functional and neuronal mechanisms of LC's treatments for CD in scopolamine-induced mice.

METHODS

Gas chromatography (GC) was used to determine the stability of LC's extraction. CD model was established by the chronic induction of scopolamine (Scop, 1 mg/kg/day) for 1 week. Behavioral tests including morris water maze (MWM) and y-maze were used to evaluate learning and memory abilities of mice after LC's treatments. Immunofluorescence was used to detected the expressions of cFOS, Brdu and Ki67 after LC's treatments. Pharmacological blockade experiments explored the role of α-Amino-3‑hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) in LC's treatments for CD and its relationships with regeneration, activities and differentiation of neurons.

RESULTS

The results showed that LC was capable of improving spatial learning and memory and spontaneous alternating abilities in Scop-induced mice, which was similar to donepezil. LC could increase the number of cFOS positive cells, which was used as a marker of neuronal activity to upregulate by neuronal activities in hippocampus, but donepezil did not. Moreover, LC could strengthen neurogenesis and neuro-differentiation by increasing the number of Brdu and Ki67 positive cells in hippocampal dentate gyrus (DG), meanwhile, donepezil could only enhance the number of Ki67 positive cells. Transient inhibition of AMPAR by NBQX blunted the function of LC's treatment for CD and inhibited the enhanced effect of LC on Scop-induced hippocampal neuronal excitability and neurogenesis in mice.

CONCLUSION

To sum up, our study demonstrated that LC had the function of treating CD by enhancing content of acetylcholine (ACh) to activate AMPAR, which further up-regulated neurogenesis and neuronal differentiation to strengthen neuroactivities in hippocampus.

Nutritional strategies cause memory damage and alter biochemical parameters without causing neuroinflammation

Obesity results from an energy imbalance and has been considered an epidemic due to its increasing rates worldwide. It is classified as a low-grade chronic inflammatory disease and has associated comorbidities. Different nutritional strategies are used for the purpose of weight loss, highlighting low-carbohydrate (LC) diets, ketogenic diets, and intermittent fasting (IF). These strategies can lead to metabolic and behavioral changes as they stimulate different biochemical pathways. Therefore, this study evaluated memory, energy metabolism, neuroinflammation, oxidative stress, and antioxidant defense parameters in mice subjected to an LC diet, ketogenic diet (KD), or IF. Eighty male Swiss mice, 60 days old, were divided into 4 groups: control, LC, KD, or IF. Body weight was measured weekly, and food intake every 48 h. After 15 days of nutritional interventions, the animals were subjected to the behavioral object recognition test and subsequently euthanized. Then, visceral fat was removed and weighed, and the brain was isolated for inflammatory and biochemical analysis. We concluded from this study that the LC and KD strategies could damage memory, IF improves the production of adenosine triphosphate (ATP), and the LC, KD, and IF strategies do not lead to neuroinflammatory damage but present damage at the level of oxidative stress.

The missing hallmark of health: psychosocial adaptation

The eight biological hallmarks of health that we initially postulated (Cell. 2021 Jan 7;184(1):33-63) include features of spatial compartmentalization (integrity of barriers, containment of local perturbations), maintenance of homeostasis over time (recycling & turnover, integration of circuitries, rhythmic oscillations) and an array of adequate responses to stress (homeostatic resilience, hormetic regulation, repair & regeneration). These hallmarks affect all eight somatic strata of the human body (molecules, organelles, cells, supracellular units, organs, organ systems, systemic circuitries and meta-organism). Here we postulate that mental and socioeconomic factors must be added to this 8×8 matrix as an additional hallmark of health ("psychosocial adaptation") and as an additional stratum ("psychosocial interactions"), hence building a 9×9 matrix. Potentially, perturbation of each of the somatic hallmarks and strata affects psychosocial factors and vice versa. Finally, we discuss the (patho)physiological bases of these interactions and their implications for mental health improvement.

Mitochondrial Dysfunction: A Key Player in Brain Aging and Diseases

Mitochondria are thought to have become incorporated within the eukaryotic cell approximately 2 billion years ago and play a role in a variety of cellular processes, such as energy production, calcium buffering and homeostasis, steroid synthesis, cell growth, and apoptosis, as well as inflammation and ROS production. Considering that mitochondria are involved in a multitude of cellular processes, mitochondrial dysfunction has been shown to play a role within several age-related diseases, including cancers, diabetes (type 2), and neurodegenerative diseases, although the underlying mechanisms are not entirely understood. The significant increase in lifespan and increased incidence of age-related diseases over recent decades has confirmed the necessity to understand the mechanisms by which mitochondrial dysfunction impacts the process of aging and age-related diseases. In this review, we will offer a brief overview of mitochondria, along with structure and function of this important organelle. We will then discuss the cause and consequence of mitochondrial dysfunction in the aging process, with a particular focus on its role in inflammation, cognitive decline, and neurodegenerative diseases, such as Huntington's disease, Parkinson's disease, and Alzheimer's disease. We will offer insight into therapies and interventions currently used to preserve or restore mitochondrial functioning during aging and neurodegeneration.

Intermittent fasting disrupts hippocampal-dependent memory and norepinephrine content in aged male and female mice

Intermittent fasting (IMF) is associated with many health benefits in animals and humans. Yet, little is known if an IMF diet affects mood and cognitive processing. We have previously identified that IMF in diet-induced obese males increases norepinephrine and dopamine content in the hypothalamus and increases arcuate neuropeptide Y (NPY) gene expression more than in ad libitum control males. This suggests that IMF may improve cognition through activation of the hindbrain norepinephrine neuronal network and reverse the age-dependent decline in NPY expression. Less is known about the association between anxiety and IMF. Although, in humans, IMF during Ramadan may alleviate anxiety. Here, we address the impact of IMF on anxiety-like behavior using the open field test, hippocampal-dependent memory using the Y-maze and spatial object recognition, and hippocampal-independent memory using novel object recognition in middle-aged male and female (12 mo) and aged male and female (18 mo) mice. Using ELISA, we determined norepinephrine (NE) content in the dorsal hippocampus (DH) and prefrontal cortex (PFC). We also investigated gene expression in the arcuate nucleus (ARC), the lateral hypothalamus (LH), and the locus coeruleus (LC). In IMF-treated females at both ages, we observed an improvement in spatial navigation although an impairment in spatial object orientation. IMF-treated females (12 mo) had a reduction and IMF-treated males (12 mo) displayed an improvement in novel object recognition memory. IMF-treated females (18 mo) exhibited anxiolytic-like behavior and increased locomotion. In the DH, IMF-treated males (12 mo) had a greater amount of NE content and IMF-treated males (18 mo) had a reduction. In the ARC, IMF-treated males (12 mo) exhibited an increase in Agrp and Npy and a decrease in Adr1a. In the ARC, IMF-treated males (18 mo) exhibited an increase in Npy and a decrease in Adr1a; females had a trending decrease in Cart. In the LH at 12 months, IMF-treated males had a decrease in Npy5r, Adr1a, and Adr1b; both males and females had a reduction in Npy1r. In the LH, IMF-treated females (18 mo) had a decrease in Hcrt. In the LC at both ages, mice largely exhibited sex effects. Our findings indicate that IMF produces alterations in mood, cognition, DH NE content, and ARC, LH, and LC gene expression depending on sex and age.

Incidence of microvascular dysfunction is increased in hyperlipidemic mice, reducing cerebral blood flow and impairing remote memory

Introduction

The development of cognitive dysfunction is not necessarily associated with diet-induced obesity. We hypothesized that cognitive dysfunction might require additional vascular damage, for example, in atherosclerotic mice.

Methods

We induced atherosclerosis in male C57BL/6N mice by injecting AAV-PCSK9DY (2x1011 VG) and feeding them a cholesterol-rich Western diet. After 3 months, mice were examined for cognition using Barnes maze procedure and for cerebral blood flow. Cerebral vascular morphology was examined by immunehistology.

Results

In AAV-PCSK9DY-treated mice, plaque burden, plasma cholesterol, and triglycerides are elevated. RNAseq analyses followed by KEGG annotation show increased expression of genes linked to inflammatory processes in the aortas of these mice. In AAV-PCSK9DY-treated mice learning was delayed and long-term memory impaired. Blood flow was reduced in the cingulate cortex (-17%), caudate putamen (-15%), and hippocampus (-10%). Immunohistological studies also show an increased incidence of string vessels and pericytes (CD31/Col IV staining) in the hippocampus accompanied by patchy blood-brain barrier leaks (IgG staining) and increased macrophage infiltrations (CD68 staining).

Discussion

We conclude that the hyperlipidemic PCSK9DY mouse model can serve as an appropriate approach to induce microvascular dysfunction that leads to reduced blood flow in the hippocampus, which could explain the cognitive dysfunction in these mice.

Dietary and Metabolic Approaches for Treating Autism Spectrum Disorders, Affective Disorders and Cognitive Impairment Comorbid with Epilepsy: A Review of Clinical and Preclinical Evidence

Epilepsy often occurs with other neurological disorders, such as autism, affective disorders, and cognitive impairment. Research indicates that many neurological disorders share a common pathophysiology of dysfunctional energy metabolism, neuroinflammation, oxidative stress, and gut dysbiosis. The past decade has witnessed a growing interest in the use of metabolic therapies for these disorders with or without the context of epilepsy. Over one hundred years ago, the high-fat, low-carbohydrate ketogenic diet (KD) was formulated as a treatment for epilepsy. For those who cannot tolerate the KD, other diets have been developed to provide similar seizure control, presumably through similar mechanisms. These include, but are not limited to, the medium-chain triglyceride diet, low glycemic index diet, and calorie restriction. In addition, dietary supplementation with ketone bodies, polyunsaturated fatty acids, or triheptanoin may also be beneficial. The proposed mechanisms through which these diets and supplements work to reduce neuronal hyperexcitability involve normalization of aberrant energy metabolism, dampening of inflammation, promotion of endogenous antioxidants, and reduction of gut dysbiosis. This raises the possibility that these dietary and metabolic therapies may not only exert anti-seizure effects, but also reduce comorbid disorders in people with epilepsy. Here, we explore this possibility and review the clinical and preclinical evidence where available.

The hormesis principle of neuroplasticity and neuroprotection

Animals live in habitats fraught with a range of environmental challenges to their bodies and brains. Accordingly, cells and organ systems have evolved stress-responsive signaling pathways that enable them to not only withstand environmental challenges but also to prepare for future challenges and function more efficiently. These phylogenetically conserved processes are the foundation of the hormesis principle, in which single or repeated exposures to low levels of environmental challenges improve cellular and organismal fitness and raise the probability of survival. Hormetic principles have been most intensively studied in physical exercise but apply to numerous other challenges known to improve human health (e.g., intermittent fasting, cognitive stimulation, and dietary phytochemicals). Here we review the physiological mechanisms underlying hormesis-based neuroplasticity and neuroprotection. Approaching natural resilience from the lens of hormesis may reveal novel methods for optimizing brain function and lowering the burden of neurological disorders.

Acute fasting modulates autonomic nervous system function and ambulatory cardiac interoception

Intermittent fasting has been associated with diverse physical and psychological health benefits. According to previous research, fasting-induced alterations in psychophysiological functioning should facilitate the accurate detection of an internal bodily signal (like the heart), which is referred to as interoceptive accuracy. In two within-subjects studies we aimed to examine whether an intermittent fasting protocol (i) evokes distinct autonomic nervous system changes in the laboratory and (ii) improves (objectifiable) interoceptive accuracy and sensibility (i.e., the subjective belief in perceiving bodily signals) in everyday life. Study 1 (N = 36) found increasing heart rate variability (precisely, the root mean square of successive differences; RMSSD) accompanied by a more vascular than myocardial response following a 16 h fast. Study 2 (N = 40) applied an ecological momentary assessment design including intermittent fasting (8 h normal eating followed by 16 h fasting) and normal eating (24 h normal eating) for three consecutive days each. Findings suggested a tendency toward higher interoceptive accuracy and sensibility during the fasting regimen, which was particularly pronounced in individuals exhibiting lower RMSSD. Together, findings suggest that (short-term) fasting seems to facilitate momentary attention to organismic cues due to alterations in autonomic nervous system function.

Physical exercise improves memory in sedentary middle-aged adults: Are these exercise-induced benefits associated with S-Klotho and 1,25-dihydroxivitamin D? The FIT-AGEING randomized controlled trial

We aimed to investigate the effect of three types of exercise interventions on memory (i.e., immediate memory (IM), long-term memory (LTM), and recognition). We also investigated whether exercise-induced changes in circulating S-Klotho and 1,25-dihydroxivitamin D (1,25(OH)2 D) levels were related to those observed in memory in healthy middle-aged sedentary adults. A 12-week randomized controlled trial was performed with a parallel-group design. Seventy-four participants (45-65 years old: 53% women) were randomly assigned to (1) no exercise (control) group, (2) concurrent training based on the international physical activity recommendations (PAR) group, (3) high-intensity interval training (HIIT) group, or (4) HIIT plus whole-body electromyostimulation (HIIT-EMS) group. Memory outcomes were assessed using the Wechsler Memory Scale-third edition. S-Klotho plasma levels were determined according to a solid-phase sandwich enzyme-linked immunosorbent assay kit while 1,25(OH)2 D plasma levels were measured using a DiaSorin-Liaison immunochemiluminometric analyzer. IM-Verbal Paired Associates (IM-VPA) and IM-Logical Memory (IM-LM) were improved in both the HIIT and HIIT-EMS groups compared with the control group (all p ≤ 0.045). Exercise-induced changes in S-Klotho plasma levels were positively associated with those observed in IM, LTM, and recognition (all p ≤ 0.007), whereas exercise-induced changes in 1,25(OH)2 D plasma levels were directly related to changes in IM and LTM (all p ≤ 0.048). In conclusion, a 12-week HIIT intervention with or without WB-EMS seems to be the most effective exercise program to improve IM. The significant and positive associations between exercise-induced changes in S-Klotho and 1,25(OH)2 D levels with those observed in memory outcomes suggest that these factors may be potentially related to exercise-induced improvements of memory in middle-aged adults.

Treadmill Exercise Reverses the Adverse Effects of Intermittent Fasting on Behavior and Cortical Spreading Depression in Young Rats

Intermittent fasting (IF) and physical exercise (PE) have beneficial psychological and physiological effects, improving memory and anxiety-like behavior. However, the impact of this combination on brain electrophysiological patterns is unknown. We aimed to evaluate the behavior and parameters of a brain excitability-related phenomenon named cortical spreading depression (CSD) in young rats (31-87 days of life) submitted to IF and treadmill PE for eight weeks. Sixty-four male and female Wistar rats aged 24 days were randomized into control, IF, PE, and IF+PE groups. Behavioral tests (open field (OF), object recognition, and elevated plus maze (EPM)) were performed, and the CSD propagation features were recorded. IF caused behavioral responses indicative of anxiety (lower number of entries and time spent in the OF center and EPM open arms). IF also reduced the discrimination index for object recognition memory tests and increased the propagation velocity of CSD. PE rats displayed more entries into the OF center and lowered CSD propagation speed. Data suggest that IF worsens anxiety-like behavior and memory and accelerates CSD in young rats. In contrast, PE reverted the unfavorable effects of IF. The brain effects of IF and PE at younger ages are recommended for study.

The 5:2 diet does not increase adult hippocampal neurogenesis or enhance spatial memory in mice

New neurones are generated throughout life in the mammalian brain in a process known as adult hippocampal neurogenesis (AHN). Since this phenomenon grants a high degree of neuroplasticity influencing learning and memory, identifying factors that regulate AHN may be important for ameliorating age-related cognitive decline. Calorie restriction (CR) has been shown to enhance AHN and improve memory, mediated by the stomach hormone, ghrelin. Intermittent fasting (IF), a dietary strategy offering more flexibility than conventional CR, has also been shown to promote aspects of AHN. The 5:2 diet is a popular form of IF; however, its effects on AHN are not well characterised. To address this, we quantified AHN in adolescent and adult wild-type and ghrelin-receptor-deficient mice following 6 weeks on a 5:2 diet. We report an age-related decline in neurogenic processes. However, the 5:2 diet does not increase AHN nor enhance memory performance, suggesting that this specific form of IF is ineffective in promoting brain plasticity to support learning.

Adult neural stem cells and neurogenesis are resilient to intermittent fasting

Intermittent fasting (IF) is a promising strategy to counteract ageing shown to increase the number of adult-born neurons in the dentate gyrus of mice. However, it is unclear which steps of the adult neurogenesis process are regulated by IF. The number of adult neural stem cells (NSCs) decreases with age in an activation-dependent manner and, to counteract this loss, adult NSCs are found in a quiescent state which ensures their long-term maintenance. We aimed to determine if and how IF affects adult NSCs in the hippocampus. To identify the effects of every-other-day IF on NSCs and all following steps in the neurogenic lineage, we combined fasting with lineage tracing and label retention assays. We show here that IF does not affect NSC activation or maintenance and, that contrary to previous reports, IF does not increase neurogenesis. The same results are obtained regardless of strain, sex, diet length, tamoxifen administration or new-born neuron identification method. Our data suggest that NSCs maintain homeostasis upon IF and that this intervention is not a reliable strategy to increase adult neurogenesis.

Chronic pain accelerates cognitive impairment by reducing hippocampal neurogenesis may via CCL2/CCR2 signaling in APP/PS1 mice

Patients with chronic pain often have cognitive impairment; this is especially true in elderly patients with neurodegenerative diseases such as Alzheimer's disease (AD), but the mechanism underlying this association remains unclear. This was addressed in the present study by investigating the effect of chronic neuropathic pain on hippocampal neurogenesis and cognitive impairment using amyloid precursor protein/presenilin 1 (APP/PS1) double transgenic mice subjected to spared-nerve injury (SNI). The Von Frey test was performed to determine the mechanical threshold of mouse hind limbs after SNI. The Morris water maze test was used to evaluate spatial learning and memory. Doublecortin-positive (DCX+), 5-bromo-2'-deoxyuridine (BrdU)+, BrdU+/neuronal nuclei (NeuN)+, and C-C motif chemokine ligand 2 (CCL2)+ neurons in the dentate gyrus of the hippocampus were detected by immunohistochemistry and immunofluorescence analysis. CCL2 and C-C chemokine receptor type 2 (CCR2) protein levels in the mouse hippocampus were analyzed by western blotting. The results showed that APP/PS1 mice with chronic neuropathic pain induced by SNI had significant learning and memory impairment. This was accompanied by increased CCL2 and CCR2 expression and decreases in the number of DCX+, BrdU+, and BrdU+/NeuN+ neurons. These results suggest that chronic neuropathic pain is associated with cognitive impairment, which may be caused by CCL2/CCR2 signaling-mediated inhibition of hippocampal neurogenesis. Thus, therapeutic strategies that alleviate neuropathic pain can potentially slow cognitive decline in patients with AD and other neurodegenerative diseases.

Intermittent Fasting as a Potential Therapeutic Instrument for Major Depression Disorder: A Systematic Review of Clinical and Preclinical Studies

Recent studies have reported positive effects of Intermittent Fasting (IF) on metabolic parameters, cognition, and mood. However, regarding depressive symptoms, the effect of IF is not clear. The purpose of this review was to assess the available evidence on IF interventions for depression in both clinical and preclinical studies. Of the 23 included studies, 15 were performed on humans and 8 on animal models. The studies on rodents suggested that IF acts as a circadian regulator, improving neurotransmitter availability and increasing the levels of neurotrophic factors in the brain. However, the investigations on humans mainly evaluated healthy volunteers and showed a great heterogeneity regarding both the IF regimen studied and the observed effects on mood. Most available clinical trials have specific limitations, such as small sample sizes and uncontrolled designs. A comprehensive systematic review was conducted on five databases, PubMed, Cochrane, the Central Register of Controlled Trials, Web of Science databases, BVS and Scopus, identifying 23 relevant studies up to 6 October 2022. IF has potentially relevant physiological effects for the treatment of mood disorders, but better designed studies and controlled evaluations are needed to evaluate its efficiency in the treatment of major depression.

Decreased Hippocampal Neurogenesis in Aged Male Wistar Rats Is Not Associated with Memory Acquisition in a Water Maze

Brain aging is associated with a progressive decrease in learning abilities, memory, attention, decision making, and sensory perception. Age-related cognitive disturbances may be related to a decrease in the functional capacities of the hippocampus. This brain region is essential for learning and memory, and the lifelong neurogenesis occurring in the subgranular zone of the dentate gyrus may be a key event mediating the mnemonic functions of the hippocampus. In the present study, we investigated whether age-related changes in hippocampal neurogenesis are associated with learning and memory disturbances. Four- and 24-month-old rats were trained to find a hidden platform in a water maze. Though the older group showed higher latency to search the platform as compared to the younger group, both groups learned the task. However, the density of proliferating (PCNA-positive), differentiating (Dcx-positive), and new neurons (pre-labeled BrdU-positive) was significantly lower in the hippocampus of aged rats as compared to young ones. This inhibition of neurogenesis could be related to increased local production of nitric oxide since the density of neurons expressing neuronal NO-synthase was higher in the aged hippocampus. Thus, we can suggest that an age-related decrease in neurogenesis is not directly associated with place learning in aged rats.

Neural stem cell self-renewal stimulation by store-operated calcium entries in adult mouse area postrema: influence of leptin

Neural stem cells (NSCs) persist in specific brain germinative niches and sustain neurogenesis throughout life in adult mammals. In addition to the two major stem cell niches in the subventricular zone and the hippocampal dentate gyrus, the area postrema located in the brainstem has been identified as a neurogenic zone as well. NSCs are regulated by signals from the microenvironment that adjust stem cell response to the needs of the organism. Evidence accumulated over the past decade indicates that Ca²⁺ channels play pivotal functions in NSC maintenance. In this study, we explored in area postrema NSCs the presence and roles of a subset of Ca²⁺ channels, the store-operated Ca²⁺ channels (SOCs) that have the capacity to transduce extracellular signals into Ca²⁺ signals. Our data show that NSCs derived from the area postrema express TRPC1 and Orai1, known to form SOCs, as well as their activator STIM1. Ca²⁺ imaging indicated that NSCs exhibit store-operated Ca²⁺ entries (SOCEs). Pharmacological blockade of SOCEs with SKF-96365, YM-58483 (also known as BTP2) or GSK-7975A resulted in decreased NSC proliferation and self-renewal, indicating a major role for SOCs in maintaining NSC activity within the area postrema. Furthermore, our results show that leptin, an adipose tissue-derived hormone whose ability to control energy homeostasis is dependent on the area postrema, decreased SOCEs and reduced self-renewal of NSCs in the area postrema. As aberrant SOC function has been linked to an increasing number of diseases, including brain disorders, our study opens new perspectives for NSCs in brain pathophysiology.

Effects of time-restricted feeding and walking exercise on the physical health of female college students with hidden obesity: a randomized trial

Purpose

Time-restricted feeding (TRF) is an emerging dietary pattern with many potential effects. This study focused on the effects of TRF and walking on the physical health of female college students with hidden obesity.

Methods

A total of 77 female college students with hidden obesity, aged 18-22 years, were randomly assigned to a control group (CON, N = 19), time-restricted feeding group (TRF, N = 19), exercise group (EXE, N = 20), and TRF combined with exercise group (TRF + EXE, N = 19). The interventions lasted for 8 weeks. Tests assessing body shape, body composition, bone mineral density, blood lipid levels, and blood pressure were performed before and after the intervention.

Results

(1) Intragroup comparison before and after the intervention revealed that the TRF, EXE, and TRF + EXE groups had significantly reduced body weight (p < 0.01), body mass index (BMI) (p < 0.05), and lean tissue mass (LTM) (p < 0.01) but increased total cholesterol (TC) levels (p < 0.05) after the intervention. Body fat percentage (BF%) increased considerably in the EXE and TRF + EXE groups (p < 0.01). (2) Post-intervention comparisons of body weight, BMI, LTM, adipose tissue mass (ATM), total bone mineral density (TBMD), blood lipid levels, and blood pressure between the intervention groups (TRF, EXE, and TRF + EXE) and the CON group showed no significant differences (p > 0.05). (3) A comparison of the changes between the groups before and after the intervention showed significant decreases in body weight in the TRF and TRF + EXE groups (p < 0.05) and in both BMI and LTM in the TRF, EXE, and TRF + EXE groups (p < 0.05) compared to those in the CON group. The BF% change in the EXE and TRF + EXE groups were significantly greater than that in the TRF group (p < 0.01).

Conclusion

TRF effectively decreased body weight and BMI in female college students with hidden obesity. However, increased blood lipid levels and decreased LTM levels were also observed. The effects of TRF combined with exercise were not superior to those of TRF or walking alone in terms of body weight, body mass index, body composition, TBMD, or blood lipid levels. Therefore, TRF cannot be considered the best option for fat reduction in female college students with hidden obesity.

The Effects of Extrinsic and Intrinsic Factors on Neurogenesis

In the mammalian brain, neurogenesis is maintained throughout adulthood primarily in two typical niches, the subgranular zone (SGZ) of the dentate gyrus and the subventricular zone (SVZ) of the lateral ventricles and in other nonclassic neurogenic areas (e.g., the amygdala and striatum). During prenatal and early postnatal development, neural stem cells (NSCs) differentiate into neurons and migrate to appropriate areas such as the olfactory bulb where they integrate into existing neural networks; these phenomena constitute the multistep process of neurogenesis. Alterations in any of these processes impair neurogenesis and may even lead to brain dysfunction, including cognitive impairment and neurodegeneration. Here, we first summarize the main properties of mammalian neurogenic niches to describe the cellular and molecular mechanisms of neurogenesis. Accumulating evidence indicates that neurogenesis plays an integral role in neuronal plasticity in the brain and cognition in the postnatal period. Given that neurogenesis can be highly modulated by a number of extrinsic and intrinsic factors, we discuss the impact of extrinsic (e.g., alcohol) and intrinsic (e.g., hormones) modulators on neurogenesis. Additionally, we provide an overview of the contribution of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection to persistent neurological sequelae such as neurodegeneration, neurogenic defects and accelerated neuronal cell death. Together, our review provides a link between extrinsic/intrinsic factors and neurogenesis and explains the possible mechanisms of abnormal neurogenesis underlying neurological disorders.

Metabolic switch in the aging astrocyte supported via integrative approach comprising network and transcriptome analyses

Dysregulated central-energy metabolism is a hallmark of brain aging. Supplying enough energy for neurotransmission relies on the neuron-astrocyte metabolic network. To identify genes contributing to age-associated brain functional decline, we formulated an approach to analyze the metabolic network by integrating flux, network structure and transcriptomic databases of neurotransmission and aging. Our findings support that during brain aging: (1) The astrocyte undergoes a metabolic switch from aerobic glycolysis to oxidative phosphorylation, decreasing lactate supply to the neuron, while the neuron suffers intrinsic energetic deficit by downregulation of Krebs cycle genes, including mdh1 and mdh2 (Malate-Aspartate Shuttle); (2) Branched-chain amino acid degradation genes were downregulated, identifying dld as a central regulator; (3) Ketone body synthesis increases in the neuron, while the astrocyte increases their utilization, in line with neuronal energy deficit in favor of astrocytes. We identified candidates for preclinical studies targeting energy metabolism to prevent age-associated cognitive decline.

Fasting: From Physiology to Pathology

Overnutrition is a risk factor for various human diseases, including neurodegenerative diseases, metabolic disorders, and cancers. Therefore, targeting overnutrition represents a simple but attractive strategy for the treatment of these increasing public health threats. Fasting as a dietary intervention for combating overnutrition has been extensively studied. Fasting has been practiced for millennia, but only recently have its roles in the molecular clock, gut microbiome, and tissue homeostasis and function emerged. Fasting can slow aging in most species and protect against various human diseases, including neurodegenerative diseases, metabolic disorders, and cancers. These centuried and unfading adventures and explorations suggest that fasting has the potential to delay aging and help prevent and treat diseases while minimizing side effects caused by chronic dietary interventions. In this review, recent animal and human studies concerning the role and underlying mechanism of fasting in physiology and pathology are summarized, the therapeutic potential of fasting is highlighted, and the combination of pharmacological intervention and fasting is discussed as a new treatment regimen for human diseases.

Influence of anti-obesity strategies on brain function in health and review: A review

The aim of this review was to investigate in the literature the application of strategies such as low carbohydrate diet (LCD), ketogenic diet (KD) and intermittent fasting (IF) and their effects on the CNS. We performed a narrative review of the literature. The search was specifically carried out in PubMed, selecting articles in English, which had the following keywords: obesity, central nervous system, low carb diet, ketogenic diet and intermittent fasting, using the narrative review methodology. The studies found show that the benefits of the LCD, KD and IF strategies, at the CNS level, have a strong influence on the mechanisms of hunger and satiety, as well as on the reduction of food reward and show improvement in memory and mood influenced by the interventions.

Memory, Sleep, and Tau Function

Memory consolidation related to the hippocampal-cortex connection takes place during sleep. This connection may involve at least two steps- one in the NREM phase of sleep (transmission) and the other in the REM phase (consolidation). In this brief report, we comment on the role of tau protein in these two phases of sleep. The absence of tau decreases δ waves in NREM, whereas the overexpression of modified (phosphorylated and/or mutated) tau alters θ waves in REM.

Nutrition and adult neurogenesis in the hippocampus: Does what you eat help you remember?

Neurogenesis is a complex process by which neural progenitor cells (NPCs)/neural stem cells (NSCs) proliferate and differentiate into new neurons and other brain cells. In adulthood, the hippocampus is one of the areas with more neurogenesis activity, which is involved in the modulation of both emotional and cognitive hippocampal functions. This complex process is affected by many intrinsic and extrinsic factors, including nutrition. In this regard, preclinical studies performed in rats and mice demonstrate that high fats and/or sugars diets have a negative effect on adult hippocampal neurogenesis (AHN). In contrast, diets enriched with bioactive compounds, such as polyunsaturated fatty acids and polyphenols, as well as intermittent fasting or caloric restriction, can induce AHN. Interestingly, there is also growing evidence demonstrating that offspring AHN can be affected by maternal nutrition in the perinatal period. Therefore, nutritional interventions from early stages and throughout life are a promising perspective to alleviate neurodegenerative diseases by stimulating neurogenesis. The underlying mechanisms by which nutrients and dietary factors affect AHN are still being studied. Interestingly, recent evidence suggests that additional peripheral mediators may be involved. In this sense, the microbiota-gut-brain axis mediates bidirectional communication between the gut and the brain and could act as a link between nutritional factors and AHN. The aim of this mini-review is to summarize, the most recent findings related to the influence of nutrition and diet in the modulation of AHN. The importance of maternal nutrition in the AHN of the offspring and the role of the microbiota-gut-brain axis in the nutrition-neurogenesis relationship have also been included.

Low-Carbohydrate and High-Protein Diet Suppresses Working Memory Function in Healthy Mice

Low-carbohydrate and high-protein (LC-HP) diets are acceptable for improving physiological and metabolic parameters. However, the effects of LC-HP diets on the brain are unclear, which depend on glycometabolism for neuronal activity. Since astrocyte-neuron lactate shuttle (ANLS) is an essential pathway for maintaining brain functions, we investigated the changes in hippocampal memory function. In addition, the alteration of lactate transporter constituting ANLS and ANLS-related neurotrophic factors by feeding LC-HP diets was evaluated in healthy mice. C57BL/6 mice were divided into two groups: a group feeding LC-HP diet (24.6% carbohydrate, 57.6% protein, and 17.8% fat as percentages of calories) and a group feeding control diet (58.6% carbohydrate, 24.2% protein, and 17.2% fat as percentages of calories). Here, we found that 4 wk of LC-HP diet feeding suppressed memory function in mice evaluated by Y-maze. Hippocampal mRNA levels of lactate transporters, such as Mct1, Mct4, and Mct2, were unchanged with feeding LC-HP diets; however, LC-HP diets significantly decreased Dcx and Igf-1 receptor mRNA levels in the hippocampus. Bdnf and its related signaling in mice hippocampus exhibited no change by LC-HP diets. Although there was non-influence in the lactate-transport system, LC-HP diets would suppress hippocampal working memory with dysregulation of neuroplasticity. The current data propose the importance of food choices for maintaining hippocampal health.

Intermittent Fasting Alleviates Risk Markers in a Murine Model of Ulcerative Colitis by Modulating the Gut Microbiome and Metabolome

Clinical trials have demonstrated the health benefits of intermittent fasting (IF). However, the potential mechanism of IF in alleviating dextran sulfate sodium (DSS)-induced colitis is not fully understood. The present study was mainly designed to explore the dynamic changes in the gut microbiota and metabolome after short-term (2 weeks) or long-term (20 weeks) IF and therefore clarify the potential mechanisms by which IF ameliorates DSS-induced colitis in a murine model. Thirty-two C57BL/6 male mice were equally divided into four groups and underwent IF intervention for 2 weeks (SIF group, n = 8), 20 weeks (LIF group, n = 8), or were allowed free access to food for 2 weeks (SAL group, n = 8) or 20 weeks (LAL group, n = 8). The thirty-two C57BL/6 male mice were accepted for the diet intervention of 2 weeks of IF or fed ad libitum. Colitis was induced by drinking 2% DSS for 7 days. Our findings showed that short-term IF prominently elevates the abundance of Bacteroides, Muibaculum and Akkermansia (p < 0.001, p < 0.001, p < 0.001, respectively), and decreased the abundance of Ruminiclostridium (p < 0.05). Long-term IF, however, decreased the abundance of Akkermansia and obviously increased the abundance of Lactobacillus (p < 0.05, p < 0.001, respectively). Metabolites mainly associated with nucleoside, carbohydrate, amino acid, bile acid, fatty acid, polyol, steroid and amine metabolism were identified in the faeces using untargeted GC/MS. In particular, inosine was extremely enriched after short-term IF and long-term IF (p < 0.01, p < 0.01, respectively); butyrate, 2-methyl butyric acid and valeric acid were significantly decreased after short-term IF (p < 0.001, p < 0.001, p < 0.01, respectively); and 2-methyl butyric acid was significantly increased after long-term IF (p < 0.001). The abundance of lithocholic acid (LCA), one of the secondary bile acids, increased significantly after short-term and long-term IF based on UPLC−MS/MS (p < 0.001, p < 0.5, respectively). Of note, IF markedly mitigated DSS-induced acute colitis symptoms and down-regulated pro-inflammatory cytokines IL-1α, IL-6, keratinocyte-derived chemokine (KC) and G-CSF levels in the serum (p < 0.01, p < 0.001, p < 0.05, p < 0.001, respectively). Furthermore, a correlation analysis indicated that the disease activity index (DAI) score and serum levels of IL-1α, IL-6, KC, and G-CSF were negatively correlated with the relative abundance of Akkermansia and the faecal metabolites LCA and inosine. This study confirmed that IF altered microbiota and reprogramed metabolism, which was a promising development in the attempt to prevent DSS-induced colitis. Moreover, our findings provide new insights regarding the correlations among the mucosal barrier dysfunction, metabolome, and microbiome.

Activity-Dependent Induction of Younger Biological Phenotypes

In several mammalian species, including humans, complex stimulation patterns such as cognitive and physical exercise lead to improvements in organ function, organism health and performance, as well as possibly longer lifespans. A framework is introduced here in which activity-dependent transcriptional programs, induced by these environmental stimuli, move somatic cells such as neurons and muscle cells toward a state that resembles younger cells to allow remodeling and adaptation of the organism. This cellular adaptation program targets several process classes that are heavily implicated in aging, such as mitochondrial metabolism, cell-cell communication, and epigenetic information processing, and leads to functional improvements in these areas. The activity-dependent gene program (ADGP) can be seen as a natural, endogenous cellular reprogramming mechanism that provides deep insight into the principles of inducible improvements in cell and organism function and can guide the development of therapeutic approaches for longevity. Here, these ADGPs are analyzed, exemplary critical molecular nexus points such as cAMP response element-binding protein, myocyte enhancer factor 2, serum response factor, and c-Fos are identified, and it is explored how one may leverage them to prevent, attenuate, and reverse human aging-related decline of body function.

Mitochondrial function and nutrient sensing pathways in ageing: enhancing longevity through dietary interventions

Ageing is accompanied by alterations in several biochemical processes, highly influenced by its environment. It is controlled by the interactions at various levels of biological hierarchy. To maintain homeostasis, a number of nutrient sensors respond to the nutritional status of the cell and control its energy metabolism. Mitochondrial physiology is influenced by the energy status of the cell. The alterations in mitochondrial physiology and the network of nutrient sensors result in mitochondrial damage leading to age related metabolic degeneration and diseases. Calorie restriction (CR) has proved to be as the most successful intervention to achieve the goal of longevity and healthspan. CR elicits a hormetic response and regulates metabolism by modulating these networks. In this review, the authors summarize the interdependent relationship between mitochondrial physiology and nutrient sensors during the ageing process and their role in regulating metabolism.

Time-restricted feeding and cognitive function in sedentary and physically active elderly individuals: Ramadan diurnal intermittent fasting as a model

Objectives

This study aimed to investigate the effects of Ramadan diurnal intermittent fasting (RDIF) on cognitive performance, sleep quality, daytime sleepiness, and insomnia in physically active and sedentary elderly individuals.

Methods

A total of 58 participants (62.93 ± 3.99 years) were assigned to one of the following two groups: a sedentary group (control group) who observed Ramadan (n = 32) and a physically active group (n = 26) who continued to train while observing Ramadan. Participants were assessed 2 weeks before Ramadan and during the fourth week of Ramadan. On each occasion, participants completed a digital assessment of their cognitive performance and responded to the Pittsburgh sleep quality index (PSQI), the insomnia severity index (ISI) and the Epworth sleepiness scale (ESS) questionnaires to assess sleep parameters.

Results

Compared to before Ramadan, performance in executive function (p = 0.035), attention (p = 0.005), inhibition (p = 0.02), associative memory (p = 0.041), and recognition memory (p = 0.025) increased significantly during Ramadan in the physically active group. For the sedentary group, associative learning performance decreased (p = 0.041), whilst performances in the remaining domains remained unchanged during Ramadan. Global PSQI, ISI, and ESS scores indicated both groups suffered from poor sleep quality and excessive daytime sleepiness, with significantly higher negative effects of RDIF observed in the sedentary group.

Conclusion

Older adults who continue to train at least three times per week during Ramadan may improve their cognitive performance, despite the impairment of sleep quality. Future studies in older adults during Ramadan including objective measures of sleep (e.g., polysomnography, actigraphy) and brain function (e.g., functional magnetic resonance imaging) are warranted.

Intermittent fasting protects against Alzheimer's disease in mice by altering metabolism through remodeling of the gut microbiota

Alzheimer's disease (AD) is the most common form of dementia without effective clinical treatment. Here, we show that intermittent fasting (IF) improves cognitive functions and AD-like pathology in a transgenic AD mouse model (5XFAD). IF alters gut microbial composition with a significant enrichment in probiotics such as Lactobacillus. The changes in the composition of the gut microbiota affect metabolic activities and metabolite production. Metabolomic profiling analysis of cecal contents revealed IF leads to a decreased carbohydrate metabolism (for example, glucose) and an increased abundance in amino acids (for example, sarcosine and dimethylglycine). Interestingly, we found that the administration of IF-elevated sarcosine or dimethylglycine mimics the protective effects of IF in 5XFAD mice, including the amelioration of cognitive decline, amyloid-β (Aβ) burden and glial overactivation. Our findings thus demonstrate an IF regimen is a potential approach to prevent AD progression, at least through the gut-microbiota-metabolites-brain axis, and constitutes an innovative AD therapeutic avenue.

A Bibliometric and Visualization Analysis of Intermittent Fasting

CiteSpace software was utilized to visually analyze the literature on intermittent fasting from Web of Science from 2000 to 2020 in order to reveal the current status, research hotspots and emerging trends of intermittent fasting. The results show that: (1) intermittent fasting research results are increasing year by year; (2) the United States is at the core of this field and has a high influence; (3) intermittent fasting research is mainly concentrated in the fields of nutrition, cell biology and kinesiology, which embodies interdisciplinary characteristics; (4) the literature of Sutton, Mattson and Trepanowski that were published in the same period have the highest co-citation frequencies, however, their research perspectives are quite different, reflecting that the research in this field is still in a state of continuous development; (5) from the perspective of citation bursts, the evolution of research hotspots in this field in the last 20 years can be divided into 3 stages; (6) the keyword timeline mapping shows that time restricted feeding is at the forefront of this research field. This study can help researchers explore the field for the first time to quickly grasp the frontiers and obtain more valuable data, thereby providing facilitation for the follow-up research.

Pathobiology of the Klotho Antiaging Protein and Therapeutic Considerations

The α-Klotho protein (henceforth denoted Klotho) has antiaging properties, as first observed in mice homozygous for a hypomorphic Klotho gene (kl/kl). These mice have a shortened lifespan, stunted growth, renal disease, hyperphosphatemia, hypercalcemia, vascular calcification, cardiac hypertrophy, hypertension, pulmonary disease, cognitive impairment, multi-organ atrophy and fibrosis. Overexpression of Klotho has opposite effects, extending lifespan. In humans, Klotho levels decline with age, chronic kidney disease, diabetes, Alzheimer’s disease and other conditions. Low Klotho levels correlate with an increase in the death rate from all causes. Klotho acts either as an obligate coreceptor for fibroblast growth factor 23 (FGF23), or as a soluble pleiotropic endocrine hormone (s-Klotho). It is mainly produced in the kidneys, but also in the brain, pancreas and other tissues. On renal tubular-cell membranes, it associates with FGF receptors to bind FGF23. Produced in bones, FGF23 regulates renal excretion of phosphate (phosphaturic effect) and vitamin D metabolism. Lack of Klotho or FGF23 results in hyperphosphatemia and hypervitaminosis D. With age, human renal function often deteriorates, lowering Klotho levels. This appears to promote age-related pathology. Remarkably, Klotho inhibits four pathways that have been linked to aging in various ways: Transforming growth factor β (TGF-β), insulin-like growth factor 1 (IGF-1), Wnt and NF-κB. These can induce cellular senescence, apoptosis, inflammation, immune dysfunction, fibrosis and neoplasia. Furthermore, Klotho increases cell-protective antioxidant enzymes through Nrf2 and FoxO. In accord, preclinical Klotho therapy ameliorated renal, cardiovascular, diabetes-related and neurodegenerative diseases, as well as cancer. s-Klotho protein injection was effective, but requires further investigation. Several drugs enhance circulating Klotho levels, and some cross the blood-brain barrier to potentially act in the brain. In clinical trials, increased Klotho was noted with renin-angiotensin system inhibitors (losartan, valsartan), a statin (fluvastatin), mTOR inhibitors (rapamycin, everolimus), vitamin D and pentoxifylline. In preclinical work, antidiabetic drugs (metformin, GLP-1-based, GABA, PPAR-γ agonists) also enhanced Klotho. Several traditional medicines and/or nutraceuticals increased Klotho in rodents, including astaxanthin, curcumin, ginseng, ligustilide and resveratrol. Notably, exercise and sport activity increased Klotho. This review addresses molecular, physiological and therapeutic aspects of Klotho.

Intermittent Fasting: Potential Utility in the Treatment of Chronic Pain across the Clinical Spectrum

Dietary behavior can have a consequential and wide-ranging influence on human health. Intermittent fasting, which involves intermittent restriction in energy intake, has been shown to have beneficial cellular, physiological, and system-wide effects in animal and human studies. Despite the potential utility in preventing, slowing, and reversing disease processes, the clinical application of intermittent fasting remains limited. The health benefits associated with the simple implementation of a 12 to 16 h fast suggest a promising role in the treatment of chronic pain. A literature review was completed to characterize the physiologic benefits of intermittent fasting and to relate the evidence to the mechanisms underlying chronic pain. Research on different fasting regimens is outlined and an overview of research demonstrating the benefits of intermittent fasting across diverse health conditions is provided. Data on the physiologic effects of intermittent fasting are summarized. The physiology of different pain states is reviewed and the possible implications for intermittent fasting in the treatment of chronic pain through non-invasive management, prehabilitation, and rehabilitation following injury and invasive procedures are presented. Evidence indicates the potential utility of intermittent fasting in the comprehensive management of chronic pain and warrants further investigation.

Intermittent fasting reduces neuroinflammation in intracerebral hemorrhage through the Sirt3/Nrf2/HO-1 pathway

Background

Inflammation contributes to the poor prognosis of intracerebral hemorrhage (ICH). Intermittent fasting (IF) has been shown to be protective against inflammation in multiple pathogenic processes. In the present study, we aimed to investigated the beneficial effects of IF in attenuating neuroinflammation and neurological deficits in a mouse model of ICH and to investigate the underlying mechanism.

Methods

ICH was modeled by intrastriatal injection of autologous blood and IF was modeled by every-other-day feeding in male control mice (C57BL/6), mice with and microglia specific knockout Sirt3^f/f;Cx3cr1-Cre (Sirt3 cKO), and Sirt3^f/f (wild-type) mice. Brain tissues and arterial blood were harvested at 1, 3, 7 and 28 days after ICH for immunohistochemistry analysis of Iba-1, DARPP-32 and HO-1, morphological analysis by HE staining and inflammatory factor release tests by ELISA. Neurological functions were approached by corner test and cylinder test. Fluorescent double-labeled staining of Iba-1 with CD16, Arg1 or Sirt3 was used to provide direct image of co-expression of these molecules in microglia. TUNEL, cleaved caspase-3 and Nissl staining was performed to evaluate cellular injuries.

Results

IF alleviated neurological deficits in both acute and chronic phases after ICH. Morphologically, IF enhanced hematoma clearance, reduced brain edema in acute phase and attenuated striatum atrophy in chronic phase. In addition, IF decreased the numbers of TUNEL⁺ cells and increased Nissl⁺ neuron number at day 1, 3 and 7 after ICH. IF suppressed CD16⁺Iba-1⁺ microglia activation at day 3 after ICH and reduced inflammatory releases, such as IL-1β and TNF-α. The above effects of IF were attenuated by microglia Sirt3 deletion partly because of an inhibition of Nrf2/HO-1 signaling pathway. Interestingly, IF increased Iba-1⁺ microglia number at day 7 which mainly expressed Arg1 while decreased the proinflammatory factor levels. In mice with microglia-specific Sirt3 deletion, the effects of IF on Iba-1⁺ microglia activation and anti-inflammatory factor expressions were attenuated when compared with wild-type Sirt3^f/f mice.

Conclusions

IF protects against ICH by suppressing the inflammatory responses via the Sirt3/Nrf2/HO-1 pathway.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-022-02474-2.

KL1 Domain of Longevity Factor Klotho Mimics the Metabolome of Cognitive Stimulation and Enhances Cognition in Young and Aging Mice

Cognitive deficits are a major biomedical challenge-and engagement of the brain in stimulating tasks improves cognition in aged individuals (Wilson et al., 2002; Gates et al., 2011) and rodents (Aidil-Carvalho et al., 2017), through unknown mechanisms. Whether cognitive stimulation alters specific metabolic pathways in the brain is unknown. Understanding which metabolic processes are involved in cognitive stimulation is important because it could lead to pharmacologic intervention that promotes biological effects of a beneficial behavior, toward the goal of effective medical treatments for cognitive deficits. Here we show using male mice that cognitive stimulation induced metabolic remodeling of the mouse hippocampus, and that pharmacologic treatment with the longevity hormone α-klotho (KL), mediated by its KL1 domain, partially mimicked this alteration. The shared, metabolic signature shared between cognitive stimulation and treatment with KL or KL1 closely correlated with individual mouse cognitive performance, indicating a link between metabolite levels and learning and memory. Importantly, the treatment of mice with KL1, an endogenous circulating factor that more closely mimicked cognitive stimulation than KL, acutely increased synaptic plasticity, a substrate of cognition. KL1 also improved cognition, itself, in young mice and countered deficits in old mice. Our data show that treatments or interventions mimicking the hippocampal metabolome of cognitive stimulation can enhance brain functions. Further, we identify the specific domain by which klotho promotes brain functions, through KL1, a metabolic mimic of cognitive stimulation.SIGNIFICANCE STATEMENT Cognitive deficits are a major biomedical challenge without truly effective pharmacologic treatments. Engaging the brain through cognitive tasks benefits cognition. Mimicking the effects of such beneficial behaviors through pharmacological treatment represents a highly valuable medical approach to treating cognitive deficits. We demonstrate that brain engagement through cognitive stimulation induces metabolic remodeling of the hippocampus that was acutely recapitulated by the longevity factor klotho, mediated by its KL1 domain. Treatment with KL1, a close mimic of cognitive stimulation, enhanced cognition and countered cognitive aging. Our findings shed light on how cognition metabolically alters the brain and provide a plausible therapeutic intervention for mimicking these alterations that, in turn, improves cognition in the young and aging brain.

Insulin and Memory in Invertebrates

Insulin and insulin-like peptides (ILP) help to maintain glucose homeostasis, whereas insulin-like growth factor (IGF) promotes the growth and differentiation of cells in both vertebrates and invertebrates. It is sometimes difficult to distinguish between ILP and IGF in invertebrates, however, because in some cases ILP has the same function as IGF. In the present review, therefore, we refer to these peptides as ILP/IGF signaling (IIS) in invertebrates, and discuss the role of IIS in memory formation after classical conditioning in invertebrates. In the arthropod Drosophila melanogaster, IIS is involved in aversive olfactory memory, and in the nematode Caenorhabditis elegans, IIS controls appetitive/aversive response to NaCl depending on the duration of starvation. In the mollusk Lymnaea stagnalis, IIS has a critical role in conditioned taste aversion. Insulin in mammals is also known to play an important role in cognitive function, and many studies in humans have focused on insulin as a potential treatment for Alzheimer’s disease. Although analyses of tissue and cellular levels have progressed in mammals, the molecular mechanisms, such as transcriptional and translational levels, of IIS function in cognition have been far advanced in studies using invertebrates. We anticipate that the present review will help to pave the way for studying the effects of insulin, ILPs, and IGFs in cognitive function across phyla.

Intermittent fasting and cognitive performance - Targeting BDNF as potential strategy to optimise brain health

Aging is the major risk factor for neurodegenerative diseases, accelerated by excessive calorie consumption and sedentary lifestyles. Bioenergetic challenges such as intermittent fasting (IF) have shown to promote lifespan and healthspan via an adaptive stress response. Activity-dependent brain-derived neurotrophic factor (BDNF) has emerged as key regulator of cognitive performance and brain health. This review aims to investigate the pathophysiological mechanisms linking IF and cognitive function with a focus on the role of BDNF, evaluating evidence from pre-clinical and human studies. A systematic literature search was performed. 82 peer-reviewed papers were accepted, critically appraised and summarised in a narrative analysis. Aging-related loss of BDNF has been associated with reduced synaptic plasticity, memory and learning as well as increased risk of cognitive impairment and Alzheimer's disease. IF was consistently reported to upregulate BDNF and improve cognitive performance in animal models. Further research is required to assess cognitive outcomes of IF in humans.

Could a Different View of Quiescence Help Us Understand How Neurogenesis Is Regulated?

The majority of adult neural stem cells (aNSCs) are in a distinct metabolic state of reversible cell cycle exit also known as quiescence. The rate of aNSC activation determines the number of new neurons generated and directly influences the long-term maintenance of neurogenesis. Despite its relevance, it is still unclear how aNSC quiescence is regulated. Many factors contribute to this, like aNSC heterogeneity, the lack of reliable quiescence markers, the complexity of the neurogenic niches or the intricacy of the transcriptional and post-transcriptional mechanisms involved. In this perspective article I discuss possible solutions to these problems. But, first and foremost, I believe we require a model that goes beyond a simple transition toward activation. Instead, we must acknowledge the full complexity of aNSC states, which include not only activation but also differentiation and survival as behavioural outcomes. I propose a model where aNSCs dynamically transition through a cloud of highly interlinked cellular states driven by intrinsic and extrinsic cues. I also show how a new perspective enables us to integrate current results into a coherent framework leading to the formulation of new testable hypothesis. This model, like all others, is still far from perfect and will be reshaped by future findings. I believe that having a more complete view of aNSC transitions and embracing their complexity will bring us closer to understand how aNSC activity and neurogenesis are controlled throughout life.

Klotho an Autophagy Stimulator as a Potential Therapeutic Target for Alzheimer’s Disease: A Review

Alzheimer’s disease (AD) is an age-associated neurodegenerative disease; it is the most common cause of senile dementia. Klotho, a single-pass transmembrane protein primarily generated in the brain and kidney, is active in a variety of metabolic pathways involved in controlling neurodegeneration and ageing. Recently, many studies have found that the upregulation of Klotho can improve pathological cognitive deficits in an AD mice model and have demonstrated that Klotho plays a role in the induction of autophagy, a major contributing factor for AD. Despite the close association between Klotho and neurodegenerative diseases, such as AD, the underlying mechanism by which Klotho contributes to AD remains poorly understood. In this paper, we will introduce the expression, location and structure of Klotho and its biological functions. Specifically, this review is devoted to the correlation of Klotho protein and the AD phenotype, such as the effect of Klotho in upregulating the amyloid-beta clearance and in inducing autophagy for the clearance of toxic proteins, by regulating the autophagy lysosomal pathway (ALP). In summary, the results of multiple studies point out that targeting Klotho would be a potential therapeutic strategy in AD treatment.

Ghrelin Acylation-A Post-Translational Tuning Mechanism Regulating Adult Hippocampal Neurogenesis

Adult hippocampal neurogenesis—the generation of new functional neurones in the adult brain—is impaired in aging and many neurodegenerative disorders. We recently showed that the acylated version of the gut hormone ghrelin (acyl-ghrelin) stimulates adult hippocampal neurogenesis while the unacylated form of ghrelin inhibits it, thus demonstrating a previously unknown function of unacyl-ghrelin in modulating hippocampal plasticity. Analysis of plasma samples from Parkinson’s disease patients with dementia demonstrated a reduced acyl-ghrelin:unacyl-ghrelin ratio compared to both healthy controls and cognitively intact Parkinson’s disease patients. These data, from mouse and human studies, suggest that restoring acyl-ghrelin signalling may promote the activation of pathways to support memory function. In this short review, we discuss the evidence for ghrelin’s role in regulating adult hippocampal neurogenesis and the enzymes involved in ghrelin acylation and de-acylation as targets to treat mood-related disorders and dementia.

Genes and Longevity of Lifespan

Aging is a complex process indicated by low energy levels, declined physiological activity, stress induced loss of homeostasis leading to the risk of diseases and mortality. Recent developments in medical sciences and an increased availability of nutritional requirements has significantly increased the average human lifespan worldwide. Several environmental and physiological factors contribute to the aging process. However, about 40% human life expectancy is inherited among generations, many lifespan associated genes, genetic mechanisms and pathways have been demonstrated during last decades. In the present review, we have evaluated many human genes and their non-human orthologs established for their role in the regulation of lifespan. The study has included more than fifty genes reported in the literature for their contributions to the longevity of life. Intact genomic DNA is essential for the life activities at the level of cell, tissue, and organ. Nucleic acids are vulnerable to oxidative stress, chemotherapies, and exposure to radiations. Efficient DNA repair mechanisms are essential for the maintenance of genomic integrity, damaged DNA is not replicated and transferred to next generations rather the presence of deleterious DNA initiates signaling cascades leading to the cell cycle arrest or apoptosis. DNA modifications, DNA methylation, histone methylation, histone acetylation and DNA damage can eventually lead towards apoptosis. The importance of calorie restriction therapy in the extension of lifespan has also been discussed. The role of pathways involved in the regulation of lifespan such as DAF-16/FOXO (forkhead box protein O1), TOR and JNK pathways has also been particularized. The study provides an updated account of genetic factors associated with the extended lifespan and their interactive contributory role with cellular pathways.

Klotho as Potential Autophagy Regulator and Therapeutic Target

The protein Klotho can significantly delay aging, so it has attracted widespread attention. Abnormal downregulation of Klotho has been detected in several aging-related diseases, such as Alzheimer’s disease, kidney injury, cancer, chronic obstructive pulmonary disease (COPD), vascular disease, muscular dystrophy and diabetes. Conversely, many exogenous and endogenous factors, several drugs, lifestyle changes and genetic manipulations were reported to exert therapeutic effects through increasing Klotho expression. In recent years, Klotho has been identified as a potential autophagy regulator. How Klotho may contribute to reversing the effects of aging and disease became clearer when it was linked to autophagy, the process in which eukaryotic cells clear away dysfunctional proteins and damaged organelles: the abovementioned diseases involve abnormal autophagy. Interestingly, growing evidence indicates that Klotho plays a dual role as inducer or inhibitor of autophagy in different physiological or pathological conditions through its influence on IGF-1/PI3K/Akt/mTOR signaling pathway, Beclin 1 expression and activity, as well as aldosterone level, which can help restore autophagy to beneficial levels. The present review examines the role of Klotho in regulating autophagy in Alzheimer’s disease, kidney injury, cancer, COPD, vascular disease, muscular dystrophy and diabetes. Targeting Klotho may provide a new perspective for preventing and treating aging-related diseases.

Disentangling Mitochondria in Alzheimer's Disease

Alzheimer's disease (AD) is a major cause of dementia in older adults and is fast becoming a major societal and economic burden due to an increase in life expectancy. Age seems to be the major factor driving AD, and currently, only symptomatic treatments are available. AD has a complex etiology, although mitochondrial dysfunction, oxidative stress, inflammation, and metabolic abnormalities have been widely and deeply investigated as plausible mechanisms for its neuropathology. Aβ plaques and hyperphosphorylated tau aggregates, along with cognitive deficits and behavioral problems, are the hallmarks of the disease. Restoration of mitochondrial bioenergetics, prevention of oxidative stress, and diet and exercise seem to be effective in reducing Aβ and in ameliorating learning and memory problems. Many mitochondria-targeted antioxidants have been tested in AD and are currently in development. However, larger streamlined clinical studies are needed to provide hard evidence of benefits in AD. This review discusses the causative factors, as well as potential therapeutics employed in the treatment of AD.