BDNF and exercise enhance neuronal DNA repair by stimulating CREB-mediated production of apurinic/apyrimidinic endonuclease 1

SuperAgers and centenarians, dynamics of healthy ageing with cognitive resilience

Graceful healthy ageing and extended longevity is the most desired goal for human race. The process of ageing is inevitable and has a profound impact on the gradual deterioration of our physiology and health since it triggers the onset of many chronic conditions like dementia, osteoporosis, diabetes, arthritis, cancer, and cardiovascular disease. However, some people who lived/live more than 100 years called 'Centenarians" and how do they achieve their extended lifespans are not completely understood. Studying these unknown factors of longevity is important not only to establish a longer human lifespan but also to manage and treat people with shortened lifespans suffering from age-related morbidities. Furthermore, older adults who maintain strong cognitive function are referred to as "SuperAgers" and may be resistant to risk factors linked to cognitive decline. Investigating the mechanisms underlying their cognitive resilience may contribute to the development of therapeutic strategies that support the preservation of cognitive function as people age. The key to a long, physically, and cognitively healthy life has been a mystery to scientists for ages. Developments in the medical sciences helps us to a better understanding of human physiological function and greater access to medical care has led us to an increase in life expectancy. Moreover, inheriting favorable genetic traits and adopting a healthy lifestyle play pivotal roles in promoting longer and healthier lives. Engaging in regular physical activity, maintaining a balanced diet, and avoiding harmful habits such as smoking contribute to overall well-being. The synergy between positive lifestyle choices, access to education, socio-economic factors, environmental determinants and genetic supremacy enhances the potential for a longer and healthier life. Our article aims to examine the factors associated with healthy ageing, particularly focusing on cognitive health in centenarians. We will also be discussing different aspects of ageing including genomic instability, metabolic burden, oxidative stress and inflammation, mitochondrial dysfunction, cellular senescence, immunosenescence, and sarcopenia.

Effects of Physical Exercise and Motor Activity on Depression and Anxiety in Post-Mastectomy Pain Syndrome

BACKGROUND

Chronic post-surgical pain is a condition persisting for not less than 3 months after surgical intervention. It is evaluated that 25-60% of women who underwent breast cancer excision suffer from post-mastectomy pain syndrome, and anxiety, depression, sleep disturbance, and catastrophizing. Physical activity can reduce the risk of chronic diseases and has a good impact on mood and cognitive function. The aim of this study was to estimate the influence of physical activity on the intensity of pain, depression, and anxiety in women who underwent mastectomy for breast cancer removal.

METHODS

A prospective observational unicentric cohort study was performed. Patients were females who underwent unilateral or bilateral mastectomy. The Numerical Rating Scale (NRS) was used to measure pain intensity, Beck's Depression Inventory (BDI) for depression, and Generalized Anxiety Disorders-7 (GAD-7) for anxiety evaluation. Physical activity was assessed by the International Physical Activity Questionnaire (IPAQ). Interleukin (IL)-17, IL-1β, cortisol, adrenocorticotropic hormone (ACTH), and brain-derived neurotrophic factor (BDNF) were also evaluated in the blood of patients. All evaluations were assessed 3 and 6 months after the surgery.

RESULTS

Adequate physical activity reduced the intensity of pain, depression, and anxiety symptoms in women affected by post-mastectomy pain syndrome. Moreover, adequately active women showed a reduction in biomarkers of inflammation, cortisol, ACTH, and an increase of BDNF.

CONCLUSIONS

Our results suggest that physical activity can improve the quality of life, reduce the intensity of pain and inflammatory markers, and be useful in the reduction of associated anxiety and depression.

Physical Exercise as an Intervention for Depression: Evidence for Efficacy and Mu-Opioid Receptors as a Mechanism of Action

Physical exercise is often cited as an important part of an intervention for depression, and there is empirical evidence to support this. However, the mechanism of action through which any potential antidepressant effects are produced is not widely understood. Recent evidence points toward the involvement of endogenous opioids, and especially the mu-opioid system, as a partial mediator of these effects. In this chapter, we discuss the current level of empirical support for physical exercise as either an adjunctive or standalone intervention for depression. We then review the extant evidence for involvement of endogenous opioids in the proposed antidepressant effects of exercise, with a focus specifically on evidence for mu-opioid system involvement.

Does activation of oxytocinergic reward circuits postpone the decline of the aging brain?

Oxytocin supports reproduction by promoting sexual- and nursing behavior. Moreover, it stimulates reproductive organs by different avenues. Oxytocin is released to the blood from terminals of oxytocinergic neurons which project from the hypothalamus to the pituitary gland. Concomitantly, the dendrites of these neurons discharge oxytocin into neighboring areas of the hypothalamus. At this location it affects other neuroendocrine systems by autocrine and paracrine mechanisms. Moreover, sensory processing, affective functions, and reward circuits are influenced by oxytocinergic neurons that reach different sites in the brain. In addition to its facilitating impact on various aspects of reproduction, oxytocin is revealed to possess significant anti-inflammatory, restoring, and tranquilizing properties. This has been demonstrated both in many in-vivo and in-vitro studies. The oxytocin system may therefore have the capacity to alleviate detrimental physiological- and mental stress reactions. Thus, high levels of endogenous oxytocin may counteract inadequate inflammation and malfunctioning of neurons and supportive cells in the brain. A persistent low-grade inflammation increasing with age-referred to as inflammaging-may lead to a cognitive decline but may also predispose to neurodegenerative diseases such as Alzheimer's and Parkinson. Interestingly, animal studies indicate that age-related destructive processes in the body can be postponed by techniques that preserve immune- and stem cell functions in the hypothalamus. It is argued in this article that sexual activity-by its stimulating impact on the oxytocinergic activity in many regions of the brain-has the capacity to delay the onset of age-related cerebral decay. This may also postpone frailty and age-associated diseases in the body. Finally, oxytocin possesses neuroplastic properties that may be applied to expand sexual reward. The release of oxytocin may therefore be further potentiated by learning processes that involves oxytocin itself. It may therefore be profitable to raise the consciousness about the potential health benefits of sexual activity particularly among the seniors.

Irisin/BDNF signaling in the muscle-brain axis and circadian system: A review

In mammals, the timing of physiological, biochemical and behavioral processes over a 24-h period is controlled by circadian rhythms. To entrain the master clock located in the suprachiasmatic nucleus of the hypothalamus to a precise 24-h rhythm, environmental zeitgebers are used by the circadian system. This is done primarily by signals from the retina via the retinohypothalamic tract, but other cues like exercise, feeding, temperature, anxiety, and social events have also been shown to act as non-photic zeitgebers. The recently identified myokine irisin is proposed to serve as an entraining non-photic signal of exercise. Irisin is a product of cleavage and modification from its precursor membrane fibronectin type Ⅲ domain-containing protein 5 (FNDC5) in response to exercise. Apart from well-known peripheral effects, such as inducing the "browning" of white adipocytes, irisin can penetrate the blood-brain barrier and display the effects on the brain. Experimental data suggest that FNDC5/irisin mediates the positive effects of physical activity on brain functions. In several brain areas, irisin induces the production of brain-derived neurotrophic factor (BDNF). In the master clock, a significant role in gating photic stimuli in the retinohypothalamic synapse for BDNF is suggested. However, the brain receptor for irisin remains unknown. In the current review, the interactions of physical activity and the irisin/BDNF axis with the circadian system are reconceptualized.

Lycium barbarum glycopeptide alleviates neuroinflammation in spinal cord injury via modulating docosahexaenoic acid to inhibiting MAPKs/NF-kB and pyroptosis pathways

BACKGROUND

Lycium barbarum polysaccharide (LBP) is an active ingredient extracted from Lycium barbarum that inhibits neuroinflammation, and Lycium barbarum glycopeptide (LbGp) is a glycoprotein with immunological activity that was purified and isolated from LBP. Previous studies have shown that LbGp can regulate the immune microenvironment, but its specific mechanism of action remains unclear.

AIMS

In this study, we aimed to explore the mechanism of action of LbGp in the treatment of spinal cord injury through metabolomics and molecular experiments.

METHODS

SD male rats were randomly assigned to three experimental groups, and after establishing the spinal cord hemisection model, LbGp was administered orally. Spinal cord tissue was sampled on the seventh day after surgery for molecular and metabolomic experiments. In vitro, LbGp was administered to mimic the inflammatory microenvironment by activating microglia, and its mechanism of action in suppressing neuroinflammation was further elaborated using metabolomics and molecular biology techniques such as western blotting and q-PCR.

RESULTS

In vivo and in vitro experiments found that LbGp can improve the inflammatory microenvironment by inhibiting the NF-kB and pyroptosis pathways. Furthermore, LbGp induced the secretion of docosahexaenoic acid (DHA) by microglia, and DHA inhibited neuroinflammation through the MAPK/NF-κB and pyroptosis pathways.

CONCLUSIONS

In summary, we hypothesize that LbGp improves the inflammatory microenvironment by regulating the secretion of DHA by microglia and thereby inhibiting the MAPK/NF-κB and pyroptosis pathways and promoting nerve repair and motor function recovery. This study provides a new direction for the treatment of spinal cord injury and elucidates the potential mechanism of action of LbGp.

Optogenetic spinal stimulation promotes new axonal growth and skilled forelimb recovery in rats with sub-chronic cervical spinal cord injury

Objective.Spinal cord injury (SCI) leads to debilitating sensorimotor deficits that greatly limit quality of life. This work aims to develop a mechanistic understanding of how to best promote functional recovery following SCI. Electrical spinal stimulation is one promising approach that is effective in both animal models and humans with SCI. Optogenetic stimulation is an alternative method of stimulating the spinal cord that allows for cell-type-specific stimulation. The present work investigates the effects of preferentially stimulating neurons within the spinal cord and not glial cells, termed 'neuron-specific' optogenetic spinal stimulation. We examined forelimb recovery, axonal growth, and vasculature after optogenetic or sham stimulation in rats with cervical SCI.Approach.Adult female rats received a moderate cervical hemicontusion followed by the injection of a neuron-specific optogenetic viral vector ipsilateral and caudal to the lesion site. Animals then began rehabilitation on the skilled forelimb reaching task. At four weeks post-injury, rats received a micro-light emitting diode (µLED) implant to optogenetically stimulate the caudal spinal cord. Stimulation began at six weeks post-injury and occurred in conjunction with activities to promote use of the forelimbs. Following six weeks of stimulation, rats were perfused, and tissue stained for GAP-43, laminin, Nissl bodies and myelin. Location of viral transduction and transduced cell types were also assessed.Main Results.Our results demonstrate that neuron-specific optogenetic spinal stimulation significantly enhances recovery of skilled forelimb reaching. We also found significantly more GAP-43 and laminin labeling in the optogenetically stimulated groups indicating stimulation promotes axonal growth and angiogenesis.Significance.These findings indicate that optogenetic stimulation is a robust neuromodulator that could enable future therapies and investigations into the role of specific cell types, pathways, and neuronal populations in supporting recovery after SCI.

The role of aging and brain-derived neurotrophic factor signaling in expression of base excision repair genes in the human brain

DNA damage is a central contributor to the aging process. In the brain, a major threat to the DNA is the considerable amount of reactive oxygen species produced, which can inflict oxidative DNA damage. This type of damage is removed by the base excision repair (BER) pathway, an essential DNA repair mechanism, which contributes to genome stability in the brain. Despite the crucial role of the BER pathway, insights into how this pathway is affected by aging in the human brain and the underlying regulatory mechanisms are very limited. By microarray analysis of four cortical brain regions from humans aged 20-99 years (n = 57), we show that the expression of core BER genes is largely downregulated during aging across brain regions. Moreover, we find that expression of many BER genes correlates positively with the expression of the neurotrophin brain-derived neurotrophic factor (BDNF) in the human brain. In line with this, we identify binding sites for the BDNF-activated transcription factor, cyclic-AMP response element-binding protein (CREB), in the promoter of most BER genes and confirm the ability of BDNF to regulate several BER genes by BDNF treatment of mouse primary hippocampal neurons. Together, these findings uncover the transcriptional landscape of BER genes during aging of the brain and suggest BDNF as an important regulator of BER in the human brain.

Effects of Acute Long- versus Short-Interval High-Intensity Interval Training on Attention and Psychological States in a Sample of Male and Female Adolescents: A Pilot Study

The aim of this study was to assess the effect of acute short- versus long-interval high-intensity interval training (HIIT) on cognitive performance and psychological states in secondary school students. Fifteen secondary school students (nine males and six females: mean age = 16.2 ± 0.4 years, mean Body Mass Index = 21.2 ± 1.5 kg/m2, and maximum oxygen uptake = 42.2 ± 5.9 mL/kg/min) participated in the current study. They performed one of the following three sessions in a randomized order: (i) a long-interval HIIT (LIHIIT), (ii) a short-interval HIIT (SIHIIT), and (iii) a control condition (CC). Cognitive performance and perceived exertion were assessed pre and immediately post each condition using the d2 test and the Rating of Perceived Exertion (RPE) tool, respectively. Mood state was quantified using the Brunel Mood Scale (BRUMS) questionnaire immediately post each condition. The findings reported higher concentration performance in the SIHIIT compared to the LIHIIT condition (p = 0.043) and the CC (p < 0.001) and in the LIHIIT compared to the CC (p = 0.023). Moreover, the total count of errors was higher in the CC than in the LIHIIT (p = 0.01) and in the SIHIIT conditions (p < 0.001) and in the LIHIIT than in the SIHIIT condition (p = 0.03). RPE value was higher in the LIHIIT and SIHIIT conditions than in the CC (both p < 0.001), whereas no statistically significant difference between LIHIIT and SIHIIT conditions (p = 0.24) was found. Regarding the BRUMS, a significant difference between conditions in the fatigue subscale was found, being higher in LIHIIT with respect to SIHIIT (p = 0.03) and CC (p < 0.05). Vigor differed between conditions, with a higher value than in the LIHIIT (p = 0.04) and CC (p < 0.001). All the remaining subscales did not significantly differ between conditions (p > 0.05). Practitioners may implement short-interval HIIT prior to any tasks that require high levels of visual attention.

Comparison of selected prooxidant-antioxidant balance and bone metabolism indicators and BDNF levels between older women with different levels of physical activity

BACKGROUND

Given a lack of studies precisely indicating how many steps elderly people should take daily for their antioxidant defence, bone metabolism, and cognitive abilities to improve, our study set out to compare the selected antioxidant, prooxidant, bone turnover, and BDNF indicators between elderly women differing in physical activity (PA) measured by the daily number of steps.

METHODS

The PA levels of 62 women aged 72.1 ± 5.4 years were assessed based on their daily number of steps and then were used to allocate the participants to three groups: group I (n = 18; <5,000 steps a day); group II (n = 22; from 5,000 to 9,999 steps a day); and group III (n = 22; ≥10,000 steps a day). Blood samples were collected from the participants in early morning hours and subjected to biochemical analysis for prooxidant-antioxidant balance indicators (SOD, CAT, GPx, GR, GSH, UA, MDA and TOS/TOC), bone metabolism indicators (Ca, 25-OH vitamin D, osteocalcin, CTX-I, and PTH), and BDNF levels.

RESULTS

The groups were not statistically significantly different in the activity of SOD, CAT, GPx, and GR, but their concentrations of GSH (H = 22.10, p < 0.001) and UA (H = 12.20, p = 0.002) proved to be significantly associated with the groups' daily PA. The between-group differences in the concentrations of MDA and TOS/TOC were not significant, with both these indicators tending to take higher values in group I than in groups II and III. Significant differences between the groups were established for the concentrations of 25-OH vitamin D (H = 24.21, p < 0.001), osteocalcin (H = 7.88, p = 0.019), CTX-I (H = 12.91, p = 0.002), and BDNF (H = 14.47, p = 0.001), but not for Ca and PTH.

CONCLUSIONS

Significantly higher concentrations of GSH, slightly lower oxidative stress indicators, significantly higher BDNF levels, and moderately better bone turnover indicators and resorption markers in the group taking more than 5,000 steps a day suggest that this level of PA can promote successful aging. More research is, however, needed to confirm this finding.

Precious but convenient means of prevention and treatment: physiological molecular mechanisms of interaction between exercise and motor factors and Alzheimer's disease

Disproportionate to the severity of Alzheimer's disease (AD) and the huge number of patients, the exact treatment and prevention of AD is still being explored. With increasing ageing, the search for means to prevent and treat AD has become a high priority. In the search for AD, it has been suggested that exercise may be one of the more effective and less costly means of preventing and treating AD, and therefore a large part of current research is aimed at exploring the effectiveness of exercise in the prevention and treatment of AD. However, due to the complexity of the specific pathogenesis of AD, there are multiple hypotheses and potential mechanisms for exercise interventions in AD that need to be explored. This review therefore specifically summarises the hypotheses of the interaction between exercise and AD from a molecular perspective, based on the available evidence from animal models or human experiments, and explores them categorised according to the pathologies associated with AD: exercise can activate a number of signalling pathways inhibited by AD (e.g., Wnt and PI3K/Akt signalling pathways) and reactivate the effects of downstream factors regulated by these signalling pathways, thus acting to alleviate autophagic dysfunction, relieve neuroinflammation and mitigate Aβ deposition. In addition, this paper introduces a new approach to regulate the blood-brain barrier, i.e., to restore the stability of the blood-brain barrier, reduce abnormal phosphorylation of tau proteins and reduce neuronal apoptosis. In addition, this paper introduces a new concept." Motor factors" or "Exerkines", which act on AD through autocrine, paracrine or endocrine stimulation in response to movement. In this process, we believe there may be great potential for research in three areas: (1) the alleviation of AD through movement in the brain-gut axis (2) the prevention and treatment of AD by movement combined with polyphenols (3) the continued exploration of movement-mediated activation of the Wnt signalling pathway and AD.

Antisense oligonucleotides targeting basal forebrain ATXN2 enhances spatial memory and ameliorates sleep deprivation-induced fear memory impairment in mice

INTRODUCTION

Regulation of brain-derived neurotrophic factor (BDNF) in the basal forebrain ameliorates sleep deprivation-induced fear memory impairments in rodents. Antisense oligonucleotides (ASOs) targeting ATXN2 was a potential therapy for spinocerebellar ataxia, whose pathogenic mechanism associates with reduced BDNF expression. We tested the hypothesis that ASO7 targeting ATXN2 could affect BDNF levels in mouse basal forebrain and ameliorate sleep deprivation-induced fear memory impairments.

METHODS

Adult male C57BL/6 mice were used to evaluate the effects of ASO7 targeting ATXN2 microinjected into the bilateral basal forebrain (1 μg, 0.5 μL, each side) on spatial memory, fear memory and sleep deprivation-induced fear memory impairments. Spatial memory and fear memory were detected by the Morris water maze and step-down inhibitory avoidance test, respectively. Immunohistochemistry, RT-PCR, and Western blot were used to evaluate the changes of levels of BDNF, ATXN2, and postsynaptic density 95 (PSD95) protein as well as ATXN2 mRNA. The morphological changes in neurons in the hippocampal CA1 region were detected by HE staining and Nissl staining.

RESULTS

ASO7 targeting ATXN2 microinjected into the basal forebrain could suppress ATXN2 mRNA and protein expression for more than 1 month and enhance spatial memory but not fear memory in mice. BDNF mRNA and protein expression in basal forebrain and hippocampus was increased by ASO7. Moreover, PSD95 expression and synapse formation were increased in the hippocampus. Furthermore, ASO7 microinjected into the basal forebrain increased BDNF and PSD95 protein expression in the basal forebrain of sleep-deprived mice and counteracted sleep deprivation-induced fear memory impairments.

CONCLUSION

ASOs targeting ATXN2 may provide effective interventions for sleep deprivation-induced cognitive impairments.

Genotoxic effects of caffeine in female mice exposed during pregnancy and lactation period and their offspring

Caffeine is a widely consumed substance, and there is a discussion about its effects when ingested by women during pregnancy and lactation. We aimed to identify the genotoxic effects of caffeine in female mice that consumed it during pregnancy and lactation periods and its consequences in their offspring. Thirty-six couples of Swiss mice received water or caffeine (0.3 and 1.0 mg/mL) treatment during pregnancy and lactation. The male and female offspring were divided into 12 groups according to the treatment administered to the female mice. Genotoxicity was assessed using the comet assay and the micronucleus test. Both doses of caffeine showed genotoxic effects in pregnant and lactating mice groups compared to groups not administered caffeine. In relation to offspring, it can be observed that females and males of the offspring had low weight in early life. In both female and male offspring, genotoxicity was detected in the blood, liver, and kidney tissues. Thus, from the present study, we can suggest that the caffeine consumed by female mice during the periods of pregnancy and lactation led to genotoxic effects in their offspring.

Walnut polyphenols and the active metabolite urolithin A improve oxidative damage in SH-SY5Y cells by up-regulating PKA/CREB/BDNF signaling

Accumulating evidence has confirmed the health benefits of walnut diets in maintaining brain function with age. Recent studies have indicated that walnut polyphenols (WP) and their active metabolites urolithins may play an important role in the health benefits of walnut diets. In the present study, we evaluated the protective effect of WP and urolithin A (UroA) on H₂O₂-induced damage in human neuroblastoma (SH-SY5Y) cells, and investigated its mechanisms in the cAMP-response element binding protein (CREB)-mediated signaling pathway, which is tightly involved in neurodegenerative and neurological diseases. The results demonstrated that both WP (50 and 100 μg mL^-1) and UroA (5 and 10 μM) treatment significantly reversed the decrease of cell viability, the leakage of extracellular lactate dehydrogenase (LDH), the overload of intracellular calcium and cell apoptosis induced by H₂O₂ treatment. Moreover, WP and UroA treatment also relieved H₂O₂-induced oxidative stress including overproduction of intracellular reactive oxygen species (ROS) and reduced activities of superoxide dismutase (SOD) and catalase (CAT). Additionally, western blot analysis showed that WP and UroA treatment significantly increased the activity of cAMP-dependent protein kinase A (PKA) and the expression of pCREB (Ser133) and its downstream molecule brain-derived neurotrophic factor (BDNF), which were decreased by H₂O₂ treatment. Furthermore, pretreatment with the PKA inhibitor H89 abolished the protective effects of WP and UroA, indicating that up-regulation of the PKA/CREB/BDNF neurotrophic signaling pathway is required for their neuroprotective effects against oxidative stress. The current work provides new perspectives for understanding the beneficial effects of WP and UroA on brain function, which warrants further investigation.

Targeting Neuroinflammation with Abscisic Acid Reduces Pain Sensitivity in Females and Hyperactivity in Males of an ADHD Mice Model

Attention deficit/hyperactivity disorder (ADHD) is a neurodevelopmental syndrome characterized by dopaminergic dysfunction. In this study, we aimed to demonstrate that there is a link between dopaminergic deficit and neuroinflammation that underlies ADHD symptoms. We used a validated ADHD mice model involving perinatal 6-OHDA lesions. The animals received abscisic acid (ABA), an anti-inflammatory phytohormone, at a concentration of 20 mg/L (drinking water) for one month. We tested a battery of behavior tests, learning and memory, anxiety, social interactions, and pain thresholds in female and male mice (control and lesioned, with or without ABA treatment). Postmortem, we analyzed microglia morphology and Ape1 expression in specific brain areas related to the descending pain inhibitory pathway. In females, the dopaminergic deficit increased pain sensitivity but not hyperactivity. In contrast, males displayed hyperactivity but showed no increased pain sensitivity. In females, pain sensitivity was associated with inflammatory microglia and lower Ape1 levels in the anterior cingulate cortex (ACC) and posterior insula cortex (IC). In addition, ABA treatment alleviated pain sensitivity concomitant with reduced inflammation and normalized APE1. In males, ABA reduced hyperactivity but had no significant effect on inflammation in these areas. This is the first study proving a sex-dependent association between dopamine dysfunction and inflammation in specific brain areas, hence leading to different behavioral outcomes in a mouse model of ADHD. These findings provide new clues for potential treatments for ADHD.

Central Stimulatory Effect of Kynurenic Acid on BDNF-TrkB Signaling and BER Enzymatic Activity in the Hippocampal CA1 Field in Sheep

Deficiency of neurotrophic factors and oxidative DNA damage are common causes of many neurodegenerative diseases. Recently, the importance of kynurenic acid (KYNA), an active metabolite of tryptophan, has increased as a neuroprotective molecule in the brain. Therefore, the present study tested the hypothesis that centrally acting KYNA would positively affect: (1) brain-derived neurotrophic factor (BDNF)-tyrosine receptor kinase B (TrkB) signaling and (2) selected base excision repair (BER) pathway enzymes activities in the hippocampal CA1 field in sheep. Both lower (20 μg in total) and higher (100 μg in total) doses of KYNA infused into the third brain ventricle differentially increased the abundance of BDNF and TrkB mRNA in the CA1 field; additionally, the higher dose increased BDNF tissue concentration. The lower dose of KYNA increased mRNA expression for 8-oxoguanine glycosylase (OGG1), N-methylpurine DNA glycosylase (MPG), and thymine DNA glycosylase and stimulated the repair of 1,N6-ethenodeoxyadenosine and 3,N4-ethenodeoxy-cytosine as determined by the excision efficiency of lesioned nucleobases. The higher dose increased the abundance of OGG1 and MPG transcripts, however, its stimulatory effect on repair activity was less pronounced in all cases compared to the lower dose. The increased level of AP-endonuclease mRNA expression was dose-dependent. In conclusion, the potential neurotrophic and neuroprotective effects of KYNA in brain cells may involve stimulation of the BDNF-TrkB and BER pathways.

Exercise Counters the Age-Related Accumulation of Senescent Cells

We propose the beneficial effects of exercise are in part mediated through the prevention and elimination of senescent cells. Exercise counters multiple forms of age-related molecular damage that initiate the senescence program and activates immune cells responsible for senescent cell clearance. Preclinical and clinical evidence for exercise as a senescence-targeting therapy and areas needing further investigation are discussed.

The neuroprotective effects of glucagon-like peptide 1 in Alzheimer’s and Parkinson’s disease: An in-depth review

Currently, there is no disease-modifying treatment available for Alzheimer’s and Parkinson’s disease (AD and PD) and that includes the highly controversial approval of the Aβ-targeting antibody aducanumab for the treatment of AD. Hence, there is still an unmet need for a neuroprotective drug treatment in both AD and PD. Type 2 diabetes is a risk factor for both AD and PD. Glucagon-like peptide 1 (GLP-1) is a peptide hormone and growth factor that has shown neuroprotective effects in preclinical studies, and the success of GLP-1 mimetics in phase II clinical trials in AD and PD has raised new hope. GLP-1 mimetics are currently on the market as treatments for type 2 diabetes. GLP-1 analogs are safe, well tolerated, resistant to desensitization and well characterized in the clinic. Herein, we review the existing evidence and illustrate the neuroprotective pathways that are induced following GLP-1R activation in neurons, microglia and astrocytes. The latter include synaptic protection, improvements in cognition, learning and motor function, amyloid pathology-ameliorating properties (Aβ, Tau, and α-synuclein), the suppression of Ca2+ deregulation and ER stress, potent anti-inflammatory effects, the blockage of oxidative stress, mitochondrial dysfunction and apoptosis pathways, enhancements in the neuronal insulin sensitivity and energy metabolism, functional improvements in autophagy and mitophagy, elevated BDNF and glial cell line-derived neurotrophic factor (GDNF) synthesis as well as neurogenesis. The many beneficial features of GLP-1R and GLP-1/GIPR dual agonists encourage the development of novel drug treatments for AD and PD.

NADPH and Mitochondrial Quality Control as Targets for a Circadian-Based Fasting and Exercise Therapy for the Treatment of Parkinson's Disease

Dysfunctional mitochondrial quality control (MQC) is implicated in the pathogenesis of Parkinson's disease (PD). The improper selection of mitochondria for mitophagy increases reactive oxygen species (ROS) levels and lowers ATP levels. The downstream effects include oxidative damage, failure to maintain proteostasis and ion gradients, and decreased NAD⁺ and NADPH levels, resulting in insufficient energy metabolism and neurotransmitter synthesis. A ketosis-based metabolic therapy that increases the levels of (R)-3-hydroxybutyrate (BHB) may reverse the dysfunctional MQC by partially replacing glucose as an energy source, by stimulating mitophagy, and by decreasing inflammation. Fasting can potentially raise cytoplasmic NADPH levels by increasing the mitochondrial export and cytoplasmic metabolism of ketone body-derived citrate that increases flux through isocitrate dehydrogenase 1 (IDH1). NADPH is an essential cofactor for nitric oxide synthase, and the nitric oxide synthesized can diffuse into the mitochondrial matrix and react with electron transport chain-synthesized superoxide to form peroxynitrite. Excessive superoxide and peroxynitrite production can cause the opening of the mitochondrial permeability transition pore (mPTP) to depolarize the mitochondria and activate PINK1-dependent mitophagy. Both fasting and exercise increase ketogenesis and increase the cellular NAD⁺/NADH ratio, both of which are beneficial for neuronal metabolism. In addition, both fasting and exercise engage the adaptive cellular stress response signaling pathways that protect neurons against the oxidative and proteotoxic stress implicated in PD. Here, we discuss how intermittent fasting from the evening meal through to the next-day lunch together with morning exercise, when circadian NAD⁺/NADH is most oxidized, circadian NADP⁺/NADPH is most reduced, and circadian mitophagy gene expression is high, may slow the progression of PD.

Oxytocin Release: A Remedy for Cerebral Inflammaging

Oxytocin facilitates reproduction both by physiological and behavioral mechanisms. Oxytocinergic neurons emerging from the hypothalamus release oxytocin from the pituitary gland to the blood by axonal discharge to regulate reproductive organs. However, at the same time, oxytocin is secreted into neighboring areas of the hypothalamus from the dendrites of these neurons. Here, the peptide acts by autocrine and paracrine mechanisms to influence other neuroendocrine systems. Furthermore, oxytocinergic neurons project to many different locations in the brain, where they affect sensory processing, affective functions, and reward. Additional to its regulatory role, significant anti-inflammatory and restoring effects of oxytocin have been reported from many invivo and in-vitro studies. The pervasive property of the oxytocin system may enable it generally to dampen stress reactions both peripherally and centrally, and protect neurons and supportive cells from inadequate inflammation and malfunctioning. Animal experiments have documented the importance of preserving immune- and stem cell functions in the hypothalamus to impede age-related destructive processes of the body. Sexual reward has a profound stimulating impact on the oxytocinergic activity, and the present article therefore presents the hypothesis that frequent sexual activity and gratigying social experiance may postpone the onset of frailty and age-associated diseases by neural protection from the bursts of oxytocin. Furthermore, suggestions are given how the neuroplastic properties of oxytocin may be utilized to enhance sexual reward by learning processes in order to further reinforce the release of this peptide.

The Role of DNA Damage in Neural Plasticity in Physiology and Neurodegeneration

Damage to DNA is generally considered to be a harmful process associated with aging and aging-related disorders such as neurodegenerative diseases that involve the selective death of specific groups of neurons. However, recent studies have provided evidence that DNA damage and its subsequent repair are important processes in the physiology and normal function of neurons. Neurons are unique cells that form new neural connections throughout life by growth and re-organisation in response to various stimuli. This “plasticity” is essential for cognitive processes such as learning and memory as well as brain development, sensorial training, and recovery from brain lesions. Interestingly, recent evidence has suggested that the formation of double strand breaks (DSBs) in DNA, the most toxic form of damage, is a physiological process that modifies gene expression during normal brain activity. Together with subsequent DNA repair, this is thought to underlie neural plasticity and thus control neuronal function. Interestingly, neurodegenerative diseases such as Alzheimer’s disease, amyotrophic lateral sclerosis, frontotemporal dementia, and Huntington’s disease, manifest by a decline in cognitive functions, which are governed by plasticity. This suggests that DNA damage and DNA repair processes that normally function in neural plasticity may contribute to neurodegeneration. In this review, we summarize current understanding about the relationship between DNA damage and neural plasticity in physiological conditions, as well as in the pathophysiology of neurodegenerative diseases.

Recent Advances on the Role of Brain-Derived Neurotrophic Factor (BDNF) in Neurodegenerative Diseases

Neurotrophins, such as brain-derived neurotrophic factor (BDNF), are essential for neuronal survival and growth. The signaling cascades initiated by BDNF and its receptor are the key regulators of synaptic plasticity, which plays important role in learning and memory formation. Changes in BDNF levels and signaling pathways have been identified in several neurodegenerative diseases, including Alzheimer’s disease, Parkinson’s disease, and Huntington’s disease, and have been linked with the symptoms and course of these diseases. This review summarizes the current understanding of the role of BDNF in several neurodegenerative diseases, as well as the underlying molecular mechanism. The therapeutic potential of BDNF treatment is also discussed, in the hope of discovering new avenues for the treatment of neurodegenerative diseases.

Neuroprotective Mechanisms of Glucagon-Like Peptide-1-Based Therapies in Ischemic Stroke: An Update Based on Preclinical Research

The public and social health burdens of ischemic stroke have been increasing worldwide. Hyperglycemia leads to a greater risk of stroke. This increased risk is commonly seen among patients with diabetes and is in connection with worsened clinical conditions and higher mortality in patients with acute ischemic stroke (AIS). Therapy for stroke focuses mainly on restoring cerebral blood flow (CBF) and ameliorating neurological impairment caused by stroke. Although choices of stroke treatment remain limited, much advance have been achieved in assisting patients in recovering from ischemic stroke, along with progress of recanalization therapy through pharmacological and mechanical thrombolysis. However, it is still necessary to develop neuroprotective therapies for AIS to protect the brain against injury before and during reperfusion, prolong the time window for intervention, and consequently improve neurological prognosis. Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) are broadly regarded as effective drugs in the treatment of type 2 diabetes mellitus (T2DM). Preclinical data on GLP-1 and GLP-1 RAs have displayed an impressive neuroprotective efficacy in stroke, Parkinson's disease (PD), Alzheimer's disease (AD), Amyotrophic lateral sclerosis (ALS), and other neurodegenerative diseases. Based on the preclinical studies in the past decade, we review recent progress in the biological roles of GLP-1 and GLP-1 RAs in ischemic stroke. Emphasis will be placed on their neuroprotective effects in experimental models of cerebral ischemia stroke at cellular and molecular levels.

A Review on the Role of Endogenous Neurotrophins and Schwann Cells in Axonal Regeneration

Injury to the peripheral nerve is traditionally referred to acquired nerve injury as they are the result of physical trauma due to laceration, stretch, crush and compression of nerves. However, peripheral nerve injury may not be completely limited to acquired physical trauma. Peripheral nerve injury equally implies clinical conditions like Guillain-Barré syndrome (GBS), Carpal tunnel syndrome, rheumatoid arthritis and diabetes. Physical trauma is commonly mono-neuropathic as it engages a single nerve and produces focal damage, while in the context of pathological conditions the damage is divergent involving a group of the nerve causing polyneuropathy. Damage to the peripheral nerve can cause a diverse range of manifestations from sensory impairment to loss of function with unpredictable recovery patterns. Presently no treatment option provides complete or functional recovery in nerve injury, as nerve cells are highly differentiated and inert to regeneration. However, the regenerative phenotypes in Schwann cells get expressed when a signalling cascade is triggered by neurotrophins. Neurotrophins are one of the promising biomolecules that are released naturally post-injury with the potential to exhibit better functional recovery. Pharmacological intervention modulating the expression of these neurotrophins such as brain-derived neurotrophic factor (BDNF) and pituitary adenylyl cyclase-activating peptide (PACAP) can prove to be a significant treatment option as endogenous compounds which may have remarkable innate advantage showing maximum 'biological relevance'.

Cell-Free Fat Extract Improves Ovarian Function and Fertility in Mice With Advanced Age

The reduction in the quantity and quality of oocytes is the major factor affecting fertility in women with advanced age, who tend to experience delayed childbearing and declined fertility rate. However, effective therapeutic strategies to combat this decrease in ovarian function are lacking in clinical practice. Thus, identifying a new method to rescue ovarian function and improve reproduction in natural age-related decline in fertility is necessary. Cell-free fat extract (CEFFE) has been verified to possess diverse active proteins exerting anti-aging and proliferation-promoting effects. Nonetheless, whether CEFFE can rescue the decline in aged-related ovarian function and improve the fertility of females with advanced age remains unclear. In this study, a natural aging mouse model, exhibiting similarities to the physiological changes of ovarian senescence, was used to observe the anti-aging effect of CEFFE on ovarian functions. We found that CEFFE, injected via the veins, could recover the levels of the sex hormone, increase angiogenesis and the number of growth follicles in the natural aging mice model. Moreover, CEFFE promoted the development of embryos and increased the litter size of aged mice. Transcriptome analysis of the aged mouse ovaries revealed that CEFFE treatment upregulated the expression of genes involved in the repair of DNA damage. And both in vivo and in vitro experiment proved that CEFFE improved the function of granulosa cells, including promoting proliferation, alleviating senescence, and rescuing DNA damage in aged granulosa cells. Collectively, our study implied that CEFFE improved the ovarian function and fertility of naturally aging mice by ameliorating the overall microenvironment of ovary, which provided a theoretical basis for new anti-aging therapeutic strategies for cell-free therapy in ovaries.

Molecular markers of DNA repair and brain metabolism correlate with cognition in centenarians

Oxidative stress is an important factor in age-associated neurodegeneration. Accordingly, mitochondrial dysfunction and genomic instability have been considered as key hallmarks of aging and have important roles in age-associated cognitive decline and neurodegenerative disorders. In order to evaluate whether maintenance of cognitive abilities at very old age is associated with key hallmarks of aging, we measured mitochondrial bioenergetics, mitochondrial DNA copy number and DNA repair capacity in peripheral blood mononuclear cells from centenarians in a Danish 1915 birth cohort (n = 120). Also, the circulating levels of brain-derived neurotrophic factor, NAD⁺ /NADH and carbonylated proteins were measured in plasma of the centenarians and correlated to cognitive capacity. Mitochondrial respiration was well preserved in the centenarian cohort when compared to young individuals (21-35 years of age, n = 33). When correlating cognitive performance of the centenarians with mitochondrial function such as basal respiration, ATP production, reserve capacity and maximal respiration, no overall correlations were observed, but when stratifying by sex, inverse associations were observed in the males (p < 0.05). Centenarians with the most severe cognitive impairment displayed the lowest activity of the central DNA repair enzyme, APE1 (p < 0.05). A positive correlation between cognitive capacity and levels of NAD⁺ /NADH was observed (p < 0.05), which may be because NAD⁺ /NADH consuming enzyme activities strive to reduce the oxidative DNA damage load. Also, circulating protein carbonylation was lowest in centenarians with highest cognitive capacity (p < 0.05). An opposite trend was observed for levels of brain-derived neurotrophic factor (p = 0.17). Our results suggest that maintenance of cognitive capacity at very old age may be associated with cellular mechanisms related to oxidative stress and DNA metabolism.

Negative regulation by proBDNF signaling of peripheral neurogenesis in the sensory ganglia of adult rats

Neurogenesis in the adult brain is well recognized and plays a critical role in the maintenance of brain function and homeostasis. However, whether neurogenesis also occurs in the adult peripheral nervous system remains unknown. Here, using sensory ganglia (dorsal root ganglia, DRGs) as a model, we show that neurogenesis also occurs in the peripheral nervous system, but in a manner different from that in the central nervous system. Satellite glial cells (SGCs) express the neuronal precursor markers Nestin, POU domain, class 4, transcription factor 1, and p75 pan-neurotrophin receptor. Following sciatic nerve injury, the suppression of endogenous proBDNF by proBDNF antibodies resulted in the transformation of proliferating SGCs into doublecortin-positive cells in the DRGs. Using purified SGCs migrating out from the DRGs, the inhibition of endogenous proBDNF promoted the conversion of SGCs into neuronal phenotypes in vitro. Our findings suggest that SGCs are neuronal precursors, and that proBDNF maintains the SGC phenotype. Furthermore, the suppression of proBDNF signaling is necessary for neuronal phenotype acquisition by SGCs. Thus, we propose that peripheral neurogenesis may occur via the direct conversion of SGCs into neurons, and that this process is negatively regulated by proBDNF.

All roads lead to Rome - a review of the potential mechanisms by which exerkines exhibit neuroprotective effects in Alzheimer's disease

Age-related neurodegenerative disorders such as Alzheimer’s disease (AD) have become a critical public health issue due to the significantly extended human lifespan, leading to considerable economic and social burdens. Traditional therapies for AD such as medicine and surgery remain ineffective, impractical, and expensive. Many studies have shown that a variety of bioactive substances released by physical exercise (called “exerkines”) help to maintain and improve the normal functions of the brain in terms of cognition, emotion, and psychomotor coordination. Increasing evidence suggests that exerkines may exert beneficial effects in AD as well. This review summarizes the neuroprotective effects of exerkines in AD, focusing on the underlying molecular mechanism and the dynamic expression of exerkines after physical exercise. The findings described in this review will help direct research into novel targets for the treatment of AD and develop customized exercise therapy for individuals of different ages, genders, and health conditions.

Emerging roles of oxidative stress in brain aging and Alzheimer's disease

Reactive oxygen species (ROS) are metabolic byproducts that are necessary for physiological function but can be toxic at high levels. Levels of these oxidative stressors increase gradually throughout the lifespan, impairing mitochondrial function and damaging all parts of the body, particularly the central nervous system. Emerging evidence suggests that accumulated oxidative stress may be one of the key mechanisms causing cognitive aging and neurodegenerative diseases such as Alzheimer's disease (AD). Here, we synthesize the current literature on the effect of neuronal oxidative stress on mitochondrial dysfunction, DNA damage and epigenetic changes related to cognitive aging and AD. We further describe how oxidative stress therapeutics such as antioxidants, caloric restriction and physical activity can reduce oxidation and prevent cognitive decline in brain aging and AD. Of the currently available therapeutics, we propose that long term physical activity is the most promising avenue for improving cognitive health by reducing ROS while promoting the low levels required for optimal function.

Intermittent Hypoxia Training Prevents Deficient Learning-Memory Behavior in Mice Modeling Alzheimer's Disease: A Pilot Study

In mouse models of Alzheimer's disease (AD), normobaric intermittent hypoxia training (IHT) can preserve neurobehavioral function when applied before deficits develop, but IHT's effectiveness after onset of amyloid-β (Aβ) accumulation is unclear. This study tested the hypothesis that IHT improves learning-memory behavior, diminishes Aβ accumulation in cerebral cortex and hippocampus, and enhances cerebrocortical contents of the neuroprotective trophic factors erythropoietin and brain-derived neurotrophic factor (BDNF) in mice manifesting AD traits. Twelve-month-old female 3xTg-AD mice were assigned to untreated 3xTg-AD (n = 6), AD+IHT (n = 6), and AD+sham-IHT (n = 6) groups; 8 untreated wild-type (WT) mice also were studied. AD+IHT mice alternately breathed 10% O2 for 6 min and room air for 4 min, 10 cycles/day for 21 days; AD+sham-IHT mice breathed room air. Spatial learning-memory was assessed by Morris water maze. Cerebrocortical and hippocampal Aβ40 and Aβ42 contents were determined by ELISA, and cerebrocortical erythropoietin and BDNF were analyzed by immunoblotting and ELISA. The significance of time (12 vs. 12 months + 21 days) and treatment (IHT vs. sham-IHT) was evaluated by two-factor ANOVA. The change in swimming distance to find the water maze platform after 21 d IHT (-1.6 ± 1.8 m) differed from that after sham-IHT (+5.8 ± 2.6 m). Cerebrocortical and hippocampal Aβ42 contents were greater in 3xTg-AD than WT mice, but neither time nor treatment significantly affected Aβ40 or Aβ42 contents in the 3xTg-AD mice. Cerebrocortical erythropoietin and BDNF contents increased appreciably after IHT as compared to untreated 3xTg-AD and AD+sham-IHT mice. In conclusion, moderate, normobaric IHT prevented spatial learning-memory decline and restored cerebrocortical erythropoietin and BDNF contents despite ongoing Aβ accumulation in 3xTg-AD mice.

Conifers Phytochemicals: A Valuable Forest with Therapeutic Potential

Conifers have long been recognized for their therapeutic potential in different disorders. Alkaloids, terpenes and polyphenols are the most abundant naturally occurring phytochemicals in these plants. Here, we provide an overview of the phytochemistry and related commercial products obtained from conifers. The pharmacological actions of different phytochemicals present in conifers against bacterial and fungal infections, cancer, diabetes and cardiovascular diseases are also reviewed. Data obtained from experimental and clinical studies performed to date clearly underline that such compounds exert promising antioxidant effects, being able to inhibit cell damage, cancer growth, inflammation and the onset of neurodegenerative diseases. Therefore, an attempt has been made with the intent to highlight the importance of conifer-derived extracts for pharmacological purposes, with the support of relevant in vitro and in vivo experimental data. In short, this review comprehends the information published to date related to conifers' phytochemicals and illustrates their potential role as drugs.

Novel Strategies for Healthy Brain Aging

One of the best strategies for healthy brain aging is regular aerobic exercise. Commonly studied "anti-aging" compounds may mimic some effects of exercise on the brain, but novel approaches that target energy-sensing pathways similar to exercise probably will be more effective in this context. We review evidence in support of this hypothesis by focusing on biological hallmarks of brain aging.

Static Stretching Reduces Motoneuron Excitability: The Potential Role of Neuromodulation

Prolonged static muscle stretching transiently reduces maximal muscle force, and this force loss has a strong neural component. In this review, we discuss the evidence suggesting that stretching reduces the motoneuron's ability to amplify excitatory drive. We propose a hypothetical model in which stretching causes physiological relaxation, reducing the brainstem-derived neuromodulatory drive necessary to maximize motoneuron discharge rates.

The Effect of Acute High-Intensity Interval Training on Executive Function: A Systematic Review

Acute high-intensity interval training (HIIT) is a time-efficient strategy to improve physical health; however, the effect of acute HIIT on executive function (EF) is unclear. The aim of this study was to systematically review the existing evidence and quantify the effect of acute HIIT on overall EF and the factors affecting the relationship between acute HIIT and EF. Standard databases (i.e., the PubMed, Medline, Scopus, and CENTRAL databases) were searched for studies that examined the effect of acute HIIT on EF and were published up until January 2021. The overall EF and factors grouped by three categories, namely, EF assessment characteristics, exercise intervention characteristics, and sample and study characteristics, were analyzed by percentage of comparison for positive or null/negative effects. Overall, 35 of 57 outcomes (61%) across 24 studies revealed that acute HIIT has a positive effect on overall EF. In terms of factors, the results indicated that among EF assessment characteristics, groups, inhibition, updating, and the assessment occurring within 30 min may moderate the effect of acute HIIT on EF, while among exercise intervention characteristics, total time within 11 to 30 min may moderate the effect. Finally, among sample characteristics, age under 40 years may moderate the effect. Acute HIIT is generally considered a viable alternative for eliciting EF gains, with factors related to EF components, timing of the assessment, exercise total time, and age potentially moderating the effect of HIIT on EF.

Preventive and Therapeutic Potential of Physical Exercise in Neurodegenerative Diseases

Significance: The prevalence and incidence of age-related neurodegenerative diseases (NDDs) tend to increase along with the enhanced average of the world life expectancy. NDDs are a major cause of morbidity and disability, affecting the health care, social and economic systems with a significant impact. Critical Issues and Recent Advances: Despite the worldwide burden of NDDs and the ongoing research efforts to increase the underlying molecular mechanisms involved in NDD pathophysiologies, pharmacological therapies have been presenting merely narrow benefits. On the contrary, absent of detrimental side effects but growing merits, regular physical exercise (PE) has been considered a prone pleiotropic nonpharmacological alternative able to modulate brain structure and function, thereby stimulating a healthier and "fitness" neurological phenotype. Future Directions: This review summarizes the state of the art of some peripheral and central-related mechanisms that underlie the impact of PE on brain plasticity as well as its relevance for the prevention and/or treatment of NDDs. Nevertheless, further studies are needed to better clarify the molecular signaling pathways associated with muscle contractions-related myokines release and its plausible positive effects in the brain. In addition, particular focus of research should address the role of PE in the modulation of mitochondrial metabolism and oxidative stress in the context of NDDs.

Recovery From Repeat Mild Traumatic Brain Injury in Adolescent Rats Is Dependent on Pre-injury Activity State

Adolescents and young adults have the highest incidence of mild traumatic brain injury (mTBI); sport-related activities are a major contributor. Roughly a third of these patients diagnosed with mTBI are estimated to have received a subsequent repeat mTBI (rTBI). Previously, animal studies have only modeled mTBI in sedentary animals. This study utilizes physical activity as a dependent variable prior to rTBI in adolescent rats by allowing voluntary exercise in males, establishing the rat athlete (rathlete). Rats were given access to locked or functional running wheels for 10 d prior to sham or rTBI injury. Following rTBI, rathletes were allowed voluntary access to running wheels beginning on different days post-injury: no run (rTBI+no run), immediate run (rTBI+Immed), or 3 day delay (rTBI+3dd). Rats were tested for motor and cognitive-behavioral (anxiety, social, memory) and mechanosensory (allodynia) dysfunction using a novel rat standardized concussion assessment tool on post-injury days 1,3,5,7, and 10. Protein expression of brain derived neurotrophic factor (BDNF) and proliferator-activated gamma coactivator 1-alpha (PGC1α) was measured in the parietal cortex, hippocampus, and gastrocnemius muscle. Sedentary shams displayed lower anxiety-like behaviors compared to rathlete shams on all testing days. BDNF and PGC1α levels increased in the parietal cortex and hippocampus with voluntary exercise. In rTBI rathletes, the rTBI+Immed group showed impaired social behavior, memory impairment in novel object recognition, and increased immobility compared to rathlete shams. All rats showed greater neuropathic mechanosensory sensitivity than previously published uninjured adults, with rTBI+3dd showing greatest sensitivity. These results demonstrate that voluntary exercise changes baseline functioning of the brain, and that among rTBI rathletes, delayed return to activity improved cognitive recovery.

Saffron (Crocus Sativus L.), Combined with Endurance Exercise, Synergistically Enhances BDNF, Serotonin, and NT-3 in Wistar Rats

BACKGROUND

Evidence indicates that combined approaches based on exercise and nutrition benefit neural development. We aimed to determine the effect of saffron and endurance training on hippocampus neurogenic factors, neurotrophin-3 gene expression in soleus muscle, and short-term memory in Wistar rats.

METHODS

The study analyzed four groups of ten rats each: control, exercise, saffron, and saffron plus exercise. The rats in the exercise groups were trained on a rodent motor-driven treadmill. All rats were gavage daily with either saffron extract (40 mg/kg) or water. After eight weeks of intervention all rats were evaluated using the novel object recognition (NOR) test. Blood and tissue samples were collected to measure proteins and neurotrophin-3 gene expression.

RESULTS

Rats that received saffron treatment combined with exercise had significantly greater brain-derived neurotrophic factor (BDNF) and serotonin in hippocampus compared to the control and saffron-only-treated rats (p< 0.05). Neurotrophin-3 mRNA in soleus muscle was higher in the saffron plus exercise group than rats in the other three groups (p< 0.05). Hippocampus 5-hydroxyindolacetic acid and short-term memory were significantly greater in all the intervention groups than in the control group (p< 0.05).

CONCLUSION

Saffron, combined with endurance exercise, synergistically increased hippocampus BDNF, serotonin, and muscular neurotrophin-3 mRNA in Wistar rats.

Melatonin reverts methamphetamine-induced learning and memory impairments and hippocampal alterations in mice

AIMS

Methamphetamine (METH) has become a major public health problem because of its abuse and profound neurotoxic effects, causing alterations in brain structure and function, and impairing cognitive functions, including attention, decision making, emotional memory, and working memory. This study aimed to determine whether melatonin (MEL), the circadian-control hormone, which has roles beyond circadian rhythm regulation, could restore METH-induced cognitive and neuronal impairment.

MAIN METHODS

Mice were treated with either METH (1 mg/kg) or saline for 7 days, followed by MEL (10 mg/kg) or saline for another 14 days. The Morris water maze (MWM) test was performed one day after the last saline or MEL injection. The hippocampal neuronal density, synaptic density, and receptors involved in learning and memory, along with downstream signaling molecules (NMDA receptor subunits GluN2A, GluN2B, and CaMKII) were investigated by immunoblotting.

KEY FINDINGS

METH administration significantly extended escape latency in learning phase and reduced the number of target crossings in memory test-phase as well as decreased the expression of BDNF, NMDA receptors, TrkB receptors, CaMKII, βIII tubulin, and synaptophysin. MEL treatment significantly ameliorated METH-induced increased escape latency, decreased the number of target crossings and decreased expression of BDNF, NMDA receptors, TrkB receptors, CaMKII, βIII tubulin and synaptophysin.

SIGNIFICANCE

METH administration impairs learning and memory in mice, and MEL administration restores METH-induced neuronal impairments which is probably through the changes in BDNF, NMDA receptors, TrkB receptors, CaMKII, βIII tubulin and synaptophysin. Therefore, MEL is potentially an innovative and promising treatment for learning and memory impairment of humans.

Harnessing the effects of endurance exercise to optimize cognitive health: Fundamental insights from Dr. Mark P. Mattson

Dr. Mark Mattson has had a highly productive and impactful tenure as a neuroscientist at the Intramural Research Program of the National Institute on Aging. He has made notable contributions to understanding the mechanisms by which energetic stress, imparted by behaviors such as physical activity and periods of fasting, promotes rejuvenation and resilience within brain regions critical for learning and memory. In honor of Dr. Mattson's work, this manuscript will highlight the fascinating mechanisms by which endurance exercise training conveys beneficial effects upon the structure and function of the nervous system; that is, by mediating the synthesis and secretion of factors that directly support brain homeostasis, including brain-derived neurotrophic factor, FNDC5/irisin, ketone bodies, growth factors, cathepsin B, serotonin, and 4-hydroxynonenal. The molecular and cellular effects of these factors are discussed herein. In the face of population aging and an overwhelming surge in the prevalence of Alzheimer's disease and related disorders, Dr. Mattson's work as a champion and role model for physically active lifestyles is more important than ever.

Interrelationships Between BDNF, Superoxide Dismutase, and Cognitive Impairment in Drug-Naive First-Episode Patients With Schizophrenia

The pathogenesis and etiology of schizophrenia (SCZ) remains unclear. Accumulating studies showed that complex interrelationships between brain-derived neurotrophic factor (BDNF) and an imbalanced redox system has a crucial role in the psychopathology of SCZ. However, the influence of the interrelationships of BDNF and superoxide dismutase (SOD) on cognitive impairment and clinical symptomatology in drug-naive first-episode (DNFE) SCZ patients has not been studied thoroughly. Serum BDNF levels, plasma total SOD, manganese-SOD (Mn-SOD), copper/zinc-containing SOD (CuZn-SOD) activities, and malondialdehyde (MDA) levels were measured in 327 DNFE patients with SCZ and 391 healthy controls. Cognitive functions were measured using the Repeatable Battery for the Assessment of Neuropsychological status (RBANS) and clinical symptoms were evaluated by the Positive and Negative Syndrome Scale (PANSS). Compared with the controls, the DNFE patients had increased activities of total SOD and CuZn-SOD, and reduced levels of BDNF and MDA. BDNF levels were positively correlated with CuZn-SOD activity in patients. In addition, we found that elevated Mn-SOD and CuZn-SOD activities were related to PANSS depression factor. Moreover, an interactive effect of BDNF levels and Mn-SOD activity was associated with attentional index score in the patients. Therefore, our findings suggested that interrelationships between BDNF and antioxidant mechanisms might underlie the pathological mechanisms of cognitive impairments and symptomatology in the DNFE patients with SCZ.

Neurotrophic Factor BDNF, Physiological Functions and Therapeutic Potential in Depression, Neurodegeneration and Brain Cancer

Brain-derived neurotrophic factor (BDNF) is one of the most distributed and extensively studied neurotrophins in the mammalian brain. BDNF signals through the tropomycin receptor kinase B (TrkB) and the low affinity p75 neurotrophin receptor (p75NTR). BDNF plays an important role in proper growth, development, and plasticity of glutamatergic and GABAergic synapses and through modulation of neuronal differentiation, it influences serotonergic and dopaminergic neurotransmission. BDNF acts as paracrine and autocrine factor, on both pre-synaptic and post-synaptic target sites. It is crucial in the transformation of synaptic activity into long-term synaptic memories. BDNF is considered an instructive mediator of functional and structural plasticity in the central nervous system (CNS), influencing dendritic spines and, at least in the hippocampus, the adult neurogenesis. Changes in the rate of adult neurogenesis and in spine density can influence several forms of learning and memory and can contribute to depression-like behaviors. The possible roles of BDNF in neuronal plasticity highlighted in this review focus on the effect of antidepressant therapies on BDNF-mediated plasticity. Moreover, we will review data that illustrate the role of BDNF as a potent protective factor that is able to confer protection against neurodegeneration, in particular in Alzheimer's disease. Finally, we will give evidence of how the involvement of BDNF in the pathogenesis of brain glioblastoma has emerged, thus opening new avenues for the treatment of this deadly cancer.

The Effect of Allopregnanolone on Enzymatic Activity of the DNA Base Excision Repair Pathway in the Sheep Hippocampus and Amygdala under Natural and Stressful Conditions

The neurosteroid allopregnanolone (AL) has many beneficial functions in the brain. This study tested the hypothesis that AL administered for three days into the third brain ventricle would affect the enzymatic activity of the DNA base excision repair (BER) pathway in the hippocampal CA1 and CA3 fields and the central amygdala in luteal-phase sheep under both natural and stressful conditions. Acute stressful stimuli, including isolation and partial movement restriction, were used on the last day of infusion. The results showed that stressful stimuli increased N-methylpurine DNA glycosylase (MPG), thymine DNA glycosylase (TDG), 8-oxoguanine glycosylase (OGG1), and AP-endonuclease 1 (APE1) mRNA expression, as well as repair activities for 1,N6-ethenoadenine (εA), 3,N4-ethenocytosine (εC), and 8-oxoguanine (8-oxoG) compared to controls. The stimulated events were lower in stressed and AL-treated sheep compared to sheep that were only stressed (except MPG mRNA expression in the CA1 and amygdala, as well as TDG mRNA expression in the CA1). AL alone reduced mRNA expression of all DNA repair enzymes (except TDG in the amygdala) relative to controls and other groups. DNA repair activities varied depending on the tissue-AL alone stimulated the excision of εA in the amygdala, εC in the CA3 and amygdala, and 8-oxoG in all tissues studied compared to controls. However, the excision efficiency of lesioned bases in the AL group was lower than in the stressed and stressed and AL-treated groups, with the exception of εA in the amygdala. In conclusion, the presented modulating effect of AL on the synthesis of BER pathway enzymes and their repair capacity, both under natural and stressful conditions, indicates another functional role of this neurosteroid in brain structures.

Expression and Distribution Pattern of Pnn in Ischemic Cerebral Cortex and Cultured Neural Cells Exposed to Oxygen-Glucose Deprivation

Pinin (Pnn), a multifunctional protein, participates in embryonic development as well as in cellular apoptosis, proliferation, and migration through regulating mRNA alternative splicing and gene transcription. Previous studies have shown that Pnn plays important roles in neural system development and the expression level of Pnn in astrocytes is altered by ischemic stress and associated with cellular apoptosis. In the present study, we further utilized primary cultured rat neurons and astrocytes with oxygen-glucose deprivation (OGD) and a mouse model with middle cerebral artery occlusion (MCAO)-induced ischemic stroke to examine the effect of ischemic stress on Pnn expression and distribution in different types of neural cells. Under normoxia, Pnn is mainly localized in the nuclear speckle of primary cultured neurons. The expression level of Pnn was increased after the OGD treatment and then decreased in the reoxygenation period. Moreover, the cytoplasmic expression of Pnn was observed in neurons with OGD and reoxygenation (OGD/R). Unlike that in neurons, the Pnn expression in astrocytes was decreased after OGD treatment and then gradually increased during the reoxygenation period. Of interest, the nuclear–cytoplasmic translocation of Pnn was not observed in astrocytes with OGD/R. In the MCAO mouse model, the neuronal expression of Pnn in the peri-ischemic region was reduced by three days post induction of ischemic stroke. However, the Pnn expression in astrocytes was not altered. Moreover, the nuclear speckle distribution of Pnn in neurons was also diminished following ischemic stroke. In conclusion, the Pnn expression and distribution after OGD and during reoxygenation showed distinct manners in neurons and astrocytes, implying that Pnn may play different roles in different types of neural cells in the stress response to ischemic injury.

Peroxisome Proliferator-Activated Receptor γ Coactivator 1α Activates Vascular Endothelial Growth Factor That Protects Against Neuronal Cell Death Following Status Epilepticus through PI3K/AKT and MEK/ERK Signaling

Status epilepticus may cause molecular and cellular events, leading to hippocampal neuronal cell death. Peroxisome proliferator-activated receptor γ coactivator 1-α (PGC-1α) is an important regulator of vascular endothelial growth factor (VEGF) and VEGF receptor 2 (VEGFR2), also known as fetal liver kinase receptor 1 (Flk-1). Resveratrol is an activator of PGC-1α. It has been suggested to provide neuroprotective effects in epilepsy, stroke, and neurodegenerative diseases. In the present study, we used microinjection of kainic acid into the left hippocampal CA3 region in Sprague Dawley rats to induce bilateral prolonged seizure activity. Upregulating the PGC-1α pathway will increase VEGF/VEGFR2 (Flk-1) signaling and further activate some survival signaling that includes the mitogen activated protein kinase kinase (MEK)/mitogen activated protein kinase (ERK) and phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) signaling pathways and offer neuroprotection as a consequence of apoptosis in the hippocampal neurons following status epilepticus. Otherwise, downregulation of PGC-1α by siRNA against pgc-1α will inhibit VEGF/VEGFR2 (Flk-1) signaling and suppress pro-survival PI3K/AKT and MEK/ERK pathways that are also accompanied by hippocampal CA3 neuronal cell apoptosis. These results may indicate that the PGC-1α induced VEGF/VEGFR2 pathway may trigger the neuronal survival signaling, and the PI3K/AKT and MEK/ERK signaling pathways. Thus, the axis of PGC-1α/VEGF/VEGFR2 (Flk-1) and the triggering of downstream PI3K/AKT and MEK/ERK signaling could be considered an endogenous neuroprotective effect against apoptosis in the hippocampus following status epilepticus.

Intermittent fasting and 'metabolic switch': Effects on metabolic syndrome, prediabetes and type 2 diabetes

Various intermittent fasting (IF) dietary plans have gained popularity among obese individuals in recent years as a means of achieving weight loss. However, studies evaluating the effect of IF regimens in people with metabolic syndrome, prediabetes and type 2 diabetes (T2D) are limited. The aim of the present review was to briefly elucidate the biochemical and physiological mechanisms underlying the positive effects of IF, especially the effect of the proposed 'metabolic switch' on metabolism. Next, we examined the efficacy and safety of IF regimens in individuals with metabolic syndrome, prediabetes and T2D. To achieve this, we performed a MEDLINE PubMed search using combinations of various IF terms, including trials in which participants met the additional criteria for metabolic syndrome, prediabetes or T2D. We found four studies in individuals with metabolic syndrome, one study in people with prediabetes, and eight studies in people with T2D evaluating the effects of different IF regimens. The limited available evidence, with small sample sizes and short trial durations, suggests that IF regimens have a similar effectiveness compared with calorie-restriction diets for weight loss and improvement in glycaemic variables. In general, most IF regimens are effective and safe. However, there is an increased risk of hypoglycaemia in patients with T2D who are treated with insulin or sulphonylureas. Moreover, long-term adherence to these regimens appears uncertain. There is a need for large controlled randomized trials to evaluate the efficacy of IF regimens, especially in individuals with metabolic syndrome and prediabetes. If proven to be sustainable and efficacious for prolonged periods, IF could offer a promising approach to improving health at the population level, and would result in multiple public health benefits.

Phosphodiesterase Inhibitors for Alzheimer's Disease: A Systematic Review of Clinical Trials and Epidemiology with a Mechanistic Rationale

BACKGROUND

Preclinical studies, clinical trials, and reviews suggest increasing 3',5'-cyclic adenosine monophosphate (cAMP) and 3',5'-cyclic guanosine monophosphate (cGMP) with phosphodiesterase inhibitors is disease-modifying in Alzheimer's disease (AD). cAMP/protein kinase A (PKA) and cGMP/protein kinase G (PKG) signaling are disrupted in AD. cAMP/PKA and cGMP/PKG activate cAMP response element binding protein (CREB). CREB binds mitochondrial and nuclear DNA, inducing synaptogenesis, memory, and neuronal survival gene (e.g., brain-derived neurotrophic factor) and peroxisome proliferator-activated receptor-γ coactivator-1α (PGC1α). cAMP/PKA and cGMP/PKG activate Sirtuin-1, which activates PGC1α. PGC1α induces mitochondrial biogenesis and antioxidant genes (e.g.,Nrf2) and represses BACE1. cAMP and cGMP inhibit BACE1-inducing NFκB and tau-phosphorylating GSK3β.

OBJECTIVE AND METHODS

We review efficacy-testing clinical trials, epidemiology, and meta-analyses to critically investigate whether phosphodiesteraseinhibitors prevent or treat AD.

RESULTS

Caffeine and cilostazol may lower AD risk. Denbufylline and sildenafil clinical trials are promising but preliminary and inconclusive. PF-04447943 and BI 409,306 are ineffective. Vinpocetine, cilostazol, and nicergoline trials are mixed. Deprenyl/selegiline trials show only short-term benefits. Broad-spectrum phosphodiesterase inhibitor propentofylline has been shown in five phase III trials to improve cognition, dementia severity, activities of daily living, and global assessment in mild-to-moderate AD patients on multiple scales, including the ADAS-Cogand the CIBIC-Plus in an 18-month phase III clinical trial. However, two books claimed based on a MedScape article an 18-month phase III trial failed, so propentofylline was discontinued. Now, propentofylline is used to treat canine cognitive dysfunction, which, like AD, involves age-associated wild-type Aβ deposition.

CONCLUSION

Phosphodiesterase inhibitors may prevent and treat AD.

Rehabilitation training improves nerve injuries by affecting Notch1 and SYN

Objective

The aim of this study was to investigate the effects of rehabilitation training on Notch1 and synaptophysin (SYN) levels in brain tissues of rats with chronic cerebral ischemia.

Methods

Eighty-one male Sprague-Dawley rats were divided into nine groups: three Sham groups, three Model groups, and three training groups. There were nine rats in each group. At different time points, the apoptosis cell rate was analyzed by the TUNEL assay, and the expression levels of Notch1 and SYN in brain tissues were analyzed by immunohistochemical staining and RT-qPCR assay.

Results

The apoptosis cell rate of training groups was significantly higher on day 28 (P < 0.05). The protein and mRNA levels of both Noth1 and SYN in training groups were significantly higher on day 28 (P < 0.05).

Conclusion

Rehabilitation training could improve nerve cell apoptosis by increasing the expression of both Notch1 and SYN.

Differential roles of exogenous protein disulfide isomerase A3 on proliferating cell and neuroblast numbers in the normal and ischemic gerbils

INTRODUCTION

We examined the effects of exogenous protein disulfide isomerase A3 (PDIA3) on hippocampal neurogenesis in gerbils under control and ischemic damage.

METHODS

To facilitate the delivery of PDIA3 to the brain, we constructed Tat-PDIA3 protein and administered vehicle (10% glycerol) or Tat-PDIA3 protein once a day for 28 days. On day 24 of vehicle or Tat-PDIA3 treatment, ischemia was transiently induced by occlusion of both common carotid arteries for 5 min.

RESULTS

Administration of Tat-PDIA3 significantly reduced ischemia-induced spontaneous motor activity, and the number of NeuN-positive nuclei in the Tat-PDIA3-treated ischemic group was significantly increased in the CA1 region compared to that in the vehicle-treated ischemic group. Ki67- and DCX-immunoreactive cells were significantly higher in the Tat-PDIA3-treated group compared to the vehicle-treated control group. In vehicle- and Tat-PDIA3-treated ischemic groups, the number of Ki67- and DCX-immunoreactive cells was significantly higher as compared to those in the vehicle- and Tat-PDIA3-treated control groups, respectively. In the dentate gyrus, the numbers of Ki67-immunoreactive cells were comparable between vehicle- and Tat-PDIA3-treated ischemic groups, while more DCX-immunoreactive cells were observed in the Tat-PDIA3-treated group. Transient forebrain ischemia increased the expression of phosphorylated cAMP-response element-binding protein (pCREB) in the dentate gyrus, but the administration of Tat-PDIA3 robustly increased pCREB-positive nuclei in the normal gerbils, but not in the ischemic gerbils. Brain-derived neurotrophic factor (BDNF) mRNA expression was significantly increased in the Tat-PDIA3-treated group compared to that in the vehicle-treated group. Transient forebrain ischemic increased BDNF mRNA levels in both vehicle- and Tat-PDIA3-treated groups, and there were no significant differences between groups.

CONCLUSIONS

These results suggest that Tat-PDIA3 enhances cell proliferation and neuroblast numbers in the dentate gyrus in normal, but not in ischemic gerbils, by increasing BDNF mRNA and phosphorylation of pCREB.