Comparative overview of the effects of aerobic and resistance exercise on anxiety-like behavior, cognitive flexibility, and hippocampal synaptic plasticity parameters in healthy rats

Effects of different exercise modes and intensities on cognitive performance, adult hippocampal neurogenesis, and synaptic plasticity in mice

Exercise can induce beneficial improvements in cognition. However, the effects of different modes and intensities of exercise have yet to be explored in detail. This study aimed to identify the effects of different exercise modes (aerobic and resistance) and intensities (low and high) on cognitive performance, adult hippocampal neurogenesis and synaptic plasticity in mice. A total of 40 C57BL/6J mice were randomised into 5 groups (n = 8 mice per group): control, low-intensity aerobic exercise, high-intensity aerobic exercise, low-intensity resistance exercise, and high-intensity resistance exercise. The aerobic exercise groups underwent treadmill training, while the resistance exercise groups underwent ladder climbing training. At the end of the exercise period, cognitive performance was assessed by the Y-maze and Barnes maze. In addition, adult hippocampal neurogenesis was evaluated immunohistochemically by 5-bromo-2'-deoxyuridine (BrdU)/ neuronal nuclei (NeuN) co-labeling. The levels of synaptic plasticity-related proteins in the hippocampus, including synaptophysin (SYP) and postsynaptic density protein 95 (PSD-95), were analyzed by western blotting. Our results showed no significant differences in cognitive performance among the groups. However, high-intensity aerobic exercise significantly increased hippocampal adult neurogenesis relative to the control. A trend towards increased adult neurogenesis was observed in the low-intensity aerobic group compared to the control group. No significant changes in synaptic plasticity were observed among all groups. Our results indicate that high-intensity aerobic exercise may be the most potent stimulator of adult hippocampal neurogenesis.

Amelioration of nonylphenol-induced anxiety/depression-like behaviors in male rats using green tea and Zn-Se tea interventions

Objective

This study aimed to investigate the effects of exposure to nonylphenol (NP) on anxiety/depression-like behaviors in rats and alleviation of those effects via green tea and zinc selenium (Zn-Se) tea interventions.

Material and Methods

Totally, 40 male specific-pathogen free (SPF) Sprague-Dawley (SD) male rats were randomly divided into four groups (n = 10 rats per group): control group (5 ml/kg corn oil), NP group (40 mg/kg NP), NP + GT group (40 mg/kg NP + 1 g/kg/day green tea), and NP + Zn-Se tea group (40 mg/kg NP + 1 g/kg/day ZST). All dose-based groups received oral gavage of either corn oil or drugs over a 6-month period: NP at a dosage of 40 mg/kg/day was administered to rats for the initial 3 months, followed by a combination of NP with green tea and NP with Zn-Se tea for the subsequent 3 months.

Results

Tea intervention resulted in weight loss in rats. The hippocampal tissue NP level in the tea group was slightly lower than that in the NP group. Following tea intervention, compared with the NP group, the residence time in the light-dark box test was shortened PGT = 0.048, P < 0.001), and the number of entries into the closed arm in the elevated plus maze test in the tea-treated group was significantly reduced. In addition, the immobility time in the central square in the open field test decreased. The sucrose preference index score in the sucrose preference test increased, and the immobility time in the forced swimming test was reduced (PGT = 0.049, PZST < 0.001). The effects of Zn-S e tea were superior to green tea. The damage to the hippocampal tissues in the group treated with tea was less than that in the NP group. The cellular arrangement was tighter with degeneration, deepstaining, and pyknotic nerve cells were visible. The nuclei in the NP group were atrophied, and the cells were sparsely arranged. Compared with the control group, serum brain-derived neurotrophic factor (BDNF) level was lower in the NP group. The serum corticosterone level in the NP group was elevated. Compared with the NP group, serum corticosterone level was reduced in the NP + Zn-Se tea group.

Conclusion

Chronic NP exposure induced anxiety/depression-like behaviors in rats. Green tea effectively reduced the damage to the hippocampus and prefrontal cortex induced by NP. The effects of Zn-Se tea were slightly more noticeable than those of conventional green tea.

Highlights

1) Chronic NP exposure induced anxiety/depression-like behaviors in rats.2) Zn-Se tea reduced the damage of hippocampal and prefrontal cortex induced by NP.3) NP-induced depression accompanied by the changes of BDNF, CORT and neuropathology.

Effectiveness of Resistance Exercise on Cognitive Function in Animal Models of Alzheimer Disease: A Systematic Review and Meta-Analysis

AIM

Alzheimer's disease (AD) is among common cause of dementia. Complementary therapies, such as resistance exercise (RE), have been proposed as an alternative for the treatment of AD. We performed a systematic review and meta-analysis to investigate the effects of RE on the cognitive function of AD animal models and their physiological mechanisms.

METHODS

This review was submitted to PROSPERO (CRD42019131266) and was done according to PRISMA checklist. Four databases were used in the search: MEDLINE/PUBMED, SCOPUS, Web of Science and Google Scholar. We used SYRCLE and CAMAREDES to assess the risk of bias and methodological quality. We calculated the standardized mean difference using 95% confidence intervals and considered the random effects model and p < 0.05 to determine significance.

KEY FINDINGS

A total of 1,807 studies were founded, and after the selection process, only 11 studies were included in this review and 8 studies were included for meta-analysis. Four studies applied RE before AD induction, 7 studies applied RE after AD induction or in the AD condition. All studies included 550 adult and older animals weighing 25-280g. Our analysis revealed that RE had a positive effect on memory in AD animal models but did not show a significant impact on anxiety.

CONCLUSION

RE performed four or six weeks, more than three days a week, had a significant protective effect on memory. The included studies had a high risk of bias and moderate methodological quality. Therefore, RE can be a potential strategy for preventing cognitive decline in animal models.

Effect of Quinolinic Acid on Behavior, Morphology, and Expression of Inflammatory/oxidative Status in Rats' Striatum: Is Coenzyme Q10 a Good Protector?

Quinolinic acid (QUIN) is a toxic compound with pro-oxidant, pro-inflammatory, and pro-apoptotic actions found at high levels in the central nervous system (CNS) in several pathological conditions. Due to the toxicity of QUIN, it is important to evaluate strategies to protect against the damage caused by this metabolite in the brain. In this context, coenzyme Q10 (CoQ10) is a provitamin present in the mitochondria with a protective role in cells through several mechanisms of action. Based on these, the present study was aimed at evaluating the possible neuroprotective role of CoQ10 against damage caused by QUIN in the striatum of young Wistar rats. Twenty-one-day-old rats underwent a 10-day pretreatment with CoQ10 or saline (control) intraperitoneal injections and on the 30th day of life received QUIN intrastriatal or saline (control) administration. The animals were submitted to behavior tests or euthanized, and the striatum was dissected to neurochemical studies. Results showed that CoQ10 was able to prevent behavioral changes (the open field, object recognition, and pole test tasks) and neurochemical parameters (alteration in the gene expression of IL-1β, IL-6, SOD, and GPx, as well as in the immunocontent of cytoplasmic Nrf2 and nuclear p-Nf-κβ) caused by QUIN. These findings demonstrate the promising therapeutic effects of CoQ10 against QUIN toxicity.

Walking, Running, Swimming: An Analysis of the Effects of Land and Water Aerobic Exercises on Cognitive Functions and Neural Substrates

In the brain and cognitive reserves framework, aerobic exercise is considered as a protective lifestyle factor able to induce positive effects on both brain structure and function. However, specific aspects of such a beneficial effect still need to be completely clarified. To this aim, the present narrative review focused on the potential brain/cognitive/neural reserve-construction mechanisms triggered by different aerobic exercise types (land activities; such as walking or running; vs. water activities; such as swimming), by considering human and animal studies on healthy subjects over the entire lifespan. The literature search was conducted in PubMed database. The studies analyzed here indicated that all the considered kinds of activities exert a beneficial effect on cognitive/behavioral functions and on the underlying brain neurobiological processes. In particular, the main effects observed involve the cognitive domains of memory and executive functions. These effects appear related to structural and functional changes mainly involving the fronto-hippocampal axis. The present review supports the requirement of further studies that investigate more specifically and systematically the effects of each type of aerobic activity, as a basis to plan more effective and personalized interventions on individuals as well as prevention and healthy promotion policies for the general population.

Voluntary physical activity improves spatial and recognition memory deficits induced by post-weaning chronic exposure to a high-fat diet

Childhood and adolescent exposure to obesogenic environments has contributed to the development of several health disorders, including neurocognitive impairment. Adolescence is a critical neurodevelopmental window highly influenced by environmental factors that affect brain function until adulthood. Post-weaning chronic exposure to a high-fat diet (HFD) adversely affects memory performance; physical activity is one approach to coping with these dysfunctions. Previous studies indicate that voluntary exercise prevents HFD's detrimental effects on memory; however, it remains to evaluate whether it has a remedial/therapeutical effect when introduced after a long-term HFD exposure. This study was conducted on a diet-induced obesity mice model over six months. After three months of HFD exposure (without interrupting the diet) access to voluntary physical activity was provided. HFD produced weight gain, increased adiposity, and impaired glucose tolerance. Voluntary physical exercise ameliorated glucose tolerance and halted weight gain and fat accumulation. Additionally, physical activity mitigated HFD-induced spatial and recognition memory impairments. Our data indicate that voluntary physical exercise starting after several months of periadolescent HFD exposure reverses metabolic and cognitive alterations demonstrating that voluntary exercise, in addition to its known preventive effect, also has a restorative impact on metabolism and cognition dysfunctions associated with obesity.

Exercise type influences the effect of an acute bout of exercise on hippocampal neuronal activation in mice

The effects of exercise on the hippocampus depend on exercise conditions. Exercise intensity is thought to be a dominant factor that influences the effects of exercise on the hippocampus; however, it is uncertain whether the type of exercise influences its effectiveness. This study investigated whether the effect of an acute bout of exercise on hippocampal neuronal activation differs between two different types of exercise: treadmill and rotarod exercise. The intensities of both exercises were matched at just below the lactate threshold (LT), based on blood lactate concentration. Immunohistochemical examination of c-Fos, a marker of neuronal activation, revealed that treadmill exercise at 15 m/min (T15) significantly increased c-Fos expression in all subfields of the hippocampus (dentate gyrus DG, CA1, CA3), but rotarod exercise at 30 rpm (R30) did not, as compared with the respective control groups. These results demonstrate that moderate treadmill exercise more efficiently evokes hippocampal neuronal activation than does intensity-matched rotarod exercise. This suggests that exercise type is another important factor affecting the effects of exercise on the hippocampus.

Exercise Training Improves Memory Performance in Older Adults: A Narrative Review of Evidence and Possible Mechanisms

As human life expectancy increases, cognitive decline and memory impairment threaten independence and quality of life. Therefore, finding prevention and treatment strategies for memory impairment is an important health concern. Moreover, a better understanding of the mechanisms involved underlying memory preservation will enable the development of appropriate pharmaceuticals drugs for those who are activity limited. Exercise training as a non-pharmacological tool, has been known to increase the mean lifespan by maintaining general body health and improving the cardiovascular and nervous systems function. Among different exercise training protocols, aerobic exercise has been reported to prevent the progression of memory decline, provided adequate exertion level, duration, and frequency. Mechanisms underlying exercise training effects on memory performance have not been understood yet. Convergent evidence suggest several direct and indirect mechanisms at molecular and supramolecular levels. The supramolecular level includes improvement in blood circulation, synaptic plasticity and neurogenesis which are under controls of complex molecular signaling of neurotransmitters, neurotrophic factors, exerkines, and epigenetics factors. Among these various factors, irisin/BDNF signaling seems to be one of the important mediators of crosstalk between contracted skeletal muscles and the brain during exercise training. This review provides an affordable and effective method to improve cognitive function in old ages, particularly those who are most vulnerable to neurodegenerative disorders.