Dramatic impacts on brain pathology, anxiety, and cognitive function in the knock-in APPNL-G-F mouse model of Alzheimer disease following long-term voluntary exercise

Long-term voluntary running improves cognitive ability in developing mice by modulating the cholinergic system, antioxidant ability, and BDNF/PI3K/Akt/CREB pathway

Moderate physical exercise has positive effects on memory. The present study aimed to investigate the impact of long-term exercise on spatial memory in developing mice, as well as its association with the cholinergic system, antioxidant activities, apoptosis factor, and BDNF/PI3K/Akt/CREB pathway in the brain. In this study, Y maze and Novel object recognition (NOR) tests were employed to assess the impact of long-term voluntary exercise on memory. The cholinergic system, antioxidant activities, and apoptosis factors in the brain were quantified using Elisa. Additionally, western blot analysis was conducted to determine the expression of relevant proteins in the BDNF/PI3K/Akt/CREB pathway. The findings demonstrated that prolonged voluntary wheel running exercise enhanced memory in developing mice, concomitant with increased catalase (CAT) activity and decreased malondialdehyde (MDA) levels in the brain. Moreover, it could also increase the hippocampal acetylcholine (ACh) content and suppress the expression of neuronal apoptosis protein. Additionally, exercise also upregulated the expression of brain-derived neurotrophic factor (BDNF), tropomyosin receptor kinase B (TrkB), phosphoinositide 3 kinases (PI3K), Akt, cAMP response element-binding protein (CREB), and phosphorylated cAMP response element-binding protein (p-CREB) in the hippocampus. These findings suggest that long-term voluntary wheel running exercise improves the spatial memory of developing mice by modulating the cholinergic system, antioxidant activities, apoptosis factors, and activating the BDNF/PI3K/Akt/CREB pathway.

Development and validation of prechiasmatic mouse model of subarachnoid hemorrhage to measure long-term neurobehavioral impairment

Controllable and reproducible animal models of aneurysmal subarachnoid hemorrhage (SAH) are crucial for the systematic study of the pathophysiology and treatment of this debilitating condition. Despite the variety of animal models of SAH currently available, attempts to translate promising therapeutic strategies from preclinical studies to humans have largely failed. This failure is likely due, at least in part, to poor replication of pathology and disabilities in these preclinical models, especially the long-term neurocognitive deficits that drive poor quality of life / return to work in SAH survivors. Therefore, there is an unmet need to develop experimental models that reliably replicate the long-term clinical ramifications of SAH - especially in mice where genetic manipulations are straightforward and readily available. To address this need, we developed a standardized mouse model of SAH that reproducibly produced significant and trackable long-term neurobehavioral deficits. SAH was induced by performing double blood injections into the prechiasmatic cistern - a simple modification to the well-characterized single prechiasmatic injection mouse model of SAH. Following SAH, mice recapitulated key characteristics of SAH patients including long-term cognitive impairment as observed by a battery of behavioral testing and delayed pathophysiologic processes assayed by neuroinflammatory markers. We believe that this new SAH mouse model will be an ideal paradigm for investigating the complex pathophysiology of SAH and identifying novel druggable therapeutic targets for treating SAH-associated long-term neurocognitive deficits in patients.

Perinatal choline supplementation prevents learning and memory deficits and reduces brain amyloid Aβ42 deposition in AppNL-G-F Alzheimer's disease model mice

Alzheimer's disease (AD) is characterized by cognitive and memory impairments and neuropathological abnormalities. AD has no cure, inadequate treatment options, and a limited understanding of possible prevention measures. Previous studies have demonstrated that AD model mice that received a diet high in the essential nutrient choline had reduced amyloidosis, cholinergic deficits, and gliosis, and increased neurogenesis. In this study, we investigated the lifelong effects of perinatal choline supplementation on behavior, cognitive function, and amyloidosis in AppNL-G-F AD model mice. Pregnant and lactating mice were given a diet containing either 1.1 g/kg (control) or 5 g/kg (supplemented) of choline chloride until weaning and subsequently, all offspring received the control diet throughout their life. At 3, 6, 9, and 12 months of age, animals were behaviorally tested in the Open Field Test, Elevated Plus Maze, Barnes Maze, and in a contextual fear conditioning paradigm. Immunohistochemical analysis of Aβ42 was also conducted on the brains of these mice. AppNL-G-F mice displayed hippocampal-dependent spatial learning deficits starting at 3-months-old that persisted until 12-months-old. These spatial learning deficits were fully prevented by perinatal choline supplementation at young ages (3 and 6 months) but not in older mice (12 months). AppNL-G-F mice also had impaired fearful learning and memory at 9- and 12-months-old that were diminished by choline supplementation. Perinatal choline supplementation reduced Aβ42 deposition in the amygdala, cortex, and hippocampus of AppNL-G-F mice. Together, these results demonstrate that perinatal choline supplementation is capable of preventing cognitive deficits and dampening amyloidosis in AppNL-G-F mice and suggest that ensuring adequate choline consumption during early life may be a valuable method to prevent or reduce AD dementia and neuropathology.

Land/Water Aerobic Activities: Two Sides of the Same Coin. A Comparative Analysis on the Effects in Cognition of Alzheimer's Disease

 Evidence in the literature indicates that aerobic physical activity may have a protective role in aging pathologies. However, it has not been clarified whether different types of aerobic exercise produce different effects. In particular, these potential differences have not been explored in patients with Alzheimer's disease (AD). The present narrative review has the specific aim of evaluating whether land (walking/running) and water (swimming) aerobic activities exert different effects on cognitive functions and neural correlates in AD patients. In particular, the investigation is carried out by comparing the evidence provided from studies on AD animal models and on patients. On the whole, we ascertained that both human and animal studies documented beneficial effects of land and water aerobic exercise on cognition in AD. Also, the modulation of numerous biological processes is documented in association with structural modifications. Remarkably, we found that aerobic activity appears to improve cognition per se, independently from the specific kind of exercise performed. Aerobic exercise promotes brain functioning through the secretion of molecular factors from skeletal muscles and liver. These molecular factors stimulate neuroplasticity, reduce neuroinflammation, and inhibit neurodegenerative processes leading to amyloid-β accumulation. Additionally, aerobic exercise improves mitochondrial activity, reducing oxidative stress and enhancing ATP production. Aerobic activities protect against AD, but implementing exercise protocols for patients is challenging. We suggest that health policies and specialized institutions should direct increasing attention on aerobic activity as lifestyle modifiable factor for successful aging and age-related conditions.

Repeated multi-domain cognitive training prevents cognitive decline, anxiety and amyloid pathology found in a mouse model of Alzheimer disease

Education, occupation, and an active lifestyle, comprising enhanced social, physical, and mental components are associated with improved cognitive functions in aged people and may delay the progression of various neurodegenerative diseases including Alzheimer's disease. To investigate this protective effect, 3-month-old APPNL-G-F/NL-G-F mice were exposed to repeated single- or multi-domain cognitive training. Cognitive training was given at the age of 3, 6, & 9 months. Single-domain cognitive training was limited to a spatial navigation task. Multi-domain cognitive training consisted of a spatial navigation task, object recognition, and fear conditioning. At the age of 12 months, behavioral tests were completed for all groups. Then, mice were sacrificed, and their brains were assessed for pathology. APPNL-G-F/NL-G-F mice given multi-domain cognitive training compared to APPNL-G-F/NL-G-F control group showed an improvement in cognitive functions, reductions in amyloid load and microgliosis, and a preservation of cholinergic function. Additionally, multi-domain cognitive training improved anxiety in APPNL-G-F/NL-G-F mice as evidenced by measuring thigmotaxis behavior in the Morris water maze. There were mild reductions in microgliosis in the brain of APPNL-G-F/NL-G-F mice with single-domain cognitive training. These findings provide causal evidence for the potential of certain forms of cognitive training to mitigate the cognitive deficits in Alzheimer disease.

Advancing Alzheimer's Therapeutics: Exploring the Impact of Physical Exercise in Animal Models and Patients

Alzheimer's disease (AD) is the main neurodegenerative disorder characterized by several pathophysiological features, including the misfolding of the tau protein and the amyloid beta (Aβ) peptide, neuroinflammation, oxidative stress, synaptic dysfunction, metabolic alterations, and cognitive impairment. These mechanisms collectively contribute to neurodegeneration, necessitating the exploration of therapeutic approaches with multiple targets. Physical exercise has emerged as a promising non-pharmacological intervention for AD, with demonstrated effects on promoting neurogenesis, activating neurotrophic factors, reducing Aβ aggregates, minimizing the formation of neurofibrillary tangles (NFTs), dampening inflammatory processes, mitigating oxidative stress, and improving the functionality of the neurovascular unit (NVU). Overall, the neuroprotective effects of exercise are not singular, but are multi-targets. Numerous studies have investigated physical exercise's potential in both AD patients and animal models, employing various exercise protocols to elucidate the underlying neurobiological mechanisms and effects. The objective of this review is to analyze the neurological therapeutic effects of these exercise protocols in animal models and compare them with studies conducted in AD patients. By translating findings from different approaches, this review aims to identify opportune, specific, and personalized therapeutic windows, thus advancing research on the use of physical exercise with AD patients.

Exposure to quasi-ultrafine particulate matter accelerates memory impairment and Alzheimer's disease-like neuropathology in the AppNL-G-F knock-in mouse model

Exposure to traffic-related air pollution consisting of particulate matter (PM) is associated with cognitive decline leading to Alzheimer's disease (AD). In this study, we sought to examine the neurotoxic effects of exposure to ultrafine PM and how it exacerbates neuronal loss and AD-like neuropathology in wildtype (WT) mice and a knock-in mouse model of AD (AppNL-G-F/+-KI) when the exposure occurs at a prepathologic stage or at a later age with the presence of neuropathology. AppNL-G-F/+-KI and WT mice were exposed to concentrated ultrafine PM from local ambient air in Irvine, California, for 12 weeks, starting at 3 or 9 months of age. Particulate matter-exposed animals received concentrated ultrafine PM up to 8 times above the ambient levels, whereas control animals were exposed to purified air. Particulate matter exposure resulted in a marked impairment of memory tasks in prepathologic AppNL-G-F/+-KI mice without measurable changes in amyloid-β pathology, synaptic degeneration, and neuroinflammation. At aged, both WT and AppNL-G-F/+-KI mice exposed to PM showed a significant memory impairment along with neuronal loss. In AppNL-G-F/+-KI mice, we also detected an increased amyloid-β buildup and potentially harmful glial activation including ferritin-positive microglia and C3-positive astrocytes. Such glial activation could promote the cascade of degenerative consequences in the brain. Our results suggest that exposure to PM impairs cognitive function at both ages while exacerbation of AD-related pathology and neuronal loss may depend on the stage of pathology, aging, and/or state of glial activation. Further studies will be required to unveil the neurotoxic role of glial activation activated by PM exposure.