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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. However, current animal models have not been successful in replicating the pathology and disabilities seen in SAH patients, especially the long‐term neurocognitive deficits that affect the survivor's quality of life. 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, a standardized mouse SAH model is developed that reproducibly produced significant and trackable long‐term cognitive deficits. SAH is 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 cerebral edema measured by MRI ‐ an indicator of early brain injury (EBI), neuroinflammation, apoptosis, and long‐term cognitive impairment. This newly developed SAH mouse model is considered an ideal paradigm for investigating the complex SAH pathophysiology and identifying novel druggable therapeutic targets for treating SAH severity and SAH‐associated long‐term neurocognitive deficits in patients. [ABSTRACT FROM AUTHOR]

Background: An active lifestyle is associated with improved cognitive functions in aged people and may prevent or slow down the progression of various neurodegenerative diseases including Alzheimer's disease (AD). To investigate these protective effects, male APPNL-G-F mice were exposed to long-term voluntary exercise. Methods: Three-month-old AD mice were housed in a cage supplemented with a running wheel for 9 months for long-term exercise. At the age of 12 months, behavioral tests were completed for all groups. After completing behavioral testing, their brains were assessed for amyloid pathology, microgliosis, and cholinergic cells. Results: The results showed that APPNL-G-F mice allowed to voluntarily exercise showed an improvement in cognitive functions. Furthermore, long-term exercise also improved anxiety in APPNL-G-F mice as assessed by measuring thigmotaxis in the Morris water task. We also found reductions in amyloid load and microgliosis, and a preservation of cholinergic cells in the brain of APPNL-G-F mice allowed to exercise in their home cages. These profound reductions in brain pathology associated with AD are likely responsible for the observed improvement of learning and memory functions following extensive and regular exercise. Conclusion: These findings suggest the potential of physical exercise to mitigate the cognitive deficits in AD. [ABSTRACT FROM AUTHOR]

Concerns are growing that exposure to environmental pollutants, such as traffic noise, might cause cognitive impairments and predispose individuals toward the development of Alzheimer's disease (AD) dementia. In this study in a knock‐in mouse model of AD, we investigated how chronic traffic noise exposure (CTNE) impacts cognitive performance and amyloid‐beta (Aβ) pathology. A group of APPNL‐G‐F/NL‐G‐F mice was exposed to CTNE (70 dBA, 8 hr/day for 1 month) and compared with nonexposed counterparts. Following CTNE, an increase in hypothalamic–pituitary–adrenal (HPA) axis responsivity was observed by corticosterone assay of the blood. One month after CTNE, the CTNE group demonstrated impairments in cognitive and motor functions, and indications of anxiety‐like behavior, relative to the control animals. The noise‐exposed group also showed elevated Aβ aggregation, as inferred by a greater number of plaques and larger average plaque size in various regions of the brain, including regions involved in stress regulation. The results support that noise‐associated dysregulation of the neuroendocrine system as a potential risk factor for developing cognitive impairment and Aβ pathology, which should be further investigated in human studies. [ABSTRACT FROM AUTHOR]

Most studies investigating hippocampal‐dependent learning and memory in mouse models of disease use the standard version of the Morris water task (MWT), in which a place is learned over several days. While useful in determining if there are learning and memory deficits, often it is not clear if memory acquisition, consolidation, or retrieval is affected. For rats, we developed a variant of the task in which we added a single‐massed training session to a new location after the standard distributed version of the MWT. Using this version of the task, competition between these two spatial representations can then be assessed in a probe trial. We have found in rat models of Alzheimer's disease that this paradigm can detect subtle impairments that are often missed in the standard version of the MWT. To the best of our knowledge, MWT paradigm with a single‐massed training session have never been used for mice. We sought to validate this paradigm for the use of assessing mouse models of disease. In the first two experiments, control mice did not have a preference for the new platform location, but instead with extensive training in the massed session displayed a preference for both the old and new locations. In the third experiment, a novel mouse model of Alzheimer's disease was impaired in the standard version of the MWT, but not in the massed training phase of this paradigm. Importantly, these data demonstrate that our paradigm is more informative in characterizing spatial learning and memory in mouse models of disease. [ABSTRACT FROM AUTHOR]

In the present study, male C57BL/6J mice were subjected to gradual cerebral hypoperfusion by implanting an ameroid constrictor (AC) on the left common carotid artery (CCA) and a stenosis on the right CCA. In the sham group, all surgical procedures were kept the same except no AC was implanted and stenosis was not performed. One month following the surgical procedures, fear conditioning and object recognition tests were conducted to evaluate learning and memory functions and motor functions were assessed using a balance beam test. At the experimental endpoint, mice were perfused and brains were collected for immunostaining and histology. Learning and memory as well as motor functions were significantly impaired in the hypoperfusion group. The immunoreactivity to choline acetyltransferase was decreased in dorsal striatum and basal forebrain of the hypoperfusion group indicating that cholinergic tone in these brain regions was compromised. In addition, an increased number of Fluoro-Jade positive neurons was also found in cerebral cortex, dorsal striatum and hippocampus indicating neurodegeneration in these brain regions. Based on this pattern of data, we argued that this mouse model would be a useful tool to investigate the therapeutic interventions for the treatment of vascular dementia. Additionally, this model could be employed to exploit the effect of microvascular occlusions on cognitive impairment in the absence and presence of Alzheimer's disease pathology. [ABSTRACT FROM AUTHOR]