Neuroprotective Benefits of Aerobic Exercise and Organoselenium Dietary Supplementation in Hippocampus of Old Rats

Swimming exercise versus L-carnosine supplementation for Alzheimer's dementia in rats: implication of circulating and hippocampal FNDC5/irisin

Recent studies have suggested that irisin may act as a potential neurokine. Exercise and L-carnosine supplementation showed neuroprotective effects in Alzheimer's disease (AD)-like conditions. However, the regulation of irisin in the hippocampus of streptozotocin (STZ)-induced memory impairment and its relation to insulin signalling remain to be investigated. This study was designed to compare the effect of swimming exercise and L-carnosine intake on serum, CSF and hippocampal irisin in rats received intracerebroventricular (ICV) injection of STZ. Rats were recruited in swimming paradigm, received oral carnosine (100 mg/kg/day) or vehicle treated. After 5 weeks, rats were sacrificed after neurobehavioural testing. CSF and serum irisin were determined. Hippocampal tissues were used to assess expression of FNDC5/irisin, BDNF and proteins related to insulin signalling, in addition to β-amyloid peptide and phosphorylated tau protein levels. We observed decreased hippocampal, but not CSF or serum, irisin in ICV-STZ-injected rats. Exercise and carnosine intake almost normalized hippocampal FNDC5/irisin expression which was associated with reduced soluble β-amyloid peptide and phosphorylated tau protein, improved BDNF and insulin signalling proteins, with corresponding mitigated cognitive impairments. However, hippocampal FNDC5/irisin was not correlated with serum or CSF irisin levels. Histologically, both interventions ameliorated the hippocampal damage in STZ-injected rats. The current study reveals that carnosine is equivalent to exercise in reversing cognitive decline and Alzheimer's biomarkers. In both interventions, enhancement of hippocampal FNDC5/irisin and insulin signalling may be involved in mediating these neuroprotective effects.

Effects of Physical Exercise on Autophagy and Apoptosis in Aged Brain: Human and Animal Studies

The aging process is characterized by a series of molecular and cellular changes over the years that could culminate in the deterioration of physiological parameters important to keeping an organism alive and healthy. Physical exercise, defined as planned, structured and repetitive physical activity, has been an important force to alter physiology and brain development during the process of human beings' evolution. Among several aspects of aging, the aim of this review is to discuss the balance between two vital cellular processes such as autophagy and apoptosis, based on the fact that physical exercise as a non-pharmacological strategy seems to rescue the imbalance between autophagy and apoptosis during aging. Therefore, the effects of different types or modalities of physical exercise in humans and animals, and the benefits of each of them on aging, will be discussed as a possible preventive strategy against neuronal death.

Hippocampal gene expression patterns linked to late-life physical activity oppose age and AD-related transcriptional decline

Exercise has emerged as a powerful variable that can improve cognitive function and delay age-associated cognitive decline and Alzheimer's disease (AD); however, the underlying mechanisms are poorly understood. To determine if protective mechanisms may occur at the transcriptional level, we used microarrays to investigate the relationship between physical activity levels and gene expression patterns in the cognitively intact aged human hippocampus. In parallel, hippocampal gene expression patterns associated with aging and AD were assessed using publicly available microarray data profiling hippocampus from young (20-59 years), cognitively intact aging (73-95 years) and age-matched AD cases. To identify "anti-aging/AD" transcription patterns associated with physical activity, probesets significantly associated with both physical activity and aging/AD were identified and their directions of expression change in each condition were compared. Remarkably, of the 2210 probesets significant in both data sets, nearly 95% showed opposite transcription patterns with physical activity compared with aging/AD. The majority (>70%) of these anti-aging/AD genes showed increased expression with physical activity and decreased expression in aging/AD. Enrichment analysis of the anti-aging/AD genes showing increased expression in association with physical activity revealed strong overrepresentation of mitochondrial energy production and synaptic function, along with axonal function and myelin integrity. Synaptic genes were notably enriched for synaptic vesicle priming, release and recycling, glutamate and GABA signaling, and spine plasticity. Anti-aging/AD genes showing decreased expression in association with physical activity were enriched for transcription-related function (notably negative regulation of transcription). These data reveal that physical activity is associated with a more youthful profile in the hippocampus across multiple biological processes, providing a potential molecular foundation for how physical activity can delay age- and AD-related decline of hippocampal function.