Title : Effect of nacre extract from pearl oyster shells against BPSD-like symptoms in senescence-accelerated mouse p8
Abstract:
Background: Pearl powder has been utilized in Traditional Chinese medicine for convulsions, epilepsy, and myopia, as well as in functional foods and cosmetics. Patients with Alzheimer's disease (AD) and other types of dementia exhibit behavioral and psychological symptoms of dementia (BPSD), including aggression, wandering, anxiety, and depression. We have showed that an extract from nacreous layer (nacre extract) in pearl oyster shells can ameliorates lipopolysaccharide (LPS)-induced depression- and anxiety-like behavior. In this study, we aimed to investigate the effect of nacre extract against age-related anxious and depressive behavior in SAMP8 mice.
Methods: SAMP8 mice were fed a basal diet without nacre extract or with 125mg/kg nacre extract or 250mg/kg nacre extract. Control mice (SAMR1) were fed a basal diet for 6 months. Behavioral tests were performed to assess anxiety, depression, circadian rhythm, and aggressiveness of mice. Following the behavioral tests, RNA-seq analyses were conducted to investigate the bioactive mechanisms of nacre extract.
Results: Nacre extract improved anxious and depressive behaviors of SAMP8 mice in the forced swimming test and the elevated plus maze test. Treatment with nacre extract also decreased aggressiveness and normalized circadian rhythm disorder in SAMP8 mice. These results indicate that the nacre extract is also effective in mitigating age-related aggressive behavior and circadian rhythm disorders in SAMP8 mice. RNA-seq analysis showed that the expressions of some ER stress-related genes were upregulated in SAMP8 mice compared to the SAMR1 mice and the treatment with nacre extract restored the expressions. In addition, nacre extract suppressed the increase in the expressions of inflammation-related proteins in SAMP8 brain and the neuronal degenerations in hippocampus associated with aging of SAMP8 mice.
Conclusion: Our findings suggest that the nacre extract can alleviate BPSD-like behavior in SAMP8 mice by suppressing ER stress and neurodegeneration. Nacre extract may be a useful substance for suppressing BPSD.
Audience Take Away Notes:
- Oral administration of nacre extract suppresses anxiety and depressive behavior in SAMP8 mice.
- Nacre extract suppresses ER stress and inflammation in the brain.
- Nacre extract ameliorates aggressive behavior and disruption of circadian rhythms in SAMP8 mice.
