Long-term acarbose administration alleviating the impairment of spatial learning and memory in the SAMP8 mice was associated with alleviated reduction of insulin system and acetylated H4K8

•Acarbose was given to the SAMP8 mice from 3- to 9-month old.•Acarbose could alleviate the age-related defects of spatial learning and memory.•Acarbose ameliorated reduction of serum insulin and hippocampal InsRs in the old mice.•Acarbose could alleviate the age-associated decrease of H4K8ac in hippocampus.•Elevated insulin system and H4K8ac might be related to the behavioral acarbose effect.

Age-associated memory impairment (AAMI) not only reduces the quality of life for the elderly but also increases the costs of healthcare for society. Methods that can regulate glucose metabolism, insulin/insulin-like growth factor 1 (IGF-1) system and acetylated histone H4 lysine 8 (H4K8ac), one of the most well-researched facets of histone acetylation modification associating with cognition, tend to ameliorate the AAMI. Here, we used SAMP8 mice, the excellent animal model of aging and AAMI, to study the effect of long-term treatment with acarbose, an inhibitor of a-glucosidase, on AAMI and explore whether blood glucose, insulin/IGF-1 system and H4K8ac are associated with potential effects. The treatment group received acarbose (20 mg/kg/d, dissolved in drinking water) at the age of 3-month until 9-month old before the behavioral test, and the controls only received water. Compared to the young controls (3-month-old, n=11), the old group (9-month-old, n=8) had declined abilities of spatial learning and memory and levels of serum insulin, hippocampal insulin receptors (InsRs) and H4K8ac. Interestingly, the acarbose group (9-month-old, n=9) showed better abilities of spatial learning and memory and higher levels of insulin, InsRs and H4K8ac relative to the old controls. Good performance of spatial learning and memory was positively correlated with the elevated insulin, InsRs and H4K8ac. All these results suggested that long-term administration of acarbose could alleviate the age-related impairment of spatial learning and memory in the SAMP8 mice, and the alleviated reduction of an insulin system and H4K8ac might be associated with the alleviation.