The Hainan papaya extract’s effect on anti-aging,learning and memory of aging model mice induced by D-galactose

Objective:To explore the effects of Hainan papaya extract on learning and memory impairment and anti‑aging in D‑galactose‑induced aging mice.Methods:A total of 72 Kunming mice with normal cognitive ability screened by water maze test were randomly divided into negative control group,model group,piracetam group,high,medium and low dose groups of Hainan papaya extract(400 mg/kg,200 mg/kg,100 mg/kg),with 12 mice in each group.Hainan papaya extract and piracetam group were given the above drugs by gavage every day,The negative control and model groups were given the same amount of 0.9%NaCl solution in the same way.Mice in each group were weighed once a week;At the same time,except for the negative control group,mice in each group were intraperitoneally injected with 2%D‑galactose every day,and the negative control group was intraperitoneally injected with normal saline for 7 weeks.After 7 weeks,We observed each group of mice’s capacity of learning and memory by Morris water maze behavioral test;Then,the content of superoxide dismutase(SOD),malondialdehyde(MDA),catalase(CAT),and nitric oxide synthase(NOS)were measured;On the other hand,we observed the hippocampus’histopathological changes by hematoxylin‑eosin staining,and measured the protein expression of nuclear factor‑E2‑related factor(Nrf2)in brain tissue of mice in each group by Western blot.Results:After the intervention of Hainan papaya extract on aging model mice,the high,medium and low dose groups could shorten the swimming time and swimming distance of mice to varying degrees,increase the activities of SOD,CAT and NOS in mouse brain tissue and reduce the content of MDA,The performance of high dose group was better than piracetam group(P<0.01).At the same time,it can improve the histopathological changes of neurons in mouse hippocampus by reducing neuronal nuclear pyknosis,and increase the expression of Nrf2 protein in mouse brain in a dose‑dependent manner.Conclusion:Hainan papaya extract is able to postpone various physical signs of subacute aging mice caused by D‑galactose,and possesses definite anti‑aging and antioxidant effects,which may be related to the regulation of Nrf2 signal pathway.