8-型磷酸二酯酶抑制剂PF-04957325对冈田酸诱导阿尔茨海默病小鼠认知障碍的改善作用及机制OA北大核心CSTPCD

Aim To investigate the effects of the phos-phodiesterase 8(PDE8)inhibitor PF-04957325 on learning and memory,anxiety and depression in Alzhe-imer's disease(AD)mice induced by Okadaic acid(OA),and to explore its mechanism.Methods Twenty-one 2-month-old male C57BL/6J mice were se-lected for the experiment and randomly divided into the control group,AD model group,and PDE8 inhibitor group(0.1 mg·kg-1).AD model was induced by bi-lateral hippocampal localization injection of OA(50 ng on each side)in the model and PDE8 inhibitor groups of mice.Two days after the injection of OA,PDE8 in-hibitor group was given 0.1 mg·kg-1 drug,while the AD model groups and control group were given with the same volume of vehicle for 21 consecutive days.On day 13 of inhibitor administration,behavioral tests re-lated to learning and memory abilities,anxiety and de-pressive behaviors were performed in mice.HE stai-ning was used to observe the morphology of neuronal cells in the DG,CA1,and CA3 regions of the hippo-campus of mice,and Western blot was used to detect the levels of phosphorylated Tau proteins at different sites within the hippocampus of mice as well as the ex-pression of proteins related to the PDE8/cAMP/CREB pathway.Results Compared with the control group,the Y-maze Spontaneous alternation,Recognition index of NOR and Latency of PAT were significantly shorter(P＜0.01),and Entries times、Time in the target quadrant of MWM were reduced(P＜0.05)in the AD model group,which showed a decrease in the ability of learning and memory,whereas the administration of PF-04957325 significantly improved the ability of learning and memory in the AD mice;mice in the AD model group showed a significant decrease in the num-ber of entries into the central area of the OFT and the time spent in the central area(P＜0.05),and a sig-nificant increase in the Immobility time of TST(P＜0.01),suggesting that the mice had anxiety and de-pression,and the administration of PF-04957325 did not improve the anxious behavior of the mice,but im-proved the depressed behavior to a certain extent;the hippocampus of the AD model group mice showed ker-nel solidification in the DG,CA1 and CA3 regions,and neurons were not neatly arranged,and the admin-istration of PF-04957325 could alleviate the damage of hippocampal nerve cells in mice.Compared with the control group,the phosphorylation levels of Tau protein Ser1 99,Ser396 and Ser202 sites in the hippocampus of mice in the AD model group were significantly in-creased(P＜0.01),the expression of PDE8A and PDE8B proteins was significantly increased(P＜0.01),and the expression of p-PKA/PKA and BDNF proteins was decreased(P＜0.05),after administra-tion of PF-04957325,the phosphorylation levels of Tau protein Ser396 and Ser202 sites were significantly re-duced(P＜0.01),PDE8A and PDE8B protein ex-pression was significantly decreased(P＜0.01),and p-PKA/PKA,p-CREB/CREB and BDNF protein ex-pression was significantly increased(P＜0.01).Con-clusion PDE8 inhibitor PF-04957325 can improve learning memory ability,reduce cognitive dysfunction,restore Tau protein function,and attenuate neuronal cell damage in the hippocampus of AD mice with amel-iorative effects.The mechanism of action may be relat-ed to the activation of PDE8/cAMP/CREB pathway and inhibition of Tau protein phosphorylation.