[The improvement effect of scFv17 on the gait of triple-transgenic mice]

To observe the gait changes of Alzheimer's disease PS1M146V/APPswe/tauP301L triple-transgenic (3xTg-AD) mice and to investigate the improvement effect of single chain variable domain antibody fragment 17 (scFv17) on the gait.

In the present study, a selection of 6-month-old 3xTg-AD mice (n=18) and C57BL/6 wild-type mice (n=24) was performed. First, we observed their gait changes and found that the gait of 12-month-old 3xTg-AD mice was severely damaged. Then, the two groups of mice were randomly divided into four groups:WT+PBS(n=12), WT+scFv17(n=12), 3xTg-AD+PBS(n=9) and 3xTg-AD+scFv17(n=9). The gait behavior test and pathological test were performed after 12 weeks'continuous administration of scFv17 (1.5 mg/kg) or an equal volume of PBS (0.01 mol/L) by nasal gavage twice a week.

Compared with the same month old wild type mice, the rear track width of 12 month old 3xTg-AD mice was increased(P<0.01), swing time percent was decreased (P<0.01), stance time percent was increased(P<0.01), so the ability of movement coordination and balance was seriously damaged. ScFv17 could improve the coordination and balance ability of 12 month old 3xTg-AD mice(P<0.01). The morphological structure of 3xTg-AD mice cerebellar Purkinje cells was improved. The treatment of scFv17 increased the Nissl body number of the cerebellar Purkinje cells of 3xTg-AD mice (P<0.01). scFv17 reduced the amyloid β protein (Aβ) plaques in the cerebellar cortex of 3xTg-AD mice (P<0.01), and scFv17 reduced the intracellular neurofibrillary tangles (NFT) of the cerebellar Purkinje cells of the 3xTg-AD mice (P<0.01).

The coordination and balance ability of 3xTg-AD mice was significantly impaired. ScFv17 can improve gait behaviour in the 3xTg-AD significantly.The mechanism may be related to the improvement of the structure and protein function of cerebellar Purkinje cells, and the eliminating of the Aβ plaques and the neurofibrillary tangles.