In order to study the anti-inflammatory, analgesic, anti-anoxia and anti-fatigue effects of astragalus extract, 160 mice are randomly divided into 4 groups: the control group, the large, medium, and small dose groups of astragalus extract, which was chronically administered, and the control group was given an equal volume of saline the same way. The method of Xylene-induced mouse ear shell swelling was used to determine the weight of ear; acetic acid-induced writhing was calculated to in mice to determine the number of writhing responses in mice; atmospheric oxygen tolerance method was used to record mice hypoxic tolerance time; colorimetric analysis was used to determine liver glycogen and serum lactate levels in mice after 45 min swimming.

1 Effect of astragalus extract on mice’s ear swelling induced by xylene.

After comparing with the control group, large, medium and low dose groups of astragalus extract can significantly resist xylene induced ear swelling (P<0.05 or P< 0.01). The results are shown in Table 1.
Table 1 effect of astragalus extract on xylene-induced mouse ear swelling

group                                        dose C/g.kg-1       ear weight m/mg       inhibition（%）
control group                                       –                         20.1±4.7
large dose group                               0.5                       11.7±4.2**                   41
medium dose group                         0.25                     15.6±5.4*                     22
low dose group                                  0.125                   15.8±5.9*                     21

Compared with the control group, *P<0.05 **P<0.01; n=10

2 Effect of astragalus extract on writhing response of mice induced by glacial acetic acid

Compared with the control group, large, medium, and small doses of astragalus extract could significantly reduce the number of writhing in mice (P<0.05 or P<0. 01). The results are shown in Table 2.
Table 2 Effects of astragalus extract on the number of writhing in mice induced by glacial acetic acid

group                               dose C/g.kg-1               writhing numbers           analgesic rate（%）
control group                           –                                      27±12
large dose group                   0.5                                       6±3**                                78
medium dose group             0.25                                    12±6*                                 56
low dose group                      0.125                                   16±7*

Compared with the control group，*P<0.05; n=10
3 Effect of astragalus extract on anti-anoxia mice
Compared with the control group, the large and medium dose group of astragalus extract can significantly prolong the survival time of mice normal under pressure accompanying with low oxygen concentration (P<0.05), but there is no significant change in the small dose group. The results are shown in Table 3.
Table 3 Effects of astragalus extract on chlorine tolerance in mice

Dose                                 C/g.kg-1                      survival time（min）
The control group              –                                 54.3±18.7
large dose group              0.5                                94.8±45.8*
medium dose group        0.25                              74.2±24.2*
low dose group                 0.125                             77.6±22.4*

Compared with the control group, *P<0.05; n=10
4 Effects of astragalus extract on mice anti-fatigue
Compared with the control group, the liver glycogen content of mice in the large and medium dose groups increased significantly after swimming (P<0.05), and there was no significant change in the low dose group; The contents of lactic acid in all the dose groups were significantly lower than that in the control group (P<0.05).
The results are shown in Table 4.
Table 4 Effect of astragalus extract on hepatic glycogen and lactic acid content in mice

Dose                                   n         C/g.kg-1              hepatic glycogen C/mg.kg-1                lactic acid C/mg.L-1
the control group            10             –                                    23.3±5.0                                               23.3±4.5
large dose group               9            0.5                                 34.6±6.8*                                             15.4±3.2*
medium dose group        10           0.25                               33.5±5.8*                                             16.7±2.3*
low dose group                 9             0.125                             29.7±4.1*                                               17.7±3.2*

Compared with the control group, *P<0.05
Results
The experimental study shows that: astragalus extract can significantly reduce the degree of mouse ear swelling, reduce the number of mouse glacial acetic acid induced writhing reaction times, the results show that astragalus extract has obvious anti-inflammatory, analgesic effects, and the effect is especially obvious with large dose.
The experimental study found that the astragalus extract can prolong the survival time of mice under normal pressure accompanying with low oxygen concentration, and further observed that the astragalus extract can significantly increase the clearance rate of blood lactic acid after exercise and increase the content of hepatic glycogen.