Objective     To observe the effects of hyperbaric oxygen preconditioning (HBOP) and  hypobaric hypoxia preconditioning (HHP) on the infarct volume after permanent middle cerebral artery occlusion (MCAO) in rabbits and investigate the neuroprotective effects of the 2 preconditioning methods.     Methods    Totally 72 male rabbits were randomly and equally divided into 3 groups

simple MCAO group

HBOP+MCAO group and HHP+MCAO group. The improved Bederson method was used to establish rabbits permanent MCAO model. The neurological deficits

pathological changes and infarct volumes were detected at 1

3

10 and 20 d after permanent MCAO.     Results     Compared with simple MCAO group

the score of neurological deficits was reduced significantly in HBOP group and HHP group at every time points after permanent MCAO (P0.05). In the simple MCAO group

the score were (3.91±0.14)

(3.42±0.47)

(2.03±0.56) and (1.97±035) respectively

but for the HBOP and HHP groups

the scores were (3.58±0.27) and (3.47±0.46)

(2.85±0.69) and (278±0.70)

(1.63±0.81) and (1.59±1.02)

and (1.55±1.12) and (1.41±082)  respectively. The infarct volumes were (332.0±17.6) and (324.2±15.4)

(202.2±12.2) and (208.1±12.1)

and (195.3±14.3) and (201.9±9.9) in HBOP group and HHP group at 3

10

20 d after permanent MCAO

which was significantly lower than simple MCAO group.     Conclusion    HBOP and HHP can improve neurological deficits and reduce infarct volume in rabbits after permanent MCAO.