The DND could not be decreased not only, but increased in a condition of ischemic preconditioning for 5 min followed by 6 min injured ischemia at a interval of 1 d or ischemic preconditioning for 3 min followed by ischemia for 6 min at a interval of 1 h.

• 5min缺血预处理对间隔 1d后 6min缺血 ,以及 3min缺血预处理对间隔 1h后 6min缺血引起的DND不但没有保护作用 ,反而有使海马组织损伤累积加重的趋势。