Change Of HO-1 Activity And Endogenous Carbon Monoxide Level In The Brain Of Newborn Hypoxic Ischmia Rats

Objective: To study the expression of heme oxygenase-l(HO-l) and endogenous carbon monoxide in the brain of neonatal rats following cerebral hypoxia-ischemia (HI) and effect of the Znpp on it .To discuss that whether there are some relations between endogenous CO and HIE. Methods: 125 SD rats were divided into there groups : normal group, hypoxic-ischemia group(HI), hypoxic-ischemia +Znpp group (Hl+Znpp) at random. The rats in Hl+Znpp group were injected with Znpp (45 u mo I/Kg) into abdominal cavity before hypoxic-ischemia. As the method that Rice has reported, rats in HI and Hl+Znpp groups were anaesthetized with 1% pentobarbitone (30mg/kg), then their left carotids were separated and ligated .After these operations, these rats had rested for 1 hour. Then they were put into a cabin with 8%O2 and 92%N2 for 2 hours. The O2 concentration of the cabin was maintained at 8%. HO-1 activity, cGMP level in the brain tissue and carbon monoxide level in the blood were observed respectively at 0, 1,4,12 and 24 h after hypoxic-ischemia .RESULTS: (1)CO (0.84+0.18) and cGMP (0.72?.04) level offflgroupincreased as compared with control group at Oh after HI (0.52+0.15)>(0.43+0.09) (p<0.01),but there is no significant difference as compared withHI+Znpp group (P>0.05). ㏕here is no significant difference of HO-1 activity among all groups at Oh after tQ(P>0.05). (3)HO-1 activity > CO and cGMP level of HI group were significant higher than those of control and HI+Znpp groups at 1,4,12h(/*<0.01).These parameters of HI+Znpp group decreased as compared with HI group (P<0.01).Conclusion: (1) HO-1 was highly expressed in brain of hypoxic-ischemia neonatal rat, and correlated with increase of CO and cGMP level. (2) Znpp, the inhibitor of HO, can depress the activity of HO, then reduce the level of CO and cGMP. (3) HO-CO- cGMP system may play an important role in the pathogenesis of hypoxia-ischemia brain disease .