Objective To explore the expression of adrenomedulin(ADM) and its receptors mRNA in newborn rats with hypoxic-ischemic brain damage(HIBD).Methods Eighty 7-day-old Wistar neonatal rats were randomly assigned 10 groups,to the sham- operation group(the left common carotid artery without ligated and no hpoxia environment),HIBD different time points groups(0,2,4,6,8,10,12,24,48 hours).The expression of ADM mRNA was measured in cortex at different time points by the reverse-transcription polymerase chain reaction(RT-PCR).Results Expressions of ADM and its receptors mRNA in neonatal rats with HIBD increased,and after HIBD 2-4 hours,had a significant difference compared with the sharn-operation group,and reached the highest after HIBD 8-10 hours(P