SHORT-TERM CHANGES IN NADPH-DIAPHORASE REACTIVITY IN RAT-BRAIN FOLLOWING PERINATAL ASPHYXIA - NEUROPROTECTIVE EFFECTS OF COLD TREATMENT

Perinatal asphyxia (PA) produces changes in nitric oxide synthase (NOS ) activity in neuronal and endothelial cells of the striatum and neoco rtex. The changes were examined using a histochemical NADPH-diaphorase (NADPH-d) staining method. Newborn rats were exposed to severe PA at 37 degrees C and other groups were subjected to severe PA under hypoth ermic condition (15 degrees C) for 20 or 100 min, respectively. Quanti tative image analysis was performed on the striatum and neocortex in o rder to count cell number of reactive neurons and to compare the patte rn of staining between the different groups of animals. Severe asphyct ic pups showed an important neuronal loss in striatum and neocortex th at was reduced by hypothermia. NADPH-d(+) neurons with reactive proces ses were found in the lateral zone of the striatum and neocortex in as phyctic pups. Controls and hypothermic striatum showed rounded cells w ithout reactive process, while no cells were stained in cortex. There was also an increase in NADPH-d activity in endothelial cells in sever e asphyctic pups in stratium and neocortex vs control and hypothermica lly treated animals. Our data evidenced that an inappropriate activati on of NOS in neuronal and endothelial cells induced by PA is related t o neuronal injury. Hypothermia inhibits neuronal injury and may be a v aluable neuroprotective agent.