To investigate the effects of
naloxone on the cerebral resuscitation, fifteen newborn pigs were randomly divided into three
groups:gronp I serving as the normal control;group Ⅱ and Ⅲ with the left common carotid artery being tied off and inhaling a mixture of 80% oxygen and 92 % nitrogen over one hour,moreover,group Ⅲ immediately following the above precedures administrated intracardiacally with naloxone 2mg.kg-1 and thirty minutes later given a supplemental dose naloxone ling kg-1 to maitain the duration of another thirty minutes. The left
cerebral tissuses samples of three groups were taken simultanously to measure respectively the contents of lactic acid (LA), glucose (GL), superoxide dismutase (SOD) and lipid peroxides (LPO) by biochemical methods,or to observe the pathological changes by electron microscope. The results showed that as compared with those in group I,the levels of LA and LPO significantly increased,the contents of GL and SOD markedly decreased in group Ⅱ(P<0. 05 ),and except the level of LPO rose drastically (P<0. 01 ),there weren't statistical differences in the levels of other parameteres in group Ⅲ(P>0. 05). The levels of GL and SOD were higher and one of LA was lower in group Ⅲthan in group Ⅲ(P< 0. 05),and between both groups there wasn't a significant difference in the level of LPO (P>0. 05). In group Ⅱthere were the seriously
swelling mitochondria,severe hemorrhage and partial necrosis, however,in group Ⅲ mild hemorrhage and slightly swelling mitochondrias occured without necrosis. It is concluded that naloxone may have certain therapeutic effect on incomplete cerebral ischemic-hypoxic damage,which may be related to the elimination of free radicals.