THE EFFECT OF ENDOTOXIN-INDUCED STRESS ON SOME BIOCHEMICAL PARAMETERS IN BRAIN AND ITS MODULATION BY SOME ANTIOXIDANTS

Abstract

The effect of endotoxin (LPS) - induced stress on some biochemical parameters in male rats was investigated . The effect of pretreatment with some antioxidants in stressed rats was also concerned. Experimental stress was induced by injecting the rats with a single dose of LPS equivalent to 2mg I kg B.W. intraperitoneally and sacrificed 2h. later. The antioxidants used were vitamin E, selenium, 13- carotene and N­ acetylcysteine (NAC). In order to study the pretreatment effect of each antioxidant on endotoxin stress, the animals were subjected to the following treatments : A group was treated with a daily oral dose of vitamin E (400 IU/kg B.W) for one week before endotoxin injection. Two other groups were simultaneously treated with the same dose of vitamin E and 2 dose levels of selenium (0.2 mg I Lor 0.5 mg I L) in the drinking water for one week before stress induction. Another group was recieved a daily oral dose of 13- carotene (6.68 mg I kg B.W.) for 21 days before stress induction . • NAC was injected intraperitoneally in a new group of animals [7m mol.(l.14g) I kg B.W.], divided into 3 equal daily doses, the last dose was injected lh. before LPS injection . Two groups of stressed animals were given either sesame oil or corn oil and served as controls for groups treated with vitamin E or 13- carotene respectively. A group of untreated stressed animals was served as a control for the NAC- treated group. A group of normal animals was used as a control for the stressed animals. The effect of LPS and its modulation by antioxidants were assessed by estimating plasma corticosterone and glucose, and brain GSH, MDA, ATP, ADP, cholesterol and phospholipid contents in addition to the cytosolic SOD, Na\ K+-ATPase and hexokinase (cytosolic and mitochondrial) enzyme activities.