Oxygen free radicals (OFRs) have been suggested to be a contributory f
actor in complications of diabetes mellitus. In the present study, we
investigated the lipid peroxide level measured as thiobarbituric acid
reactive substances (TBARS) and activities of antioxidant enzymes viz.
, [superoxide dismutase (SOD), catalase (CAT) and glutathione-peroxida
se (GSH-Px)] in the kidney of streptozotocin induced diabetic rats at
various stages of development of diabetes. Sprague Dawley rats were di
vided into two groups: group I, control (n = 42) and group II, diabeti
c (n = 42). Each group was further subdivided into seven groups each c
onsisting of six rats. Rats in subgroups were studied at weekly interv
als (0 to 6 weeks). Blood glucose levels were estimated at the time of
sacrifice. TBARS levels and activity of antioxidant enzymes were meas
ured in kidney. The levels of TEARS in the diabetic group increased in
itially, dropped to baseline level after 2 weeks and then progressivel
y increased at 5(th) and 6(th) week (p < 0.05). There was an increase
in catalase activity at first week after that it decreased as compared
to control group. However, GSH-Px activity in the diabetic group incr
eased after 1 week and then remained at the same level except a small
drop in the 2nd week. Total SOD and CuZn-SOD activity increased signif
icantly in diabetic kidney as compared to controls at all time interva
ls, while Mn-SOD activity showed no change. The present findings sugge
st that oxidative stress accompanies at early onset of diabetes mellit
us and the susceptibility of the kidney to oxidative stress during the
early stages may be an important factor in the development of diabeti
c nephropathy.