Effects of leptin on oxidative stress in healthy and Streptozotocin-induced diabetic rats.
OBJECTIVE
It is generally accepted that oxidative stress is responsible for etiology and complications of diabetes. During uncontrolled Type 1 diabetes, plasma leptin levels rapidly fall. However, it is not known whether diabetes-induced hypoleptinemia has any role in oxidative stress related to uncontrolled Type I diabetes. The present study was designed to examine the effects of leptin treatment on plasma lipid peroxidation and reduced glutathion of normal and streptozotocin(STZ)-induced diabetic rats.


METHODS
Diabetes was induced by single injection of Streptozotocin (55 mg/kg bw). One week after induction of diabetes, rats began 5-day treatment protocol of leptin injections of (0.1 mg/kg bw i.p.) or same volume vehicle. At the end of the 5th day, rats were sacrificed by cardiac puncture under anesthesia and their plasma was taken for plasma leptin, malondialdehyde, and reduced glutathione measurements.


RESULTS
Plasma leptin levels decreased in STZ-induced diabetic rats while plasma glucose, TBARS, and GSH levels increased. Plasma leptin levels were not affected with leptin treatment in both diabetic and non-diabetic rats. The elevation in plasma TBARS associated with STZ diabetes decreased with leptin treatment. Leptin also increased plasma GSH levels in diabetic rats. In non-diabetic rats, treatment with leptin did not change plasma TBARS and GSH levels.


CONCLUSIONS
In conclusion, leptin treatment is able to attenuate lipid peroxidation in STZ-diabetic rats, in the onset of diabetes, by increasing the GSH levels without affecting hyperglycemia and hypoleptinemia.
Gülen
Sebnem
S
Department of Physiology, Faculty of Medicine, Gazi University, Ankara, Turkey. sebnem@baskent.edu.tr
Dinçer
Sibel
S
D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D003921:Diabetes Mellitus, Experimental / Q000139:chemically induced / Q000473:pathology*; D005978:Glutathione / Q000097:blood; D006262:Health; D020738:Leptin / Q000097:blood / Q000494:pharmacology*; D008297:Male; D008315:Malondialdehyde / Q000097:blood; D018384:Oxidative Stress / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar; D013311:Streptozocin; D017392:Thiobarbituric Acid Reactive Substances / Q000032:analysis
D001786:Blood Glucose; D020738:Leptin; D017392:Thiobarbituric Acid Reactive Substances; D008315:Malondialdehyde; D013311:Streptozocin; D005978:Glutathione