The effect of diabetes mellitus on active avoidance learning in rats: the role of nitric oxide.
BACKGROUND
Growing data report memory and other cognitive problems among individuals with diabetes mellitus. Nitric oxide may play a key role in many physiological and pathological situations. The aim was to investigate the role of NO in diabetes-induced changes in learning and lipid peroxidation.


METHODS
Six groups of 10 rats each were formed: control (C), diabetic (D), control+L-arginine (CA), diabetic+L-arginine (DA), control+L-NAME (CN), and diabetic+L-NAME (DN) groups. Experimental diabetes mellitus was induced by injection of streptozotocin (60 mg/kg body weight). 160 mg/kg/day L-arginine or 10 mg/kg/day L-NAME were injected intraperitoneally to the relevant groups for eight weeks. Active avoidance behavior was studied in the middle of the eighth week using an automated shuttle box. Brain and hippocampal nitrite levels were measured by a fluorometric method. TBARS levels were measured fluorometrically using 1,1,3,3-tetramethoxypropane as a standard.


RESULTS
The active avoidance training indicated that diabetes was associated with learning impairment. Administration of L-NAME and L-arginine significantly impaired active avoidance performance compared with the control group. They also decreased glucose level in group DA compared with the diabetic group. Brain nitrite level was significantly different in the diabetic group; hippocampus nitrite level tended to be lower in the L-NAME groups than the diabetic and control groups, although L-arginine increased hippocampal and brain nitrite values in the CA group compared with control groups. Brain and hippocampal TBARS levels were significantly higher in diabetic than in control rats.


CONCLUSIONS
Imbalance related to nitric oxide production may contribute to cognitive dysfunction in diabetes mellitus.
Küçükatay
Vural
V
Department of Physiology, Faculty of Medicine, Pamukkale University, Antalya, Turkey.
Hacioğlu
Gülay
G
Ozkaya
Gül
G
Ağar
Aysel
A
Yargiçoğlu
Piraye
P
D000818:Animals; D001362:Avoidance Learning; D001786:Blood Glucose / Q000378:metabolism; D001835:Body Weight; D003920:Diabetes Mellitus / Q000523:psychology*; D004327:Drinking Behavior; D005247:Feeding Behavior; D006624:Hippocampus / Q000378:metabolism; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism*; D009573:Nitrites / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism
D001786:Blood Glucose; D009573:Nitrites; D017392:Thiobarbituric Acid Reactive Substances; D009569:Nitric Oxide