title: Chronic epigallocatechin-3-gallate ameliorates learning and memory deficits in diabetic rats via modulation of nitric oxide and oxidative stress.
abstract: Due to anti-diabetic and antioxidant activity of green tea epigallocatechin gallate (EGCG) and the existence of evidence for its beneficial effect on cognition and memory, this research study was conducted to evaluate, for the first time, the efficacy of chronic EGCG on alleviation of learning and memory deficits in streptozotocin (STZ)-diabetic rats. Male Wistar rats were divided into control, diabetic, EGCG-treated-control and -diabetic groups. EGCG was administered at a dose of 20 and 40 mg/kg/day for 7 weeks. Learning and memory was evaluated using Y maze, passive avoidance, and radial 8-arm maze (RAM) tests. Oxidative stress markers and involvement of nitric oxide system were also evaluated. Alternation score of the diabetic rats in Y maze was lower than that of control and a significant impairment was observed in retention and recall in passive avoidance test (p<0.01) and EGCG treatment (40 mg/kg) of diabetic rats significantly improved these parameters (p<0.05). Also, diabetic animals exhibited fewer correct choices (p<0.01) and more errors (p<0.005) in the RAM task and EGCG (40 mg/kg) significantly ameliorated these changes (p<0.05). Further, pretreatment with l-arginine as a substrate for nitric oxide synthase (NOS) and/or 7-nitroindazole as a neuronal NOS inhibitor attenuated and potentiated the beneficial effect of EGCG regarding learning and memory respectively. Meanwhile, increased levels of malondialdehyde (MDA) and nitrite in diabetic rats significantly reduced due to EGCG treatment (p<0.05). In summary, chronic green tea EGCG dose-dependently could ameliorate learning and memory deficits in STZ-diabetic rats through attenuation of oxidative stress and modulation of NO.
authors.affiliation: Department of Physiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran. tmojarad@yahoo.com
authors.forename: Tourandokht
authors.initials: T
authors.lastname: Baluchnejadmojarad
authors.forename: Mehrdad
authors.initials: M
authors.lastname: Roghani
mesh_terms: D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects; D001786:Blood Glucose / Q000378:metabolism; D001835:Body Weight / Q000187:drug effects; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D003921:Diabetes Mellitus, Experimental / Q000150:complications* / Q000523:psychology*; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism; D007191:Indazoles / Q000494:pharmacology; D007859:Learning Disabilities / Q000188:drug therapy* / Q000209:etiology* / Q000523:psychology; D008297:Male; D008315:Malondialdehyde / Q000378:metabolism; D018782:Maze Learning / Q000187:drug effects; D008569:Memory Disorders / Q000188:drug therapy* / Q000209:etiology* / Q000523:psychology; D009419:Nerve Tissue Proteins / Q000378:metabolism; D018696:Neuroprotective Agents / Q000494:pharmacology*; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D052248:Nitric Oxide Synthase Type I / Q000037:antagonists & inhibitors; D009573:Nitrites / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D001786:Blood Glucose; D007191:Indazoles; D009419:Nerve Tissue Proteins; D018696:Neuroprotective Agents; D020030:Nitric Oxide Donors; D009573:Nitrites; D009569:Nitric Oxide; D008315:Malondialdehyde; D002392:Catechin; C045651:epigallocatechin gallate; D052248:Nitric Oxide Synthase Type I; C080122:7-nitroindazole