Scopolamine (SCOP), an anticholinergic drug, is commonly used for inducing a cognitive deficiency in experimental animal models. Ninety six Wistar male rats were divided into six groups [Control, Control + Levothyroxine (L-T4, 100), SCOP + Vehicle, SCOP + L-T4 (50 and 100), SCOP + donepezil (DP)]. During 21 consecutive days, SCOP (1 mg/kg, i.p.) was used with the purpose of inducing an animal model of cognitive impairment. Thirty min after the administration of SCOP, animals were treated with 50 and 100 mg/kg L-T4, 3 mg/kg of DP, or normal saline for 21 days. The behavioral (passive avoidance and spatial memory, anxiety, depression, locomotion, and motor coordination), and electrophysiological (hippocampal long-term potentiation (LTP)) assessments, as well as biochemical changes, were estimated.

Results indicated that the indices of depression/anxiety, spatial/passive avoidance memory, motor coordination, LTP records (amplitude and slope), and antioxidant enzyme activity were significantly decreased in SCOP groups in comparison with the control. Compared to the control group, L-T4 (50 and 100 mg/kg) treated rats showed significant improvements in memory and learning deficits, anxiety, all LTP parameters, and the antioxidant enzyme concentrations. The cerebral contents of tumor necrosis factor-alpha (TNF-α) in the L-T4 and DP treated groups were significantly lower than that of the SCOP + Veh group (p < 0.01).

This research showed that the L-T4 prevented the disruption of synaptic plasticity and cognitive deficiencies induced by SCOP. The beneficial effects of L-T4 may be due to a decrease in the concentration of TNF-α and enhancement of the antioxidant content in the hippocampus.

东co碱（SCOP）是一种抗胆碱能药物，通常用于诱发实验动物模型中的认知缺陷。将96只Wistar雄性大鼠分成六组[对照组，对照组+左甲状腺素（L-T4，100），SCOP +媒介物，SCOP + L-T4（50和100），SCOP +多奈哌齐（DP）]。在连续21天中，使用SCOP（1 mg / kg，ip）来诱导认知障碍动物模型。给予SCOP后30分钟，用50和100 mg / kg L-T4、3 mg / kg DP或生理盐水处理动物21天。评估了行为（被动回避和空间记忆，焦虑，抑郁，运动和运动协调），电生理（海马长期增强（LTP））评估以及生化变化。

结果表明，与对照组相比，SCOP组的抑郁/焦虑，空间/被动回避记忆，运动协调，LTP记录（幅度和斜率）和抗氧化酶活性的指标均明显降低。与对照组相比，L-T4（50和100 mg / kg）治疗的大鼠在记忆力和学习障碍，焦虑，所有LTP参数以及抗氧化酶浓度方面均表现出显着改善。L-T4和DP治疗组的脑坏死因子-α（TNF-α）的脑含量显着低于SCOP + Veh组（p <0.01）。

这项研究表明，L-T4可以防止SCOP引起的突触可塑性和认知缺陷的破坏。L-T4的有益作用可能是由于TNF-α浓度的降低和海马中抗氧化剂含量的增加。