Effect Of Lipoic Acid And Levothyoxine Treatment On Cognitive Deficit And Oxidative Stress Level In Hypothyroidism Rat

Objective Oxidative stress is an important factor leading to cognitive dysfunction, antioxidants in oxidative stress and improving cognitive skills in today’s world is a hot research. To assess the effects of Levothyroxine, lipoic acid(LA) and the two-drug combination therapy on improving the cognitive deficit, and level of oxidative stress in the serum and hippocampus tissue of adulthypothyroidism rat. Thus described, Stock antioxidants may improve cognitive function of thyroid hormone.Methods Fifty male SD rats were selected, by adding propylthiouracil in their daily drinking water to induce hypothyroidism model. Then they were randomly divided into five groups:the normal group, the hypothyroidism group (PTU group), L-T4treatment group (PTU+L-T4group), LA treatment group (PTU+LA group), Two-drug combination group (PTU+LT-4+LA group).These research was divided into three parts:①ehavioral Detection: After8weeks of treatment, the learning and memory abilities of the rat were evaluated by Morris Water Maze (MWM).②Oxidative stress-related enzyme assay: The contents of malondialdehyde (MDA) and the activities of superoxide dismutase (SOD) in the serum and hippocampus were respectively measured using thiobarbituric acid, xanthine-xanthine oxidase methods.③The level of Apo E: The contents of Apo E in the serum and hippocampus were measured using double antibody-step sandwich enzyme-linked immunosorbent assay (Elisa).Results①Compared with the normal group, the escape latency were longer(P<0.01), the ability of space exploration Reduced. Compared with PTU group, there was obviously significant difference of Morris Water Maze test score in PTU+L-T4group、 PTU+LA group and PTU+L-T4+LA group. Compared with PTU+L-T4group, there was obviously significant difference of Morris Water Maze test score in PTU+L-T4+LA group.②Compared with the normal group, the MDA level was increased and the SOD activity was decreased in the serum and hippocampus in the PTU group (P<0.001). Compared with PTU group, the SOD activity was increased and the MDA level was decreased in the PTU+L-T4group, PTU+LA group and PTU+L-T4+LA group(P<0.05). Compared with PTU+L-T4group, the SOD activity was increased and the MDA level was decreased in PTU+L-T4+LA group(P<0.05).③Compared with the normal group, the Apo E level was decreased in the serum and hippocampus in PTU group and PTU+L-T4group (P<0.05). Compared with PTU group, the Apo E level was increased in the PTU+L-T4+LA group(P<0.05).Compared with PTU+L-T4group, the Apo E level was increased in PTU+L-T4+LA group(P<0.05).Conclusion Hypothyroidism cause the ability of oxidative stress decreased. The L-T4and LA can significantly improve the ability of oxidative stress, what’s more, the combination therapy have an additive effect on improving cognitive function of hypothyroidism rats.