BDNF and hypothyroidism: Therefore, we constructed a rat model of hypothyroidism induced by propylthiouracil (PTU) to observe the effects of DMF on the behavior of hypothyroidism rats in the Morris water maze, serum thyroid hormone levels and BDNF, p-AKT/AKT, p-CREB/CREB expression in the hippocampus, in order to clarify the effect of DMF on the learning and memory ability of hypothyroid rats and explore its possible mechanism.