Schematic of experimental timeline. The rats were fed with the low iodine diet and administered with different drinking water from pre-pregnancy (12 weeks) until their pups reached PN21. LI (1.2 μg/d); NI (5–6 μg/d); 3HI (15–16 μg/d). The pups from the rat mothers of each treatment group (LI, NI, and 3HI) were permitted free access to normal food and water from PN21 until PN45. G, gestational day; PN, postnatal day; MWM, Morris water maze.