Methimazole-induced gestational hypothyroidism affects the offspring development and differently impairs the conditioned fear in male and female adulthood rodents.

Gestational hypothyroidism is a prevalent disorder in pregnant women and also impairs fetal development with relevant outcomes. One of the outcomes of greatest interest has been rodent fear- and anxiety-like behavior. However, the relationship between maternal hypothyroidism and onset of conditioned fear-related responses in offspring remains controversial. Here we used a well validated methimazole-induced gestational hypothyroidism to investigate the behavioral consequences in offspring. Dams were treated with methimazole at 0.02% in drinking water up to gestational day 9. Maternal body weights and maternal behavior were evaluated and the puppies ware analyzed for weight gain, physical/behavioural development and assigned for the open field and fear conditioning test. Methimazole-induced gestational hypothyroidism induced loss in maternal and litter weight, increases in maternal behavior and impairs in offspring developmental landmarks in both male and female rodents. Only male offspring enhanced responsiveness to conditioned fear-like behavior in adulthood.