Lifelong alterations in endocrine function resulting from brief perinatal hypothyroidism in the rat.
The late consequences of a brief period of perinatal hypothyroidism were studied in the rat by giving propylthiouracil (PTU) prenatally to the mothers and/or neonatally for 5 days to the pups. Perinatal hypothyroidism produced a delay in eye opening, a diminution in weaning weight, a delay in puberty and first estrus, and a prolongation of estrus cycles. The neo-PTU rats usually had a persistently enlarged thyroid gland associated with an elevated pituitary, hypothalamic, and serum thyroid-stimulating hormone (TSH) concentration. The metabolic clearance rate of TSH and response to luteinizing hormone-releasing hormone (LH-RH) were normal. The response to thyrotropin-releasing hormone (TRH) stimulation was significantly blunted in adult neo-PUT males, suggesting secondary or tertiary hypothyroidism. As a result of these studies, serious thought should be given to the possible consequences of antithyroid drug therapy of pregnant women, and certainly all pregnant hypothyroid women should receive full replacement therapy.