Maternal thyroid dysfunction and c-fos and c-jun expression in rat placenta

Maternal thyroid dysfunction is associated with perturbed fetal brain devel opment and neurological deficits in adulthood in rat and human. To investig ate whether these effects occur secondary to placental dysfunction, c-fos a nd c-jun expression in placenta from normal (euthyroid) and moderately hypo thyroid rat Jams were investigated by Northern hybridization analysis. In normal placenta, c-fos expression increased by 74 per cent between 16 an d 21 days of gestation (dg) whereas c-jun expression declined by 46 per cen t. Moderate maternal hypothyroidism depressed placental c-fos expression by 32 per cent at 19 dg, but elevated c-fos and c-jun expression by 139 and 8 6 per cent, respectively, at 21 dg. Maternal hypothyroidism may therefore i nduce c-fos/c-jun-related placental dysfunction, but only relatively late i n gestation when fetal thyroid function is already established. (C) 1999 Ha rcourt Publishers Ltd.