PROTEIN-INTAKE IN PREGNANCY, PLACENTAL GLUCOCORTICOID METABOLISM AND THE PROGRAMMING OF HYPERTENSION IN THE RAT

Hypertension is strongly predicted by a low birthweight:placental weig ht ratio. Two independent models have been described to explain this a ssociation; less than optimal maternal protein nutrition leading to fe tal undernutrition, or glucocorticoid excess. Pregnant rats were fed d iets containing 18 per cent casein (control) or 9 per cent casein, bal anced for energy. On day 20 of gestation the pregnancies were terminat ed and placentae collected for determination of 11 beta-hydroxysteroid dehydrogenase (11 beta HSD) activity. Placental 11 beta HSD normally protects the fetus from the effects of maternal glucocorticoids. Activ ity was specifically attenuated by mild protein restriction (33 per ce nt in activity), whilst activities of glucocorticoid-insensitive contr ol enzymes were unchanged and glucocorticoid-inducible glutamine synth etase activity was increased (27 per cent), relative to activity in pl acentae from control animals. The nutritional manipulation during preg nancy significantly increased systolic blood pressure (17 mmHg) in the resulting offspring in early adulthood. A possible common pathway whe reby maternal environmental factors may influence fetal and placental growth and programme disease is inferred. (C) 1996 W. B. Saunders Comp any Ltd