Évolution et contrôle de l'activité de la carbamyl phosphate synthétase et de l'ornithine transcarbamylase du foie foetal de rat au cours du développement

Effects of Administration of Hydrocortisone, Actinomycin D and Puromycin on Carbamoylphosphate Synthetase-I and Ornithine Carbamoyltransferase Activities in Fetal Rat Liver

“…Previous studies have already shown that the increase in both carbamoylphosphate synthetase-I and ornithine carbamoyltransferase activ ities during the late fetal period is dependent on the presence of glucocorticosteroids (10,11). These results show that the exogenous administration of hydrocortisone to fetuses on days 16.5, 17.5 and 18.5 causes a marked increase in the activity of carbamoylphosphate synthetase-I, this effect remains important for 2 or 3 days according to the stage.…”

“…Our recent studies show that the appearance and increase of both enzymatic activities in the rat fetus are under the control of glucocorticosteroids (10,11). Furthermore it is well known that supplementary administration of hydrocortisone caused a marked increase of the urea-cycle enzyme activities (7,18,23).…”

Effects of Corticosteroids and Pancreatic Hormones on Carbamyl Phosphate Synthetase-I and Ornithine Transcarbamylase Activities in Fetal Rat Liver

“…Our first results show that the mitochondrial level of immunoreac tive CPS-I increases after hydrocortisone acetate supply (unpublished data). Concerning OTC activity, these results are apparently inconsistent with our previous re ports [4,5]. The development of the enzyme needs the presence of adrenals, while an ex cess of hydrocortisone acetate decreases its activity.…”

“…Our ear lier studies showed that the activities of CPS-I and OTC are low in the fetus and increase rapidly after birth [4], We also reported that both activities are affected by the deprivation of glucocorticoids during the late fetal period [5]. Moreover, a hydrocortisone acetate sup ply to intact fetuses increased the level of CPS-I activity 3 days later, while OTC activ ity exhibited a paradoxical increase after an actinomycin D supply [6].…”

“…Between 18.5 and 21.5 days of pregnancy, the hormone supply pre maturely increases CPS-I activity (about 36%) and decreases the OTC activity (about 23%). However, it was previously reported that the development of these enzyme activi ties was dependent upon the presence of glu cocorticoids [4,5]. Concerning CPS-I activi ty, it is concluded that its maturation is strongly bound to the presence of glucocorti coids.…”