[Effects of glucocorticosteroids on enzymatic activity in the urea cycle in fetal rat liver]
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Insights
Urea cycle enzyme activity in rat liver rapidly increases after birth. Glucocorticosteroids are crucial for enzyme development, with hydrocortisone acetate stimulating activity and enabling premature induction.
Area of Science:
- Biochemistry
- Developmental Biology
- Enzymology
Context:
- Urea cycle is vital for nitrogen waste detoxification.
- Enzyme activity is low in fetal rat liver.
- Postnatal development involves significant enzyme upregulation.
Purpose:
- To investigate urea cycle enzyme activity during late fetal and early postnatal development in rats.
- To determine the role of glucocorticosteroids in regulating these enzymes.
Summary:
- All five urea cycle enzymes show low activity in fetal rat liver, increasing rapidly postnatally.
- Glucocorticosteroid deficiency (via in utero hypophysectomy) decreased activity of carbamyl phosphate synthetase, ornithine transcarbamylase, and argininosuccinate synthetase.
- Hydrocortisone acetate administration stimulated four enzymes (CPS, OTC, ASS, and arginase) and allowed premature carbamyl phosphate synthetase induction.
Impact:
- Highlights the critical role of glucocorticosteroids in urea cycle enzyme maturation.
- Provides insights into the hormonal regulation of nitrogen metabolism during development.
- Suggests potential for therapeutic interventions to accelerate enzyme development.
Abstract:
The five urea cycle enzyme activities of rat liver are followed during late fetal period and the first day of life. All five enzymes exhibit relatively low activities in foetal liver and a rapid postnatal increase. Lack of glucocorticosteroid (after hypophysectomy in utero) induces an important decrease of activity of three enzymes: carbamyl phosphate synthetase, ornithine transcarbamylase and argininosuccinate synthetase. Treatment with hydrocortisone acetate on decapitated fetuses results in a marked stimulation of the activity of four of the enzymes: carbamyl phosphate synthetase, ornithine transcarbamylase, argininosuccinate synthetase and arginase. Premature induction of carbamyl phosphate synthetase activity is obtained after intraperitoneal injection with hydrocortisone acetate at 16,5 days of gestation.