title: Developmental aspect of phenylalanine hydroxylase in the rat -- hormonal influences.
abstract: Interpretations of the development of phenylalanine hydroxylase (PAH) in rat liver have been controversial, and the mechanism of ontogenic changes have not yet been elucidated. Fetal PAH activity at a gestational age of 21 days appeared to reach 32% that of adult male level at birth. The in vivo effectiveness of fetal PAH activity was correlated with enhancement of blood tyrosine, while amino-transferase activity appeared only after birth. No sex difference was noted in weaning rats, whereas, in adult females, PAH activity was only 42% that of males. Investigating hormonal influences on liver PAH activity we noted no change of enzyme activity following hydrocortisone, ACTH and estradiol treatment. However, 4 days of testosterone treatment in weaning female rats increased PAH activity (X1.7). Therefore, testosterone could explain increased PAH activity in adult males.
mesh_terms: D000315:Adrenalectomy; D000324:Adrenocorticotropic Hormone / Q000494:pharmacology; D000818:Animals; D000833:Animals, Suckling; D004958:Estradiol / Q000494:pharmacology; D006854:Hydrocortisone / Q000494:pharmacology; D008099:Liver / Q000196:embryology / Q000201:enzymology* / Q000254:growth & development; D010651:Phenylalanine Hydroxylase / Q000378:metabolism*; D051381:Rats; D013739:Testosterone / Q000494:pharmacology
chemical_list: D013739:Testosterone; D004958:Estradiol; D000324:Adrenocorticotropic Hormone; D010651:Phenylalanine Hydroxylase; D006854:Hydrocortisone