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Comparison of cerebral blood flow and blood‐brain transport of phenylalanine and alanine in control and hypothyroid 16 day‐old pats
Author(s) -
Lefauconnier J.M.,
Bernard G.
Publication year - 1985
Publication title -
international journal of developmental neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.761
H-Index - 88
eISSN - 1873-474X
pISSN - 0736-5748
DOI - 10.1016/0736-5748(85)90194-7
Subject(s) - saint , cerebral blood flow , medicine , humanities , psychology , art , art history
Blood-brain extraction (E) of alanine,serine,cysteine (ASC system) has been shown to decrease during development as compared to that of large neutral amino acids (L system) (Lefauconnier and Trouv4 1983).Further work has shown that this decrease was not observed in animals rendered hypothyroid by daily subcutaneous injections of propylthlouracil beginning the first day after birth.As extraction is related to cerebral blood flow (F) this observation could be explained by a lower blood flow or a higher activity of the transport system in hypothyroid animals.We thus measured F in 16 day-old hypothyroid and control rats, as well as the blood-braln clearance (FxE) of phenylalanlne (L system) and alanine (ASC system).Clearances were obtained from the ratio of the tracer radioactivity in brain tissue,excludlng blood contamination,a short time (20 to 40 sec) after the intravenous injection of tracer amino acid,to the time integral of its level in arterial plasma. Cerebral blood flow was decreased by 50% in brain regions of hypothyroid rats.The clearance of alanlne in different brain re~ions was significantly higher (+60%) in hypothyroid than in control rats while that of phenylalanine was slightly lower (-|0%).The clearances of both amino acids in hypothyroid rats were very similar to those obtained in less mature (8 day-old)control rats.