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DEVELOPMENTAL CHANGES IN Na + , K + AND ATP AND IN THE LEVELS AND TRANSPORT OF AMINO ACIDS IN INCUBATED SLICES OF RAT BRAIN
Author(s) -
Piccoli F.,
Grynbaum Alice,
Lajtha A.
Publication year - 1971
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1971.tb12042.x
Subject(s) - taurine , incubation , glycine , amino acid , in vivo , inulin , medicine , biology , endocrinology , glutamate receptor , metabolism , glutamic acid , biochemistry , chemistry , receptor , microbiology and biotechnology
Abstract—1 Upon incubation, slices of brain tissue took up fluid; the degree of swelling increased with increasing age. No sweiling occurred in slices from foetal brain. Since this swelling was associated with increases in the inulin space, the percentage of inulin space in slices at the end of incubation increased during brain development. 2 Most of the capacity for ion transport seemed to be absent from foetal brain. In vivo and in slices, Na + was very high and K + was very low in comparison to levels at other ages. There was a rapid change around birth, but no significant change at later ages. Upon incubation, Na + levels increased in other slices, but not in slices of foetal brain. 3 Upon incubation of the slices, ATP levels were restored to levels close to those in the living brain; there were no significant alterations in available energy during development to explain changes in amino acid transport. 4 The composition of the free pool of cerebral amino acids in vivo changed with development, with some compounds (glutamic acid and related compounds) increasing, others (mostly‘essential’amino acids) decreasing, with age. These changes were not linear with time, and the level of a compound might exhibit several peaks during development. 5 The uptake (influx) of taurine, glutamate and glycine into brain slices increased rapidly during the foetal and early neonatal periods, reached a maximum between 2 and 3 weeks of postnatal age and then declined to adult levels. The levels of steady‐state uptake with glycine also exhibited a maximal peak at 2‐3 weeks of postnatal age. Steady‐state uptake of taurine and glutamate reached adult levels by about 3 weeks of age. 6 The pattern of inhibition of amino acid transport by two specific amino acid analogues changed during development for some amino acids (GABA, glycine and glutamate), indicating an alteration in substrate specificity. 7 The results demonstrate complex changes in cerebral amino acid transport during development, with several maxima or minima and with changes in specificity for at least some compounds.