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UPTAKE AND METABOLISM OF [ 3 H]NOREPINEPHRINE IN THE CEREBRAL HEMISPHERES OF CHICK EMBRYOS 1, 2
Author(s) -
Kellogg C.,
Vernadakis A.,
Rutledge C. O.
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.tb09599.x
Subject(s) - norepinephrine , embryo , metabolism , deamination , medicine , endocrinology , biology , embryonic stem cell , embryogenesis , metabolite , period (music) , chemistry , biochemistry , dopamine , enzyme , microbiology and biotechnology , physics , gene , acoustics
— The uptake and metabolism of [ 3 H]norepinephrine were studied in slices of cerebral hemispheres removed from chick embryos at 10, 15 and 20 days of embryonic age, as well as from 90‐day‐old hens. Brain tissue from all age groups concentrated [ 3 H]norepinephrine to much greater levels at 37°C than at 0°C. There was a marked increase in the rate of accumulation of [ 3 H]norepinephrine in tissues from 10 to 15 days of embryonic age, with no further increase in the rate observed from 15 to 20 days of embryonic age. Tissue slices were incubated for 20 min with [ 3 H]norepinephrine, and the deaminated metabolites of norepinephrine were separated by paper chromatography. In tissues from all age groups, the neutral metabolites were produced in greater amounts than the acid metabolites. A significant increase in the amounts of deaminated metabolites formed was observed in the period from 10 to 15 days of embryonic age and a significant decrease in the amounts formed was observed in the period from 15 to 20 days of embryonic age. The deamination at 20 days was very similar to that observed in the adult. A significant decrease in the level of the deaminated metabolites was noted in all age groups in response to cocaine (an inhibitor of neuronal uptake mechanisms), an observation suggesting that mechanisms for neuronal uptake of NE are functional by 10 days of embryonic development in the chick. However, a significant increase in the level of deaminated metabolites in response to reserpine (an inhibitor of uptake of NE into storage granules) was observed only in slices taken from 20‐day embryos and from the 90‐day‐old hen. The effect in the hen was more prominent than in the 20‐day embryo. These results were interpreted to indicate that mechanisms for the uptake of NE develop at an earlier embryonic age than mechanisms for the storage of NE and that mechanisms for storage continue to develop after hatching.