ALTERATIONS OF BRAIN BIOCHEMISTRY AND DEVELOPMENT OF BEHAVIOR,
MINNESOTA UNIV MINNEAPOLIS
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These studies were undertaken to provide a basis for future experiments in which the catecholamine andor serotonin of the brain would be altered at various stages of embryonic and neonatal development and the influence of such changes on subsequent development of certain types of behavior determined. Infant rats were killed at different times after birth. The entire brain, including the medulla, was quickly removed and immediately homogenized in two volumes of cold 0.01 N hydrochloric acid. Total catecholamines were determined in aliquots of the homogenate by a slight modification of the procedure of Shore and Olin. There appear to be two periods in the young, developing rat at which rather abrupt increases in total catecholamine concentration occur. The first of these is at some time between one and one half and four days after birth and the second when the animal is twenty-four to twenty-eight days of age. At the latter time concentrations of brain serotonin are more than twice those found in the newly born animal.