Histamine and spermidine content in brain during development.

Histamine concentration in fetal rat brain is high at 17 days gestation but decreases sharply just before birth. Values subsequently increase to a maximum postnatal concentration 5 to 10 days after birth, and then steadily decline to low adult values by time of weaning. Spermidine follows a pattern similar to that of histamine but with a 24- to 48-hour lag. The developmental pattern for histamine in the central nervous system is different from that for other neural amines. It appears that the marked fetal and neonatal changes in brain histamine correlate best with periods of rapid cell proliferation and growth during brain maturation.