HISTAMINE AND MAST-CELLS IN DEVELOPING RAT-BRAIN

The number and distribution of mast cells in rat brain were determined at different postnatal ages. The number of brain mast cells changed during ontogenic development following the same pattern as brain histamine (HA) levels. The calculated HA content of brain mast cells was close to the HA content of the crude nuclear fraction at every age studied. Since most of the brain HA in the newborn sediments with the crude nuclear fraction. The developmental pattern of brain HA apparently reflects changes in the number of brain mast cells, i.e., in the size of the mast cell HA pool. The HA content of the supernatant of the crude nuclear fraction corrected for mast cell HA contamination follows a developmental pattern similar to that of other known neurotransmitters.