Regional changes in adrenaline of rat brain during development.

The changes of adrenaline during development were studied in several regions of rat brain. Adrenaline is present in hypothalamus, medulla oblongata-pons, midbrain, and cerebellum. Adult levels are attained between 15 and 30 days, depending on the region. These adult levels are attained earlier in the caudal regions than in the rostral regions. In cerebellum and medulla oblongata-pons, the adrenaline content reaches a maximum at 15 days which is close to the time in which the levels of phenylethanolamine-N-methyltransferase (PNMT) reach their maximum. In midbrain and hypothalamus, there is a lag between the adult levels of adrenaline and the activity of PNMT. Adrenaline reaches adult levels at 25 days in midbrain and at 30 days in hypothalamus, while PNMT activity adult levels are attained at 15 days.