Expression and release of neuroregulators during development: monoamines and neuropeptides.

The turnover of catecholamines (CA) was determined in the adrenal medulla and brain of rat fetuses and pups. In general we found a considerable increase soon after birth. The expression of mRNA for CA-synthesizing enzymes was also considerably enhanced in the adrenals shortly after birth. Furthermore, we demonstrated increased expression of neuropeptides after birth, increased synthesis of mRNA encoding for neuropeptide Y in the adrenals 24 h after birth; and considerable activation of the substance P gene in a respiratory nuclei of rabbit pups which had been breathing for 2 h as compared with fetuses at term.