Melanocortins, non-corticotropic fragments of adrenocorticotropic horm
one, accelerate growth of the developing neuromuscular system and regr
owth of damaged neurons, both in the adult and neonatal rat. Morpholog
ical, electrophysiological and behavioral characteristics are all impr
oved by melanocortins, which, however, vary in potency, with alpha-MSH
being the most effective. Tissue substrate, dosage, critical time per
iods and pattern of neuropeptide administration are all important vari
ables. Melanocortins protect central neurons affecting motor behavior
during development or following neuronal damage in the adult brain. Po
ssible mechanisms of melanocortin action are discussed.