Studies are being conducted to elucidate the development interrelationships of putative neurotransmitter catecholamines, acetylcholine, GABA and serotonin in the brain. The metabolism of neurotransmitters will be altered at specific periods of neurochemical maturation during gestational or neonatal stages by (1) placement of discrete lesions in the nuclei or origin of neurons containing dopamine, norepinephrine, serotonin, acetylcholine or GABA in 10,21 and 39 day old rats, and (2) with the use of drugs that are known to act by altering the activity of neurons containing biogenic amines, acetylcholine and GABA. The hypothesis that the manipulation of biochemical and morphological differentiation during gestational or neonatal stages of growth has longlasting and permanent consequences on normal neurochemistry of brain will be tested. Another study will be conducted to elucidate the effects of the chronic administration of antidepressant drugs, L-DOPA and corticosteroids during gestation and neonatal stages. The hypothesis will be tested that elevation of biogenic amines during a critical period may permanently alter the capacity of the neuron to synthesize amines and that corticosteroids may induce N-methylating enzymes in the brain to form potentially psychoactive metabolities of biogenic amines. BIBLIOGRAPHIC REFERENCES: Schmidt, R.H., E. Lewis and R.K. Bhatnagar: Characterization of 6-hydroxydopamine-induced neurochemical alterations in the catecholamine containing neurons of CNS. Neurosciences Abstracts 2:770, 1976. Schmidt, R.H., R. Roskoski, Jr. and R.K. Bhatnagar: 6-Hydroxydopamine (6-OHDA) administration to neonatal rats fails to affect the development of tyrosine hydroxylase (TH), choline acetyltransferase (CAT) and glutamic acid decarboxylase (GAD) in the CNS. Fed. Proceedings 35: 669, 1976.