Ontogeny of GABA pathway in human fetal brains.

The developmental profiles of gamma-aminobutyric acid (GABA), its biosynthesizing enzyme L-glutamic acid decarboxylase (GAD) and its degradating enzymes gamma-aminobutyric acid-alpha-ketoglutaric acid transaminase (GABA-T) and succinic semialdehyde dehydrogenase (SSADH) in four different regions of human fetal brains have been evaluated. The GABA pathway was found to be maximally active in fetal brains during the third trimester of pregnancy. The relative activities of the enzymes as well as GABA content were least in pons compared to cerebrum, cerebellum and mid brain regions throughout the period of fetal development.