Gamma-aminobutyric acid system in rat oviduct

A considerable amount of gamma-aminobutyric acid (GABA) was found in the rat oviduct, representing over 2.5 times the amount present in the whole brain. The oviduct also contained L-glutamic acid decarboxylase, 4-aminobutyrate-2-oxoglutarate aminotransferase, and succinic semialdehyde-NAD+ oxidoreductase enzymes with properties similar to those of brain enzymes. The GABA oviduct level varied during the ovarian cycle. It was concluded that this amino acid is synthesized and degraded in the oviduct although its physiological significance has not yet been determined.