GABA (Gamma-Aminobutyric Acid)
Here's your citation in American Psychological Association (APA) format:
GABA (Gamma-Aminobutyric Acid). (n.d.). In Alleydog.com's online glossary. Retrieved from: https://www.alleydog.com/glossary/definition-cit.php?term=GABA+%28Gamma-Aminobutyric+Acid%29