After the discovery of γ-aminobutyric acid (GABA) in the mammalian brain, its inhibitory actions were first demonstrated in this tissue:(A) Mammalian brain(B) Mammalian spinal cord(C) Mammalian peripheral nervous system(D) Crustacean (crayfish) central nervous system(E) Crustacean (crayfish) peripheral nervous system Checking your answer...