Multiple choice Which of the following substances lead(s) to the inhibition of central nervous system? Glycine GABA Norepinephrine Both 1 and 2 Reveal answer Fill a bubble to check yourself D Correct answer Explanation Gamma amino butyric acid (Gaba) and glycine are inhibitory transmitters. An inhibitory transmitter is released by an inhibitory neuron. It can inhibit impulse at a synapse.