<prompt> Which one is excitatory neurotransmitter?AcetylcholineHistamineMelatoninGABA  <response>: acetylcholine serves excitatory and inhibitory functions, which means that ACh can speed up or slow down nerve signals. In the central nervous system, its function is mainly excitatory Ref : guyton and hall textbook of medical physiology 12 edition page number:677,678,679 