title: Chemical mechanisms in pain modulation.
mesh_terms: D004723:Endorphins / Q000134:cerebrospinal fluid / Q000502:physiology*; D006801:Humans; D010146:Pain / Q000134:cerebrospinal fluid / Q000503:physiopathology*; D013373:Substance P / Q000502:physiology; D009435:Synaptic Transmission
chemical_list: D004723:Endorphins; D013373:Substance P