There are many neurotransmitters in the brain. Three which are known to affect depression are dopamine, norepinephrine, and serotonin. Some medicines for depression increase just one of these neurotransmitters, while others increase two or more. This section shows the primary neurotransmitters thought to be important in depression and which medicines increase which neurotransmitters. With all medications it is important to discuss any questions you have with your physician, physician's assistant, or nurse.