Neurons located in which area release serotonin as their neurotransmitter?

Neurons of the nucleus raphe magnus release serotonin at their nerve endings. These terminate in the spinal cord on interneurons that in turn release enkephalin and block the incoming signals from the pain fibers. The analgesia system consists of three major components: Periaqueductal gray and periventricular areas of the mesencephalon and upper pons. Raphe magnus nucleus, a midline nucleus located in the lower pons and upper medulla. Dorsal pain inhibitory complex (interneurons) located in the spinal cord.