POMC and Anxiety: The stimuli that terminate on the spinal cord's posterior horn cause enkephalinergic neurons to release enkephalin, a neurotransmitter that inhibits the perception of pain by blocking the substance P. The stimuli proceed primarily down the lateral spinothalamic tract until they reach the brainstem, where they increase cortisol secretion in the adrenal glands and release serotonin, which raises the endorphin and the adrenocorticotropic hormone (ACTH) levels which automatically affects the patient's stress and anxiety levels.