Depression. Computer artwork of a human brain and kidney showing hormonal pathways involved in some cases of depression. In the centre of the brain is the hypothalamus (pink), which controls autonomic functions. Within the hypothalamus is the pituitary gland (green), an endocrine (hormone secreting) gland that controls other endocrine glands in the body, including the adrenal gland (yellow, above kidney at lower left), which produces a number of hormones involved in stress responses. One of these hormones is glucocorticoid, which interacts with serotonin receptors in the hippocampus (orange). The hippocampus often shrinks and has fewer serotonin receptors in depressed patients, although the mechanism for this change is not fully understood.