Prolactin is a protein that acts as a hormone; known to enable mammals to produce milk. It is an important protein and has over 300 separate processes in a wide range of animals, including humans. The protein is secreted by the pituitary gland and is done in response to eating, procreating, ovulation and child-rearing. The protein is secreted in pulses to give the body a wide range of physiological changes. As a compound in the human body, it has a broad set of roles, assisting in metabolism, immunity regulation and development of the pancreatic system in babies. The secretion of the hormone is controlled by endocrine neurons in the hypothalamus of the brain.