Abstract
Evidence that the endorphins, metabolites of the pituitary hormone beta-lipotropin, profoundly affect mood and behavior, are secreted with ACTH in response to stress, and may act as neurotransmitters in the GI tract, suggests that they play an important role in CNS homeostasis. The fact that these peptides are synthesized in the GI tract as well as the brain casts new light on CNS-endocrine-environmental interrelationships.