neurohormone
A hormone synthesized and released by specialized neurons that acts on distant target tissues via the bloodstream.
Full Definition
A neurohormone is a bioactive substance produced by neurosecretory neurons that is released into the circulation to exert effects on distant target organs, combining characteristics of both neural and endocrine signaling. Unlike classical neurotransmitters that act locally at synapses, neurohormones are released into blood vessels or stored in neurohaemal organs for systemic distribution. Examples include hypothalamic releasing and inhibiting hormones, posterior pituitary hormones (oxytocin and vasopressin), and catecholamines from chromaffin cells. Neurohormones represent an evolutionary adaptation allowing the nervous system to coordinate long-term physiological responses and integrate complex regulatory networks across multiple organ systems.
Usage
Usage note: Emphasize systemic, hormonal action rather than local synaptic effects when distinguishing from neurotransmitters.
In Context
- "The neurohormone oxytocin facilitates both parturition and maternal bonding behaviors." — Reproductive endocrinology review
- "Stress triggers the release of multiple neurohormones including CRH and catecholamines." — Stress physiology textbook