Definition

Noun: A neurohormone is a type of hormone that is produced and released by specialized nerve cells (neurons) directly into the bloodstream or surrounding fluid. Unlike neurotransmitters, which act across a tiny synaptic gap between two neurons, neurohormones are secreted to travel through the circulatory system to affect distant target cells or organs.

Examples

• Norepinephrine acts as both a neurotransmitter and a neurohormone. When released into the bloodstream from the adrenal medulla, it functions as a neurohormone to increase heart rate and blood pressure.
• Vasopressin, also known as antidiuretic hormone (ADH), is a neurohormone released from the pituitary gland that helps regulate water balance in the body.
• The release of the neurohormone oxytocin during childbirth stimulates uterine contractions.

Advanced Usage

• Neurohormonal: The adjective form describes processes or systems involving neurohormones.
  • The body's response to stress involves a complex neurohormonal cascade.
• The term is often used in scientific contexts to distinguish the method of delivery (endocrine) from that of classical neurotransmitters (synaptic).

Variants and Related Words

• Neurohormonal (adjective): Pertaining to or involving neurohormones.
• Neurosecretion (noun): The process by which neurons release neurohormones. A neurohormone is a type of neurosecretory substance.

Synonyms

• Neurosecretory substance
• Neural hormone

Different Meanings / Clarifications

• Neurohormone vs. Neurotransmitter: This is a key distinction. Both are chemical messengers released by neurons. A neurotransmitter acts locally at a synapse between two neurons (e.g., dopamine in the brain). A neurohormone is released into the blood to have a more widespread, endocrine effect (e.g., vasopressin acting on the kidneys).
• Neurohormone vs. Hormone: All neurohormones are hormones, but not all hormones are neurohormones. A neurohormone is specifically secreted by neurons. Other hormones are secreted by dedicated endocrine glands (e.g., insulin from the pancreas, which is not a neurohormone).

Noun

1. a hormone that is released by nerve impulses (e.g., norepinephrine or vasopressin)