Neurohormones Definition

A neurohormone is any hormone that is produced and released into the bloodstream by neuroendocrine cells. Hormones are secreted into the circulation for systemic effect, but they can also function as neurotransmitters or in other roles such as autocrine or also as paracrine messengers.

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What are Hormones?

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A chemical messenger molecule secreted (or released) by endocrine cells in endocrine glands.


By definition, a hormone molecule is released into the bloodstream as it travels throughout the body to find its target cells. Although target cells can be found within the intravascular compartment (i.e., within blood vessels), the majority of hormones have target cells in tissues other than blood vessels.

Neurohormones in Brief

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A neurohormone is any of a class of substances produced by specialized cells (neurosecretory cells) that are structurally similar to those found in the nervous system rather than the endocrine system. Neurohormones are hormones that travel along nerve-cell extensions (axons) before entering the bloodstream at neurohemal organs. As a result, neurohormones serve as an intermediary between sensory stimuli (events or conditions perceived by the nervous system) and chemical reactions (endocrine secretions that act on other tissues of the endocrine system or on tissues of other systems, such as those involved with excretion or reproduction).


In most mammals, neurohormones such as oxytocin and vasopressin are produced in the hypothalamic region of the brain and secreted into the bloodstream by the neurohypophysis (part of the pituitary gland). The hypothalamus also produces a second class of neurohormones known as releasing hormones (the first of which was chemically identified in 1969). Members of this group, on the other hand, are transmitted within neural cells to a second location in the brain, from which they travel in the bloodstream to the adenohypophysis, which is also a part of the pituitary gland. They either stimulate or inhibit adenohypophyseal hormone release.


Enkephalins and other endorphins are a third class of neurohormones that were discovered in 1975 during research into the mechanism of action of morphine and other analgesics. Endorphins are effective pain relievers, which appears to be related to their function as neurotransmitters, which transmit nerve impulses from one neuron to another. Their neurohormonal activity is manifested by an indirect process involving a site other than the secretory neuron in the central nervous system that stimulates somatotropin and vasopressin secretion.

Function of Neurohormones

Neurohormones are chemical messenger molecules released by neurons that travel to distant target sites throughout the body via the bloodstream. As a result, neurohormones have properties that are similar to those of neurotransmitters and hormones.

The Seven “small Molecule” Neurotransmitters Listed Below Do the Majority of the Work -

  1. Acetylcholine

  2. Dopamine 

  3. Gamma-aminobutyric acid (GABA)

  4. Glutamate

  5. Histamine

  6. Norepinephrine

  7. Serotonin

Where are Neurohormones Produced?

The hypothalamus produces neurohormones that regulate pituitary gland hormone biosynthesis and secretion, as well as mediating interactions between the external and internal environments and producing hormones that regulate metamorphosis.

Types of Neurohormone

  • Hormone.

  • Oxytocin.

  • Vasopressin.

  • Neurotransmitter.

  • Norepinephrine.

  • Gonadotropin-releasing hormone.

  • Corticotropin-releasing hormone.

  • Thyrotropin-releasing hormone

What is Oxytocin?

Oxytocin is a neurohormone in mammals whose main functions are to stimulate uterine contractions during labour, to stimulate milk ejection (letdown) during lactation, and to promote maternal nurturing behaviour. Oxytocin is thought to influence a variety of other physiological and behavioural processes, including sexual and social behaviour in both men and women. The hypothalamus produces oxytocin in both sexes, which is then stored and secreted into the bloodstream by the posterior pituitary gland. Other tissues that synthesise and secrete it includes the brain, uterus, placenta, ovaries, and testes.

What is Vasopressin?

Vasopressin, also known as antidiuretic hormone (AVP), is a hormone that is important in maintaining osmolality (the concentration of dissolved particles in the serum, such as salts and glucose) and thus the volume of water in the extracellular fluid (the fluid space that surrounds cells). This is necessary to protect cells from sudden changes in water content, which can interfere with proper cell function. In healthy people, normal serum osmolality ranges between 285 and 300 milliosmoles per kilogramme (mOsm/kg). Vasopressin as well as the hormone oxytocin evolved from a single primordial neurohypophyseal hormone called vasotocin, which is found in trace amounts in humans. 


Vasopressin's Primary Function - Although it is also a vasoconstrictor and pressor agent, the primary function of AVP in the body is to regulate extracellular fluid volume by regulating renal water handling (hence, the name "vasopressin"). AVP increases water permeability in the renal collecting ducts via V2 receptors (a cAMP-dependent mechanism), resulting in decreased urine formation (hence, the antidiuretic action of "antidiuretic hormone"). Blood volume, cardiac output, and arterial pressure are all increased as a result.


Heart failure is associated with a seemingly paradoxical increase in AVP. AVP secretion should be reduced by increased blood volume and atrial pressure associated with heart failure, but it is not. It is possible that sympathetic and renin-angiotensin system activation in heart failure overrides the volume and low pressure cardiovascular receptors (as well as the hypothalamic control of AVP release) and results in an increase in AVP secretion. Nonetheless, an increase in AVP during heart failure may contribute to an increase in systemic vascular resistance as well as increased renal fluid retention that occurs with heart failure.

What are Neurotransmitters?

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Neurotransmitters are chemical messengers that send signals from one neuron to another across the synapse to a target cell, which can be another neuron, muscle cell, or gland cell. Neurotransmitters are chemical substances produced by neurons specifically to transmit a message. 

Neurotransmitter Signaling

Neurotransmitters are produced by neurons and stored in vesicles, which are typically found at the terminal end of an axon, also known as the presynaptic terminal.

What is Norepinephrine?

Norepinephrine is a chemical that occurs naturally in the body and functions as both a stress hormone and a neurotransmitter (a substance that sends signals between nerve cells). When the brain perceives a stressful event, it releases it into the blood as a stress hormone.

FAQs (Frequently Asked Questions)

Question 1) How does Norepinephrine Affect Mood?

Answer: Serotonin regulates mood, anxiety, and other functions, while norepinephrine mobilises the brain for action and can boost energy and attentiveness.

Question 2) What do You Mean by Neurohormones?

Answer: A neurohormone is any of a class of substances produced by specialised cells (neurosecretory cells) that are structurally similar to those found in the nervous system rather than the endocrine system. Neurohormones are released into the bloodstream by neurohemal organs after travelling through the nerve-cell extensions (axons). As a result, neurohormones act as a link between sensory stimuli (events or conditions perceived by the nervous system) and chemical reactions (endocrine secretions that act on other tissues of the endocrine system or on tissues of other systems, such as those involved with excretion or reproduction).