2-Minute Neuroscience: Norepinephrine

Summary

Norepinephrine, or noradrenaline, is a neurotransmitter and hormone that plays a critical role in the body’s nervous system. Synthesized from dopamine in the brain, it is primarily produced by neurons in the locus coeruleus and released by the sympathetic nervous system and adrenal glands. It affects the body by acting on adrenergic receptors, which influence processes like alertness, arousal, and attention. Norepinephrine is key in the fight-or-flight response, increasing heart rate and blood pressure. Its effects depend on the receptor type and location, making its role complex and essential for both central and peripheral nervous system functions.

Takeaways

• 😀 Norepinephrine, also known as noradrenaline, is a neurotransmitter and a catecholamine, which means it has a specific chemical structure and contains a catechol nucleus.
• 😀 It is synthesized from dopamine through a reaction catalyzed by the enzyme dopamine beta-hydroxylase.
• 😀 Norepinephrine-producing neurons are concentrated in the pons and medulla, with the locus coeruleus being the most prominent site of production in the central nervous system.
• 😀 Norepinephrine is the primary neurotransmitter used by the sympathetic nervous system, found in sympathetic ganglia near the spinal cord.
• 😀 It is also released from the adrenal glands as a hormone.
• 😀 Norepinephrine acts on adrenergic receptors (alpha-1, alpha-2, and beta-adrenergic receptors), which are G-protein coupled receptors.
• 😀 There are multiple subtypes of adrenergic receptors, each having different functions depending on where they are located.
• 😀 The actions of norepinephrine depend on the type of receptor it activates and the location of that receptor in the body.
• 😀 In the central nervous system, norepinephrine is associated with arousal, alertness, and attention, contributing to cognitive functions.
• 😀 In the sympathetic nervous system, norepinephrine's release is typically linked to responses such as elevated heart rate and blood pressure, which prepare the body for increased activity.

Q & A

What is norepinephrine and what role does it play in the body?

Norepinephrine, also known as noradrenaline, is a neurotransmitter and hormone that plays a crucial role in the body's response to stress, arousal, alertness, and attention. It is synthesized from dopamine and is involved in both the central nervous system and the sympathetic nervous system.

How is norepinephrine produced in the body?

Norepinephrine is synthesized from dopamine in a reaction catalyzed by the enzyme dopamine beta-hydroxylase. This occurs mainly in the locus coeruleus in the central nervous system and in sympathetic neurons near the spinal cord.

What is the function of norepinephrine in the central nervous system?

In the central nervous system, norepinephrine is associated with arousal, alertness, attention, and regulating the body's response to stress. It plays a key role in the brain's ability to maintain focus and respond to stimuli.

Where are norepinephrine-producing neurons located?

Norepinephrine-producing neurons are primarily located in the pons and medulla, particularly in the nucleus called the locus coeruleus, which is the main site of norepinephrine production in the brain.

What is the sympathetic nervous system's relationship with norepinephrine?

Norepinephrine is the primary neurotransmitter used by the sympathetic nervous system. It is released by sympathetic neurons found in clusters near the spinal cord, which are known as sympathetic ganglia.

What is the role of norepinephrine as a hormone?

As a hormone, norepinephrine is released from the adrenal glands into the bloodstream and helps regulate the body's fight-or-flight response, increasing heart rate, blood pressure, and preparing the body for increased physical activity.

What are adrenergic receptors, and how do they relate to norepinephrine?

Adrenergic receptors, or adrenoceptors, are G-protein coupled receptors that norepinephrine acts upon. There are three main types of adrenergic receptors—alpha-1, alpha-2, and beta-adrenergic receptors—each with multiple subtypes that influence different physiological responses.

How does norepinephrine affect the body when it acts on adrenergic receptors?

The effects of norepinephrine depend on the type of adrenergic receptor it activates and its location. In the central nervous system, it promotes alertness and arousal, while in the sympathetic nervous system, it increases heart rate, blood pressure, and prepares the body for action.

How is norepinephrine removed from the synaptic cleft?

Norepinephrine is removed from the synaptic cleft by a transport protein called the norepinephrine transporter, which ensures that its actions are terminated after it has transmitted a signal between neurons.

What are the key differences between the central nervous system's and the sympathetic nervous system's use of norepinephrine?

In the central nervous system, norepinephrine is primarily involved in regulating arousal, attention, and focus. In contrast, in the sympathetic nervous system, it is used for responses linked to increased activity, such as raising heart rate and blood pressure to prepare the body for physical exertion.