Raj N. Sureja, MD
As an Interventional Pain Management Physician, I often work with patients who suffer from nerve-related chronic pain aka neuropathic pain. It is very important for me to understand how nerves function and communicate with one another and the best ways to help them heal or modulate when they are damaged or overactive. Understanding neurotransmitters – the chemical agents that are used by nerve cells or neurons to communicate with each other, other cells, glands, etc. is crucial, especially those that play a role in the pain cycle. In this series of articles, I’d like to discuss the neurotransmitter norepinephrine, where it is synthesized in the body, what is does and how it helps the body to function, what I can do if the body produces too much or too little of it, and how I can treat patients using my understanding of how it communicates pain signals.
Norepinephrine, aka noradrenaline, is both a neurotransmitter and a hormone. That means it is synthesized in two places in your body and can act in different ways. In your brain, it is synthesized from another neurotransmitter, dopamine, by specialized nerve cells near your brain stem and in your spinal cord. As a hormone, it is manufactured by the adrenal glands which sit atop your kidneys.
As a neurotransmitter: norepinephrine has these functions:
- Affects cognition and mood
- Affects circadian rhythms (wake-sleep cycle)
- Increases awareness, arousal, urgency
- During stress, constricts blood vessels and maintains blood pressure
Norepinephrine is a part of the “fight or flight” response mechanism in your sympathetic nervous system during times of stress or danger. It is what kicks into action when you are confronted by a snarling lion running at you or when you are faced with giving a speech in front of a crowded auditorium full of people you don’t know. Your brain and body have to decide in an instant whether to stay and fight/speak or to run for your life/leave the stage. Some incredible things happen when this neurotransmitter starts communicating between neurons, cells, and muscles. They are:
- Breathing – it becomes faster and your airways clear, so more oxygen flows to your muscles
- Cardiac volume increases as your heart pumps blood faster to muscles
- Blood pressure increases
- Blood is diverted to your muscles and internal organs, your skin pales
- Your pupils dilate to let in light so you can see more clearly
- Stored sugar in your liver is released as energy for your muscles
In my next article, I’ll talk about conditions where patients have too little or too much norepinephrine and how we treat those patients.