Norepinephrine is both a hormone and a neurotransmitter. When released as a hormone in response to excitement, which can include both positive and negative stimuli, norepinephrine also helps in cementing memories caused by the excitement.Norepinephrine’s role in responding to excitement may sound similar to Epinephrine, which I wrote about in my previous post. It turns out that norepinephrine is epinephrine that has reached the brain.
When released as a neurotransmitter, norepinephrine helps carry messages across synapses. It also plays a role in retrieving memories, according to this Science Daily 2004 article about research at the University of Pennsylvania Medical Center. Norepinephrine is also useful in telling the brain to shake, rattle, and roll in an attempt to make the brain alert and focused. However, too high levels can be a cause of aggression. Serotonin, dopamine, and endorphin, working as a trio, can help balance high levels of norepinephrine and somewhat control the aggressive behavior.
You can tinker with a 3D model of norepinephrine at the 3Dchem site, which focuses on chemistry, structures and 3D molecules and is maintained by Dr Karl Harrison from the Department of Chemistry at the University of Oxford. Folks with Parkinson’s have a decrease in production of norepinephrine. Marilee Sprenger, citing Wurtman & Suffes, 1996, notes that “Norepinephrine and dopamine, sometimes called the alertness chemicals, are produced when tyrosine reaches the brain. Tyrosine is found in protein.” That’s certainly a plug for having proteins in the diet. There will be more on what makes for a “really good brain diet” in a future post.