I don’t know why you asked this but I sure like the question.
Here’s what I found, according to Rebecca Seal, a neuroscientist at the University of California, San Francisco: (excerpt)

“Neuroscientists now know, however, that it is common for neurons to release a classical transmitter with another type of messenger, such as a gas (nitric oxide, for instance) or a neuropeptide (a small protein that can act as a transmitter). With the aid of new techniques for manipulating and imaging neurons, researchers have found that a number of neurons communicate using more than one classical neurotransmitter. Indeed, some of our auditory neurons simultaneously release three different classical transmitters during a brief period in development.

So we see that “one neuron, one transmitter” is a bit too simplistic. But what about the original principle put forth by Dale that all axonal branches of a neuron release the same transmitter? There now appear to be at least a few exceptions to this principle. Motor neurons, which are important for voluntary muscle movements, have long been known to release acetylcholine onto both muscle cells in the body and neurons in the spinal cord. Recent studies show, however, that motor neurons also release a second transmitter, glutamate. Remarkably, they appear to release glutamate only onto neurons in the spinal cord and not onto muscle cells—in other words, certain branches of a single neuron release glutamate, and others do not.”

Source

@worriedguy Thanks! I just spent quite a while reading a neuroscience textbook without finding a definitive statement one way or the other. GA!

Edit: My textbook has diagrams referring to the distribution of specific neurotransmitter axons in the CNS, which seems to imply that axons can only release one type of neurotransmitter, but neurons can have different types of axons releasing different neurotransmitters. For example, it says that “Most of the serotonin (5-HT) containing fibres in the CNS arise from the raphe nuclei in the brainstem. They are distributed to all parts of the CNS.” Concise Text of Neuroscience, by Robert E Kingsley.

@worriedguy What a superb answer…thanks you soooo much! I asked because I’m writing an essay on how our knowledge of neurons and how they function aids our understanding of human behaviour…and to what extent exactly. I had already picked pain sensations and behaviours along with drug taking as two of my ‘case studies’ but wasn’t exactly clear as to the above question.

My text book (which is pretty basic to say the least) says that they are exclusive (or it hints at that anyway) so a serotonergic neuron is one that emits serotonin. However, your source has some excellent information, which is invaluable. It does seem to make the whole thing a lot more complicated but interesting and useful!! Can’t thank you enough xxxx

@nebule, @FireMadeFlesh May your neurons be bathed in dopamine, serotonin, melatonin, oxytocin, endorphins and enkephalins.

@worriedguy I could use some epinephrine as well if you don’t mind ;-) x

@FireMadeFlesh My book doesn’t cover axons and dendrites… I’m presuming the axons are the very edges of the neuron process? (what I would call the ‘tail’ which branches off into many different other little branches… Is it saying that each of these little axons could give off different neurotransmitters within the same neuron?... Ah yes…just googled it… like this…

“how do they know which to emit?”

As to the “how” question, I suggest the ncRNA is what engages the neuron to fire…

The zebra finch genome will be a valuable tool for neuroscientists, says lead author Wes Warren, PhD, research professor of genetics at Washington University’s Genome Center. They can now carry out studies to identify a core set of genes in the zebra finch brain involved in both hearing and producing song and then look to see if any of these genes are disrupted in people with speech disorders.

To the researchers’ surprise, many genes activated by bird song do not act like genes in the traditional sense and code for proteins. Instead, DNA from these genes is transcribed into short stretches of non-coding RNA that control the expression of other genes in the zebra finch brain involved in vocal communication. Among the genes suppressed in the moments after a zebra finch hears a new song, two-thirds are non-coding RNAs, the researchers noted… Non-coding RNAs are already known to play key roles in developmental processes in humans and in animals.

Not only can the each neuron release multiple neurotransmitters, but the action of each neurotransmitter can change depending on what kind of receptor it binds to postsynaptically!

To answer your question about axons and dendrites—if you look at a picture of a neuron, you’ll see that it usually has one* big branch that projects away from the cell body, right? That’s the axon. Projections that are receiving input that send information TO the cell body are dendrites.

Also I feel obligated to say that I think @RealEyesRealizeRealLies has some novel ideas but as a neuroscientist, I know of absolutely no empirical support for them.

*neurons can have more than one axon, like bipolar cells in your retina.

For your reading pleasure @nikipedia… here is Warrens paper as printed in Journal Nature accepted January 6 2010.

@RealEyesRealizeRealLies I have read the paper and I find your take on it diverges rather sharply from the authors’.

How so?

@worriedguy great answer, saved me from typing, cheers :)

ouch my head hurts… just finished my first draft…will return tomorrow to read above detailed posts…. Thank you all for your contributions… xxx

@nebule It seems you and @nikipedia already answered your question. Good luck with the paper!

Stump’d me, those dang neurons are interchangeable-what’s up with that?

one neuron = one neurotransmitter