Posted by boBB on June 2, 2000, at 23:55:55
In reply to Info on Neurotransmitters, posted by Jon Barnes on May 28, 2000, at 19:55:36
JB, I checked out the http://www.beatcfsandfms.org/html/BrainChem.html site, but I wouldn't give it two stars on my five star scale.
The problem I had was that it went from introducing the concept of a neurotransmitter right into talking drugs. We would never learn what role a neurotransmitter plays in a healthy brain. Even if we agree that someone has a neurochemical imbalance and that psychmeds could improve the balance, MOST of your neurochemical balance will continue to function properly. In med school, you might go through a year of learning healthy anatomy and physiology before your got to a year of pathology, and only then after a year of studying pathologies of diseases before you started studying treatments.
pre-synaptic means things that happen inside the neuron (brain cell) before (pre) the synapse. All of the blocking and mimicking drugs work at the synapse, but the call them post-synaptic.
you probably understand synapses - nerves fire electric signals, but nerves are separated across gaps, and the neurochemicals carry signals across the gaps. There is some really cool chemistry that explains how the neurochemical turns back into electricity, but that is another story. The big deal with psychopharmacolgy and neurochemistry these days is what is going on at the gap. Any one gap might have numerous "receptor sites" that are sensitive to one chemical or another. (some pictures would help, here). Things change all the time at these synapses, they might get dull to one chemical, or develop more receptors. And some of the chemical floats back into the structure of the synapse and some is lost or consumed (metabolized) in the gap.
Drugs can either act like a neurochemical, or block a receptor for a neurochemical, or stimulate the synapse to release a neurochemical, among other things.
Isn't this already on Dr. Bob' site somewhere? And somebody else can fill in the "agony" labels - there’s agonists, partial agonists, antagonists - depending on if they block or mimic or stimulate a chemical.
Of more concern, I would think, for a person interested in neurotransmitters is what they DO.
For example, GABA is an inhibiting neurotransmitter.
Serotonin and dopamine are reinforcing neurotransmitters.
Norepenephrine is a stimulating or exciting neurotransmitter.
Acetecholine is the primary neurotransmitter that works at the muscle end of nerve fibers - it is acetecholine that operates your muscles, making some venitian-blind looking arrangement of cells in your muscle open or close so your muscle will expand or contract.
Your neurons might be mobilizing both NorE and GABA and whichever one prevails will determine whether you get a reaction, from the NorE, or, if the GABA "wins" whatever nerve network is getting dosed will freeze, or do nothing.
Dopamine is found exclusively in networks from the frontal area - mostly the frontal lobes, to the amygdala/hypocampus, which is in the limbic system, inside the temporal lobes, (behind your temples). Dopamine networks (dopaminergic) are associated with "pleasure centers." these are areas of the brain associated with pleasure. (DUh!). When they implant mice with probes that let them self stimulate these areas, they will often stimulate rather than eat or sleep, until they starve to death. Evolutionary psychologists suggest we evolved these networks to learn what was good for us in terms of survival.
Basically, dopamine signals tell neurons to "keep doing this" Since dopamine is found mostly in the front of the brain, where we have complex networks that we use for making plans and thinking complex thoughts, it is associated with some of our persistent drives. If we attenuate our dopamine networks to seeking, say, cocaine, they will set up their own little plan to tell us "find more cocaine. Yeh, there’s some. Take it. Ummmm good. Oh, darn, Im out, find more, etc." In a well functioning brain, these dopamine networks will form around healthy behaviors, like hugs (not drugs) or going to work and study or having fun at the lake or whatever we are *supposed* to do. But most of this behavioral planning and reinforcement is the same kind of addiction mechanism, so we might always wonder if what we are doing is really an original, well thought out plan or if it is just an echo of whatever was fun last time.
Norepenephrine AKA noradrenaline is what gets things going. When we have some sort of stimulus, NorE is the first chemical that spreads through our networks. If we spread NorE with no stimulus, it feels like anxiety or panic. I forget the ironic twist of fate that makes drugs that simulate NorE effective at treating panic and anxiety, but many of them stimulate dopamine to. NorE is like the phone ringing and dopamine is like and answer, so if it rings, and there is no answer, we might take Dexedrine or Ritalin to make it ring louder and more consistently so we will get that good dopa feeling. But see, now I am digressing to talking drugs rather than normal function.
Serotonin is a reinforcer, like dopamine, but it is found more in the middle and back of the upper brain (cerebral cortex) Serotonin is associated with more mundane tasks, like movements and repetitive tasks. That is why exercise helps boost serotonin levels - repetition produces serotonin and serotonin facilitates repetition. repeatedly.
There are a bunch of other neurotransmitters. These BIG 5 get a lot of attention, though. Most neurons that are sensitive to NorE are also sensitive to Adrenaline, which is not kept inside the structure of the synapse like most neurochemicals, but rather washes in through the blood, more like a drug. When your pituitary(?) releases a dose of adrenocorticotropic hormone your adrenal gland give off a shot of adrenaline, which not only bumps up your sympathetic nervous system (the red line nerves that constrict blood vessels, increase heart rate and what not - the other side - the "blue" in my book, does the opposite, slows breathing, opens arteries and slows the heart) but adrenaline also washes into your NorE sensitive neurotransmitters (like a shot of crystal meth, or coke) and sets your brain on track looking for something familiar up in the neuron networks - some dopamine response and serotonin response. If it doesn't get a response, well, you get a full-blown fight or flight, and unless you are trained well, your liable to start acting out one way or the other.
A good book on the neurochemistry that deals with deviations from the "normal" states, as part of everyday life (like as a result of fatigue, or fright) is called Chemistry of Conscious States. The same author (sorry, I don't have his name handy) wrote the neurochemistry volume for Scientific American's most recent Brain book series.
Oh, yeh - Acetecholine - when you go to sleep, nore- dopa- and serotonin levels drop and this other chemical comes into play. It does not fire neurons along well organized dopamine and serotonin networks. You see, experience and learning seems to build serotinon and dopamine connections, so things that are connected by these two chemicals seem familiar. But when nore- dopa- serotinon levels drop (these are aminergic transmitters) the acetecholine gets more of a wild, unconnected kind of thoughts going. instead of the stimulation coming from the sensory side, kicked up by some norE coming down a nerve input, The acetecholine just kind of fires the dopa- serotonin networks apparently at random, that is how we dream.
I could prattle and babble on and on, but lets see who picks at this. There are probably some small flaws in my explanations, but I think this is a handy sketch of basic functions. If it is flawed, it is because it is oversimplified. But I also find people who can talk all kinds of advanced microbiology, but are not familiar with the basic function of the brain machine. I think we should be learning this much about the time we get into junior high school. IF we can learn the capitals of all 50 states, why not learn the basics of how our brain works at about the same time we are going to start to be exposed to choices about using tobacco, coffee, pot or cocaine?boBB
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> Hi Gang,
>
> Would like to know if anyone knows of any good information which is written in layman's terms about the neurotransmitters and how they work. I've got the basics down (serotonin, dopamine, ne) I think, but don't understand things like alpha 1, post vs pre synapitic, etc. Any good books or web pages out there which covers this stuff?
> Thanks
> JB
poster:boBB
thread:35005
URL: http://www.dr-bob.org/babble/20000526/msgs/35789.html