Posted by Cam W. on May 17, 2000, at 0:05:28
In reply to Cam--Need explanation??, posted by tina on May 16, 2000, at 21:36:06
Tina - I dunno.
As you know from this board, serotonin is just one of the neurotransmitters. They seem to find more everyday. All are different, but do or don't work differently. They all work as a unit, kinda like a sports team on a roll, or when the defence falters, we get depression. Lack of serotonin doesn't "cause" a depression anymore than a goaltender "causes" a loss (his team just didn't score enough goals). We can deplete serotonin from the body and it doesn't cause depression, but adding serotonin (or in other cases, norepinephrine) can resolve the"symptoms of depression". Like adding a good goaltender to the team and the team starts working as a unit again.
Serotonin is one of the neurotransmitters involved in the body's stress response system (HPA axis). Serotonin receptors and neurons are located throughout the body and brain (even in platelets), but are concentrated in a midbrain structure called the raphe nuclei. Serotonin nerves mainly start from this structure and extend out to various other nerve cells and brain structures. This widespread distribution of serotonin "innervation" affects a variety of bodily functions, including: the sleep-wake cycle, sexual behavior, feeding behavior, control of body temperature, pain control, etc. as well as mood control.
Serotonin system "dysfunction" (or breakdown) is implicated in (but probably not a direct cause of) a number of "neuropathological processes" (disorders) such as: sleep disorders, anxiety disorders, aggression, bulemia, anorexia, as well as depression. Also, serotonin problems are seen in Alzheimer's, Parkinson's and Huntington's diseases.
There are many types of serotonin receptors in the body (at least 15 that I have read about) that all do something slightly (or majorly) different. For example, stimilating one type of serotonin receptor can increase dopamine release, while stimulating another serotonin receptor can decrease dopamine release.
By interacting in different ways at these different receptors and acting on and being acted upon by other chemicals (eg in combination with other neurotransmitters, neuropeptides, amino acids, etc., each with their own complement of different receptors) serotonin is a major player in the control of mood. Change the amount of serotonin and mood changes (but not to the point of major depression - different, mostly unknown breakdowns, have to also occur to induce depressive symptoms).
Serotonin and these other chemicals bind to receptors, which alters the shape of the cell membrane that they attach to, causing a chain reaction of chemical signals inside the cell that basically tells the DNA in the cell nucleus to produce an enzyme, protein, etc. from specific genes. These products are released into the blood stream and interact with other receptors, causing further interactions with other cells and signaling more DNA to produce different chemicals, ad nauseum.
All this produces what we call a human being, including all of our body functions, thoughts, movements, etc.
Somewhere in all this, serotonin is helping to maintain the HPA axis, so that the body can respond appropriately to stress. Prolonged stress can cause a breakdown of the HPA axis and manifest as the symptoms we call depression. Serotonin, in conjunction with a bunch of other neuropeptides (chemicals) regulates what we call mood. In this system, it seems that serotonin is a major player (Gretzky), but it takes the whole team working together to win.
See, I dunno. I hope this muddles you as much as it does me. The further you look into these processes, the more lost you get (until you absolutely do not know what is going on and then they call you an expert).
I really hope this helps - Thanks for listening - Cam
poster:Cam W.
thread:33678
URL: http://www.dr-bob.org/babble/20000508/msgs/33735.html