Posted by Louise on September 8, 1999, at 4:56:14
In reply to Anhedonia, Agonist, Antagonist....???, posted by JohnL on September 8, 1999, at 3:53:42
> I am hoping someone might explain some terms so I might understand them better. First, how is "anhedonia" pronounced? My general practioner didn't even know what this word meant. After that, I didn't even venture trying to ask him my next question, which was to explain to me what is meant by "agonist" and "antagonist". Dictionary meanings didn't clarify this much to me. Can you share with me examples of these words in action? For example, Remeron I believe is an antagonist...what does that mean? Does it hamper something or enhance something? What is the end result of an agonist? What is the end result of an antagonist? I hope this doesn't sound too silly, it's probably psych 101, but I read these words all the time and never really understand what they mean or how they work. Thanks in advance for your help.
Hi John
Psychotropic drugs (or any substance affecting brain chemistry) may be described as agonist or antagonist according to how they effect neurotransmitter action in the brain. When a neuron fires, neurotransmitters are released from the cell via the synapse and one mechanism that takes place is binding to receptors on a subsequent neuron. Think of it like a chain reaction running between cells through the brain, with the neurotransmitters which have been released passing the link / message on from one neuron to another. A further mechanism is the re-uptake of neurotransmitters which are 'floating around' after release. Although some bind to another cell (post synaptic receptors) to carry on the 'chain', some are taken back (called re-uptake) into the neuron which released them. Remaining neurotransmitters are broken down by enzymes.
Drugs can interfere with these (and other) processes of neurotransmitter action. Drugs which facilitate the effect of a specific neurotransmitter action are called agonists. They 'heighten' the effect of the neurotransmitter (you could think of it as allowing this neurotransmitter to flow more freely around the brain). The agonistic drugs work e.g. by destroying the enzymes which break the target neurotransmitter down; blocking deactivation by blocking reuptake.
Antagonistic drugs do the opposite; they inhibit the effects of a the target neurotransmitter e.g by blocking a receptor site on the (2nd / receiving) cell so that the neurotransmitters can't permeate the cell.
Different drugs / chemicals can act as agonists / antagonists for different types of receptors in the brain. e.g. an anti-psychotic drug such as chlorpromazine can inhibit / block dopamine action. Drugs such as LSD stimulate seratonin receptors, producing a 'high', this is therefore an agonist.
I hope this helps. If it's still unclear, post another message and I'll try again!
Louise
P.S. I haven't got a clue how you pronounce anhedonia!
poster:Louise
thread:11222
URL: http://www.dr-bob.org/babble/19990829/msgs/11224.html