 |
 |
Hello Alastair, Mon, 22 Jun 1998 09:14:46 +0000 Alastair Wyse <[log in to unmask]> wrote: <<<< There seems to be a view that an agonist can be best understood as the opposite of antagonist . Rager produces the two definitions below: > antagonistic effect > This is the consequence of one chemical (or group of chemicals) > counteracting the effects of another chemical, the opposing chemicals > cancel out each other's effects. The opposite of this in the case of dopamine would be to define the agonist effect as " the consequence of one chemical ( or group of chemicals ) increasing ( ? ) the effect of another chemical ( ? )" .>>>> NO!, the opposite of "counteracting the effects of another chemical" is "acting WITHOUT another chemical counteracting the effects" So redefining "agonist effect": This is the consequence of one chemical (or group of chemicals) acting without another chemical counteracting the effects. The effects of the chemical are not canceled out by an opposing chemical. Redefining dopamine-agonist: A chemical (or group of chemicals) acting as dopamine (=mimics dopamine). <<<< antagonist > <pharmacology> A substance that tends to nullify the action of another, > as a drug that binds to a cell receptor without eliciting a biological > response. > agonist > 1. <anatomy> A prime mover. Aristotelean philosophy ?>>>> NO! In anatomy there are also agonists and antagonists: E.G.: when you bend your arm, the biceps is the agonist, causing the move. The triceps is the antagonist: by "counteracting and meanwhile letting go" the bending goes in a coordinated way. When you extend your arm the triceps is the agonist and the biceps the antagonist. <<<< > 2. <pharmacology> A drug that has affinity for and stimulates > physiologic activity at cell receptors normally stimulated by naturally > occurring substances, thus triggering a biochemical response. This definition would mean that a " dopamine agonist " has an affinity for and stimulates the dopamine receptors. Sounds good but what does it mean in practice ?? Has there been any description of any so called dopamine agonist's method of stimulating the dopamine receptor ?? The only method that I know of is that that " dopamine agonist " mimics the dopamine . In other words it becomes a replacement neurotransmitter.>>>> CORRECT! <<<< If the term " dopamine agonist " is confined to a replacement neurotransmitter for dopamine then it has meaning.>>>> YES! <<<< But I would like to give an analogy of why I made the original posting. The original posting concerned the term " dyskinesia ". I feel knowledge is like an ice skater skating on the ice of language . As more and more people use the word "dyskinesia " in the same way the ice gets thicker and one can skate more confidently over it. But in Judith's posting some medical people were redefining the term " dyskinesia ".>>>> I think that the word "dyskinesia" was NOT redefined, but was defined in a complicated and detailed way. So the definition was correct! Greetings, Hans.