The cause of fibromyalgia is unknown; however, it is believed to involve a combination of genetic and environmental factors with half the risk attributed to each. The condition runs in families and many genes are believed to be involved.
Agonist: A substance that acts like another substance and therefore stimulates an action. Agonist is the opposite of antagonist. Antagonists and agonists are key players in the chemistry of the human body and in pharmacology.
agonist. 1  a person engaged in a contest, conflict, struggle, etc., especially the protagonist in a literary work. 2  a person who is torn by inner conflict. 3  Physiology. a contracting muscle whose action is opposed by another muscle. Compare antagonist (def 3).