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.
Antagonists will block the binding of an agonist at a receptor molecule, inhibiting the signal produced by a receptor-agonist coupling. A receptor antagonist is a type of receptor ligand or drug that blocks or dampens agonist-mediated responses rather than provoking a biological response itself upon binding to a receptor. They are sometimes called blockers; examples include alpha blockers, beta blockers, and calcium channel blockers.