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.
Types of agonists [edit]. Receptors can be activated by either endogenous (such as hormones and neurotransmitters) or exogenous (such as drugs) agonists, resulting in a biological response.A physiological agonist is a substance that creates the same bodily responses but does not bind to the same receptor.nverse agonists exert the opposite pharmacological effect of a receptor agonist, not merely an absence of the agonist effect as seen with antagonist. An example is the cannabinoid inverse agonist rimonabant. A co-agonist works with other co-agonists to produce the desired effect together.