Chemical substances having a specific regulatory effect on the activity of a certain organ or organs. The term was originally applied to substances secreted by various ENDOCRINE GLANDS and transported in the bloodstream to the target organs. It is sometimes extended to include those substances that are not produced by the endocrine glands but that have similar effects.

Synonyms: Agonists, Hormone Receptor, 0, Hormone, Hormone Receptor Agonists, Receptor Agonists, Hormone, Hormones