In the field of pharmacology and neuroscience, antagonists refer to substances that inhibit or block the activity of neurotransmitters, hormones, enzymes, or other molecules in the body. Antagonists are often used in research to study the effects of specific molecules on physiological processes, and they can also be used as therapeutic agents to treat various medical conditions. Antagonists typically bind to receptors on cells and prevent the natural ligands (agonists) from binding and activating the receptor. By blocking the activity of these molecules, antagonists can provide valuable insights into the function of specific pathways in the body. There are different types of antagonists, including competitive antagonists, which compete with agonists for binding to receptors, and non-competitive antagonists, which bind to a different site on the receptor and inhibit its activity. Antagonists are widely used in drug development and research to study the effects of different molecules on biological systems and to develop new therapeutics for a variety of conditions.