What characterizes agonists in relation to receptors?

Agonists are substances that bind to specific receptors and activate them to produce a biological response. This mechanism is fundamental to their function, as the activation of receptors by agonists can lead to a range of physiological effects depending on the type of receptor they interact with. For example, when a neurotransmitter acts as an agonist, it initiates a cascade of cellular events that can enhance or modulate various functions within the body.

In pharmacology and the study of chemical dependency, understanding the role of agonists is crucial because they can be used in treatment settings. For instance, in the context of opioid addiction, certain medications function as agonists to activate opioid receptors, which can help manage withdrawal symptoms and cravings.

The other options do not accurately represent the role of agonists with respect to receptors. For instance, substances that block agonists from binding do not classify as agonists themselves. Instead, they would be better described as antagonists, which have the opposite interaction with receptors. Similarly, saying that agonists inhibit the effects of antagonists misrepresents their primary function. Lastly, stating that they have no interaction with receptors also contradicts the very definition of agonists as agents that actively engage and activate receptors. Therefore, the characterization of agon