Agonist

Agonist An endogenous substance or a drug that can interact with a RECEPTOR and initiate a physiologi­cal or a pharmacological response characteristic of that receptor (contraction, relaxation, secretion, enzyme activation, etc.).

agonist or Agonistic behavior This behavior usually involves two animals in a competitive contest, which can be in the form of combat, threat, or ritual, for food, a sexual partner, or other need. The end result is one becoming a victor while the other surrenders or becomes submis­sive. Both exhibiting different traits. When one surren­ders, it stops the combat because the continued battle could end up injuring both. Likewise, any future com­bat between the two individuals will likely end with the same result.

Many animal social groups are maintained by ago­nistic or agonist behavior where one individual becomes domi­nant. And the others become subdominant, and so on down the line. They control the others in a dominance hierar­chy or “pecking order.” This dominant behavior can be used to control access to food or mates. Chickens, gorillas, and wolves are good examples of social groups maintained by dominance.