Kappa-opioid receptors (KORs) are a type of receptor in the brain that belong to the opioid receptor family. They are activated by specific substances, including natural peptides like dynorphins and synthetic drugs. KORs play a role in regulating pain, mood, and stress responses, and their activation can lead to effects such as sedation and dysphoria. Research on KORs is important for understanding various conditions, including depression and addiction. By studying these receptors, scientists aim to develop new treatments that can provide pain relief without the addictive properties associated with other opioid receptors, such as mu-opioid receptors.