Kappa opioid receptors are a type of protein found in the brain and spinal cord that play a key role in pain regulation and mood. They are part of the opioid receptor family, which also includes mu opioid receptors and delta opioid receptors. When activated by specific substances, such as endorphins or certain drugs, kappa receptors can produce effects like pain relief and sedation. These receptors are also involved in the body's response to stress and can influence feelings of anxiety and depression. Research into kappa opioid receptors is important for developing new treatments for pain and mental health disorders, as they may offer benefits without the addictive properties associated with other opioid receptors.