Opiate receptors are proteins found in the spinal cord, brain, and gastrointestinal tract. The opiate receptors in the brain and spinal cord can be divided into the delta, mu, nociceptin, and kappa groups. Medications such as morphine and oxycodone bind to these receptors in the brain to reduce feelings of pain, and these drugs may also cause feelings of euphoria. Increasing the scientific understanding of opiate receptors may help pharmaceutical companies develop medications for pain without the threat of addiction.
Opiate receptors control some autonomic functions of the body. They may cause variations in body temperature and cause alterations to both the heart rate and respiratory function. The endocrine system of the body is susceptible to changes in the receptors.
Some researchers consider opiate receptors to be an integral part of the immune response. Opiate receptors may play a part in the release of a luteinizing hormone necessary for the reproductive organs to function properly. Medications are in development that prevents binding to these receptors. These medicines may be useful for people combating an addiction to alcohol, prescription medications, or illegal drugs. The euphoric feelings from those substances are blocked when they cannot bind to the opiate receptors.
Opiate receptors regulate the neurotransmitters acetylcholine, norepinephrine, dopamine, and serotonin. These neurotransmitters are responsible for the feelings of well-being and euphoria that human beings experience. A deficit or overabundance of these naturally occurring chemicals can significantly alter the mood of a person.
Mu receptors are responsible for the body developing a dependence on an opioid medication. The mu receptors cause the feelings of euphoria commonly associated with narcotic medicines. They are necessary to obtain the supraspinal pain relief effects from these medications. The mu receptors are so sensitive that they can cause respiratory depression if medication is overused.
Delta receptors mainly function to make pain relief available to the body. The delta receptors allow the medication or naturally occurring neurotransmitters to have antidepressant effects. Delta receptors may play a part in the formation of a physical dependence on opioid drugs.
Nociceptin receptors are also found in the brain and spinal cord. These receptors control the sensation of appetite. They may play a role in the development of depressive disorders and anxiety attacks.
The kappa receptors are targeted when complete sedation is the goal of the anesthesiologist. Pupil constriction is dependent on the kappa receptors when opiate medications have been administered. Epidurals, a spinal cord anesthesia, would be ineffective for pain relief without kappa receptors.