A dynorphin is a type of chemical substance called an opioid peptide that is produced naturally by the human body and affects the function of the brain, as well as the nervous system. Dynorphin's effects on the body are similar to that of natural and synthetic opiates, such as opium, morphine and methadone, and it is sometimes referred to as a brain opiate. There are various types of dynorphin, such as dynorphin A and dynorphin B, but they are all involved in regulating basic physical functions such as appetite, emotion, motivation, how one responds to stress and how one experiences pain. Dynorphins are very potent even in small amounts, and scientific studies suggest that the painkilling effect of a dynorphin is at least six times that of morphine. Current research is studying the effects of dynorphins on various conditions such as neuropathic pain, depression, stress, drug addiction and overeating.
The production of dynorphins takes place mainly in the hypothalamus, the hippocampus and the spinal cord. The hypothalamus and hippocampus are part of the brain itself, and have important effects on both the central and autonomic nervous systems. The spinal cord is part of the central nervous system and extends from the brain, through the spine, connecting the brain to the rest of the body. Dynorphins produced and released by the brain and the spinal cord regulate and influence vital body functions such as body temperature, long-term memory, hunger, thirst, sleep and the processing of sensory information.
Dynorphins are one of three types of opioid peptides produced by the body. The other two are endorphins, which is actually a group of substances that includes beta-endorphin and gamma-endorphin, and enkephalins. Endorphins and enkephalins provide pain relief as well as producing a feeling of euphoria, for example during exercise, sex and excitement. Research indicates that dynorphins are different from the other opioid peptides. Under certain circumstances, dynorphins can stimulate pain instead of relieving it and are also linked to depression rather than euphoria.
Scientific studies suggest that the pain experienced after a spinal cord injury can be related to increased levels of dynorphins. Other studies show that blocking dynorphin, and thereby inhibiting its effect on the brain and nervous system, can reduce depression and stress. High levels of dynorphins have been linked to a diverse range of behaviors and body functions such as an increased resistance to cocaine addiction, overeating and hyperthermia, a condition where the body fails to regulate its temperature, resulting in overheating.