Dynorphin is a very powerful group of endogenous (meaning that is made inside the body) opioid ligand (pleasure producing molecule/substance). Dynorphin works by stimulating receptors specially designed for opioids, much like how a key fits into a lock. In this case, the dynorphin molecule (ligand) is the key and the receptor is the lock. Dynorphin is widely distributed in the human body. It is composed of 17 amino acid residues (the remains of a certain type of organic chemicals). Amino acids are a group of chemical substances that form proteins.Dynorphin contains a pleasure producing substance known as leu5-enkephalin as the end part of this molecule. The end part of this molecule is technically known as the NH2 terminal (end) sequence. Dynorphin is created by a precursor protein known as prodynorphin. There are different types of dynorphin such as dynorphin A, dynorphin B, and big dynorphin. Dynorphin is found in high amounts in the spinal cord, which is one area it is made. An example is the back part of the spinal cord known as the posterior horn.DynorphinDynorphin is also found widely throughout the brain but mostly in the brainstem and hypothalamus. The brainstem is an area in the lower part of the brain that connects it with the spinal cord. The hypothalamus is an area within the brain that is important for many bodily functions such as sleep, appetite, and temperature control. The hypothalamus also produces dynorphin as does the hippocampus. The hippocampus is a structure in the lower part of the brain that is important for memory.