Some science behind the scenes

Dynorphin

Dynorphin A, dynorphin B, and α/β-neo-endorphin are all dynorphins  found widely distributed in the CNS, they have the highest concentrations in the hypothalamus, medulla, pons, midbrain, and spinal cord.  

Dynorphins are stored in large dense-core vesicles that differ from the normal small synaptic vesicles in that a more intense and prolonged stimulus is needed to cause the large vesicles to release their contents.  Dynorphin is an extraordinarily potent opioid peptide. The peptide was called dynorphin (from the Greek dynamis=power) to describe its potency.

Dynorphins exert their effects primarily through the κ-opioid receptor (KOR), with some affinity for the mu μ-opioid receptor (MOR), delta δ-opioid receptor (DOR) and interestingly enough the  N-methyl-D-aspartic acid (NMDA)-type glutamate receptor.