When a body area is damaged, nociceptors – pain receptors – travel through the spinal cord and communicate information to the brain. This immediately orders the production of a neurotransmitter, endorphin . This is an opiate with analgesic action. In certain circumstances that require overexertion, such as sexual intercourse, the production of this neuropeptide increases and thus pain can be turned into pleasure more easily.
There is something paradoxical about this conversion. Many biologists believe that the origin of endorphins must be found in the need to make death at the hands of a predator more bearable. In fact, more of these pleasure substances are found in animals that are potential prey for carnivores. Its secretion would help them have a happier death. According to this theory, the old union between sex and death would reappear when we unite pleasure and pain.
