ENKEPHALINS & ENDORPHINS             [home]   [topic page]

Animals have areas of their brains which are "receptors" to opiates. In other words, opiates chemically lock on to these areas and trigger analgesic and other effects. These regions were first discovered in the 1970s. It was natural to conclude that if such regions exist, then the brain must produce and use its own morphine-like substances.

In the 1960's Choh Chi isolated a hormone, B-Lipotropin with a region which had analgesic properties. In 1974, Hughes and Kosterlitz discovered the section of the above hormone as a free agent in the brain. It is morphine like. The pituitary hormone of Choh Chi is called an endorphin while the free agent in the brain is an enkephalin. At least two enkephalins (encephalins) are known to exist.

Personal pain and opiate receptors.

Tolerance to pain has both psychological and physiological reasons. Pain may well be a genetically regulated problem.

The opiate receptors identified lock, not only to enkephalins which are the body's natural pain killers but also to morphine and other opiate drugs including the artificially derived heroin.

The receptor has 3 main binding areas.

• The anionic site, which is 0.8 nanometres by 0.65 nanometres that is generally negative in overall charge and binds to the nitrogen. The nitrogen has an overall positive charge.
• A cavity into which the "black loopy structure" - the ring to which the nitrogen belongs (called a piperidine ring)
• - and a flat structure for binding the benzene ring. (This ring is called an aromatic ring. See benzene.)

All enkephaloids seem to have the benzene ring and nitrogen loop as essential requirements to bind to the brain receptors. See Link to Pictures of Enkephalins

For more information on this topic, start with

narcotics

For much more advanced information, go to Advanced study on receptors