Neurotransmitter role of endogenous morphine in CNS
Guarna M, Ghelardini C, Galeotti N, Stefano GB, Bianchi E.
Department of Anatomical and Biomedical Sciences,
University of Siena, Italy.
Med Sci Monit. 2005 Jun;11(6):RA190-193.


Endogenous morphine is present in the mammalian brain as determined by gas chromatography/mass spectrometry. The criteria essential for satisfying the definition of morphine as a neurotransmitter are examined. The detection of endogenous morphine-like compounds inside brain neurons by immunocytochemistry and the Ca(+) dependent release of endogenous morphine from rat brain slices provide evidence for its transmitter status. Indirect evidence that endogenous morphine modulates thermonociception and weakens memory through mu opioid receptors again supports a neurotransmitter role for this chemical messenger. Evidence has been found for its endogenous synthesis in animal tissues as well. These findings indicate that endogenous morphine might function as neuromodulator/neurotransmitter agent in the CNS.
Morphine: structure
Endogenous morphine
Morphine biosynthesis?
Is morphine an antidepressant?
Morphine and sleep architecture
Morphinergic signalling system utilising NO
Opioids, depression and learned helplessness
Human white blood cells synthesize morphine
Morphine in amygdala and the mu3 opiate receptor
Morphine directly inhibits nociceptors in inflamed skin
Once-daily slow release oral morphine (SROM) capsules
Endogenous morphine and ACTH association in the brain
Endogenous morphine has signaling functions in Purkinje cells
Opioids, pain and the immune system in evolutionary perspective

and further reading

Future Opioids
BLTC Research
Utopian Surgery?
The Abolitionist Project
The Hedonistic Imperative
The Reproductive Revolution
Critique of Huxley's Brave New World

The Good Drug Guide
The Good Drug Guide

The Responsible Parent's Guide
To Healthy Mood Boosters For All The Family