|SOFT - TIAFT 1998||Poster Session 1||Wednesday October 7, 1998|
ENDOGENOUS MORPHINE - A PROTAGONIST IN PAIN MECHANISM?|
Carla Neri, Enrica Bianchi*, Massimo Guarna**
Institute of Forensic Medicine University of Verona, Italy
The presence of endogenous morphine has been clearly demonstrated by gas chromatography/ mass spectrometry in the brain and in other tissue or fluids of mammals. Brain morphine concentration become significantly higher after prolonged food deprivation. Five-fold higher morphine levels were detected by gas chromatography/ mass spectrometry in rats fasted for four days rising from 0.23 ± 0.013 ng/g (normally fed rats) to 1.06 ± 0.13 ng/g in rats after 96 hours of fasting with free access to water.
The release of endogenous morphine from rat brain slices was studied in vitro using different incubation media.
All samples were hydrolyzed, extracted by solid phase and derivatized before GC/MS analysis which was performed in selected ion mode (SIM). GC/MS analysis of perfusate samples demonstrated that depolarization due to high potassium concentration increased the release of endogenous morphine from rat brain slices and this effect was calcium dependent.
After the replacement of the normal incubation medium (Krebs bicarbonate) with another medium containing high concentration of potassium (KCL), the amount of morphine in the perfusate rose from 0.11 0.021 ng/g/min (basal value) to 0.48 0.06 ng/g/min. Morphine levels at the end of the depolarization were higher than initial brain content. This may be due to the continuous morphine synthesis in the brain in response to stimulation, as it happens for other neurotransmitters.
These findings indicate that endogenous morphine might function as a neuromodulator/neurotransmitter agent in the CNS of mammals.