Pain inhibition by endomorphins
by
Przewlocki R, Labuz D, Mika J,
Przewlocka B, Tomboly C, Toth G
Department of Molecular Neuropharmacology,
Polish Academy of Sciences,
Krakow, Poland.
nfprzewl@cyf-kr.edu.pl
jzadina@mailhost.tcs.tulane.edu
Ann N Y Acad Sci 1999; 897:154-64


ABSTRACT

Spinal analgesic effects of endomorphin-1 and endomorphin-2 were studied during acute, inflammatory, and neuropathic pain in rats chronically implanted with intrathecal cannulas. Endomorphin-1 and endomorphin-2 (2.5-10 micrograms i.t.), as well as their analogues, increased the tail-flick and the paw pressure latencies. In a model of inflammatory pain, the formalin-induced behavior was attenuated by endomorphins; however, the effect studied was not dose-dependent and was less pronounced in comparison with that evoked by morphine. On the other hand, in rats with a sciatic nerve injury (crush), endomorphins antagonized allodynia in a dose-dependent manner, whereas morphine was found to be ineffective in a similar dose range. Endomorphins also exhibited an antinociceptive potency in rats tolerant to morphine. In conclusion, our results show a powerful analgesic action of endomorphins at the spinal level. The most interesting finding is a strong effect of endomorphins in neuropathic pain, which opens up a possibility of using these compounds in pain therapy.
Mu
Pain
NMDA
Signalling
Fetal pain
Nociceptin
Endomorphins
Opium timeline
Opioid receptors
NMDA anatagonists
Adjuvant analgesics
Spinal opioid therapy
Endomorphins 1 and 2
The Pleasures of Opium
Opioids and anaesthesia
Is morphine a smart drug?
Endomorphins and the mouse
Endomorphins and rodent brains
The degradation of endomorphins
Endomorphinergic neurons in the CNS
Analgesia and combination analgesics
Endomorphins and the mu-opioid receptor
How to increase blood-brain barrier penetration of endomorphin 1