Cannabinoids and pain

[Guest guest]

Handb Exp Pharmacol. 2007;(177)

Cannabinoids and pain.

Lever IJ, Rice AS.

Pain Research Group, Department of Anaesthetics, Intensive Care and

Pain Medicine, Imperial College London, Chelsea and Westminster

Hospital Campus, 369 Fulham Road, London SW10 9NH, UK.

Convincing evidence from preclinical studies demonstrates that

cannabinoids can reduce pain responses in a range of inflammatory

and neuropathic pain models. The anatomical and functional data

reveal cannabinoid receptor-mediated analgesic actions operating at

sites concerned with the transmission and processing of nociceptive

signals in brain, spinal cord and the periphery.

The precise signalling mechanisms by which cannabinoids produce

analgesic effects at these sites remain unclear; however,

significant clues point to cannabinoid modulation of the functions

of neurone and immune cells that mediate nociceptive and

inflammatory responses. Intracellular signalling mechanisms engaged

by cannabinoid receptors-like the inhibition of calcium transients

and adenylate cyclase, and pre-synaptic modulation of transmitter

release-have been demonstrated in some of these cell types and are

predicted to play a role in the analgesic effects of cannabinoids.

In contrast, the clinical effectiveness of cannabinoids as

analgesics is less clear. Progress in this area requires the

development of cannabinoids with a more favourable therapeutic index

than those currently available for human use, and the testing of

their efficacy and side-effects in high-quality clinical trials.