Cannabinoid control of neuroinflammation related to multiple sclerosis

The cannabis plant (Cannabis sativa) has been known by many names but the question remains ‘Can we call it medicine?’ There has been renewed interest in the value of cannabis for the control of neuroinflammatory conditions such as multiple sclerosis, where it has been shown to have some effect on spasticity and pain both experimentally and in clinical trials in humans. However, in addition to symptom control potential, the question remains whether cannabinoids can modify the neuroinflammatory element which drives relapsing neurological attacks and the accumulation of progressive disability. In experimental studies it has been recently shown that synthetic cannabinoids can affect the immune response both indirectly via CB1 receptor‐mediated signalling nerve centres controlling the systemic release of immunosuppressive molecules and directly by CB2 receptor‐mediated inhibition of lymphocyte and macrophage/microglial cell function. However, these immunosuppressive possibilities that would limit the frequency of relapsing attacks will probably not be realized clinically, following use of medical cannabis, due to dose constraints. However, cannabinoids may still affect the glial response within the damaged central nervous system, which facilitate the slow, neurodegenerative processes that account for progressive neurodegeneration, and therefore may have utility in addition to value of cannabis‐related drugs for symptom control. British Journal of Pharmacology (2007) 152, 649–654; doi:10.1038/sj.bjp.0707458; published online 24 September 2007