Pubdate: Mon, 23 May 2005
Source: Guardian, The (UK)
Copyright: 2005 Guardian Newspapers Limited
Author: John von Radowitz, Press Association science correspondent
Bookmark: (Cannabis)


Excessive use of cannabis can lead to brittle bones, new research suggests. 
Scientists have found that molecules on the surface of bone cells are 
targeted by cannabis chemicals. They discovered that drugs which block 
these cannabinoid receptors may prevent bone loss.

But the flip-side to the research is that smoking cannabis is likely to 
promote osteoporosis.

Professor Stuart Ralston, who led the research at the University of 
Aberdeen, said: "We hadn't studied cannabis users, but the work we've done 
would suggest that if you use a lot of cannabis it could stimulate 
bone-absorbing cells, and that would be bad."

Receptors are molecules that act like a "lock" into which other molecules 
fit. Molecules that affect cells are activated when they bind to specific 

Prof Ralston's team was investigating the way natural cannabinoids in the 
body attach to receptors to help regulate bone density and turnover. These 
"endogenous" cannabinoids seemed to stimulate the absorption of bone - and 
it was very likely that chemicals in cannabis did the same.

Because both molecules had a similar structure they were highly likely to 
bind to the same receptors.

Experiments with mice showed that blocking the cannabinoid receptors 
effectively inhibited bone loss.

Conversely, stimulating them with drugs that mimicked the effects of 
cannabis was detrimental to bone.

"This is an important finding since it demonstrates that the receptors 
which cannabis acts upon are not only important in the nervous system, but 
also in the control of bone metabolism," said Prof Ralston, who is now at 
the University of Edinburgh.

"The fact that compounds which blocked cannabinoid receptors are highly 
effective at preventing bone loss is particularly exciting, since it shows 
that these drugs could provide us with a completely new approach to the 
treatment of osteoporosis and other bone diseases."

The findings appear in the online edition of the journal Nature Medicine.

Prof Ralston, one of Britain's leading osteoporosis experts, said he saw 
many patients with bone loss who used drugs of various types.

But he pointed out that diet, smoking, and other lifestyle issues may also 
be involved.

"If using cannabis is one of the factors involved, we ought to know about 
it," he added.

More than 250,000 people in Britain suffer osteoporosis-related fractures 
each year; related health costs exceed UKP1.7bn.

A spokesman for the National Osteoporosis Society said: "It is always 
interesting to hear about these pieces of research and we will watch with 
interest to see what happens."
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