MYSTERY OF THE MUNCHIES SOLVED

The mystery of the munchies, the craving for food experienced by
cannabis users, has been unravelled. Neuroscientists hope that by
piecing together the brain circuits involved in switching on the urge
to eat they will be able to identify ways to block the craving with
new anti-obesity drugs. David Talmage's team at Columbia University,
New York, whose work appears in the journal Neuron, took slices from
parts of the mouse brain called the lateral hypothalamus, known to
regulate appetite. They then used ultra-slim electrodes to measure
the electrical activity along single neurons. Cannabis produces a
"high" thanks to an active ingredient called tetrahydrocannabinol,
but a similar chemical or cannabinoid is also produced naturally in
the body. The researchers found that when neurons were exposed to the
natural cannabinoid they became more excitable.

The researchers then tested neurons from mice bred to lack an
appetite-suppressing hormone, leptin. They found that when these
neurons were exposed to the natural cannabinoid they were even more
excitable. The researchers believe leptin suppresses appetite by
"short-circuiting" the effect of cannabinoids by changing how calcium
ions flow along neurons. Calcium is needed to make cannabinoids in the body.

"What this gives us is a neural circuit for the well-known munchies
effect that makes you hungry," said Dr Talmage.