THC MAY INTENSIFY EPILEPTIC SEIZURES

Your Epileptic Rat Doesn't Want Pot

While the benefits of medical marijuana are often praised as an
alternative to traditional Western medicine, research at the U of S
have found that in rats, marijuana might not be as helpful as
previously believed. Research produced by the Neural Systems and
Plasticity Group, a new multi discipline research group at the U of S,
have found that with certain types of epilepsy, marijuana may do more
harm than good in rats.

Project leader Prof. Michael Corcoran, from the Department of Anatomy
and Cell Biology, led the study into the long neglected field of
marijuana research but for him it was rekindling an old interest.

"About 30 years when I was a Post-Doc at University of British
Columbia, tetrahydro-cannabinol, had just become available for
research. We did a whole series of experiments on looking at the
effects THC and found that THC had anti-epileptic properties but
typical at high doses, which are toxic.

"Research on marijuana dwindled off in the 80's, because no
spectacular effects were seen. Things remained that way until the 90's
when there was a whole spate of new research that revealed how
marijuana affects the nervous system. Starting in the early 90's
people discovered that there were receptors for marijuana called
'cannabinoid receptors,' present on various types of cells, including
nerve cells."

There are multiple types of epilepsy that act in different parts of
the brain. In seizures that affect the brain stem, "it turns out that
those seizures in rats are suppressed by those drugs. But the type [of
epilepsy] we study more commonly are associated with the neural
circuits in the forebrain, called forebrain seizures and they are
either not suppressed or made worse by cannabinoid drugs."

The research was conducted using rats which were given cannabinoids, a
synthetic form of THC, the active compound in marijuana and using a
procedure known as 'kindling.' Kindling involves placing a small
electrical current in a specific site on the rat's brain that
generates epileptic type behaviour. "It's probably no coincidence that
the parts of the brain that thought to be involved with learning and
memory are also very susceptible to epilepsy and kindling," Corcoran
said. The study found that epilepsy was intensified when applied to
the fore brain when used in conjunction with cannabinoids. "Contrary
to our expectations, the cannbinoid like drugs, that activate the
receptor have very unimpressive anti epileptic effects; the seizures
become more intense."

"This was the opening salvo," Corcoran said. He is currently in his
third year of a five-year project with a grant from the Canadian
Institute of Health Research. For his next project, Corcoran will be
looking at some old research, "We'll soon be looking at a plant
derived cannnbinoid that 20 years ago people said it might be useful
in animal studies, for suppressing seizures at nontoxic doses. There
was a clinical trial in Brazil about 25 years ago; the results were
promising but were never followed up on. We're going back to look at
that particular compound to see if there is some promise than has been
previously recognized."