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Until 1980 the cell membrane perturbation theory dominated
scientific research on marijuana, and consequently the cell
membrane perturbation theory formed the basis for policy decisions
by the Department of Justice on the scheduling of marijuana
under the CSA. Herkenham's 1990 discovery proved that the
cell membrane perturbation theory was incorrect, and that
this was due to technical flaws with the research. Ironically,
Martin's 1986 paper which concludes with marijuana affects
every biological system studied is now oft-cited as a reference
to those technical flaws.
The primary technical problem is that it is hard to make
a liquid cannabis solution to test on animals and cell tissue.
Cannabinoids are not water soluble, and the creation of usable
solutions for experimental research was fraught with problems.
Even Gabriel Nahas took note of these difficulties:
"Many different methods for suspending, solubilizing,
or emulsifying delta-9-THC have been suggested. These include
the use of surficants (Tween 80, Triton X-110, Pluronic),
solvents (ethanol, propylene glycol, dimethylsulfoxide, olive
or sesame oil), and suspending agents (resin, albumin, dextrans),
as well as ultra sonic emulsifiers. None of these methods
is entirely satisfactory, because they all influence the rate
of absorption as well as pharmacological activity. The fact
that all of these methods have been used by various investigators
makes quantitative comparison difficult."(5)
This problem was also widely recognized by his contemporaries.
Sir Paton warned as early as 1975:
"A technical warning note that the pattern of extracting
cannabinoids by different solvents varies with the tissue
carries intriguing physiochemical implications."(6)
With hindsight, those two comments exhibit considerable
understatement. According to Miles Herkenham of the National
Institute of Mental Health, the early biochemical studies
have three flaws:
"Most of the biochemical studies employed concentrations
of D9-THC that were in excess of physiologically meaningful
concentrations that might be found in brain. In addition,
the criterion of structure-activity relationship was not met
-- that is, the potencies of the various cannabinoids in the
in vitro assays did not correlate with their relative potencies
in eliciting characteristic behavioral effects. Particularly
damaging to the relevance of these in vitro studies was the
absence of enantioselectivity."(7)
In simpler terms, it took incredibly unrealistic potencies
to produce results, and there were no guarantees that the
solutions did not alter the compounds being studied.
Cannabinoids are sticky, although scientists refer to
this as a "tendency to adhere to glass and plastic in in vitro
experiments." One problem is that this stickiness is not uniform.
Different amounts of the compound precipitate out of various
test solutions. British pharmacologist R.G. Pertwee explains
that this feature contributes to variance in the concentrations
of the cannabinoid compounds used in research, complicating
interpretation of results. (8)
As explained in 1986 by B.R. Martin:
"These properties of cannabinoids disallow an estimate
of the concentration of agent at its site of action and hence
compromise assessment of responsiveness."(9)
Given the available evidence and technology, Martin's
concerns had foundation. However technology changes, and as
it changes it radically alters the evidence available to scientists
for theory evaluation. As Herkenham reiterates in 1992:
"Until recently, very little was known about the cellular
mechanisms through which cannabinoids act . . .Without evidence
that cannabinoids act through a specific receptor coupled
to a functional effector system, researchers were prone to
study the effects of cannabinoids on membrane properties,
membrane-bound enzymes, eicosanoid production, metabolism,
and other neurotransmitter systems in vitro."(10)
This is a very confusing point for non-scientists to
grasp, but conclusions based on many of the studies on membrane
properties and the like are no longer scientifically valid.
The researchers most responsible for the 1990 breakthrough
explain.
"Because the cellular and biochemical mechanisms of action
of psychoactive cannabinoids were not understood, neuroscientists
were allowed great breadth to speculate upon the influence
that these compounds might have on the neurons of the brain."(11)
For the same reason, policy making was also allowed the
same breadth of speculation. Marijuana's current schedule
I status is based on an FDA conclusion
"that abuse of the plant material may lead to severe
psychological dependence in some individuals but the information
was insufficient to determine with certainty whether the plant
material produce physical dependence."(12)
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