Agriculture Reference
In-Depth Information
family, tetrahydrocannabinol (THC) is the main
psychoactive principal and is responsible for the
popularity of the plant among people seeking to
exploit it as a drug for hedonistic purposes. This
family includes all the substances similar to
THC, whether they are obtained from cannabis
or synthesized chemically. Considerable progress
has been made since the early 1990s in further-
ing our understanding of the various effects of
cannabinoids on living organisms and the many,
as well as fundamental, roles of the endocan-
nabinoid system.
receptors was established in the early 1990s
(Richard, 2009). These substances are termed
endocannabinoids (eCB) and are produced by the
organism and can act like cannabinoids. The
principal eCB are anandamide (AEA) and
2-arachidonoglycerol (2-AG). These are lipid in
nature and are eliminated rapidly by the organism
following their breakdown, a process catalysed by
the enzyme, fatty acid aminohydrolase (FAAH).
They are released in a range of tissues, in particu-
lar the central nervous system, where they modu-
late neurotransmission. Levels of anandamide in
the brain are comparable to those of other neuro-
transmitters such as dopamine and serotonin.
This substance is particularly produced in areas of
the brain that show a strong expression of CB1
receptors (cortex, hippocampus, striatum and
cerebellum) and shows a stronger affinity for this
receptor than for the CB2 receptor.
15.4 Cannabinoid Receptors
Both naturally occurring and synthetic cannabi-
noids exert their pharmacological effect by bind-
ing to specific cellular receptors. These receptors
are termed cannabinoid receptors. Their exist-
ence was demonstrated in 1990 with the isola-
tion of receptor type CB1 by the American
pharmacologist, Lisa A. Matsuda (Richard,
2009). Two types of cannabinoid receptor have
since been identified.
15.6
Cannabis and Cannabinoids
in Therapeutics
Many patients in the Anglo-Saxon countries,
as well as in Holland and in Germany, provide
testimony in favour of the use of cannabis to
treat certain pathologies (medical problems).
The claimed indications include diseases that
are liable to benefit from other types of treat-
ment and include nausea, vomiting, asthma,
glaucoma, epilepsy, anorexia in AIDS patients
and the treatment of certain painful conditions
(phantom limb pain, rheumatic pain, etc.)
(Grinspoon and Bakalar, 1993; BMA, 1997;
Rosenthal
et al
., 1997; EMCDDA, 2008, Vol
1). That said, it is synthetic cannabinoids rather
than the plant itself that have been the subject
of clinical investigations and will continue to be
researched (EMCDDA, 2008, Vol 1; Hosking
and Zajicek, 2008; Hanus, 2009).
1. The CB1 receptor, isolated from a rat brain,
is expressed in both the central and peripheral
nervous systems, in testicular and uterine tissue,
within the immune system, the intestine, bladder,
retinal cells, endothelial cells (blood vessels) and in
adipocytes. It is one of the most common neuro-
nal receptors found in the brain. The location of
these receptors correlates well with the behav-
ioural effects (action on memory, action on sen-
sory perception and on motor function) produced
by natural and synthetic cannabinoid agonists
such as levonantradol, nabilone, CP55940, etc.
The CB1 receptor is not expressed within the
brain stem, where the cardiovascular and respira-
tory control centres are located. This probably
explains the fact that cannabinoid derivatives do
not demonstrate any acute somatic toxicity.
2. The CB2 receptor, isolated in 1993, is
expressed in peripheral tissues and, in particu-
lar, in cells of the immune system.
15.6.1 Cannabis and natural
cannabinoids as a therapeutic agent
There are two forms of natural cannabinoids
that can be used in therapeutics. In the first
instance, the plant or its immediate derivative
(hashish) can be used, or alternatively, titrated
extracts of the plant can be used.
15.5 The Endocannabinoids
The existence of endogenous physiological
ligands capable of binding to cannabinoid
