Cannabis psychoactive effects

Cannabis is one of civiiization s oidest cuitivated nonfood plants, and does not seem to exist anymore in its wiid form (figure 10.1). In addition to its psychoactive effects, the cannabis plant has also been used for its fibers. Hemp fibers have been found in China dating from 4000 B.C.E., and hemp ropes were dated to 3000 B.C.E. in Turkestan, but it is not certain that cannabis was used for psychoactive purposes at those piaces and times (Schuites and Hofman 1992). 

The Scythians are credited with spreading the use of cannabis to the Greeks from the steppes (Rudgiey 1993). The ancient Greeks knew of the psychoactive effects of cannabis, aithough the prevaience of its use is... 

Several products are derived from the cannabis plant (table 10.1). Hashish and charas are the dried resin exuded from the female flowers. These have the highest content of A9-tetrahydrocannabinol (TFIC) at 10-20% and have the most potent psychoactive effects. Ganja and sinsemilla are the dried tops of the female plants, which averages 5-8%. Marijuana and bhang are derived from the rest of the plant and have the lowest TFIC concentration (2-5%). 

Cannabinoids are the psychoactive components of marijuana, which has the species name Cannabis sativa. Concentrations of cannabinoids vary greatly from plant to plant. The original strains of this plant species contain very little of these psychoactive components and have been used for many centuries for their great fiber qualities. Strains of Cannabis that may be smoked for psychoactive effects on average contain about 4 percent cannabinoid derivatives. The most active of these derivatives is the compound A9-tetrahydrocannabinol (THC), shown in Figure 14.33 on page 504. 

A9-Tetrahydrocannabinol is the major psychoactive cannabinoid in marijuana (Cannabis sativa). Its synthetic form, dronabinol, became available in the U.S. in 1985 as an antiemetic for patients receiving emetogenic chemotherapy. However, it is seldom used as a first-line antiemetic because of its psychoactive effects, and its use is usually limited to patients who have a low tolerance or minimal response to other antiemetic drugs (see Chapter 18). 

For thousands of years, cannabis has enjoyed historical significance as a recreational drug, a useful fiber, an oil, an edible seed, and a medicine. It has been used to aid religious practices, alter mood (psychoactive effect), stimulate creativity, treat disease, relieve anxiety and boredom, enhance sensory experience and pleasure, rebel against authority, and go along with peer influence. That is a lot of work for one plant to do. This probably explains why cannabis has always been an important cultivated crop and is currently a cornerstone of controversial debate in all sectors of U.S. and international society. 

Despite society s focus on the marijuana high, cannabis historically has provided many meaningful industrial and medicinal values that are not attributed to its psychoactive effects. Researchers discovered that cannabis crops farmed as far back as 12,000 years ago yielded hemp, a distinct variety of the cannabis plant associated with little or no psychoactivity. The first evidence of the medicinal use of cannabis can be traced to a Chinese health publication from... 

The main active ingredients of cannabis are cannabinol, cannabidiol and several isomers of tetrahydrocannabinol, of which delta-9-tetrahydro-cannabinol (THC) is probably responsible for most of the psychoactive effects of the various preparations. It is of interest to note that THC does not contain nitrogen in its three-membered ring system. The structure of THC is shown in Figure 15.8. 

Cannabinoid receptors include the CB1 receptors (which have a high incidence in the CNS and inhibit adenylyl cyclase, close Ca2+ channels and open K+ channels via Gai) and CB2 receptors (which are present in immune cells and act via Gai proteins to inhibit adenylyl cyclase). CB1 and CB2 receptors bind the endogenous ligand anandamide (arachi-donylethanolamide) as well as A9-tetrahydroc.annabinol from marijuana (Cannabis saliva). A9-Tetrahydroc,annabinol antagonizes the peripheral CB2 receptor but acts as an agonist for the CNS CB1 receptor. Cannabinoid receptor agonists have appetite stimulant and psychoactive effects and have therapeutic potential for relief from nausea and pain. 

Additive psychoactive effects sought by users may be achieved by combinations of cannabis and alcohol, but at the same time the ability of THC to induce microsomal enzymes will increase the rate of metabolism of alcohol... 

Additive psychoactive effects sought by users may be achieved by combinations of cannabis and short-acting... 

Cannabis saliva, more commonly known as marijuana, is a hemp plant that grows freely throughout the world. The cannabis plant is known most commonly today as a potent psychoactive substance, but for many years it was harvested primarily for its fiber. These strong hemp fibers were employed in the production of rope, clothes, and ship -sails. Although cannabis was used for several centuries in other parts of the world for its mind-altering properties, it was not until the first third of this century that its psychoactivc properties were recognized in the United States. Then the hemp plant was more often harvested for its psychoactive effects. 

The plant Cannabis sativa is more commonly known as marijuana. It once was harvested primarily for its fiber but now is most often grown for its psychoactive effects. 

The investigations conducted to date on the pharmacological effects mediated by cannabinoid receptors show that the non-psychoac-tive effects of Cannabis derivatives are mediated by CB2 peripheral receptor. Furthermore, the CB2 receptor localization proves that said non-psychoactive effects, i.e. the effects on the immune system, the anti-inflammatory, myorelaxant and antinociceptive effects, as well as the effects on pressure systems, are mediated by said receptor. 

The proportion of these substances in the plant varies according to where it is grown. Cannabis grown in the temperate climates, where its fiber is strong, contains little delta-9-THC and a relatively high proportion of cannabidiol. On the other hand, in hot climates where the plant is grown for its psychoactive effects, it contains a high proportion of delta-9-THC and relatively little cannabidiol. 

The CBi cannabinoid receptor is the major mediator of the psychoactive effects of cannabis and its derivatives. In addition, this G protein-coupled receptor transduces many of the effects of the endogenous cannabinoids. Understanding the distribution of CBi receptors has proved helpful to both predict and understand the effects of cannabinoids. For example, the high CBi receptor levels found in cortex, basal ganglia, and cerebellum coincide with the prominent effects cannabinoids have on functions subserved by these brain regions. By comparison, the low levels present in the medullary nuclei responsible for regulating respiration are consistent with the modest effects cannabinoids have on respiratory drive. Furthermore, the strong presynaptic localization of the receptor found in ultra-structural studies underscores its major role as a modulator of neurotransmitter release. 

Cannabis sativa is the genus and species name of a flowering plant which has been used medicinally for thousands of years. Delta-9-tetrahydrocannabi-nol (A -THC) is responsible for almost all the psychoactive effects of cannabis, but is only one of more than 60 similar compounds found in cannabis which, together, are collectively known as cannabi-noids. Cannabinoid agonists that share the basic chemical structure of delta-9-tetrahydrocannabinol have been increasingly studied in recent years for potential benefits in various types of pain and pain syndromes. 

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