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Cannabis sativa, a hemp mother plant made of male and female plant, is the source of marijuana. The female plant is the most important. The flowering tops of the female plant is the most potent which contains the hashish and charos, also the dried leaves and the flowering shoots of the female plants are important in increasing the strength of the toxicity in marijuana. Tetrahydrocannabinol (THC- intoxicative compound from marijuana) is one of the highly used, though prohibited, abused, addictive substance especially by youth generation across the globe. The usage of THC (hashish/ hash, marijuana), brings undesirable effects such as social disharmony, crime, financial constrains and psycho-active effects. According to the general statistics, it has been found that THC usage mainly dominates in the youth as it is easily accessible and affordable.
The objective of this discussion includes the effect of THC on central nervous system, the long term effects of THC and its current research uses.
Definition: THC is a product of marijuana that can be used to treat nausea and vomiting (antiemetic). It also has abundant cannabinoids which are the primary psychoactive ingredients. THC (formula C21H30O2 ) is the primary intoxicant in Marijuana and hashish. Marijuana (also known as weed, dope, pot and smoke) is the final product after the leaves and flower buds are harvested and dried from cannabis sativa plant. Hashish is the resin from the maturing flower tops being harvested.
THC (derivative of Marijuana) has been used since ancient times starting back from 2737 BC.THC was discovered in china and then spread to India, North Africa and Europe.2 During that era THC was mainly used for labour pains, nausea and Rheumatism. In the early 1930's a campaign was conducted that suggested that Marijuana has powerful and addictive effects. In 1975 most Marijuana came from Mexico, and then the main supplier became Columbia.1
This drug is commonly inhaled from smoking, the effects occur in 10 to 20 minutes, last for 2 to 4 hours depending on the dosage and If ingested (mostly commonly through cookies and brownies) it last twice as long.7
PHARMACOLOGICAL ACTION OF THC
THC initially starts its effects after inhaling marijuana from smoking, if ingested its effect occurs in the GI tract and in the liver. Delta-9-THC, one of the principal psychoactive metabolites found in marijuana and hashish, crosses the blood brain barrier more than THC and may be more active than the THC. 2
The actions of THC occur from its binding to the cannabinoid receptors CB1 mainly found in the central nervous system, and the CB2 receptor mainly with cells of the immune system. It acts as a partial agonist on both receptors (I.e. it activates them but not to their full capacity). 2,3 The psychoactive effects of THC are mediated by its activation of the CB1 receptor, the most abundant G protein-coupled receptor in the brain. 1
Due to its extremely high lipid solubility, THC stays in the body for a long time even with a small dose. 2 It can be traced from the body after weeks depending on the amount taken and the sensitivity of the machine used. 4 THC alters mood and cognition through its agonist actions on CB1 receptors inhibiting the secondary messenger system (adenylate cyclase) in a dose dependent manner. 1 This action can be inhibited by selective CB1 receptor antagonist which has been shown to be effective treatment of weight loss, to quit smoking, and as a way of controlling and reduce metabolic syndrome. 1,3
The mechanism of endocannabinoid synaptic transmission occur as follows: First, transmission of the excitatory neurotransmitter glutamate stimulates an influx of calcium ions into the post-synaptic neuron. 4 Through a mechanism not yet fully understood, the presence of post-synaptic calcium induces the production of endocannabinoids in the post-synaptic neuron. 3 These endocannabinoids (such as anandamide), then, are released into the synaptic cleft, where binding occurs at cannabinoid receptors present on pre-synaptic neurons, where they modulate neurotransmission. 1 This form of neurotransmission is termed retrograde transmission, as the signal is carried in the opposite direction of orthodox propagation, which previously was thought to be exclusively one way. 4
THC imposes longer actions and suppresses the release of neurotransmitter skipping the initial step. Instead of presynaptic neurons signaling to the postynaptic neurons by the release of a neurotransmitter , indicating that no further neurotransmitter needs to be released, THC send message to presynaptic neurons that they have sent the neurotransmitter to postsynaptic neuron when in fact the neurotransmitter was not sent. 5
THC is an agonist at cannabinol-1 receptors on axon terminal that have GABA binding to it. 6 GABA which is an inhibitory neurotransmitter distributed in the brain, its function is to reduce activity of neurons to which it binds, acting as a natural tranquilizer in the body, causing relaxation and a reduction in muscle tension. 7 Due to the fact that THC exerts both excitatory and inhibitory effects( by suppressing the release of inhibiting neurotransmitter GABA and the excitatory neurotransmitter glutamate) is now thought to account for its ability to induce a variety of mood disorder i.e. excitatory and depressant physiological effects e.g. euphoria and sedation. 4
EFFECTS OF THC ON CENTRAL NERVOUS SYSTEM
Marijuana soaked in formaldehyde and dried has produced unusual effects including autonomic discharge and severe though transient cognitive impairment. 5 With moderate dosage of marijuana inhaled, the following effects produced:
Mild euphoria followed by sleepiness2
Acute state, the user has an altered time perception2
Less inhibited emotions, 2
Psychomotor problems 2
Impaired immediate memory. 2
High dosage produces transient psychomotor effects. Marijuana frequently aggravate existing mental illness and adversely affects motor performance (also trigger onset of new causes of mental illnesses). When marijuana is used for long period it causes laryngitis, schizophrenia and rhinitis, chronic usage has resulted in causing depression of plasma testosterone level and reduce sperm count. 7,8
In women it causes abnormal menstruation and failure to ovulate have occurred in some women. Sudden withdrawal produces insomnia, nausea, myalgia, irritability 7.
THC effects on the CNS differs, three major components are affected in the brain namely: brain stem, cortex and the limbic system.
On brain stem which controls the autonomic response( many basic functions including arousal, the vomiting reflex, blood pressure,respirations and heart rate. Also plays a role in pain sensation, muscle tone and movement) ,THC induces sympathetic responce on the brain stem. 7,8
On the cortex, it affects the mass of grey matter at the top of the mammalian brain which specializes in complex information processing. The cortex is associated with verbal language, memory and the ability to read.8
The limbic system consist of structures between midbrain and cortex, it affects structures like amygdale and the hippocampus which is associated with the emotions and the development of more complex learning and social behaviour.7
The effects THC are divided into two groups which are the short term effects and long term effects.7 The short term effects are: problem with memory loss and difficulty learning, distorted perception, difficulty in thinking and problem solving, loss of coordination, raised heart rate, anxiety, panic attack. All of these will happen due to the involvement of brainstem, diencephalon and limbic system.8
In the long term effects a person will have abnormal functioning of the lung tissue being injured or destroyed by marijuana, the medulla oblongata is also involved.7 Impairment of critical skills related to attention, memory and learning will occur when the cerebrum is affected by the increased dose of THC7. With some studies done, there are some indications that marijuana while taken with cocaine has the potential of severe heart rate increase and blood pressure, which will have an effect on the medulla oblongata.3
METHOD OF ADMINISTRATION
There are several methods of administration of THC, including vaporizing or smoking dried buds, drinking, or eating extracts, and taking capsules. 8
Treatment is based on the individual's needs for therapy, it is often voluntary. Patient can learn to control their addiction and live a better life. Drug addicts in therapy learn behaviour changes and often are prescribed medication as part of their treatment regimen.3 A long term goal of therapy is to achieve lasting abstinence, the sudden goal or aim is to reduce drug use, improve patient's functionality, minimize medical and social complications.3
Treatments for marijuana dependence are similar therapies offered for other drug abuse problems, including: detoxification, behavioural therapies, and regular attendance at support groups meetings like narcotics anonymous.2 There are no medication to cure or help in drug abstinence, treatment programs focus on counselling and group support system.
Programs set for adolescent marijuana users also prove to be effective, family physician are a good information source in dealing with adolescent marijuana users. Parents' interaction with their children, helps the children's life and their choices. Constantly showing of love, care and investing on toys like private urine drug testing kit improves openness of children.4
MEDICAL USE OF THC
The use of THC is beneficial in treatment of nausea and vomiting, stimulation of hunger in chemotherapy and AIDS patients, lowered intraocular eye pressure (shown to be effective for treating glaucoma), as well as gastrointestinal illness, Addiction, Arthritis, Appetite Loss, Cancer Chemotherapy, Nausea From Cancer Chemotherapy, Multiple Sclerosis, Depression, Parkinson's Disease, Movement Disorders, Dystonia, Brain Injury/Stroke, Crohn's Disease, Ulcerative Depression, Mental Illness, Epilepsy, Fibromyalgia, High Blood Pressure/Hypertension, Migraine, Nail Patella Syndrome, Schizophrenia, Tourette's Syndrome. 7
Also can treat premenstrual syndrome, unintentional weight loss, insomnia.7 Other "relatively well-confirmed" Preliminary findings indicate that cannabis-based drugs could prove useful in treating inflammatory bowel disease, migraines, and related conditions. Medical cannabis has also been found to relieve certain symptoms spinal cord injuries by exhibiting antispasmodic and muscle-relaxant properties.7 Its effectiveness as an analgesic has been suggested to be effective such as the treatment of spasticity, painful conditions, especially neurogenic pain, asthma.
Arthritis: The old people use the drug to ease the pain of such ailments as arthritis and rheumatism. Cannabidiol (CBD), one of the main active ingredients in cannabis is a very effective anti-inflammatory agent.2 Cannabis can be smoked or eaten to relieve the general pain, inflammation and discomfort of arthritis. Cannabis poultices can be applied topically to troubled areas. Cannabis in alcohol or as a cream can also be rubbed on the skin.2
Cancer Chemotherapy Conditions characterised by kidney failure, tuberculosis, hyperemesis gravidarum (magnified form of morning sickness) and anorexia and the side effects of chemotherapy, all these conditions can be relieved by the use of THC.2
Glaucoma: The Cannabis relieves symptoms by reducing intra ocular pressure, thereby slowing down the progress of the condition, sometimes bringing it to a complete halt. 2The pressure relieving effects is achieved by using cannabis within four to five hours.2
Multiple Sclerosis. Patients who use cannabis report a soothing of the painful muscle spasms and improved muscle coordination.7 Some are able to walk unaided when they were previously unable to do so. It also helps blurred vision, tremors, loss of bladder control, insomnia and depression.7
Depression: A significant difference between the two(THC and pharmaceutical antidepressants) is that the mood lifting effects of cannabis occur within a few minutes of smoking or about an hour after ingesting while pharmaceutical antidepressants usually take several days or weeks to kick in - and the same or longer to safely get off them.4
Movement Disorders: Cannabis has proved to be surprisingly helpful. Research indicates that the reason may have something to do with the presence of receptors for cannabinoids in the 'basal ganglia', a part of the nervous system involved in the coordination of movement. 4
The sides effects of Parkinson's Disease include most of the symptoms of the disease it is intended to treat! These include nausea, loss of libido, vomiting, irritability, insomnia, loss of appetite, headache, dystonias, and muscle spasms. Cannabis has demonstrated a beneficial impact on all of them.4
Cannabis has been shown to be helpful for dystonia in studies with both humans and animals when conventional drugs are rarely effective and have dangerous side effects. Cannabis used in conjunction with standard medications can help achieve a more effective overall treatment.
In Diabetes, there is some evidence that cannabis lowers blood sugar. smoking cannabis can lower blood sugar in diabetics. 8
Synthetic cannabinoids are available as prescription drugs in some countries. Examples include Marinol, available in the United States and Canada, and Cesamet, available in Canada, Mexico, the United Kingdom, and also in the United States.3
The recreational use is illegal in all parts of the world, though decriminalized in some, its use as a medicine is legal in a number territories. Distribution is usually done within a framework defined by local laws. Medical cannabis remains a controversial issue worldwide.3
Alzheimer's disease Research done by the Scripps Research Institute in California shows that the active ingredient in marijuana, THC, prevents the formation of deposits in the brain associated with Alzheimer's disease.2 THC was found to prevent an enzyme called acetylcholinesterase from accelerating the formation of "Alzheimer plaques" in the brain more effectively than commercially marketed drugs.2 THC is also more effective at blocking clumps of protein that can inhibit memory and cognition in Alzheimer's patients, as reported in Molecular Pharmaceutics.2
Columbia University published a clinical trial data in 2007 showing that HIV/AIDS patients who inhaled cannabis four times daily experienced substantial increases in food intake with little evidence of discomfort and no impairment of cognitive performance.7 They concluded that smoked marijuana has a clear medical benefit in HIV-positive patients. In another study in 2008, researchers at the University of California, San Diego School of Medicine found that marijuana significantly reduces HIV-related neuropathic pain when added to a patient's who are already-prescribed pain management regimen, and may be an effective option for pain relief in those whose pain is not controlled with current medications.2 A study examining the effectiveness of different drugs for HIV associated neuropathic pain, found that smoked Cannabis was one of only three drugs that showed evidence of efficacy.2
According to a 2007 study at the California Pacific Medical Centre Research Institute, cannabidiol (CBD) may stop breast cancer from spreading throughout the body.2These researchers believe their discovery may provide a non-toxic alternative to chemotherapy while achieving the same results minus the painful and unpleasant side effects.3 The research team says that CBD works by blocking the activity of a gene called Id-1, which is believed to be responsible for a process called metastasis, which is the aggressive spread of cancer cells away from the original tumor site. 3
Having gone through the literature about THC with regard to its effects, it was concluded that though most of its effect are undesirable, some of them have been found to be beneficial in medical fields, Such as treating patients with low appetite, relief of low to moderate pain and as stated previously. It has also been echoed by current researchers with regard to its positive effect on well being of patients.
We therefore conclude that THC should only be used for medical benefits under control situations.