Tag Archives: CB1 receptor

medical marijuana

Cannabinoids and effects on other organ systems: cardiomyocytes and the gastrointestinal system

Virginia Thornley, M.D., Neurologist, Epileptologist

@VThornleyMD

May 8, 2018

Introduction

Cannabinoids are being more and more widely used in a variety of neurological conditions. This always leads to the questions of side effects and will it interacts with other medications? Because this is wholly unchartered territory,  in order to answer these questions, it is necessary to understand the underlying mechanisms.

Cannabinoids can cause tachycardia

Phytocannabinoids, when ingested, can induce tachycardia. The metabolism of cannabinoids by cardiomyocytes likely impacts the side effects elicited in cardiac cells. CYP2J2 is the most significant cytochrome p450 which metabolizes endocannabinoid anandamide (AE) into the cardioprotective epoxides. 6 phytocannabinoids were studied in one paper including delta-9-tetrahydrocannabinol, cannabinol, cannabidiol, cannabigerol, and cannabichromene. These were found to be metabolized more quickly compared to anandamide. The cannabinoids may potentially inhibit the metabolism of anandamide by CYPJ2 such that its effects are still circulating in the system. The most significant inhibition was from delta-9-tetrahydrocannabinol. It follows a non-competitive inhibition model such that the cardioprotective epoxides are not formed as abundantly as they should by the cytochrome p450 CYP2J2 (1).

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The cytochrome P450 system has a significant impact on the metabolism of cannabinoids. Tetrahydrocannabinol is metabolized by CYP2C19 and CYP3A4. cannabinol is metabolized by CYP2C9 and CYP3A4. Synthetic cannabinoids include JWH-018 which is metabolized by CYP1A2 and CYP2C9 and AMC2201 which is metabolized by CYP1A2 and CYP2C9.

The cytochrome P450 enzymes are also thought to be involved in the metabolism of tetrahydrocannabinol. CYP2C9 greatly influences the metabolism of tetrahydrocannabinol. Cytochrome P450 3A4 is important in the metabolism of THC and CBD (2).

Cannabinoids in relation to hyperemesis syndrome

Once abdominal pain has been explored regarding medical etiologies, and there is a presence of 1-year history of cannabis use usually weekly, this diagnosis comes to mind. It usually involves cyclical vomiting associated with nausea. The mechanism is thought to be related to dysregulation by the endocannabinoid pathway in relation to the gastrointestinal tract. The CB1 receptor by which THC or tetrahydrocannabinol exerts it actions is also present in the GI tract. Exogenous cannabinoids may dysregulate the normal endocannabinoid pathway thereby affecting the GI tract through the down-regulation of the normal CB1 receptors so that it is no longer sensitive to endocannabinoids which regulate the system. This results in a dysfunction of the GI tract clinically manifested as cyclical nausea and vomiting. A disruption of the cannabinoid receptors may occur resulting in slowed motility of the gut. Relief can occur with use of hot water which influences the TRPV receptor a G-related coupled protein

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References

  1. Arnold, et al, “Cross-talk of cannabinoid and endocannabinoid metabolism is mediated via human cardiac CYP2J2,” J. Inorganic. Biochem., 2018, Apr., 7(184):88-99 doi: 10.1016/j.jinorgbio.2018.03.016. (Epub ahead of print)
  2. Stout, et al, “Exogenous cannabinoids as substrates, inhibitors, and inducers of human drug metabolizing enzymes: a systematic review,” Drug Metab. Rev., 2014, Feb., 46(10:86-95.
  3. Lapoint, et al, “Cannabinoid hyperemesis syndrome: public health implications and a novel model treatment guideline,” West J Emerg Med, 2018, Mar., 19(2):380-386.

 

 

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schizophrenia

Cannabidiol may treat psychosis while tetrahydrocannabinol can induce schizophrenia in those susceptible  

Virginia Thornley, M.D., Neurologist, Epileptologist

@VThornleyMD

May 6, 2018

Introduction

There is a well-known correlation of use of cannabis whether it is medical or recreational to the onset of schizophrenia. It unclear if this could be to a direct correlation and disinhibition of the genetic component or the behavior of using it is a prodrome leading up to schizophrenia. This review seeks to elucidate the mechanisms in the correlation of the use of cannabis and onset of schizophrenia.

Mechanisms related to the underlying genetic composition

Schizophrenia may be linked when some of the normal pathways become disrupted with an introduction of THC.  There are 4 genes that were described after a lifetime use of cannabis including KCNT2 which were THC responsive, NCAM1 and CADM2 are significant in functioning in post-synapse. With THC in the system, there are more post-synaptic density genes (1).

Mechanisms related to other neurotransmitter pathways influenced by cannabinoids

In one study, because of the alarming rate of potent synthetic cannabis used recreationally which was found to leave long-lasting schizophrenia disorder in recreational users, this has accelerated research into the pathophysiology. Because cannabinoids work on the CB1 receptor, it is likely that it plays a modulatory role on the other neurotransmitters that can give rise to schizophrenia including dopaminergic, glutamatergic and serotonergic pathways. These pathways are well-established as playing a role in a pro-psychotic state. High efficacy synthetic cannabinoids which are manufactured for recreational purposes are highly more potent compared to natural organic cannabinoids and there is an alarming increase in the correlation of schizophrenia in these users (2).

In one study it is thought to be due to the hypofunctioning of the glutamate system which is directly affected by THC. Exposure to tetrahydrocannabinol appears to reduce the activity at the level of the glutamate receptor as well as deregulate genes for synaptic function(1).

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Susceptibility is related to the development of schizophrenia

In one animal model, the set-up tried to mimic a more real state seen where not all adolescents exposed to synthetic cannabinoids react by developing schizophrenia, there are some studies where all animals develop schizophrenia with exposure. In this animal model, they provided a model that resembles the human model more closely and found that exposure to synthetic cannabinoids in schizophrenia-prone animals caused hyperfunctioning of dopaminergic pathways compared to the control group who were not susceptible at the same dosages. There may be underlying genetic or environmental factors that cause certain individuals to become more prone (2).

THC can cause anxiety and behavioral disorders but can be prevented with CBD

In one animal study, it was found in a rat study that THC can induce anxiety and behavioral disorders. With THC  administration object recognition was impaired in adolescent rates. The studies support effect on the developing brain in relation to cognitive impairment in the animal model. In addition, when rats were exposed to THC there was increased marble burying behavior which in scientific research is thought to signify anxiety or obsessive-compulsive type behavior usually ameliorated with serotonin reuptake inhibitors or benzodiazepines(4).

It was found, however, that a combination of CBD and THC or cannabidiol alone was administered, these behaviors were not produced or produced only minimally. The thought is that CBD is an allosteric competitive inhibitor at the CB1 receptor so that one sees less of the toxic undesirable effects of THC if administered alone (4).

Cannabinoids have a similar profile to atypical anti-psychotics and may be a possible adjunctive treatment in the treatment of psychotic events (5).

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In summary

There is historical evidence that exposure to THC can give rise to schizophrenia in those individuals that are susceptible accounting for the fact that it does not happen to everybody exposed to it. This is related to its influence on serotonergic, dopaminergic and glutamate pathways. THC can induce anxiety, repetitive behaviors which are ameliorated by CBD. CBD may be a useful adjunctive treatment for psychotic disorders. However, the elucidated mechanisms are based on scientific research based on animal models which may not translate into humans.

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References

  1. Guennewig, et al, “THC exposure of human iPSC neurons impacts genes associated with neuropsychiatric disorder,” Transl. Psychiatry, 2018, Apr., 8(1):89.
  2. Fantegrossi, et al, “Pro-psychotic effects of synthetic cannabinoids: interactions with central dopamine, serotonin and glutamate systems, Drug Metab. Review, 2018, Jan, 50(1)
  3. Aguilar, et al, “Adolescent synthetic cannabinoid exposure produces enduring changes in dopamine neuron activity in the rodent model of schizophrenia,” Int. J. Neurpsychopharmacol., 2018, Apr., 31 (4):393-403.
  4. Murphy, et al, “Chronic adolescent delta9-tetrahydrocannabinol treatment of male mice leads to long-term cognitive behavioral dysfunction which is prevented by concurrent cannabidiol treatment,” Cannabis Cannabinoid Res., 2017, 2(1):235-246.
  5. Deiana, et al, “Medical use of cannabis: a new light for schizophrenia?” Drug Test Analysis, 2013, Jan., (5)1:46-51
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medical marijuana

A review of mechanisms in medical marijuana: the endocannabinoid pathway, receptors, tetrahydrocannabinol, and cannabidiol 

Virginia Thornley, M.D., Neurologist, Epileptologist

@VThornleyMD

April 28, 2018

Introduction

The Cannabis sativa plant has been known since the beginning of time. It can be traced back 5000 years ago when it was first known to man to alleviate common complaints. It came into the American pharmacopeia in the 19th century then abolished in the 1930’s, likely not coincidentally as the era of prohibition was lifted. It is known to treat ailments such as chronic pain and migraine. In the middle ages, it was used to treat headaches, vomiting, diarrhea, bacterial infections and pain from rheumatological conditions. It was previously known for its psychoactive properties.  It is recently making a resurgence in popularity regarding its medical value. The issue is a topic of hot debate as state laws are at odds with federal laws. Currently, as of April 2018, it is still recognized as a category 1 drug, meaning it is not officially proclaimed to have any medical value despite the long rich history of treating medical symptoms. It is lumped in with other drugs of abuse such as heroin and cocaine.

Background on the Cannabis sativa plant and their metabolites

The Cannabis sativa plant is abundantly rich in phytocannabinoids, the most commonly known and used for its therapeutic value are cannabidiol and tetrahydrocannabinol. The endocannabinoid pathway is comprised of receptors that are coupled with G proteins and cannabinoids (1). In the Cannabis sativa plant, there are 80 phytocannabinoids that can bind to a cannabinoid receptor.

There are 8 major cannabinoids including cannabigerolic acid, delta-9-tetrahydrocannabolinic acid A, cannabidiolic acid A, delta-9-tetrahydrocannabinol, cannabigerol, cannabidiol, cannabichromene, and tetrahydrocannabivarin in the different strains of Cannabis sativa (1).

Ehlsoly, et al, classified it into 11 categories: cannabigerol, cannabichromene, cannabidiol, ∆9-trans-tetrahydrocannabinol, ∆8-trans-tetrahydrocannabinol, cannabicyclol, cannabielsoin, cannabinol, cannabinodiol, cannabitriol, and miscellaneous. ∆9 -trans-tetrahydrocannabinol , cannabinol, and cannabidiol are the most well-studied and well-known.

Cannabidiol is extracted from the hemp portion of the plant considered a male part of the plant, there are no psychoactive properties in cannabidiol. Psychoactivity is defined as anything above 0.3% of THC. Tetrahydrocannabinol is derived from the female portion of the plant, particularly the flowers. Conditions are such that in nurseries only a certain amount of sunlight is given to the plants so that specific strains can be grown. Some plants will be richer in cannabidiol, others will be more THC pure and other swill have an equal amount of CBD and THC but it depends on how the plants are grown and under what conditions.

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Endocannabinoid pathway

It is through the endocannabinoid pathway that one gets the sense of well being after exercise or eating chocolate. It is not through endorphins, serotonin or noradrenergic neurotransmitters as they are too large to cross the blood-brain barrier. Tetrahydrocannabinol acts as a mimetic of Anandamide while cannabidiol acts as a mimetic of 2-Arachidinoylglyerol (or 2-AG). The endocannabinoid system works through cannabinoids, the receptors, transporters, and enzymes.

Receptors

The phytocannabinoids work on cannabinoid receptors. The endocannabinoid system is mediated by 3 parts: the cannabinoids, the cannabinoid receptors, and the enzymes. The receptors are of 2 types, CB1 which is found primarily in the nervous system especially in the areas that subserve pain modulation, memory and movement. The CB2 receptor is more peripherally found specifically in the immune system. The CB2 receptor is found to a lesser extent in other organs including tissues of reproduction, pituitary, heart, lungs, adrenal and gastrointestinal systems.  Cannabinoids also react with the TRPV receptor or the transient receptor cation channel subfamily V. They can also act on G receptors including GPR55 thought to be significant in controlling seizures. Other receptors include GPR12, GPR18, and GPR119 (2).

Tetrahydrocannabinol and cannabidiol and their effect on receptors

THC and CBD are the most well-known and well-studied. THC has psychoactive properties and works as a partial agonist on the CB1 receptor and the CB2 receptor. Cannabidiol which has no psychoactive properties works as an antagonist on CB1/CB2 receptor and an agonist on the CB1 and CB2 receptor. Rather than decreasing the effects of THC, it works in a synergistic manner in combination with THC. It potentiates the THC effects by increasing the CB1 densities. CBD increases vanilloid pain receptors, reduces metabolism and reduces re-uptake of anandamide, THC’s mimetic component. Other studies suggest CBD acts as an indirect agonist by interacting with the CB1 receptor so there are less psychoactive symptoms from THC when the two are combined.

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Pharmacokinetics of tetrahydrocannabinol

Regardless of the way of taking it, the protein binding and the and volume of distribution are not affected by the route of taking it. Pharmacokinetics of creams and vaporizers are unclear. Smoking THC appears to exert an effect within minutes of intake and bioavailability is variable depending upon the extent of inhalation ranging between 2-69%. The effect is within minutes. Half-life increases with each inhalation at 2 puffs inhaled for THC it is 1.9 hours and 5.3 hours in CBD at 8 inhalations it is 5.2 hours in THC and 9.4 hours in CBD at a dosage of 5.4mgTHC/5.0mg CBD and 21.5mg THC/20 mg CBD respectively.

Oral routes may seem to be safer but have more adverse effects including GI symptoms such as nausea, vomiting, and diarrhea. Oral mucosal absorption is rapid within 15 minutes to 60 minutes. Oral tablets are lower in the rate of absorption at about 0.6 to 2.5 hours. The rate of elimination, when taken orally, is biphasic, initially occurring at 4 hours then 24-38 hours after ingestion.

In summary

There is much research ongoing on the mechanisms underlying the medical value of medical marijuana. It is now thought that cannabigerolic acid may have medicinal properties as well. So far, the most well-known and well studied are delta-9-tetrahydrocannabinol and cannabidiol. Most likely as research continues, greater value will likely be attributed towards the phytocannabinoids.

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References

  1. Wang, et al, “Quantitative Determination of delta 9-tetrahydrocannabinol, CBG, CBD, their acid precursors and five other neutral cannabinoids by UHPLC-UV-MS,” Planta. Med, 2019, mar., 84 (4):260-266.
  2.  Landa, et al, “Medical cannabis in the treatment of cancer pain and spastic conditions and options of drug delivery in clinical practice,”Biomed. Pap. Med. Fac. Univ. Palacky Olomouc Czech Repub., 2018, Mar; 162(1):18-25.
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chronic pain

Medical Marijuana: a non-intoxicating pain-relieving solution to the opioid epidemic?

Virginia Thornley, M.D., Neurologist, Epileptologist

March 24, 2018

Introduction

Any news outlet you peruse is bound to have mention of the current opioid crisis looming on the horizon. Opioids are commonly prescribed as the last resort for patients with chronic pain who have failed conventional medications, interventional measures such as epidural injections or surgery, non-pharmacologic measures such as physical therapy and even Eastern techniques such as acupuncture. With tolerance a common problem and patients needing higher and higher dosages for pain control because of the properties of opioids, it is little wonder that chronic pain control is difficult to maintain.

The hot topic of debate in many states is the recognition of medical marijuana as a legitimate medication for chronic ailments. However, because of the stigma it has incurred being well-known for its psychoactive properties and widely seen in pop culture in movies with kingpins smoking it for recreation, the medicinal values are often overshadowed and lack of side effects in low doses is easily overlooked.

Not your stereotypical patient and not your direct referral

Patients and even physicians likely have a preconceived notion of who seeks medical marijuana. While chronic pain is top of the list, often times, it is discovered by the hard-working carpenter who discovered it online and found a small scientific article on non-pharmacologic treatments trying to come off sedating pain-relieving medications. It will be the former business owner who lived an enjoyable life being active dancing or the woman afflicted with an autoimmune disorder and has failed every medication under the sun. Many times patients come in not because they want to feel good but because it is their last resort and they’ve exhausted every treatment option known to mankind. They dislike the side effects of the strong painkillers such as opioids and just want the pain to stop and live a normal life. It is amazing how indirectly patients hear about the wonders of medical marijuana, it will usually be a neighbor who swears by it, or somebody’s friend who mentions it out of the blue.  Oftentimes, it is by word of mouth since the few physicians interested in recommending it are very reluctant to advertise with good reason.

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Mechanisms of cannabidiol and tetrahydrocannabinol

Medical marijuana has been used since B.C. period for thousands of years as a medication. It was incorporated into the pharmacopeia of American medicine in the 1850’s until it was banned in the 1930’s. It regained popularity and notoriety as a recreational substance. However, more and more patients are turning towards this now alternative medication after years of frustration towards the ineffectiveness and adverse effects of conventional medications.  The endocannabinoid pathway is found inherently in the system and is responsible for the runner’s high that people get after a vigorous run or after exercising and gives the sense of well-being. The CB1 receptor is found most abundantly in the central nervous system which is likely why many neurological conditions are found to benefit from its use. The CB2 receptor is most commonly found in the immune system. As more research is pursued, there are CB receptors found diffusely throughout many organ systems.  Cannabidiol weakly interacts with the CB1 receptor. It takes at least 100 times cannabidiol to attain the same intoxication one gets with tetrahydrocannabinol, the substance which is more popular and found in the marijuana joints people smoke to obtain euphoria. THC at low concentrations is effective in treating many different medical conditions. It must be used in conjunction with CBD so that side effects are offset. Cannabidiol has no intoxication while low doses of THC does not give euphoria one associates with this drug. There is no tolerance.

Scientific evidence cannabidiol and tetrahydrocannabinol work in chronic pain and other medical diseases

In animal studies, it is well known to reduce seizures by inhibiting the excitation within the hippocampus of the brain where seizures are commonly propagated (http://www.pnas.org/content/early/2017/09/26/1711351114).There are many clinical trials in humans attesting its efficacy at controlling seizures effectively.  CB1 receptors appear to be increased in many neurological disorders which implies it is a compensatory mechanism for diseases. In Parkinson’s disease, there are increased CB1 receptors which may help with the reduced dopamine commonly found in Parkinson’s disease. 9tetrahydrocannabinol was found to lower intraocular pressure in glaucoma in rabbits (https://www.ncbi.nlm.nih.gov/pubmed/6329602). Sativex is a combination of THC:CBD which reduces spasms in patients with multiple sclerosis and has been available in Europe for several years now with very little side effects http://jnnp.bmj.com/content/87/9/944. There is extensive evidence in both animal and human models that it works in chronic pain (https://www.ncbi.nlm.nih.gov/pubmed/26830780). Many diseases are being evaluated for mechanisms on which CBD and THC may exert its effects. It has been found to have anti-oxidant and anti-inflammatory properties which are important mechanisms by which many diseases cause pathology. In cancer cell cultures, it has been found to reduce proliferation of tumor cells in urologic cancer and reduce the pro-inflammatory states that are necessary for metastatic conditions (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5434502/).CBD interacts with the 5HT1 receptor where many anti-depressants and anxiolytic medications exert their effects, making CBD an effective anxiolytic. It works to stimulate appetite and is commonly used by patients with cancer for anorexia and end-stage cancer pain.

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In conclusion

In summary, cannabidiol and tetrahydrocannabinol are effective medications in treating pain from many chronic illnesses and is not reserved for patients with terminal illness. Despite the reticence of physicians, Congress and even patients, there is overwhelming evidence that cannabidiol and tetrahydrocannabinol are effective in many different diseases, although in some conditions there’s a long way to go from preclinical data to human trials.  It is fairly clear in many disease states, medical marijuana is significantly effective. There is no tolerance and may be an effective treatment for patients with chronic pain. CBD by itself has no euphoric properties and low concentrations of THC do not give intoxicating psychoactive effects. These are 2 alternatives that may provide relief and solution to the growing epidemic of the opioid crisis.

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Tumor

The state of medical marijuana in urologic tumor burden control through inflammation reduction and reduction of tumor cell proliferation in cell cultures

IMG_0923_previewVirginia Thornley, M.D., Neurologist, Epileptologist

March 10, 2018

Introduction

Cannabinoids, which are cannabis plant-based non-synthetic medications including cannabidiol (CBD) and tetrahydrocannabinol (THC), are being used more frequently in palliative care to reduce the pain associated with end-stage cancer. In addition, it is well-established that it helps with lack of appetite found in cancer patients and reduces nausea and vomiting associated with many of the chemotherapeutic drug regimens (2), although current studies are needed given the newer chemotherapeutic agents available. Although there were more reported side effects using cannabinoids including euphoria, dizziness, dysphoria, and somnolence it is not clear if low dosages were used or what the ratio of cannabidiol to THC was used. It is well known that using higher doses of THC products will control the pain more adequately but at high doses may cause the side effect. Cannabidiol alone has no intoxication or euphoria and a low dose of cannabidiol combined with THC will ameliorate some of the side effects of THC.   Questions regarding its anti-tumor properties often arise which physicians managing patients with cancer are not prepared to answer. Since most of the studies are done in animal models and are often difficult to translate into the human model, research is needed with randomized clinical trials in the patient population. Currently, most anti-tumor literature is found in cell culture lines and extrapolated. The future is promising but large human studies are needed.

In renal cancer

Cannabinoids work through 2 receptors CB1 found in highest numbers in the brain and CB2 which is predominant in the immune system. In renal cancer, the CB1 receptor is found to be lower in number which may suggest that a reduced number of cannabinoid receptors leads to less control over the proliferation of tumor cells. There is a high concentration in the proximal convoluted tubule which suggests that a down-regulation may be associated with less inhibition of tumor cell proliferation (1). In another study, CB1 receptors were similar in chromophobe tissue lines were similar to renal cells with no tumor. This may serve as a diagnostic tool for differentiating it from clear cell tumors. It is often difficult to differentiate between the two. Chromophobe tumors have the same number of CB1 receptors while clear cell carcinomas have less CB1 receptors. This is important from the histological and diagnostic standpoint (1).

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In prostatic cancer

In prostate cancer, some mechanisms suggested through studies include working through phosphatase induction. It was found that CB1 and CB2 are expressed during later stages of prostatic cancer. Treatment of prostate cancer culture cells with cannabinoids was found to reduce the multiplication of tumor cells, suggesting a role through apoptotic mechanisms. The effect was dependent on dosage. In another study, cannabinoids were found to increase cytokine IL-6 in prostate cancer that is androgen resistant. This suggests that CB2 agonists may play an important role in reducing epithelial cell proliferation and may lead to a means to treat prostatic cancer (1). More studies are needed to elucidate mechanisms leading to treatment of prostatic cancer.

In bladder cancer

There is much evidence that inflammation found in cancer may lead to the metastatic stage. Cancer can lead to a pro-inflammatory state inducing cytokine and growth factor release leading to the environment conducive to metastasis and invasion of cancer cells into other tissues. In one study of the CB1 and CB2 receptors, it was found that activation of CB1 receptors played an important role in regulating tumor cell proliferation while CB2 was important in influencing an inflammatory state (1). Further studies are needed to further elucidate the mechanisms of cannabinoids on bladder cancer.

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Reference

  1. Ghandhi, et al, “Systemic review of the potential role of cannabinoids as anti-proliferative agents for urological cancer,” Can. Urol. Assoc. J., 2017, May,-April., 11(3-4):E138-E142.
  2. Smith, et al, “Cannabinoids for nausea and vomiting in adults receiving chemotherapy,” Cochrane Database Syst. Rev., Nov., 12(11):CD009464. doi: 10.1002/1465
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Glaucoma

Tetrahydrocannabinol and novel mechanisms in reducing intraocular pressure in glaucoma

Virginia Thornley, M.D.,  Neurologist, Epileptologist

February 28, 2018

Introduction

The endocannabinoid system is composed of 3 systems: (the cannabinoid receptors, (2) endocannabinoid transportation system and (3) enzymes that break down the ligands. Two endocannabinoids anandamide (AEA) and 2-arachidonyl glycerol (2-AG) are elevated in response to a wide variety of pathological events. This suggests a compensatory response of endocannabinoids in response to damage or pathology within the system (3). Activation of the endocannabinoid system appears to correlate with cell repair and survival. The G-receptors discovered called CB1 and CB2 trigger transducer signal cascades and influence peripheral central cell functions.

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Cannabidiol in glaucoma

Cannabidiol is becoming a topic of hot debate in pain, anti-tumor effects, epilepsy and in glaucoma.  Glaucoma can result in increased intraocular pressure resulting in damage to the optic nerve at the retinal attachment. There is the narrowing of the visual field and eventual blindness through retinal damage. and blindness. Cannabinoid receptors have been found in the ocular cells leading to speculation of benefits of cannabinoids in glaucoma.

In one study of 32 different types of cannabinoids, it was found that certain derivatives of delta 9THC and delta 8THC were more effective at lowering intraocular pressure in glaucoma than the parent derivative cannabidiol (1).

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Mechanism for treating glaucoma

One possible mechanism in ameliorating intraocular pressure is by suppressing N-methyl D-aspartate or NMDA receptor excitability, increasing neural vasculature circulation, suppressing apoptosis and damaging free radicals. Separation of the novels effects appears possible from the toxic side effect through novel technique (2).

Involvement of cannabinoid and their receptors in retinal cells have been well documented in fish cells to primates and more recently in neurodegeneration and neuroprotection. There is a fine balance of biosynthetic and degrading enzymes that influence endocannabinoids and exert neuroprotection during trauma, inflammation, ischemia and neurotoxicity found in brain damage (4).

In addition, in one study in 21 dogs, when 2% of tetrahydrocannabinol was applied, the intraocular pressure was reduced (5) which was found statistically significant.

 

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References

  1. ElSohly, et al, “Cannabinoids in glaucoma II: the effect of different cannabinoids on intraocular pressure on rabbits,”Current Eye Research, 1984, Jun., 3(6):841-50.
  2. Jarvinen, T., “Cannabinoids in treatment of glaucoma,” 2002, Aug., 95(2):203-20.
  3.  Karanian, et al, “Cannabinoid drugs and enhancement of endocannabinoid responses: strategies for a wide array of disease states,” Current Molecular Med., 2006, Sep., 6(6):677-84.
  4.  Rapino, et al, “Neuroprotection by endocannabinoids in glaucoma and retinal neurodegenerative diseases,” Current Neuropharmacology, 2017, Jul., doi:10.2174 (Epub ahead of print)
  5. Fischer, et al, “Effects of a topically applied 2% delta-9-tetrahydrocannabinol ophthalmic solution on intraocular pressure and aqueous humor flow rate in clinically normal dogs,” American J. Vet. Res., 2013, Feb., 74(2):275-80.

 

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Parkinson's disease

Parkinson’s disease: cannabidiol, tetrahydrocannabinol, CB1 and CB2 receptors and anti-oxidant properties in neuroprotection 

Virginia Thornley, M.D., Neurologist, Epileptologist

March 2, 2018

Introduction

Cannabinoids are compounds part of the endocannabinoid pathways found inherent to the brain comprising of endocannabinoids, transporters and receptors. Cannabidiol is a mimetic for 2-2-arachidonyl (2-AG) and tetrahydrocannabinol is a mimetic for Anandamide (AEA). 2 receptors for cannabidiol are found in the brain CB1 mainly seen in the basal ganglia and limbic system and CB2 found in the immune system. The receptors are G-coupled and suppress adenylate.

With Parkinson’s disease, there is reduced production of dopamine in the substantia nigra which means there is less inhibitory effect on the basal ganglia resulting in increased acetylcholine from the basal ganglia which results in tremors. Cannabinoids appear to influence the neurotransmitter system within the brain and have found to be beneficial in movement disorders in the animal model.

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Mechanisms of cannabidiol and THC in Parkinson’s disease animal model

There are more CB1 receptors in brains with Parkinson’s disease and the MPTP model, likely a result of less inhibition from the dopaminergic substances and a compensatory mechanism in the brain. There are more CB1 receptors possibly as a response to the reduced dopaminergic effect (2). It was postulated that CB1 agonists may exert a neuroprotective effect against 3 toxins paraquat, MPP+, and lactasyn. However, using experimental techniques, the neuroprotection from 9THC is likely not related to the CB1 receptor. Evidence supports that the neuroprotection afforded by THC may be related to its antioxidant properties. This may be through the effects of PPARy or the peroxisome proliferator-activated receptor gamma.

Other studies propose that the neuroprotective effects of cannabidiol and THC are independent of the CB1 receptor and related to the antioxidant effects. It was found that CB2 receptor activation may slow the progression of neurodegeneration on Parkinson’s disease. CB2 receptors are found naturally in the cells but appear upregulated in diseased cells such as in Parkinson’s disease, suggesting an endogenous protective effect. It may exert effects by reducing proinflammatory responses. Activation of CB2 receptors may represent a promising role of CB2 receptors in the treatment of Parkinson’s disease (3).

Cannabidiol and clinical studies in Parkinson’s disease

In one study of 119 patients, cannabidiol was given at 75mg/day or 300mg/day. Patients were assessed using variables of motor symptoms according to the UPDRS, well-being and life quality (PDQ-39) and neuroprotective effects.

One week before the trial and in the last week of treatment participants were assessed in respect to (i) motor and general symptoms score (UPDRS); (ii) well-being and quality of life (PDQ-39); and (iii) possible neuroprotective effects (BDNF and H(1)-MRS). They found no difference in motor assessment and neuroprotection but the quality of life seemed to improve in the group taking 300mg compared with placebo(1).

 

Medical marijuana has been demonstrated to be effective in bradykinesia, tremors seen in the Parkinson’s disease. Cannabinoids have been found effective in psychosis and sleep disorders seen in Parkinson’s disease(4).

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References

  1. Chagas, et al, “Effects of cannabidiol in the treatment of patients with Parkinson’s disease: an exploratory double-blind trial,” Journal of Psychopharmacology, 2014, Nov., 28(110):1088-1098.
  2.  Carroll, et al, “9-Tetrahydrocannabinol exerts a direct neuroprotective effect in human cell culture model of Parkinson’s disease,” Neuropathology and Applied Neuropharmacology, 2012, Oct., 38(6):3535-547.
  3. Fernandez-Ruiz, et al, “Prospects of cannabinoid therapies in basal ganglia disorder,” British Journal of Pharmacology, 2011, Aug., 163 (7):1365-1378.
  4. Babyeva, et al, “Marijuana compounds: a non-conventional approach to Parkinson’s disease therapy,” Parkinson’s Disease, 2016:1279042.
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