Medical Marijuana: Just the Beginning of a Long, Strange Trip?

Physical Therapy Journal

“Medical marijuana continues to gain acceptance and become legalized in many states. Various species of the marijuana plant have been cultivated, and this plant can contain up to 100 active compounds known as cannabinoids.

Two cannabinoids seem the most clinically relevant: Δ9-tetrahydrocannabinol (THC), which tends to produce the psychotropic effects commonly associated with marijuana, and cannabidiol (CBD), which may produce therapeutic effects without appreciable psychoactive properties.

Smoking marijuana, or ingesting extracts from the whole plant orally (in baked goods, teas, and so forth), introduces variable amounts of THC, CBD, and other minor cannabinoids into the systemic circulation where they ultimately reach the central and peripheral nervous systems.

Alternatively, products containing THC, CBD, or a combination of both compounds, can also be ingested as oral tablets, or via sprays applied to the oral mucosal membranes. These products may provide a more predictable method for delivering a known amount of specific cannabinoids into the body.

Although there is still a need for randomized controlled clinical trials, preliminary studies have suggested that medical marijuana and related cannabinoids may be beneficial in treating chronic pain, inflammation, spasticity, and other conditions seen commonly in physical therapist practice.

Physical therapists should therefore be aware of the options that are available for patients considering medical marijuana, and be ready to provide information for these patients.”

http://www.ncbi.nlm.nih.gov/pubmed/27660328

Selective modulator of cannabinoid receptor type 2 (CB2) against biochemical alterations and brain damage in chronic cerebral hypoperfusion induced vascular dementia.

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“Vascular dementia is the second most common cause of cognitive decline in aged people but the effectual therapeutic target is still missing.

Chronic cerebral hypoperfusion (CCH) has been widely found in vascular dementia (VaD) patients. CCH is thought to link with neurodegenerative disorders and their subsequent cognitive impairment.

The present study has been framed to investigate the role of selective agonist of CB2 receptor (1-phenylisatin) in CCH induced VaD.

These results indicate that 2VO induced CCH in rats, which was attenuated with the treatment of 1-phenylisatin.

Hence, it may be suggested that modulation in cannabinoid receptor may provide benefits in CCH as cognitive impairment and VaD.

Therefore, pharmacological positive modulation of CB2 receptors may be a potential research target for alleviation of VaD.”

http://www.ncbi.nlm.nih.gov/pubmed/27599483

Protection against septic shock and suppression of tumor necrosis factor alpha and nitric oxide production by dexanabinol (HU-211), a nonpsychotropic cannabinoid.

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“Dexanabinol, HU-211, a synthetic cannabinoid devoid of psychotropic effects, improves neurological outcome in models of brain trauma, ischemia and meningitis.

Recently, HU-211 was found to inhibit brain tumor necrosis factor (TNFalpha) production after head injury. In the present study, we demonstrate the ability of HU-211 to suppress TNFalpha production and to rescue mice and rats from endotoxic shock after LPS (Escherichia coli 055:B5) inoculation.

Administration of LPS to Sprague-Dawley rats resulted in a 30% reduction in the mean arterial blood pressure within 30 min, which persisted for 3 hr. HU-211, given 2 to 3 min before LPS, completely abolished the typical hypotensive response. Furthermore, the drug also markedly suppressed in vitro TNFalpha production and nitric oxide generation (by >90%) by both murine peritoneal macrophages and rat alveolar macrophage cell line exposed to LPS.

HU-211 may, therefore, have therapeutic implications in the treatment of TNFalpha-mediated pathologies.”

http://www.ncbi.nlm.nih.gov/pubmed/9353414

Activation of type 1 cannabinoid receptor (CB1R) promotes neurogenesis in murine subventricular zone cell cultures.

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“The endocannabinoid system has been implicated in the modulation of adult neurogenesis.

Here, we describe the effect of type 1 cannabinoid receptor (CB1R) activation on self-renewal, proliferation and neuronal differentiation in mouse neonatal subventricular zone (SVZ) stem/progenitor cell cultures.

There is an emerging consensus that endocannabinoid signaling plays a major role in adult neurogenesis.

Cannabinoids act on at least two types of receptors, the type 1 and type 2 cannabinoid receptors (CB1R and CB2R), which are, respectively, predominantly distributed in the central nervous system (CNS) and immune system, although some studies have described the presence of low levels of CB2R in the brain.

Taken together, these results demonstrate that CB1R activation induces proliferation, self-renewal and neuronal differentiation from mouse neonatal SVZ cell cultures.

 Collectively, CB1R agonists render neurons less excitable and thus promote neuroprotection.”

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3660454/

Orchestrated activation of mGluR5 and CB1 promotes neuroprotection.

“The metabotropic glutamate receptor 5 (mGluR5) and the cannabinoid receptor 1 (CB1) exhibit a functional interaction, as CB1 regulates pre-synaptic glutamate release and mGluR5 activation increases endocannabinoid synthesis at the post-synaptic site. Since both mGluR5 and CB1promote neuroprotection, we delineated experiments to investigate a possible link between CB1 and mGluR5 activation in the induction of neuroprotection using primary cultured corticostriatal neurons. We find that either the pharmacological blockade or the genetic ablation of either mGluR5 or CB1 can abrogate both CB1– and mGluR5-mediated neuroprotection against glutamate insult. Interestingly, decreased glutamate release and diminished intracellular Ca2+ do not appear to play a role in CB1 and mGluR5-mediated neuroprotection. Rather, these two receptors work cooperatively to trigger the activation of cell signaling pathways to promote neuronal survival, which involves MEK/ERK1/2 and PI3K/AKT activation. Interestingly, although mGluR5 activation protects postsynaptic terminals and CB1 the presynaptic site, intact signaling of both receptors is required to effectively promote neuronal survival. In conclusion, mGluR5 and CB1 act in concert to activate neuroprotective cell signaling pathways and promote neuronal survival.”

Cannabinoids in pain and inflammation.

“Cannabinoids exhibit medicinal properties including analgesic, anti-inflammatory and immunosuppressive properties. This paper reviews some of the recent findings in the study of cannabinoids in pain and inflammation. Some of the effects of cannabinoids are receptor mediated and others are receptor independent. Endocannabinoids naturally reduce pain and are cerebroprotective. Natural and synthetic cannabinoids have the potential to reduce nociception, reverse the development of allodynia and hyperalgesia, reduce inflammation and inflammatory pain and protect from secondary tissue damage in traumatic head injury.”

http://www.ncbi.nlm.nih.gov/pubmed/15265314

Effects of Cannabidiol and Hypothermia on Short-Term Brain Damage in New-Born Piglets after Acute Hypoxia-Ischemia.

“Hypothermia is a standard treatment for neonatal encephalopathy, but nearly 50% of treated infants have adverse outcomes.

Pharmacological therapies can act through complementary mechanisms with hypothermia improving neuroprotection.

Cannabidiol could be a good candidate.

Our aim was to test whether immediate treatment with cannabidiol and hypothermia act through complementary brain pathways in hypoxic-ischemic newborn piglets.

Individually, the hypothermia and the cannabidiol treatments reduced the glutamate/Nacetyl-aspartate ratio, as well as TNFα and oxidized protein levels in newborn piglets subjected to hypoxic-ischemic insult. Also, both therapies reduced the number of necrotic neurons and prevented an increase in lactate/N-acetyl-aspartate ratio.

The combined effect of hypothermia and cannabidiol on excitotoxicity, inflammation and oxidative stress, and on cell damage, was greater than either hypothermia or cannabidiol alone.

The present study demonstrated that cannabidiol and hypothermia act complementarily and show additive effects on the main factors leading to hypoxic-ischemic brain damage if applied shortly after the insult.”

http://www.ncbi.nlm.nih.gov/pubmed/27462203

Type-2 Cannabinoid Receptors in Neurodegeneration.

“Based on its wide expression in immune cells, type 2 cannabinoid (CB2) receptors were traditionally thought to act as “peripheral receptors” with an almost exclusively immunomodulatory function. However, their recent identification in mammalian brain areas, as well as in distinct neuronal cells, has opened the way to a re-consideration of CB2 signaling in the context of brain pathophysiology, synaptic plasticity and neuroprotection. To date, accumulated evidence from several independent preclinical studies has offered new perspectives on the possible involvement of CB2signaling in brain and spinal cord traumatic injury, as well as in the most relevant neurodegenerative disorders like Alzheimer’s disease, Parkinson’s disease and Huntington’s chorea. Here, we will review available information on CB2 in these disease conditions, along with data that support also its therapeutic potential to treat them.”

http://www.ncbi.nlm.nih.gov/pubmed/27450295

Cannabinoids and Neuro-Inflammation: Regulation of Brain Immune Response.

“Cannabinoid receptors are involved in neurophatogenic mechanisms of inflammatory disorders of the central nervous system and their expression can be modulated during the disease.

Brain inflammatory processes are characterized by infiltration of numerous types of cells, peripheral immune cells, brain resident immune cells, the microglial cells and numerous other neuronal cells. The disruption of the blood brain barrier favours cell infiltration in the central nervous system with consequent neuronal damage, common event in many neuro-inflammatory diseases.

In this review we evidence the role of cannabinoid receptor, their expression at peripheral and central levels in order to better understand their implication in neuro-inflammation.

Cannabinoids affect brain adaptive and immune response, have regulatory action on inflammatory mediators and can exert a role in blood brain barrier damage prevention.

Furthermore, in numerous neurodegenerative diseases with inflammatory component the beneficial effects of cannabinoids have been widely reported, so current knowledge of cannabinoid involvement in these central nervous system disorders are also reviewed.”

http://www.ncbi.nlm.nih.gov/pubmed/27334610

CB1 Receptor Antagonism Prevents Long-Term Hyperexcitability after Head Injury by Regulation of Dynorphin-KOR System and mGluR5 in Rat Hippocampus.

“Both endocannabinoids and dynorphin are feedback messengers in nervous system that act at the presynaptic nerve terminal to inhibit transmitter release. Many studies showed the cannabinoid-opioid cross-modulation in antinociception, hypothermia, sedation and reward.

The aim of this study was to assess the influence of early application of cannabinoid type 1 (CB1) receptor antagonism SR141716A after brain injury on dynorphin-κ opioid receptor (KOR) system and the expression of metabotropic glutamate receptors (mGluRs) in a rat model of fluid percussion injury (FPI).

Firstly, seizure latency induced by pentylenetetrazole was significantly prolonged 6 weeks after brain injury in group of SR141716A treatment. Then, PCR and western blot showed that SR141716A inhibited the long-term up-regulation of CB1 receptors in hippocampus. However, SR141716A resulted in long-term potentiation of dynorphin release and did not influence the up-regulation of KOR in hippocampus after brain injury. Furthermore, SR141716A reverse the overexpression of mGluR5 in the late stage of brain injury.

We propose that during the induction of epileptogenesis after brain injury, early application of CB1 receptor antagonism could prevent long-term hyperexcitability by up-regulation of dynorphin-KOR system and prevention of mGluR5 induced epileptogenesis in hippocampus.”

http://www.ncbi.nlm.nih.gov/pubmed/27262683