Cannabinoid in CNS Diseases: A Potential Therapeutic Target

Xiang Fang, MD, PhD.

Assistant Professor

Department of Neurology

University of Texas Medical Branch

Galveston, TX 77555

University of Iowa, IA

Harbor Hospital, Baltimore, MD

Old Red at UTMB, TX

Marijuana is the dried flowers, leaves and stems of the Cannabis sativa plant.

97.8 million Americans aged 12 or older tried marijuana at least once in their lifetimes, representing 39.8% of the U.S. population in that age group. NSDUH, 2006

• A potent drug that has strong impact on the brain and the rest of the body. • In addition to producing an intoxicating "high," marijuana can ease anxiety and pain, stimulate hunger, and impair memory. • A long history in folk medicine. It's been used for menstrual pain and the muscle spasms associated with multiple sclerosis.

CB1 receptors (red) are widely distributed

in the brain

CB2 receptors are presented in the peripheral immune cells

Molecular structure of CB1 and CB2 Receptors

• Inhibit adenylyl cyclase

• Activate mitogen-activated protein (MAP) kinase

• Inhibit voltage-gated Ca2+ channels

• Activate K+ channels

• Activate focal adhesion kinase

• Activate cytosolic phospholipase A2

• Activate (CB1R) or inhibit (CB2R) NO synthase

Signal Transduction of Cannabiods Receptors

Biological actions of Cannabioids

• Cortex, cerebellum and spinal cordBlock N-methyl-d-aspartate (NMDA) receptors, control tremor and spasticity.

• Basal ganglia, striatum and globus pallidusControl psychomotor disorders, interfer with dopamine transmission, inhibit GABA-mediated transmission, induce long-term depression, potentiate GABA-mediated catalepsy.

• Thalamus, hypothalamus and hippocampusControl pain initiation, wake–sleep cycles, thermogenesis, appetite and food intake, impair working memory, memory consolidation, inhibit glutamate-mediated transmission.

Endogenous Cannabinoid Ligands and Biological Activities

N-Arachidonylethanolamide (Anandamide, AEA)

2-Arachidonylglycerol (2-AG)

CB1 and CB2

Biosynthesis of Anandamide

Transport and degradation of Anandamide

Modulation of Degeneration and Inflammation in the CNS by the Endogenous Cannabinoids System

Zajicek J et al., Lancet 2003, 362:1517-26

Cannabinoid and MS: CAMS Trial

Baker D et al., Nature, 2000; 404: 84-87.

a, c: before b.d after 5 mg kg-1 i.p. with R(+)-WIN 55,212.e. Power spectra of hindlimb tremors

Cannabinoid receptor agonism inhibits tremor in autoimmune encephalomyelitis

Before

After

Spasticity Develops in Autoimmuno Encephalomyelitis

Control of spasticity by the cannabinoid system

Control

Control

SR141716A

SR141716A10 min

SR144528

R(+)WIN55212

Centonze, D. et al. Brain 2007 130:2543-2553; doi:10.1093/brain/awm160

Endocannabinoid levels in the CSF of control and MS subjects

Centonze, D. et al. Brain 2007 130:2543-2553; doi:10.1093/brain/awm160

Endocannabinoid metabolism in peripheral lymphocytes of control and MS subjects

Centonze, D. et al. Brain 2007 130:2543-2553; doi:10.1093/brain/awm160

Endocannabinoid metabolism in striatal and cortical slices of control and EAE mice

Centonze, D. et al. Brain 2007 130:2543-2553; doi:10.1093/brain/awm160

Effects of CB1 receptor stimulation on evoked glutamate-mediated EPSCs in corticostriatal slices of control and EAE mice

Centonze, D. et al. Brain 2007 130:2543-2553; doi:10.1093/brain/awm160

Effects of CB1 receptor stimulation on evoked GABA-mediated IPSCs in corticostriatal slices of control and EAE mice

Centonze, D. et al. Brain 2007 130:2543-2553; doi:10.1093/brain/awm160

Cannabinoid receptor binding in striatal and frontal cortical slices of control and EAE mice

Ortega-Guitierrez et al., FASEB J, 2005

UCM707 inhibits microglial activation and decreases the Microglial MHC class II antigen expression.

Spinal Cord Section5 mg/kg UCM, ip

Microglia/macrophages (CD11b+ cells)

Microglia/macrophages (tomato lectin binding)

Theiler’s murine encephalomyelitis virus-induced demyelinating disease (TMEV-IDD)

Effects of AMT Inhibitor on Microglial Activation and the Production of Inflammatory Cytokines

in TMEV-IDD MS model

Cannabidiol and Alzheimer's disease

• AD is the most common form of dementia in the elderly

• AD is characterized by the β-amyloid peptide (βA) within one of its pathological hallmark: the senile plaque. Activated microglia cluster at senile plaques, and this seems to be responsible for the ongoing inflammatory process in the disease.

B.G. Ramirez et al., J. Neurosci. 2005, 25: 1904–1913

Cannabinoid Receptor Localization in AD Brain

Frontal cortical

Nitration of CB1 and CB2 is increased in AD brain.

N-Tyr-immunoreactive astrocytes in control

Nuclear N-Tyr expression In control

Cytoplasmic N-TyrExpression in AD

Cannabinoid treatment prevents βA-induced Microglial activation in rats.

Tomato lectin binding – activated microglial in frontal Cortex, SCR or βA for 8 days

Cannabinoids prevent β-A-induced microglial activation in vitro

Cultured rat cortex microglial, Fibrillar βA

Effects of compounds acting on the elements of EC system in experimental models of AD

Compound Function Effects

Noladin CB1 agonist To counteract Aβ neurotoxicity

WIN55,212-2 CB1 and CB2 agonist To counteract Aβ-induced microglial activation

JWH-015 CB2 agonist To counteract Aβ-induced microglial activation

Rimonabant CB1 antagonist To counteract amnesia induced by Aβ peptides

Cannabidiol TRPV1 agonist >CB1 and CB2 To counteract Aβ-induced neuroinflamm. responses

VDM-11 EC reuptake inhibitor To counteract amnesia/neuro damage by Aβ peptides

Micale et al., Pharmacol. Res. 2007,56:382-392

The Involvement of the Endocannabinoid System in the Pathophysiology of AD

Cannabinoids and Amyotrophic lateral sclerosis

ALS: A fatal neurodegenerative disorder that selectively damages upper and lower motorneurons of the spinal cord, brainstem and motor cortex.

-- Glutamate excitotoxicity-- Mitochondrial dysfunction-- Oxidative stress-- Protein aggregation-- Proteosomal dysfunction-- Axonal transport deficits-- Cytoskeletal abnormalities -- Microglial activation-- Neuroinflammation and aberrant growth factor signaling

Levels of endocannabinoids in spinal cords of WT and symptomatic SOD1G93A mice.

L.G. Bilsland et al., FASEB J. 20 (2006):1003–1005.

Effect of treatment with WIN55,212–2 on the contractile characteristics of EDL muscles in SOD1G93A mice at 120 d of age

Extensor digitorum longus (EDL)

WT SOD1G93A WIN + SOD1G93A

Succinate dehydrogenase, an indicator of oxidative capacity

The neuroprotective effect of treatment with WIN55,212–2 in SOD1G93A mice

Spinal cord Section

Nissl statin

a: controlb: SOD1G93Ac: Win treated SOD

Motoneuron survival in SOD1.Faah –/– and SOD1.Cnr1 –/– mice.

(a) WT(b) SOD1G93A(c) SOD1.Faah –/–(d) SOD1.Cnr1 –/– mice.

The effect of Faah and CB1 receptor ablation on muscle force and motor unit survival in SOD1G93A

90 days of age

The potential neuroprotective mechanisms of cannabinoids in SOD1G93A mouse model of ALS.

• HD is an autosomal dominant, progressive neurodegenerative disorder

• Caused by a mutation in the IT15 gene of chromosome 4 coding for huntingtin (htt).

• Followed by an unstable expanded trinucleotide cytosine-adenine-guanine (CAG) repeat, which encodes for the amino acid glutamine.

• In HD, the gene has 40 and 60 CAG repeats leading to a mutant form of htt where glutamine is repeated dozens of times. The polyglutamines causes degeneration of medium spiny striato-efferent GABAergic neurons and atrophy of the caudate nucleus.

The Cannabinoid Pathway in Huntington’s Disease

The distribution of cannabinoid CB1 and dopamine D1 receptors in the SN of control and Huntington's disease Brain

SN: substantia nigra, autoradiograph

The binding of [3H]CP55,940 to CB1receptors in the caudate nucleus and putamen

Glass et al., Neuroscience, 2000, 97:505-519

The binding of [3H]SCH23390 to dopamine D1 receptors in the caudate nucleus and putamen

The binding of [3H]Raclopride to dopamine D2 receptors in the caudate nucleus and putamen

The binding of [3H]FNZ to GABAA receptors in the putamen and globus pallidus of the lenticular nucleus

CB1 Binding Capacity CB1 mRNA level

Wide-type Control

Transgenic HD

Lastres-Becker et al., 2002

Cannabinoid receptor stimulation depresses GABA transmission in WT but not in R6/2 HD mice

Effects of CB1 receptor stimulation on spontaneous glutamate-mediated EPSCs (sEPSCs) recorded from WT and R6/2 mice

Effects of compounds acting on the elements of EC system in experimental models of HD

Compound Function Effects

CP55940 CB1 & CB2 agonist Anti-hyperkinetic effects

Arvanil CB1 and TRPV1 agonist Anti-hyperkinetic effects

Cannabidiol antioxidant properties Neuroprotective and reverse GABAergic damage

Capsaicin TRPV1 agonist Anti-hyperkinetic, improvement DAergic and GABAergic system

AM404 EC reuptake inhibitor & TRPV1 agoonist Same as above

UCM707 EC reuptake inhibitor Anti-hyperkinetic effects

● PD -- degeneration of dopamine (DA)-containing neurons of the substantia nigra. The irreversible loss of the DA-mediated control of striatal function leads to the typical motor symptoms.

● Degeneration of dopamine neurons during experimental PD can be reduced by agonists of CB1, CB2, and non-CB1 or non-CB2 receptors – an effect that involves modulating the interactions between glial cells and neurons. CB1 receptors, however, also exert detrimental effects on dopamine cell survival by potentiating the toxic effects of the TRPV1 agonist capsaicin.

Cannabinoids and Parkinson's disease

Lastres-Becker et al Eur J Neurosci. 2001, 14:1827-32.

Cannabinoids reduce the frequency of glutamatergic sEPSCs in striatal spiny neurons of naïve and parkinsonian (6-OHDA) rats