Endocannabinoids An Emotional Buffer?

 Lipid neuromodulators and hormones  Made from Membrane phospholipids  Synthesized On Demand   stimulated production  Provide the Framework ( receptors etc ) for  the mechanisms of actions for  Cannabis sativa What are Endocannabinoids ?

 2 Primary Bioactive molecules  AEA = Anadamide  A rachidonyl E thanol A mide  2AG = 2-A rachidonoyl G lycerol  Many other less active forms  Virodhamine, Nolandin Ether, NADA  HEA, DEA, PEA, OEA Endocannabinoids (eCBs)

Endocannabinoid Structure

Comparison to Phytocannabinoids

 AEA precursor = N-arachidonoyl Phosphatidylethanolamine  Main Enzyme = NAPE-PLD  N-acylphosphatidylethanolamine phospholipase D  Catabolic enzyme = FAAH (fatty acid amide hydrolase)  2-AG precursor = Diacylglycerol (DAG)  2 nd Messenger: PLC → PIP 2 → DAG → PKC  Main Enzyme = DAG Lipase  Catabolic enzyme = MAG Lipase (monoacylglycerol Lipase) eCB Synthesis/Breakdown

 Cannabinoid Receptors: 2 classic + 1 or 2  CB 1 : high density in central nervous system  CB 2 : low density in CNS; high peripherally  GPR 55 : CB 3 – but another CB 3 in hippocampus  Cationic Channel Vanilloid Receptor: TRP V1  Transient Receptor Potential – Vanilloid 1  Nuclear Receptor: PPARs  Peroxisome proliferator-activated receptors  Transporters: EMT, FLAT Mechanism of Action: Receptors

 High density Neuronal Receptor  Presynaptic on GABA and Glu neurons  Lipid raft microdomains - concentrating  Binds AEA, 2-AG, Δ 9 THC  Triggers G i/o protein →  →↓ AC/cAMP/PKA →↑ K + channels, ↓ Ca ++ channels  →↑ MAPK →↑ ERK, p38  Inhibits Glu or GABA release Mechanisms: CB 1 Receptors

 Rare pre & postsynaptic Neuronal Receptor  Highly Inducible (100X) – Trauma, Anxiety  More CB 2 on microglia  Binds 2-AG, AEA, Δ 9 THC  Triggers G i/o protein → ( functional selectivity)  →↓ AC/cAMP/PKA →↑ K + channels, ↓ Ca ++ channels  →↑ MAPK →↑ PI 3 K/Akt (PKB)  Inhibits Glu or GABA release (44% homology to CB 1 ) Mechanisms: CB 2 Receptors

eCB control of Glu/GABA release

The Endocannabinoids are Retrograde Messengers Therefore:

eCB control of Glu release

 Widely expressed in Brain  Lowers blood pressure?  Binds AEA, 2-AG, Δ 9 THC,CBD  Triggers G 13 α protein →  →↑[ Ca ++ ], ↑ RhoA, Rac, Cdc 42 (Ras GTPases)  →↑ pERK  Actin Cytoskeleton Remodeling Mechanisms: CB 3/GPR 55 Receptors

 Transient Receptor Potential cation channel subfamily V member 1  Located on Nociceptors, found in CNS  Binds capsaicin (jalapeño, habanero), allyl isothiocyanate (wasabi)  Binds 2-AG, AEA, Δ 9 THC  Also opened by acid, T ° > 43 ° C (109°F)  →↑[ Ca ++ ]  →↑ Caspases, Cytochrome C release, mitochondrial uncoupling, Pro-apoptosis Kinases  Sensation of Scalding Heat and Pain Mechanisms: TRP v1 Channels

 Peroxisome Proliferator-Activated Receptor  Nuclear: genomic + rapid non-genomic action  Act as Transcription Factors  Long-lasting  Heterodimerize with Retinoid X Receptors  ↑ Tyrosine Kinases  ↑ Adiponectin/Lipoprotein Lipase  Opposite effects of CB 1/2 Mechanisms: PPARs

Therapeutic Effects

I.AEA + 2-AG are Synthesized on Demand 1.In Discrete Brain Areas 2.Depending on i.Nature and Intensity of Environmental Stimuli II.CB 1 + CB 2 receptors are widely expressed 1.In Brain regions responding to Stressful Stimuli i.May be opposite effects ii.Depending on Anatomical Location eCB Buffering and Homeostasis 1

III. CB 1 + CB 2 are expressed presynaptically 1. Suppresses release of Glu + GABA i. Retrograde inhibition is Negative Feedback 2. CB 2 relevant for emotional responses 3. PPARs modulate aversive memory consolidation 4. TRP V1 mediate opposing emotional responses compared to CB 1 IV.D ensities of eCB molecular components 1. Differ between synapse types (Glu or GABA) eCB Buffering and Homeostasis 2

CB 1 / CB 2 action on corticosterone WIN55,212-2 = CB 1 & CB 2 receptor agonist Novelty Habituated to Novelty Stress No Stress

 Therefore:  The effect of Endocannabinoids can be  Direct  Indirect  Synergistic  Modified by Environmental Conditions  Modified by Social Factors AEA + 2-AG affect Stress Hormones

CB 1 / CB 2 affects Learning Stress No Stress Influenced by Stress and Timing Object Recognition Learning

CB 1 / CB 2 effect on Learning depends on Corticosterone (B) ↓ [B] Object Recognition

Synergistic Actions

 Inhibit Short-term Learning  Enhance Long-term Learning  During Stressful Conditions  Modify the Effects of Stress Hormones  Stimulated/modified by stress hormones  Moderate Environmental Impacts  on Emotional Memory  Attenuate Excessive Behavioral Responses Do AEA/2-AG-CB 1 /CB 2 act as buffers against Environmental Stressors ?