# Presentation: 394467

## Slide 1

## Overview of the striatum

- dorsal

- ventral

- Dorsal striatum important for motor planning and adaptive behaviors. Main inputs arise from motor cortex.
- Disorders involving dorsal striatum include Parkinson’s disease and Huntington’s disease.
- Ventral striatum (nucleus accumbens) is important for reward. Main inputs arise from amygdala and prefrontal cortex.
- Drug addiction, depression are  disorders involving the striatum.

## Neurotransmission and neuromodulation:

- Adrenaline (ca. 1900-)
- Acetylcholine (ca. 1900-)
- Neuropeptides (1930-)
- Amino Acids (GABA and Glutamate) (1950-)
- Monoamines (5-HT and Dopamine) (1950-)
- Endogenous opioids (1975-)
- Endogenous cannabinoids (1992-)
**	****	**-CB1 receptor cloned (1990)
** ****	****	**-discovery of endogenous endocannabinoids (1992)
- 		-modulation of synaptic function (2001)

## Endocannabinoid signaling in the striatum

- CB1 immunoreactivity

- Gerdeman et al., **Nat Neurosci** (2002)

- Corticostriatal LTD

## Anatol Kreitzer

- Sheela Singla
- Brad Grueter
- Percy Luu

## Experimental Methods

- Acute coronal brain slices – recordings performed from medium spiny neurons (MSNs) in **dorsolateral** striatum of 3- to 4-week-old rats and mice
- CsMeSO3 based-internal solution, 0.2 mM EGTA, QX-314 to block Na currents
- External saline: 2 mM Ca, 1 mM Mg. Picrotoxin (50 M) present to block GABAA-mediated currents.
- Experiments performed at room temperature (RT) and 30-32 °C

## Tetanus induces endocannabinoid-mediated LTD

- (eCB-LTD)

- Time (min)

## eCB-LTD requires mGluRs

## Endocannabinoids are released by activation of postsynaptic mGluRs

- DHPG (100 uM)

## eCB-LTD requires D2 receptors

- EPSC (% baseline)

## Model of endocannabinoid release and LTD in the striatum

- 1. mGluR activation, combined with subthreshold depolarization, leads to endocannabinoid (eCB) synthesis and release
- 2. Dopamine D2 receptor activation enhances eCB synthesis, while D2 inhibition reduces eCB synthesis
- 3. Released eCBs bind to presynaptic CB1 receptors and induce presynaptic LTD
- 4. Neurotransmitter release is reduced for tens of minutes or more

- (Kreitzer and Malenka, 2005)

## The striatum is not homogeneous 

- dorsal

- ventral

- The striatum is not homogeneous
- (2 populations of medium spiny neurons)

## Basal ganglia motor circuit: direct pathway

**Caudate/**
**Putamen**

**Motor Cortex**

**Motor**
**Thalamus**

**Premotor**
**Cortex**

***Glutamate***

***GABA***

**GPe**

**GPi/SNr**

**STN**

***Dopamine***

**SNc**

**+**

## Basal ganglia motor circuit: indirect pathway

**Caudate/**
**Putamen**

**Motor Cortex**

**Motor**
**Thalamus**

**Premotor**
**Cortex**

***Glutamate***

***GABA***

**GPe**

**GPi/SNr**

**STN**

***Dopamine***

**SNc**

**-**

## X

- Parkinson disease

**Striatum**

**Motor Cortex**

**Motor**
**Thalamus**

**Premotor**
**Cortex**

**+ *****Glutamate***

**- *****GABA***

**GPe**

**GPi/SNr**

**STN**

***Dopamine***

**SNc**

**+**

**-**

**X**

## Nucleus accumbens direct and indirect pathways?

## M4- and D2-GFP BAC-transgenic mice label direct 

- M4- and D2-GFP BAC-transgenic mice label direct
- and indirect pathway medium spiny neurons

- GENSAT Program (N. Heintz, M. Hatten,  W. Yang)

## Direct and indirect pathway synapses display 

- Direct and indirect pathway synapses display
- different paired-pulse ratios

## Indirect pathway synapses have a higher 

- Indirect pathway synapses have a higher
- release probability

## Direct and indirect pathway synapses display 

- Direct and indirect pathway synapses display
- different paired-pulse ratios in nucleus accumbens

## Indirect (D2+) pathway synapses have a higher 

- Indirect (D2+) pathway synapses have a higher
- release probability in nucleus accumbens?

## Indirect pathway medium spiny neurons are more excitable

## Indirect (D2+) pathway medium spiny neurons are more excitable in nucleus accumbens

- Direct

- Indirect

## Endocannabinoid-mediated LTD occurs only at indirect pathway synapses

- Time (min)

## Endocannabinoid-mediated(?) LTD occurs only at indirect pathway synapses in nucleus accumbens

## Indirect pathway eCB-LTD requires dopamine D2 receptor activation

- AM251: cannabinoid CB1 receptor antagonist
- sulpiride: dopamine D2 receptor antagonist

## CB1 receptor agonists inhibit transmitter release at both direct and indirect pathway synapses 

- WIN55,212: cannabinoid CB1 receptor agonist
- AM251: cannabinoid CB1 receptor antagonist

## Postsynaptic mGluR-driven endocannabinoid release occurs primarily at indirect pathway synapses

## Postsynaptic mGluR-driven LTD occurs primarily at indirect pathway synapses in nucleus accumbens

## Indirect pathway eCB-LTD is absent in an animal model of Parkinson disease

- Time (min)

## Endocannabinoid biosynthesis and inactivation

- (URB754)

- (URB597)

## Rescue of indirect pathway LTD in a Parkinson’s disease model (reserpine)

- quinpirole: dopamine D2 receptor agonist
- URB754: monoacylglycerol lipase (MGL) inhibitor
- URB597: FAAH inhibitor

## Rescue of indirect pathway LTD in a Parkinson’s disease model (6-OHDA)

- quinpirole: dopamine D2 receptor agonist
- URB597: FAAH inhibitor

## An important role for dopamine D2 receptors and cannabinoid CB1 receptors in movement

**D2-/-**

**wt**

## Inhibition of eCB degradation enhances D2-receptor-mediated recovery from catalepsy in animal models of Parkinson disease 

## Inhibition of eCB degradation enhances D2-receptor-mediated recovery of locomotor activity in animal models of Parkinson disease 

## X

**Caudate/**
**Putamen**

**Motor Cortex**

**Motor**
**Thalamus**

**Premotor**
**Cortex**

**+ *****Glutamate***

**- *****GABA***

**GPe**

**GPi/SNr**

**STN**

***Dopamine***

**SNc**

**+**

**-**

**X**

**(L-DOPA)**

**STN Pacemaker**

**Pallidotomy**

**eCB biosynthesis**

- Basal ganglia motor circuit: Parkinson’s disease treatments

## Conclusions

-  eCB-LTD in the striatum is restricted to indirect 	pathway cells
-  it is synapse specific because it requires presynaptic 	activity in addition to CB1 receptor activation
-  eCB-LTD is prevented by dopamine depletion but can 	be rescued by a D2 agonist and an inhibitor of 	eCB degradation
-  inhibition of eCB degradation improves motor 	performace in animals models of Parkinson 	disease
-  D2(+) and D2(-) cells in the accumbens also have 	different synaptic properties

## Anatol Kreitzer

- Sheela Singla
- Brad Grueter
- Percy Luu

- Nathaniel Heintz (Rockefeller)
- X. William Yang (UCLA)

## Is presynaptic eCB-LTD activity-dependent?

- -Spillover onto synapses that did not participate in depolarizing the postsynaptic cell could cause LTD.
- -Synapse specificity may be achieved if LTD depended on presynaptic activity and not just receptor activation.

## Testing the effect of synaptic activity on LTD

- _pathway 1: no _
- _synaptic stimulation_

- _pathway 2: 0.05 Hz-1 Hz_
- _synaptic stimulation_

## A CB1 agonist is sufficient to induce LTD in the striatum, but not the cerebellum

## WIN-induced LTD is activity-dependent 

- WIN-induced LTD is activity-dependent

## eCB-LTD is activity-dependent 

- eCB-LTD is activity-dependent

## Imbalanced activity in striatal motor circuits in vivo in a Parkinson disease model

- Mallet et al (2006) **J Neurosci**

**(direct)**

**(indirect)**

- Imbalanced activity in striatal motor circuits *in vivo* in a Parkinson disease model

## Muscarinic M1 receptors do not regulate striatal endocannabinoid release or eCB-LTD

- 100 Hz tetanus

- pirenzepine: muscarinic M1 receptor antagonist
- sulpiride: dopamine D2 receptor antagonist

## Dopamine-depleted mice do not have alteredpaired-pulse plasticity or sensitivity to cannabinoids

- Dopamine-depleted mice do not have alteredpaired-pulse plasticity or sensitivity to cannabinoids

## Indirect pathway synapses have larger NMDA/AMPA current ratios

## Inhibition of eCB degradation enhances D2-receptor-mediated recovery from catalepsy in animal models of Parkinson disease 

## Inhibition of eCB degradation enhances D2-receptor-mediated recovery of locomotor activity in animal models of Parkinson disease 

## Signaling through CB1 receptors

- Adapted from DiMarzo et al., **Nature Reviews Drug Discovery** (2004)

**heterotrimeric G-protein**

**CB1R**

**agonist**

**Anandamide (endogenous agonist)**

**2-AG (endogenous agonist)**

**THC (partial agonist)**

## Endocannabinoid biosynthesis and inactivation

**Calcium**

**Phosphatidylethanolamine (PE)**

**N-arachidonoyl PE**

**N-Acyltransferase**

**Calcium **

**Phosphatidylinositol (PI)**

**Diacylglycerol (DAG)**

**Phospholipase C******

**Receptor activation**
**(mGluR or mAChR)**

**NAPE-PLD**

**Anandamide (AEA)**

**Calcium**

## Inhibition of endocannabinoid degradation enhances D2-receptor-mediated recovery of movement in a Parkinson disease model

## D2 receptor activation enhances endocannabinoid release in response to brief mGluR activation

- DHPG

## Signaling through CB1 receptors

**agonist**

**heterotrimeric G-protein**

**THC (partial agonist)**

**2-AG (endogenous agonist)**

**Anandamide (endogenous agonist)**

- Adapted from DiMarzo et al., **Nature Reviews Drug Discovery** (2004)

## Endocannabinoid biosynthesis and inactivation

- (URB754)

- (URB597)

## CB1 receptor distribution in rat brain

- (from Pettit *et al.,* 1998)

## Endocannabinoids are not released by medium spiny neuron depolarization

## mGluR-mediated endocannabinoid release requires L-type calcium channels

- DHPG (100 uM)

- EPSC (% baseline)

## mGluR-mediated endocannabinoid release is enhanced by subthreshold depolarization

- DHPG (100 uM)

- Time (min)

- EPSC (% baseline)

## Medium spiny neurons: up and down states

**Down state**: -60 to –90 mV
- calcium influx mediated by T- and R-type VSCCs
**Up state:** -40 to –70 mV,
- calcium influx mediated by L- and R-type VSCCs

- Wilson and Kawaguchi (1996), J Neurosci
- Carter and Sabatini (2004), Neuron

- Stern et al.(1998), Nature

## Imbalanced activity in striatal motor circuits in vivo in a Parkinson disease model

- Mallet et al (2006) **J Neurosci**

**(direct)**

**(indirect)**

- Imbalanced activity in striatal motor circuits *in vivo* in a Parkinson disease model