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Merging the Pathophysiology and Pharmacotherapy of Tics Cover

Merging the Pathophysiology and Pharmacotherapy of Tics

Open Access
|Jan 2019

Figures & Tables

Table 1

Pharmacological Agents and their Representative Receptors in the Cortical-Basal Ganglia-Thalamo-Cortical Circuit

Pharmacological AgentDAGlutGABAHist5-HTAChOpioid ReceptorCBRs
Pimozide(D2)1
Haloperidol(D2)1
Fluphenazine(D1/D2)1
Ecopipan(D1)
Aripiprazole(D2/D3)3H3R35-HT1/23
Risperidone(D2)15-HT21
Olanzapine(D1-D4)1H1R15-HT21M2/31
Ziprasidone(D2)1-5-HT21
Quetiaprine(D2)1A11H1R15-HT1/21
Tetrabenazine, valbenazine, deutetrabenazine(VMAT2)
d-SerineNMDA2
RiluzoleNMDA1
BaclofenGABAB2
ClonazepamGABAB2
TopiramateGABAA2
LevetiracetamGABAA2/A22
ClonidineGABAA1/A22
AZ5213H3R1
r-Aminomethyl-histamine-H3R2
ImmepipH3R2
PhysostigminenAChR2
MecamylaminenAChR1
β-EndorphinsMu1/2 and Delta2
EnkephalinsMu1/2 and Delta2
Dynorphin AMu1/2 and Kappa2
Naloxone and naltrexoneMu, Delta, Kappa1
Nalbuphine, butorphanol, pentazocine, and nalorphineMu1 and Kappa2
Delta-9-tetrahydrocannabinol (THC)CB1/22
Cannabidiol (CBD)CB1/CB21

[i] Abbreviations: 5-HT, 5-Hydroxytryptamine; ACh, Acetylcholine; CBR, Cannabinoid Receptors; DA, dopamine; GABA, Gamma-Aminobutyric Acid; NMDA, N-methyl-D-Aspartate.

[ii] 1Antagonist.

[iii] 2Agonist.

[iv] 3Mix agonist/antagonist.

tre-08-595-g001.jpg
Figure 1

Cortical-Basal Ganglia-Thalamo-Cortical Circuit and their Interconnected Pathways. Abbreviations: CM-PF, Centromedial-parafascicular Nucleus; GPe, Globus Pallidus Externa; GPi, Globus Pallidus Interna; Hypo, Hypothalamus; Mthal, Motor Thalamus; NAc, Nucleus Accumbences; SMA, Supplemental Motor Area; SNT, Subthalamic Nucleus; SNpc, Sustantia nigra paras compacta; SNpr, Sustantia nigra paras reticulate; PN, Pontine Nucleus; PPTg, Peduculopontine Tegmental Nucleus; VTA, Ventral Tegmental Area.

tre-08-595-g002.jpg
Figure 2

Neurotransmitters within Cortical-Basal Ganglia-Thalamo-Cortical and Interconnecting Pathways. Abbreviations: ACh, Acetylcholine; CM-PF, Centromedial-parafascicular nucleus; Glu, Glutamate; GABA, Gamma (γ)-aminobutyric acid; GPe, Globus Pallidus Externa; GPi, Globus Pallidus Interna; Hypo, Hypothalamus; Mthal, Motor Thalamus; NAc, Nucleus Accumbences; SMA, Supplemental Motor Area; SNT, Subthalamic Nucleus; SNpc, Sustantia nigra paras compacta; SNpr, Sustantia nigra paras reticulate; PN, Pontine Nucleus; PPTg, Peduculopontine Tegmental Nucleus; VTA, Ventral Tegmental Area.

tre-08-595-g003.jpg
Figure 3

Diagram Showing the Interactions of Pharmacological Agents Used for Tic Suppression, and their Proposed Pre and Post-Synaptic Effects. α2-Agonists exert their effects on the pre and post synaptic α2-receptors while allosterically enhancing the affinity of GABA for the GABA-receptor complex (GABA-R). Post-synaptically, α2-Agonists enhance the synaptic impulses in recipient neurons by closing the hyperpolarization-activated cyclic nucleotide gated (HCN) channels and decreasing the cation ion efflux. Pre-synaptically, α2-Agonists inhibit excitatory glutamatergic transmission of the pyramidal cells in the prefrontal cortex. The effects of D1 and D2 receptor agonist/antagonist interactions have been recently reviewed.54 The mechanistic effects of D1-H3 and D2-H3 receptor heterodimers are inhibitory at the post-synaptic terminals. Dopamine has been shown to exert an inhibitory control over medium-sized spiny neurons (MSNs) when acting through D1-H3 heterodimers. This is in contrast to D1 receptor functionality in the direct pathway, where dopamine has an excitatory effect on D1 expressing MSNs. Cannabinoid receptor type 1 (CB1), on the glutamatergic and GABAergic corticostriatal projections is activated by 2-AG and AEA binding. These endocannabinoids are released by post synaptic membrane phospholipids. One intracellular effect of presynaptic CB1 activation on GABAergic interneurons is the increased production of mitochondrial H2O2. This H2O2 diffuses to adjacent axonal release sites, where it activates H2O2-sensitive KATP channels, leading to synaptic depression. Opioid receptors (mu, kappa, and delta) are activated by endogenous and exogenous opioid agonists. Although the exact mechanisms are unknown, however, the endogenous opioids are proposed to decrease the GABAergic tone within mesolimbic-mesocortical system by inhibiting voltage-sensitive Ca2+ channels, enhancing the outflow of K+ ions, and inhibiting the intracellular adenylate cyclase.

DOI: https://doi.org/10.5334/tohm.442 | Journal eISSN: 2160-8288
Language: English
Submitted on: Jul 30, 2018
Accepted on: Sep 28, 2018
Published on: Jan 9, 2019
Published by: Columbia University Libraries/Information Services
In partnership with: Paradigm Publishing Services
Publication frequency: 1 issue per year

© 2019 Farhan Augustine, Harvey S. Singer, published by Columbia University Libraries/Information Services
This work is licensed under the Creative Commons License.