title: Inhibition of Phosphodiesterase 10A Increases the Responsiveness of Striatal Projection Neurons to Cortical Stimulation.
abstract: The cyclic nucleotide phosphodiesterase 10A (PDE10A) is highly expressed in striatal medium-sized spiny projection neurons (MSNs), apparently playing a critical role in the regulation of both cGMP and cAMP signaling cascades. Genetic disruption or pharmacological inhibition of PDE10A reverses behavioral abnormalities associated with subcortical hyperdopaminergia. Here, we investigate the effect of PDE10A inhibition on the activity of MSNs using single-unit extracellular recordings performed in the dorsal striatum of anesthetized rats. Antidromic stimulation of the substantia nigra pars reticulata was used to identify striatonigral (SNr+) MSNs. Intrastriatal infusion of the selective PDE10A inhibitors papaverine or TP-10 [2-{4-[-pyridin-4-yl-1-(2,2,2-trifluoroethyl)-1H-pyrazol-3-yl]-phenoxymethyl}-quinoline succinic acid] by reverse microdialysis did not affect spontaneous firing but robustly increased measures of cortically evoked spike activity in a stimulus intensity-dependent manner. Systemic administration of TP-10 also increased cortically evoked spike activity in a stimulus intensity- and dose-dependent manner. A robust increase in cortically evoked activity was apparent in SNr- MSNs (primarily striatopallidal). It is interesting that TP-10 administration did not affect cortically evoked activity in SNr+ MSNs. However, TP-10 administration increased the incidence of antidromically activated (i.e., SNr+) MSNs. These findings indicate that inhibition of striatal PDE10A activity increases the responsiveness of MSNs to depolarizing stimuli. Furthermore, given the lack of effect of TP-10 on SNr+ MSNs, we speculate that PDE10A inhibition may have a greater facilitatory effect on corticostriatal synaptic activity in striatopallidal MSNs. These data support further investigation of selective targeting of PDE signaling pathways in MSN subpopulations because this may represent a promising novel approach for treating brain disorders involving dysfunctional glutamatergic and dopaminergic neurotransmission.
authors.affiliation: Department of Neuro-science, Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL 60064. Anthony.west@rosalindfranklin.edu.
authors.forename: Sarah
authors.initials: S
authors.lastname: Threlfell
authors.forename: Stephen
authors.initials: S
authors.lastname: Sammut
authors.forename: Frank S
authors.initials: FS
authors.lastname: Menniti
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Schmidt
authors.forename: Anthony R
authors.initials: AR
authors.lastname: West
mesh_terms: D000818:Animals; D003342:Corpus Striatum / Q000187:drug effects / Q000502:physiology*; D004558:Electric Stimulation; D004594:Electrophysiology / Q000379:methods; D005071:Evoked Potentials / Q000187:drug effects / Q000502:physiology; D005625:Frontal Lobe / Q000187:drug effects / Q000502:physiology; D005917:Globus Pallidus / Q000187:drug effects / Q000502:physiology; D008297:Male; D017551:Microdialysis; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D010208:Papaverine / Q000494:pharmacology; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology*; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism*; D017966:Pyramidal Cells / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013378:Substantia Nigra / Q000187:drug effects / Q000502:physiology
chemical_list: D010726:Phosphodiesterase Inhibitors; D010208:Papaverine; C512064:PDE10A protein, rat; D010727:Phosphoric Diester Hydrolases