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Properties of distinct ventral tegmental area synapses activated via pedunculopontine or ventral tegmental area stimulation in vitro.
J Physiol. 2009 Mar 15; 587(Pt 6):1233-47.JP

Abstract

Anatomical studies indicate that synaptic inputs from many cortical and subcortical structures converge on neurons of the ventral tegmental area (VTA). Although in vitro electrophysiological studies have examined synaptic inputs to dopamine (DA) and non-DA neurons in the VTA, they have largely relied upon local electrical stimulation to activate these synapses. This provides little information regarding the distinct properties of synapses originating from different brain areas. Using whole-cell recordings in parasagittal rat brain slices that preserved subcortical axons from the pedunculopontine nucleus (PPN) to the VTA, we compared these synapses with those activated by intra-VTA stimulation. PPN-evoked currents demonstrated longer latencies than intra-VTA-evoked currents, and both VTA and PPN responses were mediated by GABA(A) and AMPA receptors. However, unlike VTA-evoked currents, PPN currents were exclusively mediated by glutamate in 25-40% of the VTA neurons. Consistent with a cholinergic projection from the PPN to the VTA, nicotinic acetylcholine receptors (nAChR) were activated by endogenous acetylcholine released during PPN, but not VTA, stimulation. This was seen as a reduction of PPN-evoked, and not VTA-evoked, synaptic currents by the alpha7-nAChR antagonist methyllycaconitine (MLA) and the agonist nicotine. The beta2-nAChR subunit antagonist dihydro-beta-erythroidine had no effect on VTA- or PPN-evoked synaptic currents. The effects of MLA on PPN-evoked currents were unchanged by the GABA(A) receptor blocker picrotoxin, indicating that alpha7-nAChRs presynaptically modulated glutamate and not GABA release. These differences in physiological and pharmacological properties demonstrate that ascending PPN and presumed descending inputs to VTA utilize distinct mechanisms to differentially modulate neuronal activity and encode cortical and subcortical information.

Authors+Show Affiliations

Electrophysiology Research Section, Cellular Neurobiology Branch, National Institute on Drug Abuse Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA.No affiliation info available

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural
Research Support, N.I.H., Intramural
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

19188251

Citation

Good, Cameron H., and Carl R. Lupica. "Properties of Distinct Ventral Tegmental Area Synapses Activated Via Pedunculopontine or Ventral Tegmental Area Stimulation in Vitro." The Journal of Physiology, vol. 587, no. Pt 6, 2009, pp. 1233-47.
Good CH, Lupica CR. Properties of distinct ventral tegmental area synapses activated via pedunculopontine or ventral tegmental area stimulation in vitro. J Physiol (Lond). 2009;587(Pt 6):1233-47.
Good, C. H., & Lupica, C. R. (2009). Properties of distinct ventral tegmental area synapses activated via pedunculopontine or ventral tegmental area stimulation in vitro. The Journal of Physiology, 587(Pt 6), 1233-47. https://doi.org/10.1113/jphysiol.2008.164194
Good CH, Lupica CR. Properties of Distinct Ventral Tegmental Area Synapses Activated Via Pedunculopontine or Ventral Tegmental Area Stimulation in Vitro. J Physiol (Lond). 2009 Mar 15;587(Pt 6):1233-47. PubMed PMID: 19188251.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Properties of distinct ventral tegmental area synapses activated via pedunculopontine or ventral tegmental area stimulation in vitro. AU - Good,Cameron H, AU - Lupica,Carl R, Y1 - 2009/02/02/ PY - 2009/2/4/entrez PY - 2009/2/4/pubmed PY - 2009/5/12/medline SP - 1233 EP - 47 JF - The Journal of physiology JO - J. Physiol. (Lond.) VL - 587 IS - Pt 6 N2 - Anatomical studies indicate that synaptic inputs from many cortical and subcortical structures converge on neurons of the ventral tegmental area (VTA). Although in vitro electrophysiological studies have examined synaptic inputs to dopamine (DA) and non-DA neurons in the VTA, they have largely relied upon local electrical stimulation to activate these synapses. This provides little information regarding the distinct properties of synapses originating from different brain areas. Using whole-cell recordings in parasagittal rat brain slices that preserved subcortical axons from the pedunculopontine nucleus (PPN) to the VTA, we compared these synapses with those activated by intra-VTA stimulation. PPN-evoked currents demonstrated longer latencies than intra-VTA-evoked currents, and both VTA and PPN responses were mediated by GABA(A) and AMPA receptors. However, unlike VTA-evoked currents, PPN currents were exclusively mediated by glutamate in 25-40% of the VTA neurons. Consistent with a cholinergic projection from the PPN to the VTA, nicotinic acetylcholine receptors (nAChR) were activated by endogenous acetylcholine released during PPN, but not VTA, stimulation. This was seen as a reduction of PPN-evoked, and not VTA-evoked, synaptic currents by the alpha7-nAChR antagonist methyllycaconitine (MLA) and the agonist nicotine. The beta2-nAChR subunit antagonist dihydro-beta-erythroidine had no effect on VTA- or PPN-evoked synaptic currents. The effects of MLA on PPN-evoked currents were unchanged by the GABA(A) receptor blocker picrotoxin, indicating that alpha7-nAChRs presynaptically modulated glutamate and not GABA release. These differences in physiological and pharmacological properties demonstrate that ascending PPN and presumed descending inputs to VTA utilize distinct mechanisms to differentially modulate neuronal activity and encode cortical and subcortical information. SN - 1469-7793 UR - https://www.unboundmedicine.com/medline/citation/19188251/Properties_of_distinct_ventral_tegmental_area_synapses_activated_via_pedunculopontine_or_ventral_tegmental_area_stimulation_in_vitro_ L2 - https://doi.org/10.1113/jphysiol.2008.164194 DB - PRIME DP - Unbound Medicine ER -