title: Cholinergic regulation of the posterior medial thalamic nucleus.
abstract: We previously showed that the GABAergic nucleus zona incerta (ZI) suppresses vibrissae-evoked responses in the posterior medial (POm) thalamus of the rodent somatosensory system. We proposed that this inhibitory incertothalamic pathway regulates POm responses during different behavioral states. Here we tested the hypothesis that this pathway is modulated by the ascending brain stem cholinergic system, which regulates sleep-wake cycles and states of vigilance. We demonstrate that cholinergic inputs facilitate POm responses to vibrissae stimulation. Activation of the cholinergic system by stimulation of brain stem cholinergic nuclei (laterodorsal tegmental and the pedunculopontine tegmental) or by tail pinch significantly increased the magnitude of POm responses to vibrissae stimulation. Microiontophoresis of the muscarinic receptor agonist carbachol enhanced POm responses to vibrissae stimulation. Application of carbachol to an in vitro slice preparation reduced the frequency but not the amplitude of miniature inhibitory postsynaptic currents, indicating a presynaptic site of action for carbachol. We conclude that the cholinergic system facilitates POm responses by suppressing GABAergic inputs from ZI. We propose the state-dependent gating hypothesis, which asserts that differing behavioral states, regulated by the brain stem cholinergic system, modulate the flow of information through POm.
authors.affiliation: Department of Anatomy and Neurobiology, University of Maryland School of Medicine, 20 Penn Street, Baltimore, MD 21201, USA.
authors.forename: Radi
authors.initials: R
authors.lastname: Masri
authors.forename: Jason C
authors.initials: JC
authors.lastname: Trageser
authors.forename: Tatiana
authors.initials: T
authors.lastname: Bezdudnaya
authors.forename: Ying
authors.initials: Y
authors.lastname: Li
authors.forename: Asaf
authors.initials: A
authors.lastname: Keller
mesh_terms: D000759:Adjuvants, Anesthesia; D000758:Anesthesia; D000818:Animals; D002217:Carbachol / Q000008:administration & dosage / Q000494:pharmacology; D003627:Data Interpretation, Statistical; D004558:Electric Stimulation; D005110:Extracellular Space / Q000502:physiology; D005260:Female; D005283:Fentanyl; D006221:Halothane; D007478:Iontophoresis; D018721:Muscarinic Agonists / Q000008:administration & dosage / Q000494:pharmacology; D010275:Parasympathetic Nervous System / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017661:Receptors, Presynaptic / Q000187:drug effects / Q000378:metabolism; D013681:Tegmentum Mesencephali / Q000502:physiology; D014520:Urethane; D020651:Ventral Thalamic Nuclei / Q000502:physiology*; D014738:Vibrissae / Q000294:innervation / Q000502:physiology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
chemical_list: D000759:Adjuvants, Anesthesia; D018721:Muscarinic Agonists; D017661:Receptors, Presynaptic; D014520:Urethane; D005680:gamma-Aminobutyric Acid; D002217:Carbachol; D005283:Fentanyl; D006221:Halothane