title: Dopamine D2-like receptor activation antagonizes long-term depression of orofacial sensorimotor processing in anesthetized mice.
abstract: Long-term depression (LTD) of orofacial sensorimotor processing recently has been demonstrated in anesthetized mice. Due to the remarkable role of dopamine in central nervous system LTD, the influence of dopamine D2 receptor activation on LTD of the jaw-opening reflex (JOR) was investigated. Electric low-frequency stimulation (LFS, 1 Hz) of the tongue suppressed the JOR integral by 43% for at least 1 h. After systemic administration of the dopamine D2-like receptor agonist quinpirole, LTD was significantly attenuated to 14%. JOR decreased for only about 15 min after LFS according to a short-term depression. Under systemic application of the dopamine D2-like receptor antagonist sulpiride, LTD significantly increased to 64%, again for at least 1 h. Thus, D2-like receptor activation prevented LTD, and D2-like receptor blockade amplified LTD of the reflex. The time course of inhibition may be due to a dopaminergic D2-like receptor mechanism that antagonizes the transfer from short-term into long-term depression. Considering a putative mediation of LTD by the endogenous pain control system, the results correspond to the known inhibitory control of this system by a D2-like receptor mechanism.
authors.affiliation: Department of Neurosurgery, Experimental Neurosurgery, University Hospital Aachen, Pauwelsstrasse 30, D-52074 Aachen, Germany. jellrich@ukaachen.de
authors.forename: Jens
authors.initials: J
authors.lastname: Ellrich
mesh_terms: D000704:Analysis of Variance; D000758:Anesthesia; D000818:Animals; D018491:Dopamine Agonists / Q000494:pharmacology; D018492:Dopamine Antagonists / Q000494:pharmacology; D007568:Jaw / Q000187:drug effects / Q000294:innervation* / Q000502:physiology; D036881:Long-Term Synaptic Depression / Q000187:drug effects / Q000502:physiology*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D011597:Psychomotor Performance / Q000187:drug effects / Q000502:physiology*; D019257:Quinpirole / Q000494:pharmacology; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D017448:Receptors, Dopamine D2 / Q000502:physiology*; D012018:Reflex / Q000187:drug effects / Q000502:physiology; D013469:Sulpiride / Q000494:pharmacology; D013997:Time Factors
chemical_list: D018491:Dopamine Agonists; D018492:Dopamine Antagonists; D017448:Receptors, Dopamine D2; D019257:Quinpirole; D013469:Sulpiride