title: Distribution of dopamine D(2)-like receptors in the rat amygdala and their role in the modulation of unconditioned fear and anxiety.
abstract: Amygdaloid dopamine D(2) receptors play an important role in the modulation of fear/anxiety. Their topographical distribution within the amygdala is however unclear, and their role in unconditioned fear/anxiety remains largely unknown. The aim of this paper was to study the intra-amygdaloid distribution of D(2) receptors and to ascertain their role in unconditioned anxiety. Chemical anatomical studies in the rat, using D(2) and D(3)in situ hybridization, quantitative receptor autoradiography with either [(3)H]raclopride or [(125)I]sulpiride, and D(2)-like immunocytochemistry showed that the highest density of dopamine D(2) receptors is present in the central amygdaloid nucleus, particularly within its latero-capsular division, in which a D(2) but not a D(3) mRNA signal was observed. However, although at considerably reduced densities dopamine D(2) receptors were also found in other locations within the amygdala, including the basolateral nucleus. Behaviorally, the infusion of raclopride (0.75-4 μg/side) in the area of the central amygdaloid nucleus resulted at low doses in the appearance of anxiogenic-like effects in the Shock-Probe Burying test, whereas no effects of raclopride treatment were found at any dose in the Elevated Plus-Maze and the Open-Field test. Our results indicate that amygdaloid dopamine D(2)-like receptors have a topographically differentiated distribution within the rat amygdala, the major location being in the central amygdaloid nucleus. D(2)-like receptors play a role in the modulation of anxiety responses involving a potential differential function of D(2)-like receptors in the central amygdaloid nucleus versus the basolateral amygdaloid nucleus.
authors.affiliation: Division of Neuroscience, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-253, Mexico City, Mexico. mperez@ifc.unam.mx
authors.forename: M
authors.initials: M
authors.lastname: Perez de la Mora
authors.forename: A
authors.initials: A
authors.lastname: Gallegos-Cari
authors.forename: M
authors.initials: M
authors.lastname: Crespo-Ramirez
authors.forename: D
authors.initials: D
authors.lastname: Marcellino
authors.forename: A C
authors.initials: AC
authors.lastname: Hansson
authors.forename: K
authors.initials: K
authors.lastname: Fuxe
mesh_terms: D000679:Amygdala / Q000187:drug effects / Q000378:metabolism*; D000704:Analysis of Variance; D000818:Animals; D001007:Anxiety / Q000378:metabolism / Q000473:pathology*; D001345:Autoradiography; D003213:Conditioning, Psychological / Q000502:physiology*; D018492:Dopamine Antagonists / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004597:Electroshock / Q000009:adverse effects; D005106:Exploratory Behavior / Q000187:drug effects; D005239:Fear; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D008297:Male; D018782:Maze Learning / Q000187:drug effects; D012333:RNA, Messenger / Q000378:metabolism; D020891:Raclopride / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D017448:Receptors, Dopamine D2 / Q000235:genetics / Q000378:metabolism*; D050637:Receptors, Dopamine D3 / Q000235:genetics / Q000378:metabolism
chemical_list: D018492:Dopamine Antagonists; D012333:RNA, Messenger; D017448:Receptors, Dopamine D2; D050637:Receptors, Dopamine D3; D020891:Raclopride