The Journal of Neuroscience, March 17, 2004, 24(11):2787-2796; doi:10.1523/JNEUROSCI.4132-03.2004
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Behavioral/Systems/Cognitive
Neurochemical and Behavioral Alterations in Glucocorticoid Receptor-Impaired Transgenic Mice after Chronic Mild Stress
Nicolas Froger,1
Enza Palazzo,1
Claudette Boni,1
Naïma Hanoun,1
Françoise Saurini,1
Chantal Joubert,2
Isabelle Dutriez-Casteloot,3
Michaela Enache,3
Stefania Maccari,4
Nicholas Barden,5
Charles Cohen-Salmon,2
Michel Hamon,1 and
Laurence Lanfumey1
1 Institut National de la Santé et de la Recherche Médicale U288Neuropsychopharmacologie and 2 Unité Mixte de Recherche 7593Centre National de la Recherche ScientifiquePersonnalités et Conduites Adaptatives, Institut Fédératif de Recherche 70 des Neurosciences, Centre Hospitalier Universitaire Pitié-Salpêtrière, 75013 Paris, France, 3Neuroendocrinologie du Développement, UPRES-EA 2701, and 4Stress Périnatal, UPRES-JE 2395, Université de Lille 1, 59655 Villeneuve d'Ascq, France, and 5Laval University Hospital Research Centre and Department of Anatomy and Physiology, University Laval, Ste Foy, Quebec G1V 4G2, Canada
Mice (GR-i) bearing a transgene encoding a glucocorticoid receptor (GR) antisense RNA under the control of a neuron-specific neurofilament promoter were used to investigate the effects of a 4 week chronic mild stress (CMS) on the hypothalamopituitaryadrenocortical (HPA) axis and the serotoninergic system in a transgenic model of vulnerability to affective disorders. GR-i mice showed a decrease in both GR-specific binding (hippocampus and cerebral cortex) and GR mRNA levels [hippocampus, cerebral cortex, and dorsal raphe nucleus (DRN)] as well as a deficit in HPA axis feedback control (dexamethasone test) compared with paired wild-type (WT) mice. In the latter animals, CMS exposure caused a significant decrease in both GR mRNA levels and the density of cytosolic GR binding sites in the hippocampus, whereas, in the DRN, GR mRNA levels tended to increase. In contrast, in stressed GR-i mice, both GR mRNA levels and the density of GR binding sites were significantly increased in the hippocampus, cerebral cortex, and DRN. Electrophysiological recordings in brainstem slices and [
-35S]GTP-S binding measurements to assess 5-HT1A receptor functioning showed that CMS exposure produced a desensitization of DRN 5-HT1A autoreceptors in WT, but not in GR-i, mice. In addition, CMS was found to facilitate choice behavior of WT, but not GR-i, mice in a decision-making task derived from an alternation paradigm. These results demonstrate that impaired GR functioning affects normal adaptive responses of the HPA axis and 5-HT system to CMS and alters stress-related consequences on decision-making behaviors.
Key words: 5-HT1A receptors; glucocorticoid receptors; dorsal raphe nucleus; transgenic mice; chronic mild stress; major depressive disorders
Received Sep 8, 2003;
revised December 29, 2003;
accepted January 17, 2004.