Emotional stress induces structural plasticity in Bergmann glial cells via an AC5–CPEB3–GluA1 pathway

Stress alters brain function by modifying the structure and function of neurons and astrocytes. The fine processes of astrocytes are critical for the clearance of neurotransmitters during synaptic transmission. Thus, experience-dependent remodeling of glial processes is anticipated to alter the output of neural circuits. However, the molecular mechanisms that underlie glial structural plasticity are not known. Here we show that a single exposure of male and female mice to an acute stress produced a long-lasting retraction of the lateral processes of cerebellar Bergmann glial cells. These cells express the GluA1 subunit of AMPA-type glutamate receptors, and GluA1 knockdown is known to shorten the length of glial processes. We found that stress reduced the level of GluA1 protein and AMPA receptor-mediated currents in Bergmann glial cells, and these effects were absent in mice devoid of CPEB3, a protein that binds to GluA1 mRNA and regulates GluA1 protein synthesis. Administration of a b-adrenergic receptor blocker attenuated the reduction in GluA1, and deletion of adenylate cyclase 5 prevented GluA1 suppression. Therefore, stress suppresses GluA1 protein synthesis via an adrenergic/adenylyl cyclase/CPEB3 pathway, and reduces the length of astrocyte lateral processes. Our results identify a novel mechanism for GluA1 subunit plasticity in non-neuronal cells and suggest a previously unappreciated role for AMPA receptors in stress-induced astrocytic remodeling.Fil: Bender, Crhistian Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Farmacología Experimental de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Farmacología Experimental de Córdoba; Argentina. State University of Louisiana; Estados UnidosFil: Sun, Xingxing. Huazhong University of Science & Technology; República de China. State University of Louisiana; Estados UnidosFil: Farooq, Muhammad. State University of Louisiana; Estados UnidosFil: Yang, Qian. State University of Louisiana; Estados UnidosFil: Davison, Caroline. State University of Louisiana; Estados UnidosFil: Maroteaux, Matthieu. State University of Louisiana; Estados UnidosFil: Huang, Yi Shuian. State University of Louisiana; Estados UnidosFil: Ishikawa, Yoshihiro. State University of Louisiana; Estados Unidos. Yokohama City University. Graduate School of Medicine; JapónFil: Liu, Siqiong June. State University of Louisiana; Estados Unido

A phosphatase cascade by which rewarding stimuli control nucleosomal response

ArticleInternational audienceDopamine orchestrates motor behaviour and reward-driven learning. Perturbations of dopamine signalling have been implicated in several neurological and psychiatric disorders, and in drug addiction. The actions of dopamine are mediated in part by the regulation of gene expression in the striatum, through mechanisms that are not fully understood. Here we show that drugs of abuse, as well as food reinforcement learning, promote the nuclear accumulation of 32-kDa dopamine-regulated and cyclic-AMP-regulated phosphoprotein (DARPP-32). This accumulation is mediated through a signalling cascade involving dopamine D1 receptors, cAMP-dependent activation of protein phosphatase-2A, dephosphorylation of DARPP-32 at Ser 97 and inhibition of its nuclear export. The nuclear accumulation of DARPP-32, a potent inhibitor of protein phosphatase-1, increases the phosphorylation of histone H3, an important component of nucleosomal response. Mutation of Ser 97 profoundly alters behavioural effects of drugs of abuse and decreases motivation for food, underlining the functional importance of this signalling cascad

Implication du facteur de transcription Zif268 dans les apprentissages guidés par la récompense

Les drogues détournent les circuits neuronaux de la récompense et y provoquent des altérations responsables des comportements d addiction. Ces circuits impliquent les ganglions de la base (GB), qui s organisent en boucles fonctionnelles formées par les voies directe et indirecte qui contrôlent l activité de ses structures de sortie. Le point d entrée des GB est le striatum (STR) qui recoit des afférences glutamatergiques du cortex, et des projections des neurones dopaminergiques. Une activation des récepteurs NMDA et D1 de la dopamine (D1R), déclenche la cascade de signalisation des ERK1/2 dans les neurones striataux de la voie directe et recrute ses cibles, dont le facteur de transcription Zif268 et active la DARPP-32. Tous deux ont des rôles cruciaux dans les effets des drogues. Nous avons cherché à comprendre les rôles de la DARPP-32 et de Zif268 dans les mécanismes d apprentissage par la nourriture. Nous avons pour cela caractérisé l expression de Zif268 après des séances d apprentissage opérant pour de la nourriture dans les deux voies des GB grâce à des souris exprimant la GFP sous la dépendance du promoteur du D1R. Nous avons ensuite mis en évidence une motivation réduite pour ce comportement opérant chez des souris portant une DARPP-32 mutée, ainsi que chez des souris où Zif268 a été invalidé. De plus nous montrons que la surexpression de Zif268 dans le STR dorso-médian est corrélée avec la réponse opérante au début de l apprentissage opérant. Nous montrons que la DARPP-32 et Zif268 sont des acteurs majeurs dans le système de la récompense. A l avenir leur étude permettra de mieux comprendre la mise en place de comportements tels que l addiction ou l obésité.PARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

Role of the Plasticity-Associated Transcription Factor Zif268 in the Early Phase of Instrumental Learning

<div><p>Gene transcription is essential for learning, but the precise role of transcription factors that control expression of many other genes in specific learning paradigms is yet poorly understood. Zif268 (Krox24/Egr-1) is a transcription factor and an immediate-early gene associated with memory consolidation and reconsolidation, and induced in the striatum after addictive drugs exposure. In contrast, very little is known about its physiological role at early stages of operant learning. We investigated the role of Zif268 in operant conditioning for food. Zif268 expression was increased in all regions of the dorsal striatum and nucleus accumbens in mice subjected to the first session of operant conditioning. In contrast, Zif268 increase in the dorsomedial caudate-putamen and nucleus accumbens core was not detected in yoked mice passively receiving the food reward. This indicates that Zif268 induction in these structures is linked to experiencing or learning contingency, but not to reward delivery. When the task was learned (5 sessions), Zif268 induction disappeared in the nucleus accumbens and decreased in the medial caudate-putamen, whereas it remained high in the lateral caudate-putamen, previously implicated in habit formation. In transgenic mice expressing green fluorescent protein (GFP) in the striatonigral neurons, Zif268 induction occured after the first training session in both GFP-positive and negative neurons indicating an enhanced Zif268 expression in both striatonigral and striatopallidal neurons. Mutant mice lacking Zif268 expression obtained less rewards, but displayed a normal discrimination between reinforced and non-reinforced targets, and an unaltered approach to food delivery box. In addition, their motivation to obtain food rewards, evaluated in a progressive ratio schedule, was blunted. In conclusion, Zif268 participates in the processes underlying performance and motivation to execute food-conditioned instrumental task.</p></div

Operant behavior in Zif268 mutant mice under FR1, FR5 and FR10 schedules.

<p>Experiments were carried out in homozygous (<b>KO</b>) and heterozygous (<b>Het</b>) Zif268 mutant mice and their wild type (<b>WT</b>) littermates. a) Number of nose-pokes in the reinforced target across daily sessions with FR1, FR5 and FR10 schedule training. Homozygous mutant mice perform less nose-poking under FR1 and FR5 schedules than wild type but perform similarly under FR10. b) Pellets obtained across daily sessions with FR1, FR5 and FR10 schedule training. Zif268 mutation significantly reduced the number of rewards earned in the three blocks of training sessions. Weight (c) and daily food intake (d) of groups of KO, Het and WT mice. e) The amount of rewards obtained by the KO, Het and WT mice in 1-h session is evaluated by normalizing the number of gained pellets by the daily food intake in the three genotypes. Using this parameter, Zif268 mutation significantly alters the mouse performance in the three blocks of training sessions. f) The number of visits to the empty food cup is similar in the various genotypes. g) The ratio of reinforced and total nose-pokes is not significantly different in KO, Het and WT mice in the various training sessions. In a), b), e), f) and g), the values are means ± SEM (KO, n = 11; Het, n = 16; WT, n = 18) and the data are analyzed using repeated-measures two-way ANOVA (within-subjects factor of Session and between-subjects factor of Genotype; see the various F values in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0081868#s3" target="_blank">Results</a>). Post hoc comparison (Bonferroni test): * p<0.05; ** p<0.01; *** p<0.001, homozygous vs. wild type. In a), b) and e), overall two-way ANOVA results for Genotype factor are indicated by: ° p<0.05; °° p<0.01, °°° p<0.001. In c) and d) the values are means ± SEM (KO, n = 7; Het, n = 7; WT, n = 10) and the data are analyzed using one-way ANOVA (see the various F values in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0081868#s3" target="_blank">Results</a>). Post hoc comparison (Bonferroni test): * p<0.05; *** p<0.001.</p

Mouse behavior during the first session of operant training.

<p>Behavioral parameters were measured in animals trained in 1-h session on FR1 schedule (<b>Active</b>, n = 84) and in yoked animals (<b>Yoked</b>, n = 46) receiving as many food rewards as Active animals but non-contingently. a) Cumulative number of pellets obtained by the Active group across the 1-h session. Dashed line corresponds to the curve slope at the beginning of session (between 5 and 10 min). b) Comparison of number of nose-pokes in the light-cued aperture in Active and Yoked mice during the last 15 min of 1-h session. In the Active group only, the nose-pokes into the light-cued hole provided food pellets. c) Ratio of nose-pokes in the light-cued hole and total nose-pokes in Active and Yoked mice during the last 15 min of 1-h session. d) Comparison of number of nose-pokes in the aperture not indicated by light in Active and Yoked mice during the last 15 min of the session. In both the Active and Yoked groups, poking in this orifice did not provide any reward. e) Comparison of number of visits to the empty food cup in Active and Yoked mice during the last 15 min of the session. Data (means ± SEM) were analyzed using Student's t test (see the t values in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0081868#s3" target="_blank">Results</a>). ** p<0.01; *** p<0.001.</p

Zif268 is induced in D1 and D2 receptor-expressing MSNs after a single instrumental learning session in <i>Drd1a</i>::GFP transgenic mice.

<p>Colocalisation of Zif268 (red) and DARPP-32 (green) immunolabelling in the same MSNs in the dorsomedial caudate-putamen (CPu)(a) and nucleus accumbens core (b) after a single FR1 training session (Active mice). Arrowheads indicate co-expression of Zif268 and DARPP-32 in the same neurons. Scale bar: 40 µm. Confocal images of Zif268 (c) and c-Fos (e) immunolabelling (red) and D1 receptor promoter driven GFP fluorescence (green) in the dorsomedial caudate-putamen (DM-CPu) of Active and Yoked mice. Arrowheads indicate colocalization of immunolabelling and GFP expression; Arrows indicate absence of colocalization of immunolabelling and GFP expression. Scale bar: 40 µm. Number of Zif268 (b) and c-Fos (d) immunolabeled cells in GFP-positive (Drd1a +) and GFP-negative (Drd1a −) neurons in the DM-CPu and core of nucleus accumbens (NAc) of Active (n = 6) and Yoked (n = 6) mice. All the values are means ± SEM and the data are analyzed using factorial ANOVA (Group x Brain Structure x GFP Expression, see the various F values in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0081868#s3" target="_blank">Results</a>). Post hoc comparison (Bonferroni test): ** p<0.01; *** p<0.001 Active vs. Yoked.</p

Zif268 protein expression after operant training.

<p>Zif268-positive cells were stained by immunocytochemistry after the 1^st or 5^th session of operant conditioning (FR1) in various areas of the striatum at the 0.98 mm antero-posterior coordinate <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0081868#pone.0081868-Paxinos2" target="_blank">[62]</a>. a) Representative immunolabelling in the dorsolateral caudate-putamen (CPu) after the 1^st training session (<b>Active</b>) and in a control animal (<b>Control</b>). Scale bar: 50 µm. b) Positive cells were counted in the regions (375×375 µm) indicated with squares and the letters refer to the panels in which the results are shown. Schematic representation of the projection areas of the prefrontal cortex and sensorimotor cortices in the striatum (adapted from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0081868#pone.0081868-Voorn1" target="_blank">[30]</a>). Quantification in the dorsolateral (c), dorsomedial (d), ventrolateral (e), ventromedial (f) CPu as well as in the core (g) and shell (h) of the nucleus accumbens (NAc), was performed by counting cells above a fixed threshold. Data were means ± SEM of 4 mice per group and analyzed using two-way ANOVA (Group x Session, see the F values in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0081868#s3" target="_blank">Results</a>). Post-hoc comparison (Bonferroni test) of Active vs. Control: * p<0.05; ** p<0.01; *** p<0.001. Post hoc comparisons of Day1 vs. Day5: ° p<0.05, °° p<0.01; °°° p<0.001. ACd, anterior cingulate dorsal, AI, agranular insular, IL, infralimbic, PL, prelimbic, SMC, sensorimotor cortex.</p

Operant behavior in Zif268 mutant mice under progressive ratio schedule.

<p>Groups of homozygous (<b>KO</b>, n = 11) and heterozygous (<b>Het</b>, n = 16) Zif268 mutant mice and their wild type (<b>WT</b>, n = 18) littermates were trained under progressive ratio (or PR) schedule. a) Breaking point measured during 2-h session under progressive ratio schedule. Both homozygous and heterozygous mutant mice show reduced breaking points when compared to wild type controls. The results (means ± SEM) are analyzed using one-way ANOVA (see the F value in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0081868#s3" target="_blank">Results</a>). Post hoc comparison (Bonferroni test): * p<0.05. b) Cumulative number of nose-pokes into the reinforced orifice during progressive ratio schedule session (2 h). Both homozygous and heterozygous mutant mice show a reduced activity on the reinforced hole as compared to wild type controls. At 2 h, data were analyzed with one-way ANOVA (see the F value in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0081868#s3" target="_blank">Results</a>).</p