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S.04.02 5HT-transporter dependent effects of MDMA (“ecstasy”) on the 5HT-system and hippocampal cell proliferation in mice
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S.04 Hot Topics 1
S.04 Hot Topics 1 S.04.01 Amygdala PKCe regulates corticotropin releasing factor, anxiety-like behavior and alcohol consumption H.M.B. Lesscher1 ° , J.K. Deitchman2 , J. Connolly2 , T. McMahon2 , R.O. Messing2 . 1 Rudolf Magnus Institute of Neuroscience, Department of Pharmacology and Anatomy, University Medical Center Utrecht, The Netherlands; 2 Ernest Gallo Clinic and Research Center, Neurology at UCSF, Emeryville, USA PKCe (-/-) mice show reduced alcohol self-administration and reduced anxiety-like behavior (Hodge et al., 1999, 2002). Neuropeptides in the amygdala, particularly corticotrophin releasing factor (CRF), have been implicated in anxiety, including withdrawalinduced anxiety, and in alcohol consumption. The goal of this study was to determine the role of PKCe in the amygdala in these behaviors. Amygdala CRF protein levels and mRNA abundance were reduced by 50% in PKCe (-/-) mice while CRF receptor binding was not different between genotypes. Using cultured amygdala neurons we further show that PKCe activation results in increased pro-CRF levels. After PKCe knockdown by lentiviral expression of short hairpin RNAs against PKCe, PKCe activators no longer increased pro-CRF in cultured amygdala neurons. Microinjection of 100 ng CRF into the amygdala increased anxietylike behavior of PKCe (-/-) mice to wild-type levels. We next used the lentiviral vectors for expression of shRNA against PKCe in the amygdala, which resulted in a 60% decrease in PKCe in the amygdala. Bilateral knockdown of PKCe in the amygdala decreased anxiety-like behavior in wild type mice. Finally, to explore the role of amygdala PKCe in alcohol consumption we used a limited access alcohol consumption paradigm: a two-bottle choice task with access to water and 15% alcohol in daily 2-h sessions. Local knockdown of PKCe in the amygdala reduced alcohol consumption in this paradigm, particularly after multiple daily drinking sessions. The results suggest that amygdala PKCe regulates CRF expression in the amygdala and controls anxiety and alcohol consumption in mice. References [1] Hodge CW, Mehmert KK, Kelley SP, McMahon T, Haywood A, Olive MF, Wang D, Sanchez-Perez AM, Messing RO, 1999, Supersensitivity to allosteric GABA(A) receptor modulators and alcohol in mice lacking PKCe. Nat Neurosci 2(11), 997–1002. [2] Hodge CW, Raber J, McMahon T, Walter H, Sanchez-Perez AM, Olive MF, Mehmert K, Morrow AL, Messing RO, 2002, Decreased anxiety-like behavior, reduced stress hormones, and neurosteroid supersensitivity in mice lacking protein kinase Cepsilon. J Clin Invest 110(7), 1003–1010.
S.04.02 5HT-transporter dependent effects of MDMA (“ecstasy”) on the 5HT-system and hippocampal cell proliferation in mice T. Renoir ° , F. Saurini, N. Hanoun, M. Hamon, L. Lanfumey. Facult´e de M´edecine Pierre et Marie Curie, INSERM UMR677, Paris Cedex 13, France Although numerous studies have focused on the mechanisms underlying 3,4-methylenedioxymethamphetamine (MDMA, “ecstasy”)-induced neurotoxicity, little is known about its long
term effects on 5-HT neurotransmission. The purpose of the present study was to investigate the immediate and delayed effects of MDMA on the 5-HT system and to evaluate the consequences of the inactivation of the 5-HT transporter (5-HTT) gene on these effects in mice. Acute in vitro application of MDMA on dorsal raphe nucleus (DRN) slices induced concentration-dependent 5-HT release and 5-HT cell firing inhibition. Both effects were absent in 5-HTT knock-out mice. No changes in the properties of 5-HT1A autoreceptors were found 7 days after repeated MDMA administration. Conversely, a 2-fold increase in the potency of the 5-HT1A receptor agonist ipsapirone to inhibit the discharge of DRN serotoninergic neurons and a larger hypothermic response to 8-OH-DPAT were observed in MDMA- compared to saline-treated mice on the 28th day posttreatment. In addition, this adaptive change resulted in a reduction of [5-HT] content. Finally, a reduction of cell proliferation was observed in the hippocampus of MDMA-treated mice. All these effects were abolished in 5-HTT knock-out mice. These data indicated that repeated MDMA administration in mice induced a long term reduction of [5-HT] content, an increased 5-HT1A autoreceptor function in the DRN, and a deficit in hippocampal cell proliferation. These 5-HTT-dependent effects, opposite to those of antidepressants [1,2], might contribute to MDMA-induced mood disorders. References [1] Le Poul E, Boni C, Hanoun N, Laporte AM, Laaris N, Chauveau J, Hamon M, Lanfumey L, 2000, Differential adaptation of brain 5-HT1A and 5-HT1B receptors and 5-HT transporter in rats treated chronically with fluoxetine. Neuropharmacology 39, 110–122. [2] Malberg JE, Eisch AJ, Nestler EJ, Duman RS, 2000, Chronic antidepressant treatment increases neurogenesis in adult rat hippocampus. J Neurosci 20, 9104–9110.
S.04.03 Neuron and forebrain specific deletion of the glycine transporter 1 gene enhances spontaneous object recognition memory P. Singer1 ° , D. Boison2 , H. M¨ohler3 , J. Feldon1 , B.K. Yee4 . 1 Swiss Federal Institute of Technology, Behavioral Neurobiology, Schwerzenbach, Switzerland; 2 R.S. Dow Neurobiology Laboratories, Legacy Research, Portland, USA; 3 Institute of Pharmacology and Toxicology, University of Zurich, Z¨urich, Switzerland; 4 Swiss Federal Institute ofTechnology, Behavioral Neurobiology, Schwerzenbach, Switzerland Forebrain and neuron specific deletion of the glycine transporter 1 (GlyT1) gene translates into diminished GlyT1-mediated glycine re-uptake and augments NMDA-receptor activity, presumably due to an increased availability of synaptic glycine. This is associated with enhanced associative learning in multiple paradigms (Yee et al., 2006). Here, we investigated the mutation’s potential promnesic effects on object recognition memory. First, mutant and littermate control mice were familiarized with two identical copies of a sample object for 10min. Second, following different delays (2min, 2h or 24h), the animals were exposed to a novel object and a third copy of a (now familiarized) sample object for 5min. Object recognition memory was indexed by the animals’ explorative preference towards the novel over the familiarized object. Both mutants and controls exhibited a positive preference towards the novel object at 2min delay. At 2h and 24h delays, the
S.04 Hot Topics 1
S.04 Hot Topics 1 S.04.01 Amygdala PKCe regulates corticotropin releasing factor, anxiety-like behavior and alcohol consumption H.M.B. Lesscher1 ° , J.K. Deitchman2 , J. Connolly2 , T. McMahon2 , R.O. Messing2 . 1 Rudolf Magnus Institute of Neuroscience, Department of Pharmacology and Anatomy, University Medical Center Utrecht, The Netherlands; 2 Ernest Gallo Clinic and Research Center, Neurology at UCSF, Emeryville, USA PKCe (-/-) mice show reduced alcohol self-administration and reduced anxiety-like behavior (Hodge et al., 1999, 2002). Neuropeptides in the amygdala, particularly corticotrophin releasing factor (CRF), have been implicated in anxiety, including withdrawalinduced anxiety, and in alcohol consumption. The goal of this study was to determine the role of PKCe in the amygdala in these behaviors. Amygdala CRF protein levels and mRNA abundance were reduced by 50% in PKCe (-/-) mice while CRF receptor binding was not different between genotypes. Using cultured amygdala neurons we further show that PKCe activation results in increased pro-CRF levels. After PKCe knockdown by lentiviral expression of short hairpin RNAs against PKCe, PKCe activators no longer increased pro-CRF in cultured amygdala neurons. Microinjection of 100 ng CRF into the amygdala increased anxietylike behavior of PKCe (-/-) mice to wild-type levels. We next used the lentiviral vectors for expression of shRNA against PKCe in the amygdala, which resulted in a 60% decrease in PKCe in the amygdala. Bilateral knockdown of PKCe in the amygdala decreased anxiety-like behavior in wild type mice. Finally, to explore the role of amygdala PKCe in alcohol consumption we used a limited access alcohol consumption paradigm: a two-bottle choice task with access to water and 15% alcohol in daily 2-h sessions. Local knockdown of PKCe in the amygdala reduced alcohol consumption in this paradigm, particularly after multiple daily drinking sessions. The results suggest that amygdala PKCe regulates CRF expression in the amygdala and controls anxiety and alcohol consumption in mice. References [1] Hodge CW, Mehmert KK, Kelley SP, McMahon T, Haywood A, Olive MF, Wang D, Sanchez-Perez AM, Messing RO, 1999, Supersensitivity to allosteric GABA(A) receptor modulators and alcohol in mice lacking PKCe. Nat Neurosci 2(11), 997–1002. [2] Hodge CW, Raber J, McMahon T, Walter H, Sanchez-Perez AM, Olive MF, Mehmert K, Morrow AL, Messing RO, 2002, Decreased anxiety-like behavior, reduced stress hormones, and neurosteroid supersensitivity in mice lacking protein kinase Cepsilon. J Clin Invest 110(7), 1003–1010.
S.04.02 5HT-transporter dependent effects of MDMA (“ecstasy”) on the 5HT-system and hippocampal cell proliferation in mice T. Renoir ° , F. Saurini, N. Hanoun, M. Hamon, L. Lanfumey. Facult´e de M´edecine Pierre et Marie Curie, INSERM UMR677, Paris Cedex 13, France Although numerous studies have focused on the mechanisms underlying 3,4-methylenedioxymethamphetamine (MDMA, “ecstasy”)-induced neurotoxicity, little is known about its long
term effects on 5-HT neurotransmission. The purpose of the present study was to investigate the immediate and delayed effects of MDMA on the 5-HT system and to evaluate the consequences of the inactivation of the 5-HT transporter (5-HTT) gene on these effects in mice. Acute in vitro application of MDMA on dorsal raphe nucleus (DRN) slices induced concentration-dependent 5-HT release and 5-HT cell firing inhibition. Both effects were absent in 5-HTT knock-out mice. No changes in the properties of 5-HT1A autoreceptors were found 7 days after repeated MDMA administration. Conversely, a 2-fold increase in the potency of the 5-HT1A receptor agonist ipsapirone to inhibit the discharge of DRN serotoninergic neurons and a larger hypothermic response to 8-OH-DPAT were observed in MDMA- compared to saline-treated mice on the 28th day posttreatment. In addition, this adaptive change resulted in a reduction of [5-HT] content. Finally, a reduction of cell proliferation was observed in the hippocampus of MDMA-treated mice. All these effects were abolished in 5-HTT knock-out mice. These data indicated that repeated MDMA administration in mice induced a long term reduction of [5-HT] content, an increased 5-HT1A autoreceptor function in the DRN, and a deficit in hippocampal cell proliferation. These 5-HTT-dependent effects, opposite to those of antidepressants [1,2], might contribute to MDMA-induced mood disorders. References [1] Le Poul E, Boni C, Hanoun N, Laporte AM, Laaris N, Chauveau J, Hamon M, Lanfumey L, 2000, Differential adaptation of brain 5-HT1A and 5-HT1B receptors and 5-HT transporter in rats treated chronically with fluoxetine. Neuropharmacology 39, 110–122. [2] Malberg JE, Eisch AJ, Nestler EJ, Duman RS, 2000, Chronic antidepressant treatment increases neurogenesis in adult rat hippocampus. J Neurosci 20, 9104–9110.
S.04.03 Neuron and forebrain specific deletion of the glycine transporter 1 gene enhances spontaneous object recognition memory P. Singer1 ° , D. Boison2 , H. M¨ohler3 , J. Feldon1 , B.K. Yee4 . 1 Swiss Federal Institute of Technology, Behavioral Neurobiology, Schwerzenbach, Switzerland; 2 R.S. Dow Neurobiology Laboratories, Legacy Research, Portland, USA; 3 Institute of Pharmacology and Toxicology, University of Zurich, Z¨urich, Switzerland; 4 Swiss Federal Institute ofTechnology, Behavioral Neurobiology, Schwerzenbach, Switzerland Forebrain and neuron specific deletion of the glycine transporter 1 (GlyT1) gene translates into diminished GlyT1-mediated glycine re-uptake and augments NMDA-receptor activity, presumably due to an increased availability of synaptic glycine. This is associated with enhanced associative learning in multiple paradigms (Yee et al., 2006). Here, we investigated the mutation’s potential promnesic effects on object recognition memory. First, mutant and littermate control mice were familiarized with two identical copies of a sample object for 10min. Second, following different delays (2min, 2h or 24h), the animals were exposed to a novel object and a third copy of a (now familiarized) sample object for 5min. Object recognition memory was indexed by the animals’ explorative preference towards the novel over the familiarized object. Both mutants and controls exhibited a positive preference towards the novel object at 2min delay. At 2h and 24h delays, the