title: Serotonin facilitates long-term depression induction in prefrontal cortex via p38 MAPK/Rab5-mediated enhancement of AMPA receptor internalization.
abstract: The serotonin system in prefrontal cortex (PFC) is critically involved in the regulation of cognition and emotion. To understand the cellular mechanisms underlying its physiological actions, we investigated the role of serotonin in regulating synaptic plasticity in PFC circuits. We found that tetanic stimuli coupled to bath application of serotonin induced long-term depression (LTD) at excitatory synapses of PFC pyramidal neurons. This effect was mediated by 5-HT(2A/C) receptors and was independent of NMDA receptor activation. A group I metabotropic glutamate receptor (mGluR) antagonist blocked the LTD induction by serotonin + tetani, and co-application of a group I mGluR agonist and serotonin, but not application of either drug alone, induced LTD without tetani. The effect of serotonin on LTD was blocked by selective inhibitors of p38 mitogen-activated protein kinase (MAPK), but not p42/44 MAPK. Biochemical evidence also indicated that serotonin and a group I mGluR agonist synergistically activated p38 MAPK in PFC slices. The serotonin-facilitated LTD induction was prevented by blocking the activation of the small GTPase Rab5, as well as by blocking the clathrin-dependent internalization of AMPA receptors with postsynaptic injection of a dynamin inhibitory peptide, while it was unaffected by manipulating the cytoskeleton. Interestingly, in animals exposed to acute stress, the LTD induction by serotonin + tetani was significantly impaired. Taken together, these results suggest that serotonin, by cooperating with mGluRs, regulates synaptic plasticity through a mechanism dependent on p38 MAPK/Rab5-mediated enhancement of AMPA receptor internalization in a clathrin/dynamin-dependent manner. It provides a potential mechanism underlying the role of serotonin in controlling emotional and cognitive processes that are mediated by synaptic plasticity in PFC neurons.
authors.affiliation: Department of Physiology and Biophysics, State University of New York at Buffalo, 124 Sherman Hall, Buffalo, NY 14214, USA.
authors.forename: Ping
authors.initials: P
authors.lastname: Zhong
authors.forename: Wenhua
authors.initials: W
authors.lastname: Liu
authors.forename: Zhenglin
authors.initials: Z
authors.lastname: Gu
authors.forename: Zhen
authors.initials: Z
authors.lastname: Yan
mesh_terms: D000818:Animals; D002966:Clathrin / Q000378:metabolism; D034281:Dynamins / Q000378:metabolism; D066298:In Vitro Techniques; D036881:Long-Term Synaptic Depression; D017397:Prefrontal Cortex / Q000502:physiology*; D017966:Pyramidal Cells / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D018091:Receptors, AMPA / Q000378:metabolism*; D018094:Receptors, Metabotropic Glutamate / Q000502:physiology; D011985:Receptors, Serotonin / Q000378:metabolism; D012701:Serotonin / Q000502:physiology*; D013315:Stress, Psychological / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism; D020696:rab5 GTP-Binding Proteins / Q000378:metabolism
chemical_list: D002966:Clathrin; D018091:Receptors, AMPA; D018094:Receptors, Metabotropic Glutamate; D011985:Receptors, Serotonin; D012701:Serotonin; D048051:p38 Mitogen-Activated Protein Kinases; D020696:rab5 GTP-Binding Proteins; D034281:Dynamins