title: The requirement for enhanced CREB1 expression in consolidation of long-term synaptic facilitation and long-term excitability in sensory neurons of Aplysia.
abstract: Accumulating evidence suggests that the transcriptional activator cAMP response element-binding protein 1 (CREB1) is important for serotonin (5-HT)-induced long-term facilitation (LTF) of the sensorimotor synapse in Aplysia. Moreover, creb1 is among the genes activated by CREB1, suggesting a role for this protein beyond the induction phase of LTF. The time course of the requirement for CREB1 synthesis in the consolidation of long-term facilitation was examined using RNA interference techniques in sensorimotor cocultures. Injection of CREB1 small-interfering RNA (siRNA) immediately or 10 h after 5-HT treatment blocked LTF when measured at 24 and 48 h after treatment. In contrast, CREB1 siRNA did not block LTF when injected 16 h after 5-HT treatment. These results demonstrate that creb1 expression must be sustained for a relatively long time to support the consolidation of LTF. In addition, LTF is also accompanied by a long-term increase in the excitability (LTE) of sensory neurons (SNs). Because LTE was observed in the isolated SN after 5-HT treatment, this long-term change was intrinsic to that element of the circuit. LTE was blocked when CREB1 siRNA was injected into isolated SNs immediately after 5-HT treatment. These data suggest that 5-HT-induced CREB1 synthesis is required for consolidation of both LTF and LTE.
authors.affiliation: Department of Neurobiology and Anatomy, W. M. Keck Center for Neurobiology of Learning and Memory, The University of Texas Medical School at Houston, Texas 77030, USA.
authors.forename: Rong-Yu
authors.initials: RY
authors.lastname: Liu
authors.forename: Leonard J
authors.initials: LJ
authors.lastname: Cleary
authors.forename: John H
authors.initials: JH
authors.lastname: Byrne
mesh_terms: D000818:Animals; D001048:Aplysia; D002478:Cells, Cultured; D018920:Coculture Techniques; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics / Q000378:metabolism*; D004594:Electrophysiology; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D017774:Long-Term Potentiation / Q000502:physiology*; D034741:RNA, Small Interfering; D011984:Sensory Receptor Cells / Q000502:physiology*; D013569:Synapses / Q000502:physiology*
chemical_list: D017362:Cyclic AMP Response Element-Binding Protein; D034741:RNA, Small Interfering