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Activity-dependent regulation of synaptic vesicle exocytosis and recycling
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Abstracts / Neuroscience Research 68S (2010) e4–e52
mation emerge and disappear at specific time-points. These dynamics are coupled between regions, and appear to reflect the generation and propagation of emotional information from BLA to GC, and from there to CeA. Careful examination of simultaneously recorded neurons demonstrates that taste responses are best thought of as a coherent, unified, multi-regional attractor sequence—that is, taste-specific, non-sparse, informationally rich series of quasi-stable states (with minimal between-state switching delays) that progress inexorably toward the production of emotional behavior, as the animal decides whether to reject or consume the substance in the mouth. The process is remarkably reliable across trials, but the dynamics unfold at different speeds from trial to trial, such that the full richness of the data cannot be seen when averaged across sessions. Acknowledgement This work is funded by the National Institutes of Health, and by the Swartz Foundation for Computational Neuroscience. doi:10.1016/j.neures.2010.07.321
S2-1-2-6 Role of the noradrenergic transmission within the BNST in pain-induced aversion Masabumi Minami Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Hokkaido University The bed nucleus of the stria terminalis (BNST) is involved in the regulation of negative affective states such as anxiety and fear. In this study, we examined the role of the noradrenergic transmission within the ventral BNST (vBNST) in the negative affective component of pain in rats. Noradrenaline release within the vBNST was significantly elevated by the i.pl. formalinevoked and i.p. acetic acid-evoked noxious stimuli. Intra-vBNST injection of a -adrenoceptor antagonist timolol significantly suppressed the formalininduced and acetic acid-induced conditioned place aversion (CPA) without affecting nociceptive behaviors. Intra-vBNST injection of isoproterenol, a adrenoceptor agonist, dose-dependently produced CPA even in the absence of noxious stimulation. This isoproterenol-induced CPA was suppressed by the co-injection of Rp-cyclic adenosine monophosphorothioate (Rp-cAMPS), a selective PKA inhibitor. Furthermore, intra-vBNST injection of Rp-cAMPS dose-dependently attenuated formalin-induced CPA without affecting nociceptive behaviors. Taken together, these results suggest that PKA activation within the vBNST via the enhancement of -adrenergic transmission is critical to the negative affective component of pain. doi:10.1016/j.neures.2010.07.322
S2-2-1-1 Excitation-transcription coupling mechanisms engaged by specific calcium channel types Richard W. Tsien , Damian G. Wheeler, Rachel D. Groth, Huan Ma, Scott F. Owen, Curtis F. Barrett Dept Mol Cell Physiol, Stanford Medical School Dynamic remodeling of synaptic efficacy generally calls upon coupling of neuronal electrical activity to activation of gene transcription: excitation–transcription coupling. Many cells use multiple sources of Ca2+ to generate key cellular responses, but it remains uncertain whether these sources act specifically or by supplying Ca2+ to a common pool. In neurons, CaV2 channels (principally N- and P/Q-type) dominate voltage-gated Ca2+ entry, but CaV1 channels (L-type) appear most critical for regulation of gene expression via phosphorylation of CREB. CaV2 channels can also drive CREB phosphorylation, but their relative efficacy and mode of signaling is unknown. We have found that CaV2 channels support pCREB formation with steep voltage-dependence, like CaV1, but with ∼70-fold weaker potency for the same depolarization. The voltage-dependence of activation of CaV2 channels contributes to their disadvantage. In addition, stimuli producing bulk Ca2+ increases of equal size are ∼10-fold less effective when mediated by CaV2 channels, a disparity explained by two factors. Experiments with EGTA and BAPTA show that CaV2 channels must elevate [Ca2+ ]i micrometers away whereas the CaV1 channels signal very locally near the pore mouth, where [Ca2+ ]i is higher. Furthermore, CaV2-mediated Ca2+ rises are more susceptible to Ca2+ uptake by mitochondria (shown by cytosolic and mitochondrial Ca2+ imaging), causing attenuation of requisite signal spread. The different forms of signaling were also found in cultured hippocampal neurons; and over a range of firing frequencies (10–100 Hz) in sympathetic neurons. The source-biased mitochondrial uptake may link CaV2 channel activity not only to oxidative metabolism and superoxide production but
also to mitochondria-dependent pathophysiology. Our results indicate that different kinds of Ca2+ channel can use disparate forms of Ca2+ signaling even under circumstances of a common goal. doi:10.1016/j.neures.2010.07.323
S2-2-1-2 Axonal mitochondrial transport and remodeling of synaptic transmission Zu-Hang Sheng NINDS, NIH, USA Proper transport and distribution of mitochondria along axons and at synapses are critical for the normal physiology of neurons. Mitochondria in axons display distinct motility patterns and undergo saltatory and bidirectional movement. While approximately one-third of axonal mitochondria are mobile in mature neurons, a large proportion remains stationary where energy production and calcium homeostasis capacity are in high demand. Their net movement is significantly influenced by recruitment to stationary or motile states. The coordination of mitochondrial movement and docking with axonal physiology is crucial for neuronal and synaptic function. Structure and function of axons and synapses are highly plastic and undergo spontaneous and activity-dependent remodeling, thereby changing mitochondrial mobility. We are focusing our investigation on molecular machineries that drive mitochondrial transport and mediate mitochondrial docking. Using genetic mouse models combined with time-lapse imaging in live neurons we provide mechanistic insights into the complex mobility patterns of axonal mitochondria. Syntaphilin is a neuronal specific and axonal-targeted protein and acts as a docking receptor for mitochondria through a dynamic interaction with the microtubule-based cytoskeleton. Such a mechanism enables neurons to maintain proper densities of stationary mitochondria within axons and in the proximity of synapses (Kang et al., Cell, 2008). We further provide the physiological evidence that the mobility and density of axonal mitochondria play a critical role in short-term synaptic plasticity. Since defective trafficking and dysfunction of axonal mitochondria is implicated in the pathogenesis of axonal degeneration, identification of syntaphilin as a docking molecule provides a unique genetic mouse model to address whether the selective change of axonal mitochondrial mobility has any impact on axonal homeostasis and degeneration. doi:10.1016/j.neures.2010.07.324
S2-2-1-3 Activity-dependent regulation of synaptic vesicle exocytosis and recycling Sumiko Mochida Department of Physiology, Tokyo Medical University Neuronal firing activity controls protein functions and dynamically remodels synaptic efficacy. Regulation of the neuronal efficacy involves whole cell reactions from receiving neurotransmitter through releasing neurotransmitter. The cholinergic synapse formed between rat superior cervical ganglion neurons in long-term culture is a useful model for exploring protein functions in synaptic vesicle exocytosis and recycle, monitoring the efficacy of synaptic transmission. The exocytosis is regulated by residual Ca2+ , which enters and accumulates in the presynaptic terminal accompanying action potential firings. Residual Ca2+ is sensed by Ca2+ binding proteins, among other potential effectors, mediates time- and space-dependent synaptic depression and facilitation via effects on Ca2+ channel gating and on vesicle replenishment into the readily releasable pool. Mitochondria are also associated with short-term synaptic plasticity due to sufficient ATP supply for vesicle replenishment into the readily releasable pool. Mitochondria-deficient synapses with impaired anterograde transport of mitochondria in neuronal processes, and subsequently an insufficient ATP supply in presynaptic terminals with adverse consequences for synaptic vesicles mobilization to the readily releasable pool shows defect of presynaptic short-term plasticity. doi:10.1016/j.neures.2010.07.325
S2-2-1-4 Regulating neurotransmitter release across the synaptic cleft Yukiko Goda , Nathalia Vitureira MRC Laboratory for Molecular Cell Biology, University College London The structure and function of synapses are highly heterogeneous, even among synapses formed on single neurons. Several lines of evidence suggest that presynaptic functionality is regulated retrogradely via mechanisms involving postsynaptic components. One potential class of candidate pro-
Abstracts / Neuroscience Research 68S (2010) e4–e52
mation emerge and disappear at specific time-points. These dynamics are coupled between regions, and appear to reflect the generation and propagation of emotional information from BLA to GC, and from there to CeA. Careful examination of simultaneously recorded neurons demonstrates that taste responses are best thought of as a coherent, unified, multi-regional attractor sequence—that is, taste-specific, non-sparse, informationally rich series of quasi-stable states (with minimal between-state switching delays) that progress inexorably toward the production of emotional behavior, as the animal decides whether to reject or consume the substance in the mouth. The process is remarkably reliable across trials, but the dynamics unfold at different speeds from trial to trial, such that the full richness of the data cannot be seen when averaged across sessions. Acknowledgement This work is funded by the National Institutes of Health, and by the Swartz Foundation for Computational Neuroscience. doi:10.1016/j.neures.2010.07.321
S2-1-2-6 Role of the noradrenergic transmission within the BNST in pain-induced aversion Masabumi Minami Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Hokkaido University The bed nucleus of the stria terminalis (BNST) is involved in the regulation of negative affective states such as anxiety and fear. In this study, we examined the role of the noradrenergic transmission within the ventral BNST (vBNST) in the negative affective component of pain in rats. Noradrenaline release within the vBNST was significantly elevated by the i.pl. formalinevoked and i.p. acetic acid-evoked noxious stimuli. Intra-vBNST injection of a -adrenoceptor antagonist timolol significantly suppressed the formalininduced and acetic acid-induced conditioned place aversion (CPA) without affecting nociceptive behaviors. Intra-vBNST injection of isoproterenol, a adrenoceptor agonist, dose-dependently produced CPA even in the absence of noxious stimulation. This isoproterenol-induced CPA was suppressed by the co-injection of Rp-cyclic adenosine monophosphorothioate (Rp-cAMPS), a selective PKA inhibitor. Furthermore, intra-vBNST injection of Rp-cAMPS dose-dependently attenuated formalin-induced CPA without affecting nociceptive behaviors. Taken together, these results suggest that PKA activation within the vBNST via the enhancement of -adrenergic transmission is critical to the negative affective component of pain. doi:10.1016/j.neures.2010.07.322
S2-2-1-1 Excitation-transcription coupling mechanisms engaged by specific calcium channel types Richard W. Tsien , Damian G. Wheeler, Rachel D. Groth, Huan Ma, Scott F. Owen, Curtis F. Barrett Dept Mol Cell Physiol, Stanford Medical School Dynamic remodeling of synaptic efficacy generally calls upon coupling of neuronal electrical activity to activation of gene transcription: excitation–transcription coupling. Many cells use multiple sources of Ca2+ to generate key cellular responses, but it remains uncertain whether these sources act specifically or by supplying Ca2+ to a common pool. In neurons, CaV2 channels (principally N- and P/Q-type) dominate voltage-gated Ca2+ entry, but CaV1 channels (L-type) appear most critical for regulation of gene expression via phosphorylation of CREB. CaV2 channels can also drive CREB phosphorylation, but their relative efficacy and mode of signaling is unknown. We have found that CaV2 channels support pCREB formation with steep voltage-dependence, like CaV1, but with ∼70-fold weaker potency for the same depolarization. The voltage-dependence of activation of CaV2 channels contributes to their disadvantage. In addition, stimuli producing bulk Ca2+ increases of equal size are ∼10-fold less effective when mediated by CaV2 channels, a disparity explained by two factors. Experiments with EGTA and BAPTA show that CaV2 channels must elevate [Ca2+ ]i micrometers away whereas the CaV1 channels signal very locally near the pore mouth, where [Ca2+ ]i is higher. Furthermore, CaV2-mediated Ca2+ rises are more susceptible to Ca2+ uptake by mitochondria (shown by cytosolic and mitochondrial Ca2+ imaging), causing attenuation of requisite signal spread. The different forms of signaling were also found in cultured hippocampal neurons; and over a range of firing frequencies (10–100 Hz) in sympathetic neurons. The source-biased mitochondrial uptake may link CaV2 channel activity not only to oxidative metabolism and superoxide production but
also to mitochondria-dependent pathophysiology. Our results indicate that different kinds of Ca2+ channel can use disparate forms of Ca2+ signaling even under circumstances of a common goal. doi:10.1016/j.neures.2010.07.323
S2-2-1-2 Axonal mitochondrial transport and remodeling of synaptic transmission Zu-Hang Sheng NINDS, NIH, USA Proper transport and distribution of mitochondria along axons and at synapses are critical for the normal physiology of neurons. Mitochondria in axons display distinct motility patterns and undergo saltatory and bidirectional movement. While approximately one-third of axonal mitochondria are mobile in mature neurons, a large proportion remains stationary where energy production and calcium homeostasis capacity are in high demand. Their net movement is significantly influenced by recruitment to stationary or motile states. The coordination of mitochondrial movement and docking with axonal physiology is crucial for neuronal and synaptic function. Structure and function of axons and synapses are highly plastic and undergo spontaneous and activity-dependent remodeling, thereby changing mitochondrial mobility. We are focusing our investigation on molecular machineries that drive mitochondrial transport and mediate mitochondrial docking. Using genetic mouse models combined with time-lapse imaging in live neurons we provide mechanistic insights into the complex mobility patterns of axonal mitochondria. Syntaphilin is a neuronal specific and axonal-targeted protein and acts as a docking receptor for mitochondria through a dynamic interaction with the microtubule-based cytoskeleton. Such a mechanism enables neurons to maintain proper densities of stationary mitochondria within axons and in the proximity of synapses (Kang et al., Cell, 2008). We further provide the physiological evidence that the mobility and density of axonal mitochondria play a critical role in short-term synaptic plasticity. Since defective trafficking and dysfunction of axonal mitochondria is implicated in the pathogenesis of axonal degeneration, identification of syntaphilin as a docking molecule provides a unique genetic mouse model to address whether the selective change of axonal mitochondrial mobility has any impact on axonal homeostasis and degeneration. doi:10.1016/j.neures.2010.07.324
S2-2-1-3 Activity-dependent regulation of synaptic vesicle exocytosis and recycling Sumiko Mochida Department of Physiology, Tokyo Medical University Neuronal firing activity controls protein functions and dynamically remodels synaptic efficacy. Regulation of the neuronal efficacy involves whole cell reactions from receiving neurotransmitter through releasing neurotransmitter. The cholinergic synapse formed between rat superior cervical ganglion neurons in long-term culture is a useful model for exploring protein functions in synaptic vesicle exocytosis and recycle, monitoring the efficacy of synaptic transmission. The exocytosis is regulated by residual Ca2+ , which enters and accumulates in the presynaptic terminal accompanying action potential firings. Residual Ca2+ is sensed by Ca2+ binding proteins, among other potential effectors, mediates time- and space-dependent synaptic depression and facilitation via effects on Ca2+ channel gating and on vesicle replenishment into the readily releasable pool. Mitochondria are also associated with short-term synaptic plasticity due to sufficient ATP supply for vesicle replenishment into the readily releasable pool. Mitochondria-deficient synapses with impaired anterograde transport of mitochondria in neuronal processes, and subsequently an insufficient ATP supply in presynaptic terminals with adverse consequences for synaptic vesicles mobilization to the readily releasable pool shows defect of presynaptic short-term plasticity. doi:10.1016/j.neures.2010.07.325
S2-2-1-4 Regulating neurotransmitter release across the synaptic cleft Yukiko Goda , Nathalia Vitureira MRC Laboratory for Molecular Cell Biology, University College London The structure and function of synapses are highly heterogeneous, even among synapses formed on single neurons. Several lines of evidence suggest that presynaptic functionality is regulated retrogradely via mechanisms involving postsynaptic components. One potential class of candidate pro-