TOP一般演題(ポスター)
 
一般演題(ポスター)
Higher Brain Function・Transcriptional Regulation
2P-39
SOLOIST, a novel isoform of SRF coactivator MKL2 that is enriched in neurons and negatively regulates dendritic complexity of cortical neurons
Tanaka Takuro1,Ishibashi Yuta1,Shoji Shizuku1,Kubo Yukimi1,Hakamata Tomoyuki1,Sakagami Hiroyuki2,Fukuchi Mamoru1,Tsuda Masaaki1,Tabuchi Akiko1
1Lab. of Mol. Neurobio., Grad. Sch. of Med. & Pharm. Sci., Univ. of Toyama,2Dept. Anat., Sch. of Med., Kitasato. Univ.

The accurate construction of neural network via neuronal plasticity, the morphological and functional change of neurons, are important for the acquisition of higher brain function such as memory, learning, recognition and emotion. It is thought that the rearrangement of cytoskeleton and the expression of genes related to cytoskeleton are deeply involved in neuronal plasticity.
Recently, MKL(megakaryoblastic leukemia)family members have been paid attention as molecules which are involved in neuronal morphology. MKL1 and MKL2 are SRF(serum response factor)coactivators with G-actin binding domains. Our previous studies revealed that MKL1 and MKL2 are highly expressed in the brain and regulates dendritic morphology and SRF-mediated gene expression.
In this study, we identified and characterized a novel MKL2 isoform named SOLOIST(spliced neuronal long isoform of SRF transcriptional coactivator). Our findings have shown that SOLOIST is highly expressed in the brain and is enriched in neurons. The expression of SOLOIST increased during brain development. SOLOIST regulated the SRF-mediated transcription. Additionally, overexpression of SOLOIST in cultured cortical neurons decreased dendritic complexity, whereas MKL2 isoform 1 increased. Taken together, the roles of SOLOIST in neurons seems different from other MKL2 isoforms. Interestingly, our preliminary data has shown that the influence of SOLOIST on endogenous SRF-target genes may be different from those of other MKL2 isoforms. It would be interesting if SOLOIST-target gene expression is involved in the opposite roles between SOLOIST and other isoforms in dendritic complexity.
2P-40
MAPK-mediated phosphorylation of NPAS4 regulates memory formation by modulating its interaction with CBP
Funahashi Yasuhiro1,Ariza Anthony1,Wei Shan2,Kuroda Keisuke1,Nakamuta Shinichi1,Nagai Taku2,Kaibuchi Kozo1
1Department of Cell Pharmacology, Nagoya University Graduate School of Medicine,2Department of Neuropsychopharmacology and Hospital Pharmacy, Nagoya University Graduate School of Medicine.

Dopamine(DA)is involved in emotional learning, perception, and memory formation. DA activates cAMP/Protein kinase A(PKA)-signaling pathway acting through D1 receptor and then activates Mitogen-Activated Protein Kinase(MAPK)in striatal medium spiny neurons(MSNs)and plays a pivotal role in regulating gene expression. However, how DA signaling regulates gene expression through the phosphorylation of transcriptional factors(TFs)is not fully understood. The cAMP response element-binding protein(CREB)-binding protein(CBP)is a critical for neuronal plasticity and memory formation and is believed to participate in the activities of hundreds of different TFs. The interactions of CBP with TFs are regulated by phosphorylation. To isolate the transcriptional factor regulated by phosphorylation downstream of DA, we performed proteomic analyses of CBP-interacting proteins and identified Neuronal Per Arnt Sim domain protein 4(NPAS4), as a novel CBP-interacting protein. NPAS4, a brain-specific basic helix-loop-helix transcription factor, regulates the expression of several genes that are important for synaptic plasticity and plays an important role in synapse formation and memory formation. We found that NPAS4 strongly interacted with the kinase-inducible domain interacting(KIX)domain of CBP, weakly Histone acetyltransferases(HAT)domain. NPAS4 was phosphorylated at Thr-427 by MAPK in vivo and the phosphorylation of NPAS4 increased the interaction of NPAS4 with CBP. Furthermore, the phosphomimic mutant of NPAS4 enhanced the exon I and IV-BDNF promoter activity. These results imply that MAPK phosphorylates NPAS4 at Thr-427 and increases its binding with CBP, thereby regulating BDNF expression and memory formation.
2P-41
Effects of Oxytocin on the respiratory circuit in isolated brainstem-spinal cord preparation from neonatal rat.
Arata Akiko,Nishiyama Ayae,Ito Mari
Division of Physiome, Department of Physiology, Hyogo College of Medicine

Oxytocin is well known as a hormone affecting uterine contraction and inducing lactation. Moreover, oxytocin plays a key role as a neurotransmitter affecting an autism. Previous report showed that oxytocin-containing neurons of the hypothalamic paraventricular nucleus project to the rostral ventrolateral medulla region(RVL)and phrenic motoneurons innervating the diaphragm. And oxytocin-containing neurons in the PVN is mediating increased respiratory output elicited by PVN stimulation. However, oxytocin in the neonatal breathing were not so well understood. We examined oxytocin regulate respiratory activity using brainstem-spinal cord preparation of the neonatal rats. The brainstem and spinal cord were isolated from postnatal day 0 to 4(P0-P4)with deep isoflurane anesthesia. The respiratory rate and spinal tonic activity were significant increased by application of 10 μM oxytocin in P0-2. After P3, oxytocin was not significant increased the respiratory rate and spinal tonic activity. The respiratory facilitation and spinal tonic activity were inhibited by oxytocin receptor antagonist. Furthermore, respiratory facilitation and spinal tonic activity induced by oxytocin were abolished by APV(NMDA receptor antagonist). On the other hand, respiratory increase was depressed by treatment of CNQX(non-NMDA receptor antagonist)but CNQX was not inhibited spinal tonic activity. These results suggested that 1)the respiratory facilitation and spinal tonic activity by oxytocin were seen in early neonatal stage;2)oxytocin excited respiratory rhythm via non-NMDA receptors and excited spinal tonic activity via NMDA receptor. Oxytocin may play a crucial role in assisting spontaneous breathing after birth.
2P-42
The role of ventrolateral striatal dopamine receptor type 2 expressing medium spiny neurons in motivation
Tsutsui-Kimura Iku1,Izumiseki Fumiya1,Tanaka F. Kenji1
1Department of Neuropsychiatry, Keio University School of Medicine,2JSPS Research Fellow

The ventral striatum is known as a key node mediating motivational processes. However, cell-based further understanding of ventral striatal function was not easy because researchers had to address the effects by cell location(medial vs lateral subregion)and cell type(dopamine receptor type1 vs type2(D2)expressing medium spiny neurons(MSNs)), separately. Here, we combined an expansive yet reversible loss-of-function with day-by-day instrumental task in order to search the responsible region of mediating motivation and examine how specific cells at the confined region modulate instrumental motivation. Our main findings are:
1)Bilateral loss-of-function of striatal D2-MSNs caused motivation deficits.
2)Loss-of-function of 17% of D2-MSNs within the ventrolateral striatum(VLS)was sufficient to decrease motivation.
3)Anatomical expansion of loss-of-function manipulation exacerbated motivation deficits.
4)Rescue-of-function ameliorated motiovation deficits.
Our data demonstrate that the D2-MSNs in the VLS are essential for maintaining motivation.
2P-43
How does the ventral hippocampus respond to optogenetic activation of the raphe nucleus?
Yoshida Keitaro,Takata Norio,Mimura Masaru,Tanaka Kenji
Dept. Neuropsychiatry, School of Medicine, Keio University

Serotonin(5-hydroxytryptamine or 5-HT)is a neurotransmitter involved in a wide range of brain functions such as emotion, cognition, motor control, and autonomic function. 5-HT containing axons distribute throughout the CNS and originate from cells located in the raphe nucleus. The ventral hippocampus(vHP)is one of target regions of 5-HT neurons in the raphe nucleus and expresses 5-HT receptors(Htrs)including Htr1a, 1b, 2a, 2c, 3a, 4, 5a, and 7. The vHP is involved in emotional responses, i.e. anxiety;hippocampal theta activity increases in an anxiety provoking situation, like the open arm of the elevated plus maze. However, it is unclear how 5-HT neurons behave in an anxious situation and how 5-HT neuron activation modulates vHP activities. Here we addressed the latter question by optogenetics in vivo. We previously succeeded in generating transgenic mice that expressed a step-function-type channelrhodopsin-2 variant ChR2(C128S)in 5-HT neurons. To clarify the effect of the optogenetic serotonergic manipulation on vHP activities, we recorded local field potential(LFP)in the vHP under urethane anesthesia. Our preliminary results showed that the optogenetic activation of 5-HT neurons decreased theta power in the vHP.
2P-44
Neonatal isolation augments social dominance by altering actin dynamics in the medial prefrontal cortex
Tada Hirobumi,Takahashi Takuya
Department of Physiology, Yokohama City University Graduate School of Medicine

Social maltreatment early in life can lead to the development of impaired interpersonal relationships and profound social disorders. However, the underlying cellular and molecular mechanisms involved are largely unknown. Here, we found that isolation of neonatal rats induced social dominance over nonisolated control rats from the same litter in juveniles that was glucocorticoid-dependent. Furthermore, neonatal isolation inactivated the actin-depolymerizing factor(ADF)/cofilin in the juvenile medial prefrontal cortex(mPFC). Isolation-induced inactivation of ADF/cofilin resulted in the decrease of glutamate synaptic AMPA(α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid)receptor(AMPAR)contents by the increase of stable actin fractions at dendritic spines in the juvenile mPFC. The expression of constitutively active ADF/cofilin in the mPFC rescued the effect of isolation on social dominance. Thus, neonatal isolation traumatizes spines in the mPFC by altering actin dynamics, leading to abnormal social behavior later in life.
2P-45
A New Inhibitory Pathway Toward the Mouse La via the mITC Revealed by VSD Imaging
Ide Yoshinori1,3,Fujieda Tomomi1,2,Koganezawa Noriko2,Shirao Tomoaki2,Sekino Yuko1,2
1Division of Pharmacology, National Institute of Health Sciences,2Department of Neurobiology and Behavior, Gunma University Graduate School of Medicine,3Pharmacological Evaluation Institute of Japan

It is well known that the lateral amygdala nucleus(La)receives and integrates sensory inputs from the cortex and the thalamus to establish emotional memory. Inhibitory GABAergic inputs in the La play very important roles in controlling the strength of sensory inputs and interfering with the acquisition of fear memory in the initial step. Thus, we used voltage sensitive dye(VSD)imaging, and investigated the spatial and temporal patterns of the inhibitory responses in the mouse La. Direct stimulation of the external capsule(EC)induced large and long-lasting hyperpolarizing signals in the La. We focused on these hyperpolarizing signals to identify the source of the inhibitory inputs. We prepared the slice preparation with four patterns of surgical cuts on the possible afferent pathways. The induction of the hyperpolarization were strongly suppressed by isolating the medial branch of EC(ECmed), but not the lateral branch of EC(EClat). Interestingly, the hyperpolarization was not suppressed by isolating the ECmed from the caudate putamen, while the surgical cut of the ECmed fiber tract moderately suppressed it. The hyperpolarizing signals could be completely suppressed in the presence of glutamatergic antagonists. Additionally, the early component(51-100ms)and slow component(201-300ms)of the hyperpolarizing signals could be largely suppressed by GABAA and GABAB antagonists, respectively. When directly stimulating the dorsal, middle or ventral part of ECmed fiber tract in the presence of glutamatergic antagonists, only the stimulation in the middle part of the ECmed caused hyperpolarization.These results suggest that the GABAergic neurons in the medial intercalated cluster(mITC), which receive glutamatergic excitatory inputs via two pathways, one is from the ECmed fiber tract and the other is from the La, send inhibitory afferents to the La. Here we identify a new inhibitory pathway toward the La via the mITC. This new pathway might have inhibitory effects on the acquisition of fear memory.
2P-46
γ-Aminobutyric acid in anterior cingulate cortex predicts intra-cingulum functional connectivity in human:A magnetic resonance imaging study
Fujihara Kazuyuki1,Narita Kosuke1,Suzuki Yusuke1,Kasagi Masato1,Motegi Tomokazu1,Takei Yuich1,Tagawa Minami1,Ujita Koich2,Near Jamie3,Fukuda Masato1
1Department of Psychiatry and Neuroscience, Graduate School of Medicine, Gunma University,2Department of Diagnostic Radiology and Nuclear Medicine, Gunma University Graduate School of Medicine,3Douglas Mental Health University Institute and Department of Psychiatry, McGill University

γ-Aminobutyric acid(GABA)is the major inhibitory neurotransmitter in the central nervous system and has important roles in synchronous neural activity. Recent studies employing magnetic resonance spectroscopy(MRS)and functional neuroimaging have revealed a relationship between regional GABA concentration and brain activity in human without invasive experiment. Two studies have demonstrated that GABA concentration in posterior cingulate cortex negatively correlated with functional connectivity within default mode network in healthy subjects. On the other hand, a relationship between functional connectivity at rest and GABA concentration in anterior cingulate cortex(ACC)remains unclear. In this study, we performed MRS using MEGA-PRESS sequence to determine GABA concentration in perigenual ACC(pgACC)and resting-state functional magnetic resonance imaging(fMRI)to measure intrinsic neuronal activity for 25 healthy subjects. Data processing and statistical analysis were performed by SPM8, REST and R software. SPM analysis showed that the GABA/creatine(Cr)ratio is positively associated with the strength of functional connectivity between pgACC and posterior midcingulate cortex(pMCC)[p<0.001, small volume correction for whole cingulate cortex, MNI coordinate;x=-3, y=-6, z=32]. We extracted the values of functional connectivity from the significant cluster in pMCC, then carried out post hoc correlation analysis. The analysis confirmed positive correlation between GABA/Cr and pgACC-pMCC connectivity[r=0.76, p<0.001]. In addition, the GABA/Cr in the pgACC is positively correlated with the amplitude of fMRI signal fluctuation. These findings suggest that GABA has an important role in intra-cingulum connectivity and local neuronal activity at resting state.