bluuebunny/crossref_metadata_2025 huggingface dataset:
Endogenous Regulator of G-Protein Signaling Proteins Modify N-Type Calcium Channel Modulation in Rat Sympathetic Neurons
Authors: Jeong Seong-Woo , Ikeda Stephen R.
Published: April 2018

Experiments using heterologous overexpression indicate that regulator of G-protein signaling (RGS) proteins play important roles in Gβγ-mediated ion channel modulation. However, the roles subserved by endogenous RGS proteins have not been extensively examined because tools for functionally inhibiting natively expressed RGS proteins are lacking. To address this void, we used a strategy in which GαoAwas rendered insensitive to pertussis toxin (PTX) and RGS proteins by site-directed mutagenesis. Either PTX-insensitive (PTX-i) or both PTX- and RGS-insensitive (PTX/RGS-i) mutants of GαoAwere expressed along with Gβ1and Gγ2subunits in rat sympathetic neurons. After overnight treatment with PTX to suppress natively expressed Gα subunits, voltage-dependent Ca2+current inhibition by norepinephrine (NE) (10 μm) was reconstituted in neurons expressing either PTX-i or PTX/RGS-i GαoA. When compared with neurons expressing PTX-i GαoA, the steady-state concentration–response relationships for NE-induced Ca2+current inhibition were shifted to lower concentrations in neurons expressing PTX/RGS-i GαoA. In addition to an increase in agonist potency, the expression of PTX/RGS-i GαoAdramatically retarded the current recovery after agonist removal. Interestingly, the alteration in current recovery was accompanied by a slowing in the onset of current inhibition. Together, our data suggest that endogenous RGS proteins contribute to membrane-delimited Ca2+channel modulation by regulating agonist potency and kinetics of G-protein-mediated signaling in neuronal cells.
Altered Stress-Induced Anxiety in Adenylyl Cyclase Type VIII-Deficient Mice
Authors: Schaefer Michele L. , Wong Scott T. , Wozniak David F. , Muglia Lisa M. , Liauw Jason A. , Zhuo Min , Nardi Anthony , Hartman Richard E. , Vogt Sherri K. , Luedke Christina E. , Storm Daniel R. , Muglia Louis J.
Published: April 2018

Stress results in alterations in behavior and physiology that can be either adaptive or maladaptive. To define the molecular pathways involved in the response to stress further, we generated mice deficient (KO) in the calcium-stimulated adenylyl cyclase type VIII (AC8) by homologous recombination in embryonic stem cells. AC8 KO mice demonstrate a compromise in calcium-stimulated AC activity in the hippocampus, hypothalamus, thalamus, and brainstem. Hippocampal slices derived from AC8 KO mice fail to demonstrate CA1-region long-term depression after low-frequency stimulation, and AC8 KO mice also fail to activate CRE-binding protein in the CA1 region after restraint stress. To define the behavioral consequences of AC8 deficiency, we evaluated AC8 KO mice in the elevated plus-maze and open field. Although naı̈ve AC8 KO mice exhibit indices of anxiety comparable with that of wild-type mice, AC8 KO mice do not show normal increases in behavioral markers of anxiety when subjected to repeated stress such as repetitive testing in the plus-maze or restraint preceding plus-maze testing. These results demonstrate a novel role for AC8 in the modulation of anxiety.
Unique Properties of NMDA Receptors Enhance Synaptic Excitation of Radiatum Giant Cells in Rat Hippocampus
Authors: Kirson Eilon D. , Yaari Yoel
Published: April 2018

In the hippocampus, fast excitatory synaptic transmission of principal projection neurons is mediated by non-NMDA glutamate receptors, whereas NMDA glutamate receptors serve a slower modulatory role. We used the whole-cell patch-clamp technique in adult hippocampal slices to assess the role of NMDA receptors in synaptic excitation of a recently discovered excitatory projection neuron, the CA1 radiatum giant cell (RGC). Glutamatergic synaptic activation, even after blocking non-NMDA receptors, fired an NMDA receptor-dependent burst of action potentials in RGCs. In contrast, the contribution of NMDA receptors to synaptic activation of pyramidal cells (PCs) was minimal. Stimulation of the same synaptic inputs evoked greater than threefold larger EPSCs in RGCs than in PCs. Isolated NMDA receptor-mediated EPSCs were significantly less sensitive to blockade by extracellular Mg2+and had slower decay kinetics in RGCs than in PCs. Thus, unique properties of synaptic NMDA receptors underlie enhanced synaptic excitability in a newly discovered excitatory hippocampal projection neuron.
Selective Suppression of Inhibitory Synaptic Transmission by Nocistatin in the Rat Spinal Cord Dorsal Horn
Authors: Zeilhofer Hanns Ulrich , Selbach Uta Muth- , Gühring Hans , Erb Katharina , Ahmadi Seifollah
Published: April 2018

Nociceptin/orphanin FQ (N/OFQ) and nocistatin (NST) are two recently identified neuropeptides with opposing effects on several CNS functions, including spinal nociception. The cellular mechanisms that underlie this antagonism are not known. Here, we have investigated the effects of both peptides on synaptic transmission mediated by the three fast neurotransmittersl-glutamate, glycine, and GABA in the superficial layers of the rat spinal cord horn, which constitute the first important site of integration of nociceptive information in the pain pathway. NST selectively reduced transmitter release from inhibitory interneurons via a presynaptic Bordetella pertussis toxin-sensitive mechanism but left excitatory glutamatergic transmission unaffected. In contrast, N/OFQ only inhibited excitatory transmission. In the rat formalin test, an animal model of tonic pain in which N/OFQ exerts antinociceptive activity, NST induced profound hyperalgesia after intrathecal application. Similar to glycine and GABAAreceptor antagonists, NST had no significant effects in the rat tail-flick test, a model of acute thermal pain. Our results provide a cellular basis for the antagonism of N/OFQ and NST and suggest the existence of a so far unidentified membrane receptor for NST. In addition, they support a role of NST as an endogenous inhibitor of glycinergic and GABAergic neurotransmission in the sensory part of the spinal cord and as a mediator of spinal hyperalgesia.
Retinal Ganglion Cell Axon Guidance in the Mouse Optic Chiasm: Expression and Function of Robos and Slits
Authors: Erskine Lynda , Williams Scott E. , Brose Katja , Kidd Thomas , Rachel Rivka A. , Goodman Corey S. , Tessier-Lavigne Marc , Mason Carol A.
Published: April 2018

The ventral midline of the nervous system is an important choice point at which growing axons decide whether to cross and project contralaterally or remain on the same side of the brain. InDrosophila, the decision to cross or avoid the CNS midline is controlled, at least in part, by the Roundabout (Robo) receptor on the axons and its ligand, Slit, an inhibitory extracellular matrix molecule secreted by the midline glia. Vertebrate homologs of these molecules have been cloned and have also been implicated in regulating axon guidance. Usingin situhybridization, we have determined the expression patterns ofrobo1,2andslit1,2,3in the mouse retina and in the region of the developing optic chiasm, a ventral midline structure in which retinal ganglion cell (RGC) axons diverge to either side of the brain. The receptors and ligands are expressed at the appropriate time and place, in both the retina and the ventral diencephalon, to be able to influence RGC axon guidance.In vitro,slit2is inhibitory to RGC axons, with outgrowth of both ipsilaterally and contralaterally projecting axons being strongly affected. Overall, these results indicate that Robos and Slits alone do not directly control RGC axon divergence at the optic chiasm and may additionally function as a general inhibitory guidance system involved in determining the relative position of the optic chiasm at the ventral midline of the developing hypothalamus.
Basic Fibroblast Growth Factor (Fgf2) Is Necessary for Cell Proliferation and Neurogenesis in the Developing Cerebral Cortex
Authors: Raballo Rossana , Rhee Julianne , Lyn-Cook Richard , Leckman James F. , Schwartz Michael L. , Vaccarino Flora M.
Published: April 2018

Little is known about regionally specific signals that control the number of neuronal progenitor cellsin vivo. We have previously shown that the germline mutation of the basic fibroblast growth factor (Fgf2) gene results in a reduction in the number of cortical neurons in the adult. We show here that Fgf2 is expressed in the pseudostratified ventricular epithelium (PVE) in a dorsoventral gradient and that Fgf2 and its receptor, Fgfr-1, are downregulated by mid to late stages of neurogenesis. In Fgf2 knockout mice, the volume and cell number of the dorsal PVE (the cerebral cortical anlage) are substantially smaller, whereas the volume of the basal PVE is unchanged. The dorsal PVE of Fgf2 knockout mice has a 50% decrease in founder cells and a reduced expansion of the progenitor pool over the first portion of neurogenesis. Despite this reduction, the degree of apoptosis within the PVE is not changed in the Fgf2 knockouts. Cortical neuron number was decreased by 45% in Fgf2 knockout mice by the end of neurogenesis, whereas the number of neurons in the basal ganglia was unaffected. Microscopically, the frontal cerebral cortex of neonatal Fgf2 null mutant mice lacked large neurons in deep cortical layers. We suggest that Fgf2 is required for the generation of a specific class of cortical neurons arising from the dorsal PVE.
Age at Deafening Affects the Stability of Learned Song in Adult Male Zebra Finches
Authors: Lombardino Anthony J. , Nottebohm Fernando
Published: April 2018

Male zebra finches (Taeniopygia guttata) master the imitation of a song model 80–90 d after hatching and retain it with little change for the rest of their lives. Acquisition and maintenance of this imitation require intact hearing. A previous report showed that male zebra finches deafened as adults start to lose some of the acoustic and temporal features of their song a few weeks after deafening and that by 16 weeks the learned song is severely degraded (Nordeen and Nordeen, 1992). However, this previous study noted no correlation between the age at deafening and the subsequent timing and extent of song loss. We deafened adult male zebra finches ranging in age from 81 d to 6 years. The song of birds deafened at the younger ages (81–175 d) deteriorated severely after a few weeks, and within that age bracket, the older the bird was at deafening, the longer it took for this degradation to occur and the slower the subsequent process of song deterioration. The song of birds deafened at 2 years and older showed little change during the first 51 weeks after deafening but was grossly altered by 100 weeks. We suggest (1) that this age effect could be independent of experience or (2) that each time a bird sings, a little bit of learning—motor engrainment—occurs, adding to memory duration in a cumulative manner.
Homeostatic Regulation of Serotonergic Function by the Serotonin Transporter As Revealed by Nonviral Gene Transfer
Authors: Fabre Véronique , Boutrel Benjamin , Hanoun Naı̈ma , Lanfumey Laurence , Fattaccini Claude Michelle , Demeneix Barbara , Adrien Joëlle , Hamon Michel , Martres Marie-Pascale
Published: April 2018

With the aim of exploring the relationship between the serotonin transporter (5-HTT or SERT) and the activity level of serotonin (5-HT) neurotransmission,in vivoexpression of this protein was specifically altered using a nonviral DNA transfer method. Plasmids containing the entire coding sequence or a partial antisense sequence of the 5-HTT gene were complexed with the cationic polymer polyethylenimine and injected into the dorsal raphe nucleus of adult male rats. Significant increase or decrease in both [3H]citalopram binding and [3H]5-HT synaptosomal uptake were observed in various brain areas up to 2 weeks after a single administration of the sense plasmid or 7 d after injection of the short antisense plasmid, respectively. Such changes in 5-HTT expression were associated with functional alterations in 5-HT neurotransmission, as shown by the increased capacity of 5-HT1Areceptor stimulation to enhance [35S]GTP-γ-S binding onto the dorsal raphe nucleus in sections from rats injected with the sense plasmid. Conversely, both a decrease in 5-HT1A-mediated [35S]GTP-γ-S binding and a reduced potency of the 5-HT1Areceptor agonist ipsapirone to inhibit neuronal firing were observed in the dorsal raphe nucleus of antisense plasmid-injected rats. Furthermore, changes in brain 5-HT and/or 5-HIAA levels, and sleep wakefulness circadian rhythm in the latter animals demonstrated that altered expression of 5-HTT by recombinant plasmids has important functional consequences on central 5-HT neurotransmission in adult rats.
Complete and Long-Term Rescue of Lesioned Adult Motoneurons by Lentiviral-Mediated Expression of Glial Cell Line-Derived Neurotrophic Factor in the Facial Nucleus
Authors: Hottinger Andreas F. , Azzouz Mimoun , Déglon Nicole , Aebischer Patrick , Zurn Anne D.
Published: April 2018

To date, delivery of neurotrophic factors has only allowed to transiently protect axotomized facial motoneurons against cell death. In the present report, long-term protection of these neurons was evaluated by continuously expressing the neurotrophic factor glial cell line-derived neurotrophic factor (GDNF) within the facial nucleus using a lentiviral vector system. The viral vector was injected unilaterally into the facial nucleus of 4-month-old Balb/C mice. In contrast to axotomy in other adult rodents, facial nerve lesion in these animals leads to a progressive and sustained loss and/or atrophy of >50% of the motoneurons. This model thus represents an attractive model to evaluate potential protective effects of neurotrophic factors for adult-onset motoneuron diseases, such as amyotrophic lateral sclerosis. One month after unilateral lentiviral vector injection, the facial nerve was sectioned, and the animals were killed 3 months later. Viral delivery of the GDNF gene led to long-term expression and extensive diffusion of GDNF within the brainstem. In addition, axotomized motoneurons were completely protected against cell death, because 95% of the motoneurons were present as demonstrated by both Nissl staining and choline acetyltransferase immunoreactivity. Furthermore, GDNF prevented lesion-induced neuronal atrophy and maintained proximal motoneuron axons, despite the absence of target cell reinnervation. This is the first evidence that viral-mediated delivery of GDNF close to the motoneuron cell bodies of the facial nucleus of adult mice can lead to complete and long-term protection against lesion-induced cell death.
Clinical Mutations in the L1 Neural Cell Adhesion Molecule Affect Cell-Surface Expression
Authors: Moulding Hugh D. , Martuza Robert L. , Rabkin Samuel D.
Published: April 2018

Mutations in the L1 neural cell adhesion molecule, a transmembrane glycoprotein, cause a spectrum of congenital neurological syndromes, ranging from hydrocephalus to mental retardation. Many of these mutations are single amino acid changes that are distributed throughout the various domains of the protein. Defective herpes simplex virus vectors were used to express L1 protein with the clinical missense mutations R184Q and D598N in the Ig2 and Ig6 extracellular domains, respectively, and S1194L in the cytoplasmic domain. All three mutant proteins were expressed at similar levels in infected cells. Neurite outgrowth of cerebellar granule cells was stimulated on astrocytes expressing wild-type or S1194L L1, whereas those expressing R184Q and D598N L1 failed to increase neurite length. Live cell immunofluorescent staining of L1 demonstrated that most defective vector-infected cells did not express R184Q or D598N L1 on their cell surface. This greatly diminished cell-surface expression occurred in astrocytes, neurons, and non-neural cells. In contrast to wild-type or S1194L L1, the R184Q and D598N L1 proteins had altered apparent molecular weights and remained completely endoglycosidase H (endoH)-sensitive, suggesting incomplete post-translational processing. We propose that some missense mutations in human L1 impede correct protein trafficking, with functional consequences independent of protein activity. This provides a rationale for how expressed, full-length proteins with single amino acid changes could cause clinical phenotypes similar in severity to knock-out mutants.
BDNF Protects the Neonatal Brain from Hypoxic-Ischemic InjuryIn Vivovia the ERK Pathway
Authors: Han Byung Hee , Holtzman David M.
Published: April 2018

Neurotrophins activate several different intracellular signaling pathways that in some way exert neuroprotective effects.In vitrostudies of sympathetic and cerebellar granule neurons have demonstrated that the survival effects of neurotrophins can be mediated via activation of the phosphatidylinositol 3-kinase (PI3-kinase) pathway. Neurotrophin-mediated protection of other neuronal typesin vitrocan be mediated via the extracellular signal-related protein kinase (ERK) pathway. Whether either of these pathways contributes to the neuroprotective effects of neurotrophins in the brainin vivohas not been determined. Brain-derived neurotrophic factor (BDNF) is markedly neuroprotective against neonatal hypoxic-ischemic (H-I) brain injuryin vivo. We assessed the role of the ERK and PI3-kinase pathways in neonatal H-I brain injury in the presence and absence of BDNF. Intracerebroventricular administration of BDNF to postnatal day 7 rats resulted in phosphorylation of ERK1/2 and the PI3-kinase substrate AKT within minutes. Effects were greater on ERK activation and occurred in neurons. Pharmacological inhibition of ERK, but not the PI3-kinase pathway, inhibited the ability of BDNF to block H-I-induced caspase-3 activation and tissue loss. These findings suggest that neuronal ERK activation in the neonatal brain mediates neuroprotection against H-I brain injury, a model of cerebral palsy.
Role of Inspiratory Pacemaker Neurons in Mediating the Hypoxic Response of the Respiratory NetworkIn Vitro
Authors: Thoby-Brisson Muriel , Ramirez Jan-Marino
Published: April 2018

In severe hypoxia the breathing frequency is modulated in a biphasic manner: an initial increase (augmentation) is followed by a depression and cessation of breathing (apnea). Using a mouse slice preparation that contains the functional respiratory network, we aimed at identifying the neurons responsible for this frequency modulation. Whole-cell patch recordings revealed that expiratory neurons become tonically active during anoxia, indicating that these neurons cannot be responsible for the respiratory frequency modulation. Inspiratory neurons tended to depolarize (by 6.9 mV;n= 9), and the frequency of rhythmic activity was significantly increased during anoxia (from 0.16 to 0.4 Hz;n= 9). After the blockade of network activity with 6-cyano-7-nitroquinoxaline-2,3-dione, most inspiratory neurons became tonically active (72%;n= 25, non-pacemaker). In anoxia, the membrane potential of these non-pacemaker neurons did not change (−0.26 mV;n= 6), and their tonic activity ceased. Only a subpopulation of inspiratory neurons remained rhythmically active in the absence of network activity (pacemaker neurons, 28%, 7 of 25 inspiratory neurons). In anoxia two subgroups of pacemaker neurons were differentiated; one group showed a transient increase in the bursting activity, followed by a decrease and cessation of rhythmic activity. These neurons tended to depolarize (by 10.3 mV) during anoxia. The second group remained rhythmic during the entire anoxic exposure and exhibited no depolarization. The time course of the frequency modulation in all pacemaker neurons resembled that of the intact network. We conclude that pacemaker neurons are primarily responsible for the frequency modulation in anoxia and that in the respiratory network there is a strict separation between rhythm- and pattern-generating mechanisms.
Nonphotic Entrainment by 5-HT1A/7Receptor Agonists Accompanied by ReducedPer1andPer2mRNA Levels in the Suprachiasmatic Nuclei
Authors: Horikawa Kazumasa , Yokota Shin-ichi , Fuji Kazuyuki , Akiyama Masashi , Moriya Takahiro , Okamura Hitoshi , Shibata Shigenobu
Published: April 2018

In mammals, the environmental light/dark cycle strongly synchronizes the circadian clock within the suprachiasmatic nuclei (SCN) to 24 hr. It is well known that not only photic but also nonphotic stimuli can entrain the SCN clock. Actually, many studies have shown that a daytime injection of 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH DPAT), a serotonin 1A/7 receptor agonist, as a nonphotic stimulus induces phase advances in hamster behavioral circadian rhythmsin vivo, as well as the neuron activity rhythm of the SCNin vitro. Recent reports suggest that mammalian homologs of theDrosophilaclock gene,Period(Per), are involved in photic entrainment. Therefore, we examined whether phase advances elicited by 8-OH DPAT were associated with a change ofPeriodmRNA levels in the SCN. In this experiment, we cloned partial cDNAs encoding hamsterPer1,Per2, andPer3and observed both circadian oscillation and the light responsiveness ofPeriod. Furthermore, we found that the inhibitory effect of 8-OH DPAT on hamsterPer1andPer2mRNA levels in the SCN occurred only during the hamster's mid-subjective day, but not during the early subjective day or subjective night. The present findings demonstrate that the acute and circadian time-dependent reduction ofPer1and/orPer2mRNA in the hamster SCN by 8-OH DPAT is strongly correlated with the phase resetting in response to 8-OH DPAT.
Presynaptic Cannabinoid Sensitivity Is a Major Determinant of Depolarization-Induced Retrograde Suppression at Hippocampal Synapses
Authors: Ohno-Shosaku Takako , Tsubokawa Hiroshi , Mizushima Ichiro , Yoneda Norihide , Zimmer Andreas , Kano Masanobu
Published: April 2018

Recent studies have clarified that endogenous cannabinoids (endocannabinoids) are released from depolarized postsynaptic neurons in a Ca2+-dependent manner and act retrogradely on presynaptic cannabinoid receptors to suppress inhibitory or excitatory neurotransmitter release. This type of modulation has been found in the hippocampus and cerebellum and was called depolarization-induced suppression of inhibition (DSI) or excitation (DSE). In this study, we quantitatively examined the effects of postsynaptic depolarization and a cannabinoid agonist on excitatory and inhibitory synapses in rat hippocampal slices and cultures. We found that both DSE and DSI can be induced, but DSE was much less prominent than DSI. For the induction of DSE, the necessary duration of depolarization was longer than for DSI. The magnitude of DSE was much smaller than that of DSI. To explore the reasons for these differences, we tested the sensitivity of EPSCs and IPSCs to a cannabinoid agonist, WIN55,212-2, in hippocampal cultures. IPSCs were dichotomized into two distinct populations, one with a high sensitivity to WIN55,212-2 (50% block at 2 nm) and the other with no sensitivity. In contrast, EPSCs were homogeneous and exhibited a low sensitivity to WIN55,212-2 (50% block at 60 nm). We estimated that the 5 sec depolarization elevated the local endocannabinoid concentration to a level equivalent to several nanomoles of WIN55,212-2. Using CB1 knock-out mice, we verified that both DSI and DSE were mediated by the cannabinoid CB1 receptor. These results indicate that presynaptic cannabinoid sensitivity is a major factor that determines the extent of DSI and DSE.
Caspase Cascades in Human Immunodeficiency Virus-Associated Neurodegeneration
Authors: Garden Gwenn A. , Budd Samantha L. , Tsai Elena , Hanson Lisa , Kaul Marcus , D'Emilia Danielle M. , Friedlander Robert M. , Yuan Junying , Masliah Eliezer , Lipton Stuart A.
Published: April 2018

Many patients infected with human immunodeficiency virus-1 (HIV-1) develop a syndrome of neurologic deterioration known as HIV-associated dementia (HAD). Neurons are not productively infected by HIV-1; thus, the mechanism of HIV-induced neuronal injury remains incompletely understood. Several investigators have observed evidence of neuronal injury, including dendritic degeneration, and apoptosis in CNS tissue from patients with HAD. Caspase enzymes, proteases associated with the process of apoptosis, are synthesized as inactive proenzymes and are activated in a proteolytic cascade after exposure to apoptotic signals. Here we demonstrate that HAD is associated with active caspase-3-like immunoreactivity that is localized to the soma and dendrites of neurons in affected regions of the human brain. Additionally, the cascade of caspase activation was studied using anin vitromodel of HIV-induced neuronal apoptosis. Increased caspase-3 proteolytic activity and mitochondrial release of cytochromecwere observed in cerebrocortical cultures exposed to the HIV coat protein gp120. Specific inhibitors of both the Fas/tumor necrosis factor-α/death receptor pathway and the mitochondrial caspase pathway prevented gp120-induced neuronal apoptosis. Caspase inhibition also prevented the dendrite degeneration observedin vivoin transgenic mice with CNS expression of HIV/gp120. These findings suggest that pharmacologic interventions aimed at the caspase enzyme pathways may be beneficial for the prevention or treatment of HAD.
Aberrant Sensory Innervation of the Olfactory Bulb in Neuropilin-2 Mutant Mice
Authors: Walz Andreas , Rodriguez Ivan , Mombaerts Peter
Published: April 2018

The mammalian olfactory system consists of two anatomically segregated structures, the main olfactory system and the vomeronasal system, which each detect distinct types of chemical stimuli in the environment. During development, sensory neurons establish precise axonal connections with their respective targets within the olfactory bulb. The specificity of the odorant or vomeronasal receptor expressed by the sensory neuron is crucial in this process, yet it is less clear which of the more conventional axon guidance molecules are involved. Here, we show that neuropilin-2, a coreceptor for some of the class 3 semaphorins, is expressed in subpopulations of olfactory and vomeronasal sensory neurons. We generated a knock-out mutation in the neuropilin-2 gene by gene targeting in embryonic stem cells. Neuropilin-2 mutant mice exhibit profound and distinct effects on target innervation within the olfactory bulb. In the main olfactory system, axons of olfactory sensory neurons penetrate into the deeper layers of the main olfactory bulb. In the vomeronasal system, axonal fasciculation within the vomeronasal nerve is affected; some axons are misrouted and innervate glomeruli in an ectopic domain of the accessory olfactory bulb.
Cyclin-Dependent Kinase 5/p35 Contributes Synergistically with Reelin/Dab1 to the Positioning of Facial Branchiomotor and Inferior Olive Neurons in the Developing Mouse Hindbrain
Authors: Ohshima Toshio , Ogawa Masaharu , Takeuchi Kyoko , Takahashi Satoru , Kulkarni Ashok B. , Mikoshiba Katsuhiko
Published: April 2018

Cyclin-dependent kinase 5 (Cdk5)/p35 is a serine/threonine kinase, and its activity is detected primarily in postmitotic neurons. Mice lacking Cdk5/p35 display migration defects of the cortical neurons in the cerebrum and cerebellum. In this study, we demonstrate that although most brainstem nuclei are found in their proper positions, the motor nucleus of the facial nerve is ectopically located and neurons of the inferior olive fail to position correctly, resulting in the lack of their characteristic structures in the hindbrain of Cdk5−/− mice. Despite the defective migration of these neurons, axonal exits of the facial nerve from brainstem and projections of the inferior cerebellar axons appear unchanged in Cdk5−/− mice. Defective neuronal migration in Cdk5−/− hindbrain was rescued by the neuron-specific expression of Cdk5 transgene. Because developmental defects of these structures have been reported inreelerand Dab1 mutant mice, we analyzed the double-null mutants of p35 and Dab1 and found more extensive ectopia of VII motor nuclei in these mice. These results indicate that Cdk5/p35 and Reelin signaling regulates the selective mode of neuronal migration in the developing mouse hindbrain.
Gonadal Hormones Affect Spine Synaptic Density in the CA1 Hippocampal Subfield of Male Rats
Authors: Leranth Csaba , Petnehazy Ors , MacLusky Neil J.
Published: April 2018

The effects of androgen on the density of spine synapses on pyramidal neurons in the CA1 area of the hippocampus were studied in male rats. Gonadectomy (GDNX) had no significant effect on the number of CA1 pyramidal cells but reduced CA1 spine synapse density by almost 50% (to 0.468 ± 0.018 spine synapses/μm3) compared with sham-operated controls (0.917 ± 0.06 spine synapses/μm3). Treatment of GDNX rats with testosterone propionate (500 μg/d, s.c., 2 d) increased spine synapse density to levels (1.01 ± 0.026 spine synapses/μm3) comparable with intact males. A similar increase in synapse density (1.013 ± 0.05 spine synapses/μm3) was observed in GDNX animals after treatment with dihydrotestosterone (DHT) (500 μg/d, s.c., 2 d) but not after estradiol (10 μg/d, s.c., 2 d; 0.455 ± 0.02 spine synapse/μm3). These data indicate that testosterone is important for maintenance of normal spine synapse density in the CA1 region of the male rat hippocampus. The comparable responses to testosterone and the non-aromatizable androgen DHT, coupled with the lack of response to estradiol, suggest that testosterone acts directly on hippocampal androgen receptors rather than indirectly via local estrogen biosynthesis.
A Mutation inAf4Is Predicted to Cause Cerebellar Ataxia and Cataracts in the Robotic Mouse
Authors: Isaacs Adrian M. , Oliver Peter L. , Jones Emma L. , Jeans Alexander , Potter Allyson , Hovik Berit H. , Nolan Patrick M. , Vizor Lucie , Glenister Peter , Simon A. Katharina , Gray Ian C. , Spurr Nigel K. , Brown Steve D. M. , Hunter A. Jackie , Davies Kay E.
Published: April 2018

The robotic mouse is an autosomal dominant mutant that arose from a large-scale chemical mutagenesis program. It has a jerky, ataxic gait and develops adult-onset Purkinje cell loss in the cerebellum in a striking region-specific pattern, as well as cataracts. Genetic and physical mapping of the disease locus led to the identification of a missense mutation in a highly conserved region ofAf4, a putative transcription factor that has been previously implicated in leukemogenesis. We demonstrate thatAf4is specifically expressed in Purkinje cells, and we hypothesize that the expression of mutantAf4leads to neurodegeneration. This function was not identified through knock-out studies, highlighting the power of phenotype-driven mutagenesis in the mouse to identify new pathways involved in neurological disease.
Role of Integrin-Linked Kinase in Nerve Growth Factor-Stimulated Neurite Outgrowth
Authors: Mills Julia , Digicaylioglu Murat , Legg Arthur T. , Young Clint E. , Young Sean S. , Barr Alasdair M. , Fletcher Lauren , O'Connor Timothy P. , Dedhar Shoukat
Published: April 2018

The role of integrin-linked kinase (ILK), a kinase that is involved in various cellular processes, including adhesion and migration, has not been studied in primary neurons. Using mRNA dot blot and Western blot analysis of ILK in rat and human brain tissue, we found that ILK is expressed in various regions of the CNS. Immunohistochemical and immunocytochemical techniques revealed granular ILK staining that is enriched in neurons and colocalizes with the β1 integrin subunit. The role of ILK in neurite growth promotion by NGF was studied in rat pheochromocytoma cells and dorsal root ganglion neurons using a pharmacological inhibitor of ILK (KP-392) or after overexpression of dominant-negative ILK (ILK-DN). Both molecular and pharmacological inhibition of ILK activity significantly reduced NGF-induced neurite outgrowth. Survival assays indicate that KP-392-induced suppression of neurite outgrowth occurred in the absence of cell death. ILK kinase activity was stimulated by NGF. NGF-mediated stimulation of phosphorylation of both AKT and theTaukinase glycogen synthase kinase-3 (GSK-3) was inhibited in the presence of KP-392 and after overexpression of ILK-DN. Consequently, ILK inhibition resulted in an increase in the hyperphosphorylation ofTau, a substrate of GSK-3. Together these findings indicate that ILK is an important effector in NGF-mediated neurite outgrowth.
A Regulated Interaction of Syntaxin 1A with the Antidepressant-Sensitive Norepinephrine Transporter Establishes Catecholamine Clearance Capacity
Authors: Sung Uhna , Apparsundaram Subramaniam , Galli Aurelio , Kahlig Kristopher M. , Savchenko Valentina , Schroeter Sally , Quick Michael W. , Blakely Randy D.
Published: April 2018

Norepinephrine (NE) transporters (NETs) terminate noradrenergic synaptic transmission and represent a major therapeutic target for antidepressant medications. NETs and related transporters are under intrinsic regulation by receptor and kinase-linked pathways, and clarification of these pathways may suggest candidates for the development of novel therapeutic approaches. Syntaxin 1A, a presynaptic solubleN-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) protein, interacts with NET and modulates NET intrinsic activity. NETs colocalize with and bind to syntaxin 1A in both native preparations and heterologous systems. Protein kinase C activation disrupts surface NET/syntaxin 1A interactions and downregulates NET activity in a syntaxin-dependent manner. Syntaxin 1A binds the NH2terminal domain of NET, and a deletion of this domain both eliminates NET/syntaxin 1A associations and prevents phorbol ester-triggered NET downregulation. Whereas syntaxin 1A supports the surface trafficking of NET proteins, its direct interaction with NET limits transporter catalytic function. These two contradictory roles of syntaxin 1A on NET appear to be linked and reveal a dynamic cycle of interactions that allow for the coordinated control between NE release and reuptake.
Neuronal Basis of Crossed Actions from the Reticular Formation on Feline Hindlimb Motoneurons
Authors: Jankowska Elzbieta , Hammar Ingela , Slawinska Urszula , Maleszak Katarzyna , Edgley Stephen A.
Published: April 2018

Pathways through which reticulospinal neurons can influence contralateral limb movements were investigated by recording from motoneurons innervating hindlimb muscles. Reticulospinal tract fibers were stimulated within the brainstem or in the lateral funiculus of the thoracic spinal cord contralateral to the motoneurons. Effects evoked by ipsilaterally descending reticulospinal tract fibers were eliminated by a spinal hemisection at an upper lumbar level. Stimuli applied in the brainstem evoked EPSPs, IPSPs, or both at latencies of 1.42 ± 0.03 and 1.53 ± 0.04 msec, respectively, from the first components of the descending volleys and with properties indicating a disynaptic linkage, in most contralateral motoneurons: EPSPs in 76% and IPSPs in 26%. EPSPs with characteristics of monosynaptically evoked responses, attributable to direct actions of crossed axon collaterals of reticulospinal fibers, were found in a small proportion of the motoneurons, whether evoked from the brainstem (9%) or from the thoracic cord (12.5%). Commissural neurons, which might mediate the crossed disynaptic actions (i.e., were antidromically activated from contralateral motor nuclei and monosynaptically excited from the ipsilateral reticular formation), were found in Rexed's lamina VIII in the midlumbar segments (L3–L5). The results reveal that although direct actions of reticulospinal fibers are much more potent on ipsilateral motoneurons, interneuronally mediated actions are as potent contralaterally as ipsilaterally, and midlumbar commissural neurons are likely to contribute to them. They indicate a close coupling between the spinal interneuronal systems used by the reticulospinal neurons to coordinate muscle contractions ipsilaterally and contralaterally.
Hippocampal cGMP-Dependent Protein Kinase I Supports an Age- and Protein Synthesis-Dependent Component of Long-Term Potentiation But Is Not Essential for Spatial Reference and Contextual Memory
Authors: Kleppisch Thomas , Wolfsgruber Wiebke , Feil Susanne , Allmann Rüdiger , Wotjak Carsten T. , Goebbels Sandra , Nave Klaus-Armin , Hofmann Franz , Feil Robert
Published: April 2018

cGMP-dependent protein kinase I (cGKI) is expressed in the hippocampus, but its role in hippocampal long-term potentiation (LTP) is controversial. In addition, whether cGKI is involved in spatial learning has not been investigated. To address these issues, we generated mice with a hippocampus-specific deletion of cGKI (cGKIhkomice). Unlike conventional cGKI knock-out mice, cGKIhkomice lack gastrointestinal and cardiovascular phenotypes and have a normal life expectancy, which enables us to analyze hippocampal synaptic plasticity and learning in young and adult animals. Hippocampal LTP after repetitive episodes of theta burst stimulation was impaired in adult (12–14 weeks of age) but not in juvenile (3–4 weeks of age) cGKIhkomice. The difference in LTP between adult control and cGKIhkomice was abolished by the protein synthesis inhibitor anisomycin, suggesting that the impairment of LTP in adult cGKIhkomice reflects a defect in late-phase LTP. Despite their deficit in LTP, adult cGKIhkomutants showed normal performance in a discriminatory water maze and had intact contextual fear conditioning. These results suggest that hippocampal cGKI supports an age- and protein synthesis-dependent form of hippocampal LTP, whereas it is dispensable for hippocampus-dependent spatial reference and contextual memory.
Light-Evoked Excitatory and Inhibitory Synaptic Inputs to ON and OFF α Ganglion Cells in the Mouse Retina
Authors: Pang Ji-Jie , Gao Fan , Wu Samuel M.
Published: April 2018

Bipolar cell and amacrine cell synaptic inputs to α ganglion cells (αGCs) in dark-adapted mouse retinas were studied by recording the light-evoked excitatory cation current (ΔIC) and inhibitory chloride current (ΔICl) under voltage-clamp conditions, and the cell morphology was revealed by Lucifer yellow fluorescence with a confocal microscope. Three types of αGCs were identified. (1) ONαGCs exhibits no spike activity in darkness, increased spikes in light, sustained inward ΔIC, sustained outward ΔIClof varying amplitude, and large soma (20–25 μm in diameter) withα-cell-like dendritic field ∼180–350 μm stratifying near 70% of the inner plexiform layer (IPL) depth. (2) Transient OFFαGCs (tOFFαGCs) exhibit no spike activity in darkness, transient increased spikes at light offset, small sustained outward ΔICin light, a large transient inward ΔICat light offset, a sustained outward ΔICl, and a morphology similar to the ONαGCs except for that their dendrites stratified near 30% of the IPL depth. (3) Sustained OFFαGCs exhibit maintained spike activity of 5–10 Hz in darkness, sustained decrease of spikes in light, sustained outward ΔIC, sustained outward ΔICl, and a morphology similar to the tOFFαGCs. By comparing the response thresholds and dynamic ranges of αGCs with those of the preganglion cells, our data suggest that the light responses of each type of αGCs are mediated by different sets of bipolar cells and amacrine cells. This detailed physiological analysis complements the existing anatomical results and provides new insights on the functional roles of individual synapses in the inner mammalian retina.
Caspase Inhibitors Promote Vestibular Hair Cell Survival and Function after Aminoglycoside TreatmentIn Vivo
Authors: Matsui Jonathan I. , Haque Asim , Huss David , Messana Elizabeth P. , Alosi Julie A. , Roberson David W. , Cotanche Douglas A. , Dickman J. David , Warchol Mark E.
Published: April 2018

The sensory hair cells of the inner ear undergo apoptosis after acoustic trauma or aminoglycoside antibiotic treatment, causing permanent auditory and vestibular deficits in humans. Previous studies have demonstrated a role for caspase activation in hair cell death and ototoxic injury that can be reduced by concurrent treatment with caspase inhibitorsin vitro. In this study, we examined the protective effects of caspase inhibition on hair cell deathin vivoafter systemic injections of aminoglycosides. In one series of experiments, chickens were implanted with osmotic pumps that administrated the pan-caspase inhibitor z-Val-Ala-Asp(Ome)-fluoromethylketone (zVAD) into inner ear fluids. One day after the surgery, the animals received a 5 d course of treatment with streptomycin, a vestibulotoxic aminoglycoside. Direct infusion of zVAD into the vestibule significantly increased hair cell survival after streptomycin treatment. A second series of experiments determined whether rescued hair cells could function as sensory receptors. Animals treated with streptomycin displayed vestibular system impairment as measured by a greatly reduced vestibulo-ocular response (VOR). In contrast, animals that received concurrent systemic administration of zVAD with streptomycin had both significantly greater hair cell survival and significantly increased VOR responses, as compared with animals treated with streptomycin alone. These findings suggest that inhibiting the activation of caspases promotes the survival of hair cells and protects against vestibular function deficits after aminoglycoside treatment.
Inhibitory But Not Excitatory Cortical Neurons Require Presynaptic Brain-Derived Neurotrophic Factor for Dendritic Development, as Revealed by Chimera Cell Culture
Authors: Kohara Keigo , Kitamura Akihiko , Adachi Naoki , Nishida Megumi , Itami Chiaki , Nakamura Shun , Tsumoto Tadaharu
Published: April 2018

To address questions of whether endogenous BDNF acts differentially on inhibitory and excitatory neurons, and through what routes, we used chimera culture of cerebral cortical neurons derived fromBDNF-/- mice and another type of transgenic mice that express green fluorescence protein and BDNF. Presynaptic BDNF transferred to both types of neurons, GABA-synthesizing enzyme-positive and -negative neurons. The latter neurons were confirmed to be glutamatergic with immunocytochemistry. Dendritic development of the former inhibitory neurons was promoted by endogenous BDNF transferred from presynaptic, excitatory neurons. In contrast, dendritic development of excitatory neurons was not related to the presence or absence of presynaptic BDNF, suggesting that BDNF acts on inhibitory neurons through an anterograde, transsynaptic route so as to promote dendritic development, whereas this is not the case in excitatory neurons.
PENGARUH MULTIMEDIA INTERAKTIF DAN GAYA BELAJAR TERHADAP PENGUASAAN KONSEP KALOR SISWA
Authors: Gunawan G. , Harjono A. , Imran I.
Published: April 2018

Dalam penelitian ini telah dikembangkan multimedia interaktif pada konsep kalor. Penelitian ini bertujuan menganalisis pengaruh multimedia interaktif dan gaya belajar terhadap penguasaan konsep kalor siswa. Penelitian dilaksanakan dalam tiga tahapan, yaitu studi pendahuluan, pengembangan desain, dan pengujian model. Pada tahap pengujian model digunakan metode kuasi eksperimen. Data yang diperoleh dianalisis menggunakan ANAVA dengan dua faktor, yaitu model pembelajaran dan gaya belajar. Gaya belajar siswa dibagi menjadi empat kategori berdasarkan model VARK Fleming, yaitu Visual, Auditori, Read, dan Kinestetik. Hasil penelitian menunjukkan bahwa rata-rata penguasaan konsep siswa yang belajar menggunaan multimedia interaktif lebih tinggi dibandingkan siswa yang belajar tanpa multimedia. Penguasaan konsep kalor siswa juga dipengaruhi oleh gaya belajar, dimana siswa dengan gaya belajar visual memiliki penguasaan konsep yang lebih tinggi dibandingkan siswa dengan gaya belajar lainnya.In this research, we have developed interactive multimedia on heat concepts. This research aimed to analyze the effect of interactive multimedia and learning styles towards students understanding on heat concepts. The research was conducted in three stages: a preliminary study, development, and testing of models. Testing phase of the model used a quasi-experimental method. Data were analyzed using ANOVA with two factors, namely learning models and learning styles. Students' learning styles were divided into four categories based on the model VARK Fleming; Visual, Auditory, Read, and Kinesthetic. The results showed that the average of students understanding who learned using interactive multimedia was still higher than students who learned without interactive multimedia. Students understanding on heat concepts were affected by learning styles, in which students with visual learning styles had higher understanding on heat concepts that students with any other learning styles.
INTERACTIVE MULTIMEDIA THERMODYNAMICS TO IMPROVE CREATIVE THINKING SKILL OF PHYSICS PROSPECTIVE TEACHERS
Authors: Hakim A. , Liliasari L. , Setiawan A. , Saptawati G. A. P.
Published: April 2018

This study aims to improve the creative thinking skills of prospective physics teacher as the impact of the application of interactive thermodynamics multimedia (ITMM). The research method used is quasi experiment with control group pretest-posttest design. The subjects consisted of 34 students in the experimental group and 33 students in the control group. Participant students are physics physics semester fourth, in one of the state universities in East Kalimantan. The research instrument consists of multiple choice test items charged with creative thinking skills. Data were analyzed by using difference test of two averages. The normalized gain gain score  of creative thinking skill aspect on the experimental group is 0.60 and the control group is 0.31. This indicates that the creative thinking skills of the prospective physics teacher increase significantly after they experience thermodynamic learning with interactive multimedia. Thus it can be concluded that the use of interactive multimedia improve the creative thinking skills of prospective physics teachers.
40 YEARS OF IGF1: Insulin-like growth factors: actions on the skeleton
Authors: Yakar Shoshana , Werner Haim , Rosen Clifford J
Published: April 2018

The discovery of the growth hormone (GH)-mediated somatic factors (somatomedins), insulin-like growth factor (IGF)-I and -II, has elicited an enormous interest primarily among endocrinologists who study growth and metabolism. The advancement of molecular endocrinology over the past four decades enables investigators to re-examine and refine the established somatomedin hypothesis. Specifically, gene deletions, transgene overexpression or more recently, cell-specific gene-ablations, have enabled investigators to study the effects of theIgf1andIgf2genes in temporal and spatial manners. The GH/IGF axis, acting in an endocrine and autocrine/paracrine fashion, is the major axis controlling skeletal growth. Studies in rodents have clearly shown that IGFs regulate bone length of the appendicular skeleton evidenced by changes in chondrocytes of the proliferative and hypertrophic zones of the growth plate. IGFs affect radial bone growth and regulate cortical and trabecular bone properties via their effects on osteoblast, osteocyte and osteoclast function. Interactions of the IGFs with sex steroid hormones and the parathyroid hormone demonstrate the significance and complexity of the IGF axis in the skeleton. Finally, IGFs have been implicated in skeletal aging. Decreases in serum IGFs during aging have been correlated with reductions in bone mineral density and increased fracture risk. This review highlights many of the most relevant studies in the IGF research landscape, focusing in particular on IGFs effects on the skeleton.
diploS/HIC: An Updated Approach to Classifying Selective Sweeps
Authors: Kern Andrew D , Schrider Daniel R
Published: April 2018

Identifying selective sweeps in populations that have complex demographic histories remains a difficult problem in population genetics. We previously introduced a supervised machine learning approach, S/HIC, for finding both hard and soft selective sweeps in genomes on the basis of patterns of genetic variation surrounding a window of the genome. While S/HIC was shown to be both powerful and precise, the utility of S/HIC was limited by the use of phased genomic data as input. In this report we describe a deep learning variant of our method, diploS/HIC, that uses unphased genotypes to accurately classify genomic windows. diploS/HIC is shown to be quite powerful even at moderate to small sample sizes.