Molecular validation of anthropophilic Phlebotominae sandflies (Diptera: Psychodidae) in Central Panama

Six Phlebotominae sand fly species are incriminated as biological vectors of human pathogens in Panama, but molecular corroboration is still needed. We aim at confirming the identity of Phlebotominae species documented as anthropophilic in Panama. Adult sandflies were collected from August 2010 to February 2012 in Central Panama using CDC light traps. Species confirmation was accomplished through molecular barcodes and allied sequences from GenBank. A total of 53,366 sand fly specimens representing 18 species were collected. Five species were validated molecularly as single phylogenetic clusters, but Psychodopygus thula depicted two genetically divergent lineages, which may be indicative of cryptic speciation.Six Phlebotominae sand fly species are incriminated as biological vectors of human pathogens in Panama, but molecular corroboration is still needed. We aim at confirming the identity of Phlebotominae species documented as anthropophilic in Panama. Adult sandflies were collected from August 2010 to February 2012 in Central Panama using CDC light traps. Species confirmation was accomplished through molecular barcodes and allied sequences from GenBank. A total of 53,366 sand fly specimens representing 18 species were collected. Five species were validated molecularly as single phylogenetic clusters, but Psychodopygus thula depicted two genetically divergent lineages, which may be indicative of cryptic speciation

Dikkat eksikliği/hiperaktivite bozukluğu tanısı alan çocuk ve ergenlerin dikkat eksikliği/hiperaktivite alt tiplerine göre bilgisayar tabanlı nöropsikolojik bir test bataryası olan cnsvs (The central nervous system vital signs) sonuçlarının incelenmesi

Bu çalışmada Dikkat Eksikliği Hiperaktivite Bozukluğu (DEHB) tanısı alan çocuk ve ergenlere, bilgisayar tabanlı test bataryası (CNSVS) uygulanarak DSM-IV kriterlerine göre sınıflandırılan DEHB alt tiplerinin kendi aralarındaki yürütücü işlev farklılıkları araştırılmıştır. Araştırmanın çalışma grubunu, İzmir ilinde bir çocuk-ergen psikiyatri kliniğine ilk kez başvuran ve çocuk-ergen alanında uzman bir psikiyatrist tarafından yapılan görüşme sonucunda ilk kez DEHB tanısı alan, 8-15 yaşları arasındaki 100 çocuk ve ergen oluşturmuştur. Tüm görüşmelerde: Sosyodemografik Veri Formu, Yıkıcı Davranış Bozukluklarını Tarama ve Değerlendirme Ölçeği ve psikiyatrik eş tanıları belirlemek amacıyla Okul Çağı Çocukları için Duygulanım Bozuklukları ve Şizofreni Görüşme Çizelgesi kullanılmıştır. DEHB etiyolojisini belirlemeye yönelik yapılan çalışmalar, yürütücü işlev bozukluklarının, etiyolojide önemli bir rolü olduğunu göstermiştir. Uygulanan test bataryasının alt test puanlarına göre, DEHB alt tipleri kendi aralarında değerlendirildiğinde, dikkat eksikliği alt grubunun bileşik alt gruba göre daha iyi performans gösterdiği görülmüştür. Ebeveynlere uygulanan ölçek sonuçlarının da test sonuçlarını destekler nitelikte olduğu görülmüştür

The regulation of M1 muscarinic acetylcholine receptor desensitization by synaptic activity in cultured hippocampal neurons1

To better understand metabotropic/ionotropic integration in neurons we have examined the regulation of M1 muscarinic acetylcholine (mACh) receptor signalling in mature (> 14 days in vitro), synaptically-active hippocampal neurons in culture. Using a protocol where neurons are exposed to an EC50 concentration of the muscarinic agonist methacholine (MCh) prior to (R1), and following (R2) a desensitizing pulse of a high concentration of this agonist, we have found that the reduction in M1 mACh receptor responsiveness is decreased in quiescent (+tetrodotoxin) neurons and increased when synaptic activity is enhanced by blocking GABAA receptors with picrotoxin. The picrotoxin-mediated effect on M1 mACh receptor responsiveness was completely prevented by α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor blockade. Inhibition of endogenous G protein-coupled receptor kinase 2 by transfection with the non-Gq/11α-binding, catalytically-inactive D110A,K220RG protein-coupled receptor kinase 2 mutant, decreased the extent of M1 mACh receptor desensitization under all conditions. Pharmacological inhibition of protein kinase C (PKC) activity, or chronic phorbol ester-induced PKC down-regulation had no effect on agonist-mediated receptor desensitization in quiescent or spontaneously synaptically active neurons, but significantly decreased the extent of receptor desensitization in picrotoxin-treated neurons. MCh stimulated the translocation of diacylglycerol- sensitive eGFP-PKCε, but not Ca2+/diacylglycerol-sensitive eGFP-PKCβII in both the absence, and presence of tetrodotoxin. Under these conditions, MCh-stimulated eGFP-myristoylated, alanine-rich C kinase substrate translocation was dependent on PKC activity, but not Ca2+/calmodulin. In contrast, picrotoxin-driven translocation of myristoylated, alanine-rich C kinase substrate was accompanied by translocation of PKCβII, but not PKCε, and was dependent on PKC and Ca2+/calmodulin. Taken together these data suggest that the level of synaptic activity may determine the different kinases recruited to regulate M1 mACh receptor desensitization in neurons

Influx of Calcium through L-type Calcium Channels in Early Postnatal Regulation of Chloride Transporters in the Rat Hippocampus

During the early postnatal period, GABAB receptor activation facilitates L-type calcium current in rat hippocampus. One developmental process that L-type current may regulate is the change in expression of the K+Cl− co-transporter (KCC2) and N+K+2Cl− co-transporter (NKCC1), which are involved in the maturation of the GABAergic system. The present study investigated the connection between L-type current, GABAB receptors, and expression of chloride transporters during development. The facilitation of L-type current by GABAB receptors is more prominent in the second week of development, with the highest percentage of cells exhibiting facilitation in cultures isolated from 7 day old rats (37.5%). The protein levels of KCC2 and NKCC1 were investigated to determine the developmental timecourse of expression as well as expression following treatment with an L-type channel antagonist and a GABAB receptor agonist. The time course of both chloride transporters in culture mimics that seen in hippocampal tissue isolated from various ages. KCC2 levels increased drastically in the first two postnatal weeks while NKCC1 remained relatively stable, suggesting that the ratio of the chloride transporters is important in mediating the developmental change in chloride reversal potential. Treatment of cultures with the L-type antagonist nimodipine did not affect protein levels of NKCC1, but significantly decreased the upregulation of KCC2 during the first postnatal week. In addition, calcium current facilitation occurs slightly before the large increase in KCC2 expression. These results suggest that the expression of KCC2 is regulated by calcium influx through L-type channels in the early postnatal period in hippocampal neurons

Stable Propagation of a Burst Through a One-Dimensional Homogeneous Excitatory Chain Model of Songbird Nucleus HVC

We demonstrate numerically that a brief burst consisting of two to six spikes can propagate in a stable manner through a one-dimensional homogeneous feedforward chain of non-bursting neurons with excitatory synaptic connections. Our results are obtained for two kinds of neuronal models, leaky integrate-and-fire (LIF) neurons and Hodgkin-Huxley (HH) neurons with five conductances. Over a range of parameters such as the maximum synaptic conductance, both kinds of chains are found to have multiple attractors of propagating bursts, with each attractor being distinguished by the number of spikes and total duration of the propagating burst. These results make plausible the hypothesis that sparse precisely-timed sequential bursts observed in projection neurons of nucleus HVC of a singing zebra finch are intrinsic and causally related.Comment: 13 pages, 6 figure

Contribution of the d-Serine-Dependent Pathway to the Cellular Mechanisms Underlying Cognitive Aging

An association between age-related memory impairments and changes in functional plasticity in the aging brain has been under intense study within the last decade. In this article, we show that an impaired activation of the strychnine-insensitive glycine site of N-methyl-d-aspartate receptors (NMDA-R) by its agonist d-serine contributes to deficits of synaptic plasticity in the hippocampus of memory-impaired aged rats. Supplementation with exogenous d-serine prevents the age-related deficits of isolated NMDA-R-dependent synaptic potentials as well as those of theta-burst-induced long-term potentiation and synaptic depotentiation. Endogenous levels of d-serine are reduced in the hippocampus with aging, that correlates with a weaker expression of serine racemase synthesizing the amino acid. On the contrary, the affinity of d-serine binding to NMDA-R is not affected by aging. These results point to a critical role for the d-serine-dependent pathway in the functional alterations of the brain underlying memory impairment and provide key information in the search for new therapeutic strategies for the treatment of memory deficits in the elderly

The role of inhibitory feedback for information processing in thalamocortical circuits

The information transfer in the thalamus is blocked dynamically during sleep, in conjunction with the occurence of spindle waves. As the theoretical understanding of the mechanism remains incomplete, we analyze two modeling approaches for a recent experiment by Le Masson {\sl et al}. on the thalamocortical loop. In a first step, we use a conductance-based neuron model to reproduce the experiment computationally. In a second step, we model the same system by using an extended Hindmarsh-Rose model, and compare the results with the conductance-based model. In the framework of both models, we investigate the influence of inhibitory feedback on the information transfer in a typical thalamocortical oscillator. We find that our extended Hindmarsh-Rose neuron model, which is computationally less costly and thus siutable for large-scale simulations, reproduces the experiment better than the conductance-based model. Further, in agreement with the experiment of Le Masson {\sl et al}., inhibitory feedback leads to stable self-sustained oscillations which mask the incoming input, and thereby reduce the information transfer significantly.Comment: 16 pages, 15eps figures included. To appear in Physical Review

Receptor subtype‐dependent galanin actions on gamma‐aminobutyric acidergic neurotransmission and ethanol responses in the central amygdala

The neuropeptide galanin and its three receptor subtypes (GalR1‐3) are expressed in the central amygdala (CeA), a brain region involved in stress‐ and anxiety‐related behaviors, as well as alcohol dependence. Galanin also has been suggested to play a role in alcohol intake and alcohol dependence. We examined the effects of galanin in CeA slices from wild‐type and knockout (KO) mice deficient of GalR2 and both GalR1 and GalR2 receptors. Galanin had dual effects on gamma‐aminobutyric acid (GABA)‐ergic transmission, decreasing the amplitudes of pharmacologically isolated GABAergic inhibitory postsynaptic potentials (IPSPs) in over half of CeA neurons but augmenting IPSPs in the others. The increase in IPSP size was absent after superfusion of the GalR3 antagonist SNAP 37889, whereas the IPSP depression was absent in CeA neurons of GalR1 × GalR2 double KO and GalR2 KO mice. Paired‐pulse facilitation studies showed weak or infrequent effects of galanin on GABA release. Thus, galanin may act postsynaptically through GalR3 to augment GABAergic transmission in some CeA neurons, whereas GalR2 receptors likely are involved in the depression of IPSPs. Co‐superfusion of ethanol, which augments IPSPs presynaptically, together with galanin caused summated effects of ethanol and galanin in those CeA neurons showing galanin‐augmented IPSPs, suggesting the two agents act via different mechanisms in this population. However, in neurons showing IPSP‐diminishing galanin effects, galanin blunted the ethanol effects, suggesting a preemptive effect of galanin. These findings may increase understanding of the complex cellular mechanisms that underlie the anxiety‐related behavioral effects of galanin and ethanol in CeA.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/92021/1/j.1369-1600.2011.00360.x.pd

Quantitative expression and localization of GABAB receptor protein subunits in hippocampi from patients with refractory temporal lobe epilepsy

This study investigates GABAB protein expression and mRNA levels in three types of specimens. Two types of specimens from patients with temporal lobe epilepsy (TLE), secondary to hippocampal sclerosis, sclerotic hippocampal samples (TLE-HS), and tissue from the structurally preserved non-spiking ipsilateral superior temporal gyrus (TLE-STG) removed from the same patient during epilepsy surgery; and third specimen is hippocampal tissue from individuals with no history of epilepsy (post-mortem controls, PMC). mRNA expression of GABAB subunits was quantified in TLE-HS, TLE-STG and PMC specimens by qRT-PCR. Qualitative and quantitative Western blot (WB) and immunohistochemistry techniques were employed to quantify and localize GABAB proteins subunits. qRT-PCR data demonstrated an overall decrease of both GABAB1 isoforms in TLE-HS compared to TLE-STG. These results were mirrored by the WB findings. GABAB2 mRNA and protein were significantly reduced in TLE-HS samples compared to TLE-STG; however they appeared to be upregulated in TLE-HS compared to the PMC samples. Immunohistochemistry (IHC) showed that GABAB proteins were widely distributed in PMC and TLE-HS hippocampal sections with regional differences in the intensity of the signal. The higher expression of mature GABAB protein in TLE-HS than PMC is in agreement with previous studies. However, these findings could be due to post-mortem changes in PMC specimens. The TLE-STG samples examined here represent a better 'control' tissue compared to TLE-HS samples characterized by lower than expected GABAB expression. This interpretation provides a better explanation for previous functional studies suggesting reduced inhibition in TLE-HS tissue due to attenuated GABAB currents. [Abstract copyright: Copyright © 2017. Published by Elsevier Ltd.

Deletion of the L-type calcium channel Ca V 1.3 but not Ca V 1.2 results in a diminished sAHP in mouse CA1 pyramidal neurons

Trains of action potentials in CA1 pyramidal neurons are followed by a prolonged calcium-dependent postburst afterhyperpolarization (AHP) that serves to limit further firing to a sustained depolarizing input. A reduction in the AHP accompanies acquisition of several types of learning and increases in the AHP are correlated with age-related cognitive impairment. The AHP develops primarily as the result of activation of outward calcium-activated potassium currents; however, the precise source of calcium for activation of the AHP remains unclear. There is substantial experimental evidence suggesting that calcium influx via voltage-gated L-type calcium channels (L-VGCCs) contributes to the generation of the AHP. Two L-VGCC subtypes are predominately expressed in the hippocampus, Ca V 1.2 and Ca V 1.3; however, it is not known which L-VGCC subtype is involved in generation of the AHP. This ambiguity is due in large part to the fact that at present there are no subunit-specific agonists or antagonists. Therefore, using mice in which the gene encoding Ca V 1.2 or Ca V 1.3 was deleted, we sought to determine the impact of alterations in levels of these two L-VCGG subtypes on neuronal excitability. No differences in any AHP measure were seen between neurons from Ca V 1.2 knockout mice and controls. However, the total area of the AHP was significantly smaller in neurons from Ca V 1.3 knockout mice as compared with neurons from wild-type controls. A significant reduction in the amplitude of the AHP was also seen at the 1 s time point in neurons from Ca V 1.3 knockout mice as compared with those from controls. Reductions in both the area and 1 s amplitude suggest the involvement of calcium influx via Ca V 1.3 in the slow AHP (sAHP). Thus, the results of our study demonstrate that deletion of Ca V 1.3, but not Ca V 1.2, significantly impacts the generation of the sAHP. © 2009 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/79416/1/20728_ftp.pd