Mechanisms underlying the endogenous dopaminergic inhibition of spinal locomotor circuit function in Xenopus tadpoles

This work was supported by the Biotechnology and Biological Science Research Council (BBSRC) [grant number BB/J01446X/1].Dopamine plays important roles in the development and modulation of motor control circuits. Here we show that dopamine exerts potent effects on the central pattern generator circuit controlling locomotory swimming in post-embryonic Xenopus tadpoles. Dopamine (0.5–100 μM) reduced fictive swim bout occurrence and caused both spontaneous and evoked episodes to become shorter, slower and weaker. The D2-like receptor agonist quinpirole mimicked this repertoire of inhibitory effects on swimming, whilst the D4 receptor antagonist, L745,870, had the opposite effects. The dopamine reuptake inhibitor bupropion potently inhibited fictive swimming, demonstrating that dopamine constitutes an endogenous modulatory system. Both dopamine and quinpirole also inhibited swimming in spinalised preparations, suggesting spinally located dopamine receptors. Dopamine and quinpirole hyperpolarised identified rhythmically active spinal neurons, increased rheobase and reduced spike probability both during swimming and in response to current injection. The hyperpolarisation was TTX-resistant and was accompanied by decreased input resistance, suggesting that dopamine opens a K+ channel. The K+ channel blocker barium chloride (but not TEA, glybenclamide or tertiapin-Q) significantly occluded the hyperpolarisation. Overall, we show that endogenously released dopamine acts upon spinally located D2-like receptors, leading to a rapid inhibitory modulation of swimming via the opening of a K+ channel.Publisher PDFPeer reviewe

Evolutionary Divergence in Developmental Strategies and Neuromodulatory Control Systems of Two Amphibian Locomotor Networks

Attempts to understand the neural mechanisms which produce behaviour must consider both prevailing sensory cues and the central cellular and synaptic changes they direct. At each level, neuromodulation can additionally shape the final output. We have investigated neuromodulation in the developing spinal motor networks in hatchling tadpoles of two closely related amphibians, Xenopus laevis and Rana temporaria to examine the subtle differences in their behaviours that could be attributed to their evolutionary divergence. At the point of hatching, both species can swim in response to a mechanosensory stimulus, however Rana embryos often display a more forceful, non-locomotory coiling behaviour. Whilst the synaptic drive that underlies these behaviours appears similar, subtle inter-specific differences in neuronal properties shape motor outputs in different ways. For example, Rana neurons express N-methyl-D-aspartate (NMDA)/serotonin (5-HT)-dependent oscillations, not present in hatchling Xenopus and many also exhibit a prominent slow spike after-hyperpolarisation. Such properties may endow the spinal circuitry of Rana with the ability to produce a more flexible range of outputs. Finally, we compare the roles of the neuromodulators 5-HT, noradrenaline (NA) and nitric oxide (NO) in shaping motor outputs. 5-HT increases burst durations during swimming in both Xenopus and Rana, but 5-HT dramatically slows the cycle period in Rana with little effect in Xenopus. Three distinct, but presumably homologous NO-containing brainstem clusters of neurons have been described, yet the effects of NO differ between species. In Xenopus, NO slows and shortens swimming in a manner similar to NA, yet in Rana NO and NA elicit the non-rhythmic coiling pattern

α_1L-adrenoceptors mediate contraction of human erectile tissue

α1-adrenoceptor antagonists can impact upon sexual function and have potential in the treatment of erectile dysfunction. Human erectile tissue contains predominantly α1A-adrenoceptors, and here we examined whether contractions of this tissue are mediated by the functional phenotype, the α1L-adrenoceptor. Functional experiments using subtype selective agonists and antagonists, along with radioligand ([3H]tamsulosin) binding assays, were used to determine the α1-adrenoceptor population. A61603, a α1A-adrenoceptor agonist, was a full agonist with a potency 21-fold greater than that of noradrenaline. The α1A- and α1D-adrenoceptor antagonist tamsulosin antagonized noradrenaline responses with high affinity (pKD = 9.7 ± 0.3), whilst BMY7378 (100 nM) (α1D-adrenoceptor antagonist) failed to antagonize responses. In contrast, relatively low affinity estimates were obtained for both prazosin (pKD = 8.2 ± 0.1) and RS17053 (pKD = 6.9 ± 0.2), antagonists which discriminate between the α1A- and α1L-adrenoceptors. [3H]Tamsulosin bound with high affinity to the receptors of human erectile tissue (pKD = 10.3 ± 0.1) with a receptor density of 28.1 ± 1.4 fmol mg−1 protein. Prazosin displacement of [3H]tamsulosin binding revealed a single homogenous population of binding sites with a relatively low affinity for prazosin (pKi = 8.9). Taken together these data confirm that the receptor mediating contraction in human erectile tissue has the pharmacological properties of the α1L-adrenoceptor. Keywords: Erectile tissue, α1-adrenoceptor subtypes, α1L-adrenoceptor, Tamsulosin, Prazosi

Sodium pumps mediate activity-dependent changes in mammalian motor networks

Funding: Laurence Picton [grant number BB/JO1446X/1] and Matthew Broadhead [grant number BB/M021793/1] were supported by the Biotechnology and Biological Science Research Council (BBSRC). Filipe Nascimento was supported by The Alfred Dunhill Links Foundation.Ubiquitously expressed sodium pumps are best known for maintaining the ionic gradients and resting membrane potential required for generating action potentials. However, activity- and state-dependent changes in pump activity can also influence neuronal firing and regulate rhythmic network output. Here we demonstrate that changes in sodium pump activity regulate locomotor networks in the spinal cord of neonatal mice. The sodium pump inhibitor, ouabain, increased the frequency and decreased the amplitude of drug-induced locomotor bursting, effects that were dependent on the presence of the neuromodulator dopamine. Conversely, activating the pump with the sodium ionophore monensin decreased burst frequency. When more "natural" locomotor output was evoked using dorsal-root stimulation, ouabain increased burst frequency and extended locomotor episode duration, whereas monensin slowed and shortened episodes. Decreasing the time between dorsal-root stimulation, and therefore interepisode interval, also shortened and slowed activity, suggesting that pump activity encodes information about past network output and contributes to feedforward control of subsequent locomotor bouts. Using whole-cell patch-clamp recordings from spinal motoneurons and interneurons, we describe a long-duration (∼60 s), activity-dependent, TTX- and ouabain-sensitive, hyperpolarization (∼5 mV), which is mediated by spike-dependent increases in pump activity. The duration of this dynamic pump potential is enhanced by dopamine. Our results therefore reveal sodium pumps as dynamic regulators of mammalian spinal motor networks that can also be affected by neuromodulatory systems. Given the involvement of sodium pumps in movement disorders, such as amyotrophic lateral sclerosis and rapid-onset dystonia parkinsonism, knowledge of their contribution to motor network regulation also has considerable clinical importance.Publisher PDFPeer reviewe

Blockade of ROS production inhibits oncogenic signaling in acute myeloid leukemia and amplifies response to precision therapies

Mutations in the type III receptor tyrosine kinase FLT3 are frequent in patients with acute myeloid leukemia (AML) and are associated with a poor prognosis. AML is characterized by the overproduction of reactive oxygen species (ROS), which can induce cysteine oxidation in redox-sensitive signaling proteins. Here, we sought to characterize the specific pathways affected by ROS in AML by assessing oncogenic signaling in primary AML samples. The oxidation or phosphorylation of signaling proteins that mediate growth and proliferation was increased in samples from patient subtypes with FLT3 mutations. These samples also showed increases in the oxidation of proteins in the ROS-producing Rac/NADPH oxidase-2 (NOX2) complex. Inhibition of NOX2 increased the apoptosis of FLT3-mutant AML cells in response to FLT3 inhibitors. NOX2 inhibition also reduced the phosphorylation and cysteine oxidation of FLT3 in patient-derived xenograft mouse models, suggesting that decreased oxidative stress reduces the oncogenic signaling of FLT3. In mice grafted with FLT3 mutant AML cells, treatment with a NOX2 inhibitor reduced the number of circulating cancer cells, and combining FLT3 and NOX2 inhibitors increased survival to a greater extent than either treatment alone. Together, these data raise the possibility that combining NOX2 and FLT3 inhibitors could improve the treatment of FLT3 mutant AML

Persistent Place-Making in Prehistory: the Creation, Maintenance, and Transformation of an Epipalaeolithic Landscape

Most archaeological projects today integrate, at least to some degree, how past people engaged with their surroundings, including both how they strategized resource use, organized technological production, or scheduled movements within a physical environment, as well as how they constructed cosmologies around or created symbolic connections to places in the landscape. However, there are a multitude of ways in which archaeologists approach the creation, maintenance, and transformation of human-landscape interrelationships. This paper explores some of these approaches for reconstructing the Epipalaeolithic (ca. 23,000–11,500 years BP) landscape of Southwest Asia, using macro- and microscale geoarchaeological approaches to examine how everyday practices leave traces of human-landscape interactions in northern and eastern Jordan. The case studies presented here demonstrate that these Epipalaeolithic groups engaged in complex and far-reaching social landscapes. Examination of the Early and Middle Epipalaeolithic (EP) highlights that the notion of “Neolithization” is somewhat misleading as many of the features we use to define this transition were already well-established patterns of behavior by the Neolithic. Instead, these features and practices were enacted within a hunter-gatherer world and worldview

Ontologías en disputa: Diálogos entre la antropología y la arqueología para la problematización de paisajes regionals

Objetivo/contexto: Hacia finales del siglo XX, el dualismo ontológico con el que antropólogos y arqueólogos nos hemos formado teórica y metodológicamente ha sido cuestionado y puesto en debate. En este contexto, nuestro objetivo es exponer críticamente los trabajos que se están realizando y que contribuyen a problematizar los paisajes enredados de existencias, materialidades, saberes, sentidos o prejuicios pasados y presentes, y con ello a restablecer el diálogo entre la antropología social y la arqueología. Metodología: Exponemos el estado actual de la apertura ontológica en clave latinoamericana. Problematizamos la noción de paisaje como concepto que permite diálogos teórico-metodológicos entre la antropología y la arqueología, así como con otras disciplinas. También presentamos ejes de comunicación y diálogo entre los artículos que forman parte del presente dossier para finalizar con los desafíos por delante en cuanto a traspasar fronteras disciplinarias, temporales y espaciales. Conclusiones: En contextos de históricas relaciones de poder, de profundas crisis socio-ambientales, los principales desafíos de la apertura ontológica serían: 1) generar referentes teóricos permeables a diversas disciplinas y saberes; 2) consolidar metodologías que integren lo etnográfico con lo arqueológico; 3) alentar diálogos constructivos hacia y con otras disciplinas y saberes, y 4) propiciar la comprensión del entramado político actual y la generación de políticas públicas que permitan diversas formas de relacionamiento con el entorno. Originalidad: El restablecimiento de diálogos entre la arqueología y la antropología social desde las aperturas ontológicas tiene el potencial de discutir cómo en determinados contextos se concretan y/o disputan paisajes y modos hegemónicos de habitar en el mundo, así como se problematizan los usos políticos del pasado y las políticas de uso del espacio y el ambiente.Objective/context: Towards the end of the 20th century, the ontological dualism with which anthropologists and archaeologists have trained us theoretically and methodologically has been questioned and debated. In this context, our objective is to critically expose the works that are being carried out and that contribute to problematizing the landscapes entangled with past and present existences, materialities, knowledge, senses or prejudices, and, with it, to re-establish the dialogue between social anthropology and archaeology. Methodology: We expose the current state of the ontological opening in Latin American code. We problematize the notion of landscape as a concept that allows theoretical-methodological dialogues between anthropology and archaeology, as well as with other disciplines. We also present axes of communication and dialogue between the articles that are part of this dossier, to end with the challenges ahead in terms of crossing disciplinary, temporal and spatial borders. Conclusions: In contexts of historical power relations, of deep socio-environmental crises, the main challenges for an ontological opening would be: 1) to generate theoretical referents permeable to various disciplines and fields of knowledge; 2) to consolidate methodologies that integrate the ethnographic with the archaeological; 3) to encourage constructive dialogues towards and with other disciplines and fields of knowledge; and 4) to propitiate the understanding of the current political framework and the generation of public policies that allow for diverse forms of relation with the environment. Originality: The re-establishment of dialogues between archaeology and social anthropology from ontological openings has the potential to discuss how, in certain contexts, landscapes and hegemonic ways of living are concretized and/or disputed, as well as the political uses of the past and the policies of use of space and the environment.Objetivo/contexto: No final do século XX, o dualismo ontológico com o qual antropólogos e arqueólogos se formaram teórica e metodologicamente vem sendo questionado e colocado em debate. Nesse contexto, nosso objetivo é expor criticamente os trabalhos que estão sendo realizados e que contribuem para problematizar as paisagens permeadas de existências, materialidades, saberes, sentidos ou preconceitos passados e presentes, e, com isso, reestabelecer o diálogo entre a antropologia social e a arqueologia. Metodologia: Expomos o estado atual da abertura ontológica no âmbito latino-americano. Problematizamos a noção de paisagem como conceito que permite diálogos teórico-metodológicos entre a antropologia e a arqueologia, assim como outras disciplinas. Também apresentamos eixos de comunicação e diálogo entre os artigos que fazem parte do presente dossiê para finalizar com os desafios que temos adiante sobre ultrapassar fronteiras disciplinares, temporais e espaciais. Conclusões: Em contextos de históricas relações de poder, de profundas crises socioambientais, os principais desafios para uma abertura ontológica seriam: 1) gerar referentes teóricos permeáveis a diversas disciplinas e saberes; 2) consolidar metodologias que integrem o etnográfico com o arqueológico; 3) promover diálogos construtivos com outras disciplinas e saberes; e 4) propiciar a compreensão da estrutura política atual e a geração de políticas públicas que permitam as diversas formas de relacionamentos com o ambiente. Originalidade: O reestabelecimento de diálogos entre a arqueologia e a antropologia social a partir das aberturas ontológicas tem o potencial de discutir como, em determinados contextos, se concretizam e/ou disputam paisagens e modos hegemônicos de habitar, bem como se problematizam os usos políticos do passado e as políticas de uso do espaço e do ambiente.Fil: Saldi, Leticia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Mafferra, Luis Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Barrientos Salinas, J. Alejandro. Universidad Mayor de San Andrés; Bolivi

Nitric oxide selectively tunes inhibitory synapses to modulate vertebrate locomotion

We have explored the possible modulation by nitric oxide (NO) of inhibitory synaptic transmission mediated by either glycine or GABA during episodes of rhythmic fictive swimming in postembryonic Xenopus laevis tadpoles. Extracellular ventral-root recordings suggest a stage-dependent increase in the reliability and extent of the NO donor S-nitroso-n-acetylpenicillamine (SNAP; 0.1–1 mM) to inhibit swimming by reducing the frequency and shortening the duration of swim episodes. These effects of SNAP on the swimming rhythm at both developmental stages are corroborated by intracellular recordings from presumed motor neurons with sharp microelectrodes, which also suggest that NO inhibits swimming by facilitating both glycinergic and GABAergic inhibition. However, we found no evidence for NO modulation of the excitatory drive for swimming. In addition to presynaptic effects on inhibitory transmitte

PSMA-PET detected port site recurrence of prostate cancer following minimally invasive radical prostatectomy and utilisation of hookwire localisation for excision

Biochemical recurrence following prostate cancer treatment is well-known, with predictable sites typically observed in the prostate bed, lymph nodes, or skeleton. The emergence of PSMA-PET scans has revealed the potential for early recurrence in non-conventional sites, including port site metastases. Our report presents a rare case of abdominal wall metastasis detected 97 months post-prostatectomy. The excision of this subcutaneous lesion using image-guided hookwire techniques showed promise in minimising morbidity while providing successful oncologic outcomes. Further investigation is needed to establish the efficacy of PSMA-PET-guided interventions on long-term patient outcomes in treating prostate cancer port site metastases

Synthesis of fluorinated analogues of the neurosteroid GABA(A) receptor antagonist, 17-PA

The steroid 17-PA is a GABA(A) receptor antagonist which is finding use as a tool in evaluating agonistic/antagonistic activity at GABA(A) receptors. Compounds with improved efficacy over 17-PA would be are advantageous for such studies. Accordingly a series of novel analogues of the neurosteroid 17-PA have been prepared and a convenient two-step route is presented which is amenable to the synthesis of analogues with electron-donating para-aromatic substituents including fluorine. However, for the metafluoro analogue then the original four-step route to 17-PA remains more efficient overall. The paper describes these syntheses and discusses the electronic factors which influence this synthetic chemistry. (c) 2008 Elsevier B.V. All rights reserved.</p