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Journal of Physiology

Eric Salter, Julia Sunstrum, Sara Matovic, Wataru Inoue
KEY POINTS: Glutamatergic synaptic inputs to corticotropin releasing hormone (CRH) secreting neurons in the paraventricular nucleus of the hypothalamus (PVN) are required for stress-induced activation of the hypothalamic-pituitary-adrenal (HPA) axis. These synapses also undergo stress-induced plasticity thereby influencing HPA axis stress adaptation. By using patch clamp electrophysiology, we show that, in adult non-stressed mice, action potentials at these glutamatergic afferents elicit multiquantal transmission to the postsynaptic PVN-CRH neurons (i...
June 14, 2018: Journal of Physiology
Joshua C Drake
No abstract text is available yet for this article.
June 13, 2018: Journal of Physiology
Reshma Basak, Rishikesh Narayanan
A prominent hypothesis spanning several sensory-perceptual systems implicates spatially clustered synapses in the generation of dendritic spikes that mediate sharply-tuned neuronal responses to input features. In this conductance-based morphologically-precise computational study, we tested this hypothesis by systematically analyzing the impact of distinct synaptic and channel localization profiles on sharpness of spatial tuning in hippocampal pyramidal neurons. We found that the generation of dendritic spikes, the emergence of an excitatory ramp in somatic voltage responses, the expression of several intrinsic somatodendritic functional maps and sharp tuning of place-cell responses were all attainable even when iso-feature synapses are randomly dispersed across the dendritic arbor of models with disparate channel combinations...
June 12, 2018: Journal of Physiology
David G Allen
No abstract text is available yet for this article.
June 11, 2018: Journal of Physiology
Ying-Zu Huang, Rou-Shayn Chen, Po-Yu Fong, John C Rothwell, Wen-Li Chuang, Yi-Hsin Weng, Wey-Yil Lin, Chin-Song Lu
KEY POINTS SUMMARY: Plasticity is involved in daily activities but abnormal plasticity may be deleterious. In this study, we found that motor plasticity could be modulated by suppressing the premotor cortex with the theta burst form of repetitive transcranial magnetic stimulation. Such changes in motor plasticity were associated with reduced learning of a simple motor task. We postulate that the premotor cortex adjusts the amount of motor plasticity to modulate motor learning through heterosynaptic metaplasticity...
June 11, 2018: Journal of Physiology
Stephen A Coombes, Wei-En Wang, Arnab Roy, Rachel L M Ho
No abstract text is available yet for this article.
June 9, 2018: Journal of Physiology
Virginia H Huxley, Scott S Kemp, Christine Schramm, Steve Sieveking, Susan Bingaman, Yang Yu, Isabella Zaniletti, Kevin Stockard, Jianjie Wang
KEY POINTS: Endothelial dysfunction is an early hallmark of multiple disease states that also display sex differences with respect to age of onset, frequency, and severity. Results of in vivo studies of basal and stimulated microvascular barrier function revealed sex differences difficult to ascribe to specific cells or environmental factors. The present study evaluated endothelial cells (EC) isolated from macro- and/or microvessels of reproductively mature rats under the controlled conditions of low-passage culture to test the assumption that EC phenotype would be sex-independent...
June 9, 2018: Journal of Physiology
Miguel A Zarate, Eileen I Chang, Charles E Wood
Umbilical cord occlusion (UCO) is known to cause neurological disorders in the neonate. Previously, we have reported that hypoxic hypoxia (HH) stimulates the appearance of bacteria in the fetal brain and upregulates the expression of inflammatory markers in fetal cerebral cortex (CTX), and ketamine attenuates these responses. Here, we aimed to test the hypothesis that UCO, like HH, produces an inflammatory response in the fetal CTX, and the treatment with ketamine reduces these effects. In chronically instrumented fetal sheep (∼125d), 30-minute partial UCO decreased fetal Pa O2 levels by approximately 50%...
June 8, 2018: Journal of Physiology
Christy-Lynn M Cooke, Amin Shah, Raven D Kirschenman, Anita L Quon, Jude S Morton, Alison S Care, Sandra T Davidge
Exposure to prenatal stressors, including hypoxia, micro- and macro-nutrient deficiency, and maternal stress, increases the risk of cardiovascular disease in adulthood. It is unclear whether being born from a mother of advanced maternal age (≥ 35 years old) may also constitute a prenatal stress with cardiovascular consequences in adulthood. We previously demonstrated growth restriction in fetuses from a rat model of advanced maternal age, suggesting exposure to a compromised in utero environment. Thus, we hypothesized that male and female offspring from aged dams would exhibit impaired cardiovascular function as adults...
June 7, 2018: Journal of Physiology
Daniel F Feeney, Diba Mani, Roger M Enoka
We investigated the associations between grooved pegboard times, force steadiness (coefficient of variation for force), and variability in an estimate of the common synaptic input to motor neurons innervating the wrist extensor muscles during steady contractions performed by young and older adults. The discharge times of motor units were derived from recordings obtained with high-density surface electrodes while participants performed steady isometric contractions at 10% and 20% of maximal voluntary contraction (MVC) force...
June 7, 2018: Journal of Physiology
Ludovico Messineo, Luigi Taranto-Montemurro, Ali Azarbarzin, Melania D Oliveira Marques, Nicole Calianese, David P White, Andrew Wellman, Scott A Sands
Background Increased "loop gain" of the ventilatory control system promotes obstructive sleep apnea (OSA) in some patients and offers an avenue for more personalized treatment, yet diagnostic tools for directly measuring loop gain in the clinical setting are lacking. Here we test the hypothesis that elevated loop gain during sleep can be recognized using voluntary breath-hold maneuvers during wakefulness. Methods Twenty individuals (10 OSA, 10 controls) participated in a single overnight study with voluntary breath-holding maneuvers performed during wakefulness...
June 7, 2018: Journal of Physiology
Reika Kubo, Atsu Aiba, Kouichi Hashimoto
Perioral tactile signals are transmitted via the infraorbital nerve (ION) to trigeminal nuclei. Each cerebellar Purkinje cell receives this signal as complex spikes (CSs) via a climbing fibre emerging from the inferior olive (IO). However, the anatomical pathway from the trigeminal nuclei to the IO is not clearly identified. In the present study, we recorded CSs from Purkinje cells in male mice by single unit recording, and examined the signal transduction pathway. CSs were evoked by electrical stimulation of the ipsilateral or contralateral ION with a latency of 20-70 ms...
June 6, 2018: Journal of Physiology
Charlotte Gineste, Alexandre Fouré
No abstract text is available yet for this article.
June 6, 2018: Journal of Physiology
Hikaru Hashitani, Retsu Mitsui, Kyoko Miwa-Nishimura, Michelle Lam
Mural cells in microvasculature of visceral organs develop spontaneous Ca2+ transients. However, the mechanisms underlying the integration of these Ca2+ transients within a microvascular unit remain to be elucidated. Here, the origin of spontaneous Ca2+ transients and their propagation in the bladder suburothelial microvasculature were explored. Cal-520 fluorescence Ca2+ imaging and immunohistochemistry were carried out on mural cells using mice expressing DsRed under control of the NG2 promotor. NG2(+) pericytes in both pre-capillary arterioles (PCAs) and capillaries developed synchronous spontaneous Ca2+ transients...
June 6, 2018: Journal of Physiology
Laura Thei, Eridan Rocha-Ferreira, Donald Peebles, Gennadij Raivich, Mariya Hristova
Hypoxia-ischemia (HI) is a major cause of neonatal brain injury resulting in cerebral palsy, epilepsy, cognitive impairment and other neurological disabilities. The role of Extracellular signal-Regulated Kinase (ERK) isoforms and their MEK-dependent phosphorylation in HI has previously been explored but remains unresolved at cellular level. This is pertinent given the growing awareness of the role of non-neuronal cells in neuroprotection. Using a modified Rice-Vannuccci model of HI in the neonatal mouse we observed time and cell-dependent ERK phosphorylation (pERK), with strongly up-regulated pERK immunoreactivity first in periventricular white matter axons within 15-45 min of HI, followed by forebrain astrocytes and neurons (1-4 h post HI), and return to baseline by 16 h...
June 6, 2018: Journal of Physiology
Johannes Knabbe, Joris Paul Nassal, Matthijs Verhage, Thomas Kuner
Neuronal dense core vesicles (DCVs) transport many cargo molecules like neuropeptides and neurotrophins to their release sites in dendrites or axons. The transport properties of DCVs in axons of the intact mammalian brain are unknown. We used viral expression of a DCV cargo reporter (NPY-Venus/Cherry) in the thalamus and two-photon in vivo imaging to visualize axonal DCV trafficking in thalamocortical projections of anesthetized and awake mice. We found an average speed of 1 μm/s, maximal speeds of up to 5 μm/s and a pausing fraction of ˜11 %...
June 6, 2018: Journal of Physiology
Christopher M Gonçalves, Daniel K Mulkey
KEY POINTS: changes in CO2 result in corresponding changes in both H+ and HCO3 - and despite evidence that HCO3 - can function as an independent signaling molecule, there is little evidence suggesting HCO3 - contributes to respiratory chemoreception. We show that HCO3 - directly activates chemosensitive RTN neurons. Identifying all relevant signaling molecules is essential for understanding how chemoreceptors function, and since HCO3 - and H+ are buffered by separate cellular mechanisms, having the ability to sense both modalities adds additional information regarding changes in CO2 that are not necessarily reflected by pH alone...
June 5, 2018: Journal of Physiology
Weonjin Yu, Jaehan Kwon, Jong-Woo Sohn, Suk Ho Lee, Sooyun Kim, Won-Kyung Ho
KEY POINTS: High-frequency stimulation (HFS) of the Schaffer collateral pathways activates metabotropic glutamate receptor 5 (mGluR5) signaling in the proximal apical dendrites of CA1 pyramidal neurons. The synaptic activation of mGluR5-mediated calcium signaling causes a significant increase in persistent sodium current (INa,P ) in the dendrites. Increased INa,P by HFS underlies potentiation of synaptic inputs at both the proximal and distal dendrite, leading to the enhanced probability of AP firing associated with decreased AP thresholds...
June 5, 2018: Journal of Physiology
Kimberly O O'Brien, Steven A Abrams
Skeletal mineralization is initiated in utero and continues throughout childhood and adolescence. During these key periods of the life cycle calcium retention must increase significantly to provide sufficient mineral for bone deposition and skeletal growth. Stable calcium isotopes have served as a fundamental tool to non-invasively characterize the dynamic changes in calcium physiology that occur from infancy through adolescence. These approaches have helped define the dynamics of calcium absorption and utilization in healthy children and in children with chronic diseases...
June 5, 2018: Journal of Physiology
Eva-Maria Reuter
No abstract text is available yet for this article.
June 5, 2018: Journal of Physiology
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