scholarly journals Developmental synaptic changes at the transient olivocochlear-inner hair cell synapse

2018 ◽  
Author(s):  
Graciela Kearney ◽  
Javier Zorrilla de San Martín ◽  
Lucas G. Vattino ◽  
Ana Belén Elgoyhen ◽  
Carolina Wedemeyer ◽  
...  
Keyword(s):  
Postnatal Development ◽  
Bk Channels ◽  
Inner Hair Cell ◽  
Ach Release ◽  
Short Term ◽  
Sound Stimulation ◽  
Frequency Pattern ◽  
Quantum Content ◽  
Medial Olivocochlear ◽  
And Function

AbstractIn the mature mammalian cochlea, inner hair cells (IHCs) are mainly innervated by afferent fibers that convey sound information to the central nervous system. During postnatal development, however, medial olivocochlear (MOC) efferent fibers transiently innervate the IHCs. The MOC-IHC synapse, functional from postnatal day (P)0 to hearing onset (P12), undergoes dramatic changes in the sensitivity to acetylcholine (ACh) and in the expression of key postsynaptic proteins. To evaluate whether there are associated changes in the properties of ACh release during this period, we used a cochlear preparation from mice at P4, P6-7 and P9-11 and monitored transmitter release from MOC terminals in voltage-clamped IHCs in the whole-cell configuration. The quantum content increased 5.6x from P4 to P9-11 due to increases in the size and replenishment rate of the readily releasable pool (RRP) of synaptic vesicles, without changes in their probability of release (Pvesicle) or quantum size. This strengthening in transmission was accompanied by changes in the short-term plasticity (STP) properties, which switched from facilitation at P4 to depression at P9-11. We have previously shown that at P9-11, ACh release is supported by P/Q and N-type voltage-gated calcium channels (VGCCs) and negatively regulated by BK potassium channels activated by Ca2+ influx through L-type VGCCs. We now show that at P4 and P6-7, release is mediated by P/Q-, R- and L-type VGCCs. Interestingly, L-type VGCCs have a dual role: they both support release and fuel BK channels, suggesting that at immature stages the presynaptic proteins involved in release are less compartmentalized.Significance statementDuring postnatal development prior to the onset of hearing, cochlear IHCs present spontaneous Ca2+ action potentials which release glutamate at the first auditory synapse in the absence of sound stimulation. The IHC Ca2+ action potential frequency pattern, which is crucial for the correct establishment and function of the auditory system, is regulated by the efferent MOC system that transiently innervates IHCs during this period. We show short-term synaptic plasticity properties of the MOC-IHC synapse that tightly shape this critical developmental period.

scholarly journals Smooth muscle and neural mechanisms contributing to the downregulation of neonatal rat spontaneous bladder contractions during postnatal development

2007 ◽  
Vol 292 (5) ◽  
pp. R2100-R2112 ◽  
Author(s):  
Yuen-Keng Ng ◽  
William C. de Groat ◽  
Hsi-Yang Wu
Keyword(s):  
Smooth Muscle ◽  
Postnatal Development ◽  
Electrical Field Stimulation ◽  
Bk Channels ◽  
Bk Channel ◽  
Neonatal Rat ◽  
Field Stimulation ◽  
Electrical Field ◽  
Frequency Pattern ◽  
Rat Urinary Bladder

Spontaneous bladder contractions (SBCs) in the neonatal rat urinary bladder change from a high-amplitude, low-frequency pattern to a low-amplitude, high-frequency pattern during the first 6 wk of life. Understanding the mechanism of this developmental change may provide insights into the causes of bladder overactivity in adults. In vitro whole bladder preparations from Sprague-Dawley rats were used to study the modulation of SBCs by calcium-activated potassium channels (KCa) and electrical field stimulation from 3 days to 6 wk of life. SBCs in 3-day-old bladders were unmasked by treatment with iberiotoxin (100 nM), an inhibitor of large conductance KCa (BK) channels, or apamin (100 nM), an inhibitor of small conductance KCa (SK) channels. Iberiotoxin significantly increased the magnitude of SBCs at 2–3 wk, whereas apamin was only effective at 6 wk. In 1–2 wk bladders, exposure to room temperature Krebs solution decreased SBCs. This decrease was reversed by activating intramural nerves with electrical field stimulation. The effect of electrical field stimulation was inhibited by atropine (1 μM), suramin (10 μM), or pretreatment with tetrodotoxin (1 μM) but was not reversed by tetrodotoxin applied after electrical field stimulation. BK-α mRNA increased threefold, and BK-α protein increased fivefold from 3 days to 6 wk. These data suggest that BK channels play an important role in the regulation of SBCs in the neonatal bladder and that both increased BK channel activity, as well as changes in smooth muscle sensitivity to locally released neurotransmitters contribute to the downregulation of SBCs during early postnatal development.

scholarly journals Synaptic plasticity of inhibitory synapses onto medial olivocochlear efferent neurons

2022 ◽  
Author(s):  
Lester Torres Cadenas ◽  
Hui Cheng ◽  
Catherine J.C. Weisz
Keyword(s):  
Brain Slices ◽  
Synaptic Depression ◽  
Extracellular Calcium ◽  
Outer Hair Cells ◽  
Inhibitory Synapses ◽  
Short Term ◽  
Sound Stimulation ◽  
Efferent Neurons ◽  
Medial Olivocochlear

The descending auditory system modulates the ascending system at every level. The final descending, or efferent stage, is comprised of lateral olivocochlear (LOC) and medial olivocochlear (MOC) neurons. MOC somata in the ventral brainstem project axons to the cochlea to synapse onto outer hair cells (OHC), inhibiting OHC-mediated cochlear amplification. MOC suppression of OHC function is implicated in cochlear gain control with changing sound intensity, detection of salient stimuli, attention, and protection against acoustic trauma. Thus, sound excites MOC neurons to provide negative feedback of the cochlea. Sound also inhibits MOC neurons via medial nucleus of the trapezoid body (MNTB) neurons. However, MNTB-MOC synapses exhibit short-term depression, suggesting reduced MNTB-MOC inhibition during sustained stimuli. Further, due to high rates of both baseline and sound-evoked activity in MNTB neurons in vivo, MNTB-MOC synapses may be tonically depressed. To probe this, we characterized short-term plasticity of MNTB-MOC synapses in mouse brain slices. We mimicked in vivo-like temperature and extracellular calcium conditions, and in vivo-like activity patterns of fast synaptic activation rates, sustained activation, and prior tonic activity. Synaptic depression was sensitive to extracellular calcium concentration and temperature. During rapid MNTB axon stimulation, post-synaptic currents (PSCs) in MOC neurons summated but with concurrent depression, resulting in smaller, sustained currents, suggesting tonic inhibition of MOC neurons during rapid circuit activity. Low levels of baseline MNTB activity did not significantly reduce responses to subsequent rapid activity that mimics sound stimulation, indicating that, in vivo, MNTB inhibition of MOC neurons persists despite tonic synaptic depression.

scholarly journals Plasma Neurofilament Light and Future Declines in Cognition and Function in Alzheimer’s Disease in the FIT-AD Trial

2021 ◽  
pp. 1-11
Author(s):  
Danni Li ◽  
Lin Zhang ◽  
Nathaniel W. Nelson ◽  
Michelle M. Mielke ◽  
Fang Yu
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Daily Living ◽  
Short Term ◽  
Neurofilament Light Chain ◽  
Neurofilament Light ◽  
Linear Mixed Effects ◽  
Future Studies ◽  
Rate Of Decline ◽  
And Function

Background: Utilities of blood-based biomarkers in Alzheimer’s disease (AD) clinical trials remain unknown. Objective: To evaluate the ability of plasma neurofilament light chain (NfL) to predict future declines in cognition and activities of daily living (ADL) outcomes in 26 older adults with mild-to-moderate AD dementia from the FIT-AD Trial. Methods: Plasma NfL was measured at baseline and 3 and 6 months. Cognition and ADL were assessed using the AD Assessment Scale-Cognition (ADAS-Cog) and AD Uniform Dataset Instruments and Disability Assessment for Dementia (DAD), respectively, at baseline, 3, 6, 9, and 12 months. Linear mixed effects models were used to examine the associations between baseline or change in plasma NfL and changes in outcomes. Results: Higher baseline plasma NfL was associated with greater rate of decline in ADAS-Cog from baseline to 6 months (standardized estimate of 0.00462, p = 0.02853) and in ADL from baseline to 12 months (standardized estimate of –0.00284, p = 0.03338). Greater increase in plasma NfL in short term from baseline to 3 months was associated with greater rate of decline in memory and ADL from 3 to 6 months (standardized estimate of –0.04638 [0.003], p = 0.01635; standardized estimate of –0.03818, p = 0.0435) and greater rate of decline in ADL from 3 to 12 month (standardized estimate of –0.01492, p = 0.01082). Conclusion: This study demonstrated that plasma NfL might have the potential to predict cognitive and function decline up to 12 months. However, future studies with bigger sample sizes need to confirm the findings.

Reversing the flow of short-term missions within a partnership model: Perceptual outcomes

2020 ◽  
pp. 009182962097237
Author(s):  
Simone Mulieri Twibell
Keyword(s):  
Social Capital ◽  
Social Networks ◽  
Cross Cultural ◽  
Short Term ◽  
Partnership Model ◽  
And Function ◽  
Bidirectional Flow ◽  
The Church

Short-term missions provide opportunities for the formation of cross-cultural relationships and joint evangelistic endeavors. Scholars have challenged the typical unidirectional nature of short-term mission and partnership efforts, advocating for a more bidirectional flow of resources. This article analyzes the dynamics of reverse short-term missions with the goal of understanding their contributions from the perspective of the American hosts. The author suggests that reverse short-term missions bridge social capital across social networks and function as “networks of invigoration” by bringing information benefits to their hosts. These types of exchanges have the potential to help the American church reinterpret familiar experiences and see the mission of the church in a new way. Five perceptual outcomes are identified: alteration of perspectives; service opportunities for the hosts; renewal of spiritual commitments; first-hand exposure to a different culture; and contact with faith-mission models.

Field application of pure polyethylene microplastic has no significant short-term effect on soil biological quality and function

2021 ◽  
pp. 108496
Author(s):  
Robert W. Brown ◽  
David R. Chadwick ◽  
Harriet Thornton ◽  
Miles R. Marshall ◽  
Shuikuan Bei ◽  
...  
Keyword(s):  
Field Application ◽  
Term Effect ◽  
Short Term ◽  
Short Term Effect ◽  
Biological Quality ◽  
And Function

scholarly journals Short-term post-mortality scavenging and longer term recovery after anoxia in the northern Adriatic Sea

2013 ◽  
Vol 10 (11) ◽  
pp. 7647-7659 ◽  
Author(s):  
M. Blasnig ◽  
B. Riedel ◽  
L. Schiemer ◽  
M. Zuschin ◽  
M. Stachowitsch
Keyword(s):  
Adriatic Sea ◽  
Time Lapse ◽  
Hermit Crabs ◽  
Small Scale ◽  
Short Term ◽  
Northern Adriatic Sea ◽  
Northern Adriatic ◽  
Hexaplex Trunculus ◽  
Distinct Sequence ◽  
And Function

Abstract. The northern Adriatic Sea is one of nearly 500 areas worldwide suffering widespread mortalities due to anoxia. The present study documents post-anoxia macrofauna dynamics after experimentally inducing small-scale anoxia in 24 m depth (2 plots, each 50 cm × 50 cm). Time-lapse camera deployments examined short-term scavenging of the moribund and dead organisms (multi-species clumps consisting of sponges and ascidians) over two 3-day periods (August 2009: 71.5 h, September 2009: 67.5 h). Longer term recovery (days to 2 yr) in the same two plots was examined with an independent photo series. Scavengers arrived quickly and in a distinct sequence: demersal (Gobius niger, Serranus hepatus) and benthopelagic fishes (Diplodus vulgaris, Pagellus erythrinus), followed by hermit crabs (Paguristes eremita, showing a clear day/night rhythm in presence) and gastropods (Hexaplex trunculus). This sequence is attributed to the relative speeds and densities of the organisms. The sessile fauna was largely removed or consumed within seven (August plot) and 13 (September plot) days after anoxia, confirming our first hypothesis that decaying organisms are quickly utilised. The scavengers remained in dense aggregations (e.g. up to 33 P. eremita individuals at one time) as long as dead organisms were available. No recovery of sessile macroepibenthos macroepibenthos occurred in the experimental plots one and two years after anoxia, undermining our second hypothesis that small denuded areas are more rapidly recolonised. This study underlines the sensitivity of this soft-bottom community and supports calls for reducing additional anthropogenic disturbances such as fishing practices that further impede recolonisation and threaten benthic community structure and function over the long term.

scholarly journals Effect of Short-Term Low-Nitrogen Addition on Carbon, Nitrogen and Phosphorus of Vegetation-Soil in Alpine Meadow

2021 ◽  
Vol 18 (20) ◽  
pp. 10998
Author(s):  
Zhen’an Yang ◽  
Wei Zhan ◽  
Lin Jiang ◽  
Huai Chen
Keyword(s):  
Alpine Meadow ◽  
Nitrogen Addition ◽  
Ammonium Nitrogen ◽  
N Deposition ◽  
Total Carbon ◽  
N Addition ◽  
Short Term ◽  
Nitrogen And Phosphorus ◽  
Soil Rhizosphere ◽  
And Function

As one of the nitrogen (N) limitation ecosystems, alpine meadows have significant effects on their structure and function. However, research on the response and linkage of vegetation-soil to short-term low-level N deposition with rhizosphere processes is scant. We conducted a four level N addition (0, 20, 40, and 80 kg N ha−1 y−1) field experiment in an alpine meadow on the Qinghai-Tibetan Plateau (QTP) from July 2014 to August 2016. We analyzed the community characteristics, vegetation (shoots and roots), total carbon (TC), nutrients, soil (rhizosphere and bulk) properties, and the linkage between vegetation and soil under different N addition rates. Our results showed that (i) N addition significantly increased and decreased the concentration of soil nitrate nitrogen (NO3−-N) and ammonium nitrogen, and the soil pH, respectively; (ii) there were significant correlations between soil (rhizosphere and bulk) NO3−-N and total nitrogen (TN), and root TN, and there was no strong correlation between plant and soil TC, TN and total phosphorus, and their stoichiometry under different N addition rates. The results suggest that short-term low-N addition affected the plant community, vegetation, and soil TC, TN, TP, and their stoichiometry insignificantly, and that the correlation between plant and soil TC, TN, and TP, and their stoichiometry were insignificant.

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