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1.
J Biol Chem ; 2020 Mar 24.
Artigo em Inglês | MEDLINE | ID: mdl-32209659

RESUMO

Major depression is a prevalent affective disorder characterized by recurrent low mood. It presumably results from stress-induced deteriorations of molecular networks and synaptic functions in brain reward circuits of genetically susceptible individuals through epigenetic processes. Epigenetic regulator microRNA-15b inhibits neuronal progenitor proliferation and is upregulated in the medial prefrontal cortex of mice that demonstrate depression-like behavior, indicating the contribution of microRNA-15 to major depression. Using a mouse model of major depression induced by chronic unpredictable mild stress (CUMS), here we examined the effects of microRNA-15b on synapses and synaptic proteins in the nucleus accumbens of these mice. The application of a microRNA-15b antagomir into the nucleus accumbens significantly reduced the incidence of CUMS-induced depression and reversed the attenuations of excitatory synapse and syntaxin-binding protein 3 (STXBP3A) /vesicle-associated protein 1 (VAMP1) expression. In contrast, the injection of a microRNA-15b analog into the nucleus accumbens induced depression-like behavior as well as attenuated excitatory synapses and STXBP3A/VAMP1 expression similarly to the downregulation of these processes induced by the CUMS. We conclude that microRNA-15b-5p may play a critical role in chronic stress-induced depression by decreasing synaptic proteins, innervations and activities in the nucleus accumbens. We propose that the treatment of anti-microRNA-15b-5p may convert stress-induced depression into resilience.

2.
Oncotarget ; 9(57): 30962-30978, 2018 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-30123420

RESUMO

Neuronal plasticity occurs in associative memory. Associative memory cells are recruited for the integration and storage of associated signals. The coordinated refinements and interactions of associative memory cells including glutamatergic and GABAergic neurons remain elusive, which we have examined in a mouse model of associative learning. Paired olfaction, tail and whisker stimulations lead to odorant-induced and tail-induced whisker motions alongside whisker-induced whisker motion. In mice that show this cross-modal associative memory, barrel cortical glutamatergic and GABAergic neurons are recruited to encode the newly learned odor and tail signals alongside the innate whisker signal. These glutamatergic neurons are functionally upregulated, and GABAergic neurons are refined in a homeostatic manner. The mutual innervations between these glutamatergic and GABAergic neurons are upregulated. Therefore, the co-activations of sensory cortices by pairing the input signals recruit their glutamatergic and GABAergic neurons to be associative memory cells, which undergo coordinated refinement among glutamatergic and GABAergic neurons as well as homeostatic plasticity among subcellular compartments in order to drive these cells toward the optimal state for the integrative storage of associated signals.

3.
Oncotarget ; 8(22): 35933-35945, 2017 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-28415589

RESUMO

BACKGROUND: Major depression, persistent low mood, is one of common psychiatric diseases. Chronic stressful life is believed to be a major risk factor that leads to dysfunctions of the limbic system. However, a large number of the individuals with experiencing chronic stress do not suffer from major depression, called as resilience. Endogenous mechanisms underlying neuronal invulnerability to chronic stress versus major depression are largely unknown. As GABAergic neurons are vulnerable to chronic stress and their impairments is associated with major depression, we have examined whether the invulnerability of GABAergic neurons in the limbic system is involved in resilience. RESULTS: GABAergic neurons in the nucleus accumbens from depression-like mice induced by chronic unpredictable mild stress appear the decreases in their GABA release, spiking capability and excitatory input reception, compared with those in resilience mice. The levels of decarboxylase and vesicular GABA transporters decrease in depression-like mice, but not resilience. MATERIALS AND METHODS: Mice were treated by chronic unpredictable mild stress for three weeks. Depression-like behaviors or resilience was confirmed by seeing whether their behaviors change significantly in sucrose preference, Y-maze and forced swimming tests. Mice from controls as well as depression and resilience in response to chronic unpredictable mild stress were studied in terms of GABAergic neuron activity in the nucleus accumbens by cell electrophysiology and protein chemistry. CONCLUSIONS: The impairment of GABAergic neurons in the nucleus accumbens is associated with major depression. The invulnerability of GABAergic neurons to chronic stress may be one of cellular mechanisms for the resilience to chronic stress.


Assuntos
Transtorno Depressivo Maior/etiologia , Transtorno Depressivo Maior/metabolismo , Neurônios GABAérgicos/metabolismo , Núcleo Accumbens/metabolismo , Resiliência Psicológica , Estresse Fisiológico , Animais , Comportamento Animal , Transtorno Depressivo Maior/psicologia , Modelos Animais de Doenças , Masculino , Camundongos , Modelos Biológicos , Transmissão Sináptica
4.
PLoS One ; 11(11): e0166535, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27861545

RESUMO

BACKGROUND: Stressful life leads to mood disorders. Chronic mild stress is presumably major etiology for depression, and acute severe stress leads to anxiety. These stressful situations may impair hypothalamus-pituitary-adrenal axis and in turn induce synapse dysfunction. However, it remains elusive how the stress hormones mess up subcellular compartments and interactions between excitatory and inhibitory neurons, which we have investigated in mouse amygdala, a structure related to emotional states. METHODS AND RESULTS: Dexamethasone was chronically given by intraperitoneal injection once a day for one week or was acutely washed into the brain slices. The neuronal spikes and synaptic transmission were recorded by whole-cell patching in amygdala neurons of brain slices. The chronic or acute administration of dexamethasone downregulates glutamate release as well as upregulates GABA release and GABAergic neuron spiking. The chronic administration of dexamethasone also enhances the responsiveness of GABA receptors. CONCLUSION: The upregulation of GABAergic neurons and the downregulation of glutamatergic neurons by glucocorticoid impair their balance in the amygdala, which leads to emotional disorders during stress.


Assuntos
Tonsila do Cerebelo/citologia , Tonsila do Cerebelo/fisiologia , Neurônios GABAérgicos/efeitos dos fármacos , Neurônios GABAérgicos/fisiologia , Glucocorticoides/farmacologia , Ácido Glutâmico/metabolismo , Neurônios/efeitos dos fármacos , Neurônios/fisiologia , Tonsila do Cerebelo/efeitos dos fármacos , Animais , Dexametasona/farmacologia , Potenciais da Membrana/efeitos dos fármacos , Camundongos , Receptores de GABA/metabolismo , Ácido gama-Aminobutírico/metabolismo
5.
Zhong Yao Cai ; 37(12): 2234-9, 2014 Dec.
Artigo em Chinês | MEDLINE | ID: mdl-26080511

RESUMO

OBJECTIVE: Five kinds of Ephedra alkaloids (NME, NMP, E, PE and ME) in Ephedrae Herba extracts and Ephedrae Herba-Atractylodis Macrocephalae Rhizoma herbal pair extracts of plasma pharmacokinetic and tissue distribution study in rats were carried out, to discuss the changes of Ephedrae Herba compatibility with Atractylodis Macrocephalae Rhizoma before and after METHODS: HPLC- MS method was used and the condition was as flollows: ZORBAX SB-C18 column (100 mm x 2.1 mm, 3.5 µm), column temperature of 35 °C, mobile phase of ACE-0.1% formic solution in gradient elution mode, flow rate at 0.4 mL/min; MRM positive ion detection mode. RESULTS: The distribution trends of Ephedra alkaloids were changing in plasma and tissues of rats after Ephedrae Herba compati- bility with Atractylodis Macrocephalae Rhizoma. CONCLUSION: Ephedrae Herba compatibility with Atractylodis Macrocephalae Rhizoma may increase drug efficacy and reduce the toxicity of Ephedra alkaloids at the same time.


Assuntos
Alcaloides/farmacocinética , Medicamentos de Ervas Chinesas/farmacocinética , Animais , Atractylodes/química , Cromatografia Líquida de Alta Pressão , Ephedra/química , Espectrometria de Massas , Ratos , Rizoma/química , Distribuição Tecidual
6.
Opt Express ; 18(8): 8453-8, 2010 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-20588691

RESUMO

We report the capture of images via a wedge light-guide without the margin for fan-in needed heretofore. While this lets one look out of a slim panel as if it were a periscope, half the power is lost and resolution is degraded by aperture diffraction. Volume gratings may resolve these drawbacks at certain wavelengths and we consider how these might be extruded.

7.
Opt Lett ; 33(20): 2374-6, 2008 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-18923627

RESUMO

We observe spectral hole burning in a room-temperature optical fiber pumped by a spectrally broadened pump beam. This beam drives the stimulated Brillouin process, creating an inhomogeneously broadened resonance in the material whose shape can be engineered by tailoring the beam's spectrum. A monochromatic saturating beam "burns" a narrow spectral hole that is approximately 10(4) times narrower than the inhomogeneous width of the resonance. This research paves the way toward agile optical information processing and storage using standard telecommunication components.

8.
Science ; 318(5857): 1748-50, 2007 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-18079395

RESUMO

We describe a method for storing sequences of optical data pulses by converting them into long-lived acoustic excitations in an optical fiber through the process of stimulated Brillouin scattering. These stored pulses can be retrieved later, after a time interval limited by the lifetime of the acoustic excitation. In the experiment reported here, smooth 2-nanosecond-long pulses are stored for up to 12 nanoseconds with good readout efficiency: 29% at 4-nanosecond storage time and 2% at 12 nanoseconds. This method thus can potentially store data packets that are many bits long. It can be implemented at any wavelength where the fiber is transparent and can be incorporated into existing telecommunication networks because it operates using only commercially available components at room temperature.

9.
Opt Lett ; 32(14): 1986-8, 2007 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-17632618

RESUMO

A slow-light medium based on multiple, closely spaced gain lines is studied. The spacings and relative strengths of the gain lines are optimized by using the criteria of gain penalty and eye-opening penalty to maximize the fractional delay defined in terms of the best decision time for random pulse trains. Both numerical calculations and experiments show that an optimal design of a triple-gain-line medium can achieve a maximal fractional delay about twice that which can be obtained with a single-gain-line medium, at three times higher modulation bandwidth, while high data fidelity is still maintained.

10.
Opt Express ; 15(4): 1878-83, 2007 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-19532426

RESUMO

We demonstrate, via simulation and experiment, slowing down of a phase-modulated optical signal. A 10.7-Gb/s NRZ-DPSK signal can be delayed by as much as 42 ps while still achieving error free via broadband SBS-based slow light. We further analyze the impact of slow-light-induced data-pattern dependence on both constructive and destructive demodulated ports. By detuning the SBS gain profile, we achieve 3-dB Q-factor improvement by the reduction of pattern dependence. Performance comparison between NRZ-DPSK and RZ-DPSK shows that robustness to slow-light-induced pattern dependence is modulation format dependent.

11.
Opt Express ; 14(16): 7238-45, 2006 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-19529093

RESUMO

Slow-light delay via stimulated Brillouin scattering (SBS) in optical fibers is usually achieved with delay-dependent amplification that degrades system performance. To address this problem, we propose a SBS slow-light method that makes use of two widely separated anti-Stokes absorption resonances, and achieve nearly transparent slow light in an optical fiber. We demonstrate the method in a highly nonlinear optical fiber, and achieve a slow-light bandwidth of approximately 150 MHz and a relative of delay of approximately 0.3 for approximately 9-ns pulses with a signal attenuation of approximately 4.8 dB.


Assuntos
Tecnologia de Fibra Óptica/instrumentação , Lasers , Modelos Teóricos , Fibras Ópticas , Refratometria/instrumentação , Simulação por Computador , Desenho de Equipamento , Luz , Espalhamento de Radiação
13.
Phys Rev Lett ; 94(15): 153902, 2005 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-15904146

RESUMO

We demonstrate a technique for generating tunable all-optical delays in room temperature single-mode optical fibers at telecommunication wavelengths using the stimulated Brillouin scattering process. This technique makes use of the rapid variation of the refractive index that occurs in the vicinity of the Brillouin gain feature. The wavelength at which the induced delay occurs is broadly tunable by controlling the wavelength of the laser pumping the process, and the magnitude of the delay can be tuned continuously by as much as 25 ns by adjusting the intensity of the pump field. The technique can be applied to pulses as short as 15 ns. This scheme represents an important first step towards implementing slow-light techniques for various applications including buffering in telecommunication systems.

14.
Opt Express ; 13(25): 9995-10002, 2005 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-19503210

RESUMO

We describe a methodology to maximize slow-light pulse delay subject to a constraint on the allowable pulse distortion. We show that optimizing over a larger number of physical variables can increase the distortion-constrained delay. We demonstrate these concepts by comparing the optimum slow-light pulse delay achievable using a single Lorentzian gain line with that achievable using a pair of closely-spaced gain lines. We predict that distortion management using a gain doublet can provide approximately a factor of 2 increase in slow-light pulse delay as compared with the optimum single-line delay. Experimental results employing Brillouin gain in optical fiber confirm our theoretical predictions.

15.
Opt Express ; 13(3): 998-1007, 2005 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-19494963

RESUMO

We investigate the interaction of visible supercontinuum light with fiber Bragg gratings that are UV-written in a birefringent air-silica microstructure fiber. Spectral enhancements near the grating resonance are observed, and their variations are studied by adjusting the power level and polarization of input pulses. With weak input pulses (<0.5nJ), individual Raman solitons are observed in the spectrum, and the grating generates a picosecond dispersive wave centered near its bandgap when a Raman soliton has both spatial and spectral overlap with the grating resonance. Using the nonlinear Schrödinger equation (NLSE) with a simplified model of the grating dispersion, our numerical modeling reproduces the salient features of this enhancement, and shows the important role played by grating dispersion outside the bandgap.

16.
Opt Express ; 12(4): 689-94, 2004 Feb 23.
Artigo em Inglês | MEDLINE | ID: mdl-19474872

RESUMO

Pre-chirp of the input pulse has a significant effect on pulse evolution in a photonic crystal fiber. We present numerical simulations which show that the supercontinuum bandwidth increases with the linear chirp, and that the coherence of supercontinuum improves as frequency chirping increases. An optimal positive chirp is identified that maximizes the supercontinuum bandwidth, corresponding to the formation of only one red-shifting Raman soliton.

17.
Opt Express ; 12(5): 791-6, 2004 Mar 08.
Artigo em Inglês | MEDLINE | ID: mdl-19474887

RESUMO

Besides coherence degradations, supercontinuum spectra generated in birefringent photonic crystal fibers also suffer from polarization fluctuations because of noise in the input pump pulse. This paper describes an experimental study of polarization properties of supercontinuum spectra generated in a birefringent photonic crystal fiber, validating previous numerical simulations.

18.
Opt Lett ; 28(23): 2306-8, 2003 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-14680164

RESUMO

We present a numerical study of stress-induced birefringence in microstructured optical fibers (MOFs), using a finite-element method. MOFs under lateral forces and twists are considered separately. Compared with that in standard single-mode optical fibers, stress-induced linear birefringence in MOFs under a lateral force is reduced with increasing air-hole size, whereas twist-induced circular birefringence in MOFs is enhanced when the air-hole size is small.

19.
Opt Express ; 10(17): 853-64, 2002 Aug 26.
Artigo em Inglês | MEDLINE | ID: mdl-19451938

RESUMO

In this paper we present a full-vectorial finite-difference analysis of microstructured optical fibers. A new mode solver is described which uses Yee's 2-D mesh and an index averaging technique. The modal characteristics are calculated for both conventional optical fibers and microstructured optical fibers. Comparison with previous finite difference mode solvers and other numerical methods is made and excellent agreement is achieved.

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