scholarly journals Astrocytes Amplify Neuronal Dendritic Volume Transmission Stimulated by Norepinephrine

Cell Reports ◽  
2019 ◽  
Vol 29 (13) ◽  
pp. 4349-4361.e4 ◽  
Author(s):  
Chun Chen ◽  
ZhiYing Jiang ◽  
Xin Fu ◽  
Diankun Yu ◽  
Hai Huang ◽  
...  
Keyword(s):  
Volume Transmission

Wiring and Volume Transmission in Rat Amygdala. Implications for Fear and Anxiety

2008 ◽  
Vol 33 (8) ◽  
pp. 1618-1633 ◽  
Author(s):  
Miguel Pérez de la Mora ◽  
Kirsten X. Jacobsen ◽  
Minerva Crespo-Ramírez ◽  
Candy Flores-Gracia ◽  
Kjell Fuxe
Keyword(s):  
Volume Transmission ◽  
Fear And Anxiety

Transmitter-Receptor Mismatches in Central Dopamine, Serotonin, and Neuropeptide Systems: Further Evidence for Volume Transmission

2003 ◽  
pp. 083-108 ◽  
Author(s):  
Anders Jansson ◽  
Laurent Descarries ◽  
Virginia Cornea-Hébert ◽  
Mustapha Riad ◽  
Daniel Vergé ◽  
...  
Keyword(s):  
Volume Transmission

scholarly journals Dopamine-Mediated Volume Transmission in Midbrain Is Regulated by Distinct Extracellular Geometry and Uptake

2001 ◽  
Vol 85 (4) ◽  
pp. 1761-1771 ◽  
Author(s):  
Stephanie J. Cragg ◽  
Charles Nicholson ◽  
June Kume-Kick ◽  
Lian Tao ◽  
Margaret E. Rice
Keyword(s):  
Point Source ◽  
Time Course ◽  
Volume Fraction ◽  
Extracellular Volume ◽  
Brain Slices ◽  
Extracellular Volume Fraction ◽  
Receptor Activation ◽  
Substantia Nigra Pars Compacta ◽  
Volume Transmission ◽  
Carbon Fiber Microelectrodes

Somatodendritic release of dopamine (DA) in midbrain is, at least in part, nonsynaptic; moreover, midbrain DA receptors are predominantly extrasynaptic. Thus somatodendritic DA mediates volume transmission, with an efficacy regulated by the diffusion and uptake characteristics of the local extracellular microenvironment. Here, we quantitatively evaluated diffusion and uptake in substantia nigra pars compacta (SNc) and reticulata (SNr), ventral tegmental area (VTA), and cerebral cortex in guinea pig brain slices. The geometric parameters that govern diffusion, extracellular volume fraction (α) and tortuosity (λ), together with linear uptake ( k′), were determined for tetramethylammonium (TMA+), and for DA, using point-source diffusion combined with ion-selective and carbon-fiber microelectrodes. TMA+-diffusion measurements revealed a large α of 30% in SNc, SNr, and VTA, which was significantly higher than the 22% in cortex. Values for λ and k′ for TMA+ were similar among regions. Point-source DA-diffusion curves fitted theory well with linear uptake, with significantly higher values of k′ for DA in SNc and VTA (0.08–0.09 s− 1) than in SNr (0.006 s− 1), where DA processes are sparser. Inhibition of DA uptake by GBR-12909 caused a greater decrease in k′ in SNc than in VTA. In addition, DA uptake was slightly decreased by the norepinephrine transport inhibitor, desipramine in both regions, although this was statistically significant only in VTA. We used these data to model the radius of influence of DA in midbrain. Simulated release from a 20-vesicle point source produced DA concentrations sufficient for receptor activation up to 20 μm away with a DA half-life at this distance of several hundred milliseconds. Most importantly, this model showed that diffusion rather than uptake was the most important determinant of DA time course in midbrain, which contrasts strikingly with the striatum where uptake dominates. The issues considered here, while specific for DA in midbrain, illustrate fundamental biophysical properties relevant for all extracellular communication.

Anisotropic and heterogeneous diffusion in the turtle cerebellum: implications for volume transmission

1993 ◽  
Vol 70 (5) ◽  
pp. 2035-2044 ◽  
Author(s):  
M. E. Rice ◽  
Y. C. Okada ◽  
C. Nicholson
Keyword(s):  
Time Course ◽  
Granular Layer ◽  
Volume Fraction ◽  
Molecular Layer ◽  
Extracellular Volume ◽  
Striking Difference ◽  
Volume Transmission ◽  
Anisotropic Porous Media ◽  
Parallel Fibers ◽  
Ion Shifts

1. Measurements of extracellular diffusion properties were made in three orthogonal axes of the molecular and granular layers of the isolated turtle cerebellum with the use of iontophoresis of tetramethylammonium (TMA+) combined with ion-selective microelectrodes. 2. Diffusion in the extracellular space of the molecular layer was anisotropic, that is, there was a different value for the tortuosity factor, lambda i, associated with each axis of that layer. The x- and y-axes lay in the plane parallel to the pial surface of this lissencephalic cerebellum with the x-axis in the direction of the parallel fibers. The z-axis was perpendicular this plane. The tortuosity values were lambda x = 1.44 +/- 0.01, lambda y = 1.95 +/- 0.02, and lambda z = 1.58 +/- 0.01 (mean +/- SE). By contrast, the granular layer was isotropic with a single tortuosity value, lambda Gr = 1.77 +/- 0.01. 3. These data confirm the applicability of appropriately extended Fickian equations to describe diffusion in anisotropic porous media, including brain tissue. 4. Heterogeneity between the molecular and granular layer was revealed by a striking difference in extracellular volume fraction, alpha, for each layer. In the molecular layer alpha = 0.31 +/- 0.01, whereas in the granular layer alpha = 0.22 +/- 0.01. 5. Volume fraction and tortuosity affected the time course and amplitude of extracellular TMA+ concentration after iontophoresis. This was modeled by the use of the average parameters determined experimentally, and the nonspherical pattern of diffusion in the molecular layer was compared with the spherical distribution in the granular layer and agarose gel by computing isoconcentration ellipsoids. 6. One functional consequence of these results was demonstrated by measuring local changes in [K+]o and [Ca2+]o after microiontophoresis of a cerebellar transmitter, glutamate. The ratios of ion shifts in the x- and y-axes in the granular layer were close to unity, with a ratio of 1.04 +/- 0.08 for the rise in [K+]o and 1.03 +/- 0.17 for the decrease in [Ca2+]o. In contrast, ion shifts in the molecular layer had an x:y ratio of 1.44 +/- 0.14 for the rise in [K+]o and 2.10 +/- 0.42 for the decrease in [Ca2+]o. 7. These data demonstrate that the structure of cellular aggregates can channel the migration of substances in the extracellular microenvironment, and this could be a mechanism for volume transmission of chemical signals. For example, the preferred diffusion direction of glutamate along the parallel fibers would help constrain an incoming excitatory stimulus to stay "on-beam."

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