scholarly journals Gonadotropin-Releasing Hormone Neurons Extend Complex Highly Branched Dendritic Trees Outside the Blood-Brain Barrier

Endocrinology ◽  
2011 ◽  
Vol 152 (10) ◽  
pp. 3832-3841 ◽  
Author(s):  
Michel K. Herde ◽  
Katrin Geist ◽  
Rebecca E. Campbell ◽  
Allan E. Herbison
Keyword(s):  
Blood Brain Barrier ◽  
Fluorescent Protein ◽  
Brain Barrier ◽  
Electron Microscopic ◽  
Dendritic Trees ◽  
Blood Brain ◽  
Electrophysiological Recordings ◽  
Gnrh Neurons ◽  
Output Neurons ◽  
Green Fluorescent

GnRH neurons project axons to the median eminence to control pituitary release of gonadotropins and, as such, represent the principal output neurons of the neuronal network controlling fertility. It is well established that the GnRH neurons exhibit a simple bipolar morphology with one or two long dendrites. Using adult GnRH-green fluorescent protein transgenic mice and juxtacellular cell filling, we report here that a subpopulation of GnRH neurons located in the rostral preoptic area exhibit extremely complex branching dendritic trees that fill the organum vasculosum of the lamina terminalis (OVLT). The dendritic nature of these processes was demonstrated at both light and electron microscopic levels by the presence of spines, dendritic ultrastructure, and synapses. Further, electrophysiological recordings showed that GnRH neurons were excited by glutamate as well as kisspeptin puffed onto their dendrites located within the OVLT. Using iv injection of horseradish peroxidase, a molecule unable to penetrate the blood-brain barrier (BBB), we show that GnRH neuron cell bodies and dendrites within 100 μm of the OVLT reside outside the BBB. Approximately 85% of GnRH neurons in this area express c-Fos at the time of the GnRH surge. These observations demonstrate that GnRH neurons extend complex, highly branched dendritic trees beyond the BBB into the OVLT, where they will be able to sense directly molecules circulating in the bloodstream. This indicates a new mechanism for the modulation of GnRH neurons that extends considerably the range of factors that are integrated by these neurons for the control of fertility.

scholarly journals Electron Microscopic Characterization of Functionalized Multi-Walled Carbon Nanotubes and Their Interactions with the Blood Brain Barrier

2014 ◽  
Vol 20 (S3) ◽  
pp. 1744-1745
Author(s):  
Angela E. Goode ◽  
Nicholas D. M. Hine ◽  
Shu Chen ◽  
Shane D. Bergin ◽  
Michael Motskin ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Blood Brain Barrier ◽  
Brain Barrier ◽  
Electron Microscopic ◽  
Blood Brain ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

LIGHT AND ELECTRON MICROSCOPIC BLOOD-BRAIN BARRIER (BBB) CHANGES FOLLOWING CARDIOPULMONARY RESUSCITATION IN YOUNG PIGLETS

1992 ◽  
Vol 77 (Supplement) ◽  
pp. A712 ◽  
Author(s):  
C. L. Schleien ◽  
M. J. Caceres ◽  
J. W. Kuluz ◽  
B. Gelman ◽  
W. D. Dietrich
Keyword(s):  
Cardiopulmonary Resuscitation ◽  
Blood Brain Barrier ◽  
Brain Barrier ◽  
Electron Microscopic ◽  
Blood Brain

Development and characterisation of a rat brain capillary endothelial culture: towards an in vitro blood-brain barrier

1992 ◽  
Vol 103 (1) ◽  
pp. 23-37 ◽  
Author(s):  
N.J. Abbott ◽  
C.C. Hughes ◽  
P.A. Revest ◽  
J. Greenwood
Keyword(s):  
Endothelial Cells ◽  
Rat Brain ◽  
Blood Brain Barrier ◽  
Brain Barrier ◽  
Electron Microscopic Level ◽  
Electron Microscopic ◽  
Ulex Europaeus ◽  
Blood Brain ◽  
Microcarrier Beads

Primary culture of rat brain endothelial cells is described, based on the method of C. C. W. Hughes and P. L. Lantos. The cells have been characterised using morphological and immunocytochemical techniques, and systematic studies undertaken to determine the optimal culture medium and conditions required to grow the cells at high purity on a variety of substrata. The endothelial cells have a spindle-shaped morphology, and proliferate as plaques from small clusters of cells associated with capillary fragments in the starting material. Tight junction-like cell:cell appositions are seen at the electron-microscopic level. The cells show characteristic staining for antigens recognized by antibodies against von Willebrand factor (Factor VIII-related antigen), angiotensin-converting enzyme (ACE), the transferrin receptor (Ox-26), actin and vimentin. They also show binding of the lectin from Ulex europaeus (UEA I). Potential contaminating cells include smooth muscle, fibroblasts, pericytes and meningeal cells. Contaminants can be kept to < ca. 5% by careful removal of large vessels and meninges during dissection, by brief treatment with Ca(2+)- and Mg(2+)-free saline, by growth in medium supplemented with plasma-derived serum treated for removal of platelet-derived growth factor (PDGF), and by occasional use of medium in which D-valine is substituted for L-valine. Cells attach well to collagen-coated plastic, less well to glass. Cells can be grown on transparent collagen filters (ICN, Cellagen and Costar, Transwell-Col), and on microcarrier beads (Pharmacia, Cytodex-3). The culture has proved to be a useful preparation for studies of cellular physiology, pharmacology and biochemistry of the brain endothelium, and represents a first step in producing an in vitro model of the rat blood-brain barrier.

scholarly journals An Electron Microscopic Immunogold Analysis of Developmental Up-Regulation of the Blood—Brain Barrier GLUT1 Glucose Transporter

1993 ◽  
Vol 13 (5) ◽  
pp. 841-854 ◽  
Author(s):  
Eain M. Cornford ◽  
Shigeyo Hyman ◽  
William M. Pardridge
Keyword(s):  
Electron Microscopy ◽  
Blood Brain Barrier ◽  
Glucose Transporter ◽  
Polyclonal Antiserum ◽  
Brain Barrier ◽  
Rabbit Brain ◽  
Immunogold Electron Microscopy ◽  
Electron Microscopic ◽  
Brain Capillary ◽  
Blood Brain

Electron microscopy was used to quantitate blood–brain barrier (BBB) glucose transporters in newborn, 14-day-old suckling, 28-day-old weanling, and adult rabbits. A rabbit polyclonal antiserum to a synthetic peptide encoding the 13 C-terminal amino acids of the human erythrocyte glucose transporter (GLUT1) was labeled with 10-nm gold particle–secondary antibody conjugates and localized immunoreactive GLUT1 molecules in rabbit brain capillary endothelia. Three distinct populations of brain capillary profiles were identified in newborn rabbits: prepatent capillary buds, partially patent capillaries with highly amplified luminal membranes, and patent capillaries. Immunogold analyses indicated that the GLUT1 transporter abundance positively correlated with capillary developmental status. The mean number of gold particles per capillary profile increased at each developmental age examined, suggesting that developmental up-regulation of the BBB glucose transporter occurred in rabbits. GLUT1 immunoreactivity was three- to fourfold greater on the abluminal than luminal capillary membranes among all ages examined. Changes in the proportions of GLUT1 transporter were also seen, and possible reasons for the postnatal decrease in the percentage of cytoplasmic GLUT1 transporter are discussed. The numbers of cytoplasmic and membrane-associated immunogold particles increased with age. We conclude that regulatory modulations of BB glucose transport may be characterized by increases in BBB glucose transporter density with age and state of development. In addition, modulation of glucose transporter activity may be reflected by minor postnatal shifts of GLUT1 from cytoplasmic to membrane compartments, which can be demonstrated with quantitative immunogold electron microscopy.

scholarly journals Knockdown of GABAA Receptor Signaling in GnRH Neurons Has Minimal Effects upon Fertility

Endocrinology ◽  
2010 ◽  
Vol 151 (9) ◽  
pp. 4428-4436 ◽  
Author(s):  
Kiho Lee ◽  
Robert Porteous ◽  
Rebecca E. Campbell ◽  
Bernhard Lüscher ◽  
Allan E. Herbison
Keyword(s):  
Gabaa Receptor ◽  
Fluorescent Protein ◽  
Feedback Mechanism ◽  
Postnatal Life ◽  
Negative Feedback Mechanism ◽  
Postsynaptic Currents ◽  
Electrophysiological Recordings ◽  
Gnrh Neurons ◽  
Positive Feedback Mechanism ◽  
Green Fluorescent

The amino acid γ-aminobutyric acid (GABA) is thought to play a key role in shaping the activity of the GnRH neurons throughout embryonic and postnatal life. However, the physiological roles of direct GABA inputs to GnRH neurons remain unknown. Using a Cre-LoxP strategy, we generated a targeted mouse line, in which all (98 ± 1%) GnRH neurons had the γ2-subunit of the GABAA receptor deleted. Electrophysiological recordings of GABAA-mediated postsynaptic currents from green fluorescent protein-tagged GnRH neurons with the γ2-subunit knocked out (GnRH γ2 KO) showed that the amplitude and frequency of GABAA postsynaptic currents were reduced by 70% (P < 0.01) and 77% (P < 0.05), respectively, and that the response to exogenous GABA was reduced by 90% (P < 0.01). Evaluation of male and female GnRH γ2 KO mice revealed completely normal fecundity, estrous cycles, and puberty onset. Further investigation with gonadectomy and different steroid replacement regimens showed normal basal levels of LH in both sexes, and a normal estradiol-evoked positive feedback mechanism in females. However, the increment in LH after gonadectomy in GnRH γ2 KO female mice was double that of controls (P < 0.05) and also more potently suppressed by 17-β-estradiol (P < 0.05). A similar but nonsignificant trend was observed in GnRH γ2 KO male mice. Together, these findings show that 70–90% reductions in the normal levels of GABAA receptor activity at the GnRH neuron appear to impact upon the estrogen negative feedback mechanism but are, nevertheless, compatible with normal fertility in mice.

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