Abstract P235: Reduced Uterine Perfusion Pressure Impairs Seizure-induced Downregulation Of Neurotransmitter Transporters In Mice

Hypertension ◽  
2021 ◽  
Vol 78 (Suppl_1) ◽  
Author(s):  
Maria Jones- Muhammad ◽  
Kennedi Stancil ◽  
Qingmei Shao ◽  
Junie P Warrington
Keyword(s):  
Group Treatment ◽  
Perfusion Pressure ◽  
Excitatory Amino Acid ◽  
Glutamate Transporter ◽  
Receptor Expression ◽  
Hypertensive Disorder ◽  
Gaba Concentration ◽  
Excitatory Amino Acid Transporter ◽  
Chemically Induced ◽  
Uterine Perfusion

Preeclampsia, a hypertensive disorder of pregnancy, can advance to eclampsia, if new onsetseizures occur. Previous work showed increased susceptibility to chemically-induced seizures inthe reduced uterine perfusion pressure (RUPP) rat model of preeclampsia; however, theunderlying mechanisms are unknown. Because seizures occur due to neurotransmitter activityimbalance, we hypothesized that RUPP mice have elevated excitatory and reduced inhibitoryactivity and that seizures exacerbate this imbalance.Timed-pregnant SMA-GFP mice (n=5-6 per group/treatment) were subjected to sham or RUPPsurgery on gestational day (GD) 13.5 and seizures were induced using 40mg/kg pentylenetetrazolon GD18.5. Tissues were harvested 30 minutes post-seizure induction. Maximum seizure scoreswere similar in sham (4.7±0.3) and RUPP (4.5±0.3) mice; p=0.37. Fluorometric assay showsseizures increased [F (1, 16) = 5.99, p=0.03], while RUPP had no effect [F (1, 16) = 1.15, p=0.3]on hippocampal glutamate concentration. No pairwise differences were observed within the shamand RUPP groups exposed to seizures (p>0.05). Seizures increased [F (1, 16) = 6.96, p=0.02],while RUPP had no effect [F (1, 16) = 0.61, p=0.45] on GABA concentration, with no significantpairwise difference in GABA concentration (p>0.05).Western blot analysis shows seizures significantly reduced hippocampal NMDAR1 (1.0±0.5 vs0.6±0.96, p=0.02; 1.0±0.1 vs 0.6±0.0, p=0.04) and GABAAR receptor expression (1.0±0.4 vs0.35±0.1, p<0.5; 1.05±0.3 vs 0.3±0.1, p<0.05) in sham and RUPP mice. Following seizureexposure, vesicular glutamate transporter (VGLUT1: sham: 1.0±0.3 vs 0.5±0.1; p<0.01, RUPP:0.8±0.2 vs 0.6±0.1; p=0.11), excitatory amino acid transporter 1 (EAAT1: sham: 1.0±0.4 vs0.6±0.2; p=0.02, RUPP: 0.9±0.1 vs 0.6±0.2; p=0.17) and GABA transporter (GAT1: sham: 1.0±0.5vs 0.4±0.1, p=0.01; RUPP: 0.8±0.2 vs 0.5±0.1, p=0.12) was reduced in sham mice, but not RUPPmice.Although RUPP does not change baseline GABA or glutamate related receptor or transporterexpression, our findings suggest seizure-induced reductions in vesicular and astrocyticneurotransmitter transporters is impaired by the RUPP procedure. Ongoing studies assesswhether other receptors and transporters are affected.

scholarly journals Protective Effect of Memantine on Bergmann Glia and Purkinje Cells Morphology in Optogenetic Model of Neurodegeneration in Mice

2021 ◽  
Vol 22 (15) ◽  
pp. 7822
Author(s):  
Anton N. Shuvaev ◽  
Olga S. Belozor ◽  
Oleg I. Mozhei ◽  
Elena D. Khilazheva ◽  
Andrey N. Shuvaev ◽  
...  
Keyword(s):  
Excitatory Amino Acid ◽  
Average Length ◽  
Glutamate Transporter ◽  
Bergmann Glia ◽  
Spinocerebellar Ataxias ◽  
Excitatory Amino Acid Transporter ◽  
Glial Glutamate Transporter ◽  
Gfap Immunoreactivity ◽  
Cerebellar Ataxias ◽  
Receptor Blockers

Spinocerebellar ataxias are a family of fatal inherited diseases affecting the brain. Although specific mutated proteins are different, they may have a common pathogenetic mechanism, such as insufficient glutamate clearance. This function fails in reactive glia, leading to excitotoxicity and overactivation of NMDA receptors. Therefore, NMDA receptor blockers could be considered for the management of excitotoxicity. One such drug, memantine, currently used for the treatment of Alzheimer’s disease, could potentially be used for the treatment of other forms of neurodegeneration, for example, spinocerebellar ataxias (SCA). We previously demonstrated close parallels between optogenetically induced cerebellar degeneration and SCA1. Here we induced reactive transformation of cerebellar Bergmann glia (BG) using this novel optogenetic approach and tested whether memantine could counteract changes in BG and Purkinje cell (PC) morphology and expression of the main glial glutamate transporter—excitatory amino acid transporter 1 (EAAT1). Reactive BG induced by chronic optogenetic stimulation presented increased GFAP immunoreactivity, increased thickness and decreased length of its processes. Oral memantine (~90 mg/kg/day for 4 days) prevented thickening of the processes (1.57 to 1.81 vs. 1.62 μm) and strongly antagonized light-induced reduction in their average length (186.0 to 150.8 vs. 171.9 μm). Memantine also prevented the loss of the key glial glutamate transporter EAAT1 on BG. Finally, memantine reduced the loss of PC (4.2 ± 0.2 to 3.2 ± 0.2 vs. 4.1 ± 0.3 cells per 100 μm of the PC layer). These results identify memantine as potential neuroprotective therapeutics for cerebellar ataxias.

Abstract 052: Placental Growth Factor (PlGF) Reduces Blood Pressure and Improves Endothelin Type B Receptor (ETBR)-Mediated Microvascular Dilation in Hypertensive Pregnant Rats

Hypertension ◽  
2015 ◽  
Vol 66 (suppl_1) ◽  
Author(s):  
Marc Q Mazzuca ◽  
Zongli Ren ◽  
Chen Lin ◽  
Jose S Possomato-Vieira ◽  
Minglin Zhu ◽  
...  
Keyword(s):  
Perfusion Pressure ◽  
Mesenteric Arteries ◽  
Hypertensive Disorder ◽  
Type B ◽  
Pregnant Rats ◽  
Western Blots ◽  
New Approach ◽  
Nitrite Production ◽  
Uterine Perfusion ◽  
Mesenteric Microvessels

Preeclampsia is a pregnancy-related hypertensive disorder (HTN-Preg) with an imbalance between anti-angiogenic soluble fms-like tyrosine kinase-1 (sFlt-1) and angiogenic PlGF, but the vascular targets involved are unclear. We have shown downregulation of endothelial ET B R in Preg rats with reduced uterine perfusion pressure (RUPP), and studies have shown increased plasma sFlt-1 in RUPP rats. We tested if raising PIGF/sFlt-1 ratio by infusing PIGF (10 μg/kg/day) in RUPP rats would improve BP and microvascular ET B R signaling, and vice versa, if lowering PIGF/sFlt-1 ratio by infusing sFlt-1 (10 μg/kg/day) in Preg rats increases BP and reduces ET B R signaling. On day 19, BP was recorded and mesenteric microvessels were isolated for measurement of diameter and [Ca 2+ ] i (fura-2 340/380 ratio). BP was in PlGF-RUPP 105±2 < RUPP 126±1 and in sFlt-Preg 125±4 > Norm-Preg 97±5 mmHg. ET-1 vasoconstriction was in PlGF-RUPP 62.6±3.0 < RUPP 83.4±5.3 and in sFlt-Preg 76.1±4.7 > Norm-Preg 52.1±3.2%. ET-1 caused parallel increases in microvascular [Ca 2+ ] i that was in PlGF-RUPP 0.87±0.02 < RUPP 0.92±0.01 and in sFlt-Preg 0.93±0.02 > Norm-Preg 0.85±0.01. Endothelium removal or microvessel treatment with ET B R antagonist BQ-788 enhanced ET-1 vasoconstriction and [Ca 2+ ] i in Norm-Preg and PlGF-RUPP, but not RUPP or sFlt-Preg. The ET B R agonists sarafotoxin 6c (S6c) and IRL-1620 caused relaxation that was in PlGF-RUPP 42.9±10.8, 38.0±11.2% > RUPP 4.7±3.4, 7.5±2.3% and in sFlt-Preg 3.1±1.0, 5.4±1.6% < Norm-Preg 29.9±7.8, 28.0±9.1%. L-NAME partially reduced ACh- and ET B R-induced relaxation in Norm-Preg, PlGF-RUPP, but not RUPP or sFlt-Preg, suggesting that PlGF improves the decreased NO-dependent and ET B R-mediated vasorelaxation in HTN-Preg. Basal, ACh-, S6c-, and IRL-1620-induced nitrate/nitrite production was enhanced in mesenteric arteries of PIGF-RUPP and Norm-Preg vs. RUPP rats. Western blots and immunohistochemistry revealed greater levels of endothelial ET B R in PlGF-RUPP and Norm-Preg vs. RUPP and sFlt-Preg. Thus improving PlGF/sFlt-1 balance reduces BP and ET-1 vasoconstriction, and enhances ET B R-mediated NO-dependent vasodilation in RUPP rats, and could be a new approach in the management of HTN-Preg.

scholarly journals Light-evoked glutamate transporter EAAT5 activation coordinates with conventional feedback inhibition to control rod bipolar cell output

2020 ◽  
Vol 123 (5) ◽  
pp. 1828-1837
Author(s):  
Gregory W. Bligard ◽  
James DeBrecht ◽  
Robert G. Smith ◽  
Peter D. Lukasiewicz
Keyword(s):  
Amino Acid ◽  
Feedback Inhibition ◽  
Excitatory Amino Acid ◽  
Glutamate Transporter ◽  
Bipolar Cells ◽  
Major Contributor ◽  
Excitatory Amino Acid Transporter ◽  
Control Rod ◽  
Neuronal Output ◽  
Rod Bipolar Cells

Excitatory amino acid transporter 5 (EAAT5) glutamate transporters have a chloride channel that is strongly activated by glutamate, which modulates excitatory signaling. We found that EAAT5 is a major contributor to feedback inhibition on rod bipolar cells. Inhibition to rod bipolar cells is also mediated by GABA and glycine. GABA and glycine mediate the early phase of feedback inhibition, and EAAT5 mediates a more delayed inhibition. Together, inhibitory transmitters and EAAT5 coordinate to mediate feedback inhibition, controlling neuronal output.

scholarly journals Expression of Glutamate Transporters in Mouse Liver, Kidney, and Intestine

2018 ◽  
Vol 66 (3) ◽  
pp. 189-202 ◽  
Author(s):  
Qiu Xiang Hu ◽  
Sigrid Ottestad-Hansen ◽  
Silvia Holmseth ◽  
Bjørnar Hassel ◽  
Niels Christian Danbolt ◽  
...  
Keyword(s):  
Mouse Liver ◽  
Plasma Membranes ◽  
Excitatory Amino Acid ◽  
Splice Variants ◽  
Glutamate Transporter ◽  
Quantitative Information ◽  
Current View ◽  
Excitatory Amino Acid Transporter ◽  
Distal Small Intestine ◽  
Protein Levels

Glutamate transport activities have been identified not only in the brain, but also in the liver, kidney, and intestine. Although glutamate transporter distributions in the central nervous system are fairly well known, there are still uncertainties with respect to the distribution of these transporters in peripheral organs. Quantitative information is mostly lacking, and few of the studies have included genetically modified animals as specificity controls. The present study provides validated qualitative and semi-quantitative data on the excitatory amino acid transporter (EAAT)1–3 subtypes in the mouse liver, kidney, and intestine. In agreement with the current view, we found high EAAT3 protein levels in the brush borders of both the distal small intestine and the renal proximal tubules. Neither EAAT1 nor EAAT2 was detected at significant levels in murine kidney or intestine. In contrast, the liver only expressed EAAT2 (but 2 C-terminal splice variants). EAAT2 was detected in the plasma membranes of perivenous hepatocytes. These cells also expressed glutamine synthetase. Conditional deletion of hepatic EAAT2 did neither lead to overt neurological disturbances nor development of fatty liver.

scholarly journals Loss of the glial glutamate transporter eaat2a leads to a combined developmental and epileptic encephalopathy in zebrafish

2021 ◽  
Author(s):  
Adriana L. Hotz ◽  
Ahmed Jamali ◽  
Nicolas N. Rieser ◽  
Stephanie Niklaus ◽  
Ecem Aydin ◽  
...  
Keyword(s):  
Neuronal Excitability ◽  
Excitatory Amino Acid ◽  
Brain Activity ◽  
Glutamate Transporter ◽  
Epileptic Seizures ◽  
Synaptic Cleft ◽  
Epileptic Encephalopathy ◽  
Network Activity ◽  
Excitatory Amino Acid Transporter ◽  
The Impact

ABSTRACTAstroglial excitatory amino acid transporter 2 (EAAT2, GLT-1, SLC1A2) regulates the duration and extent of neuronal excitation by removing glutamate from the synaptic cleft. Human patients with altered EAAT2 function exhibit epileptic seizures, suggesting an important role for astroglial glutamate transporters in balancing neuronal excitability. To study the impact of EAAT2 function at the neural network levels, we generated eaat2a mutant zebrafish. We observed that eaat2a-/- mutant zebrafish larvae display recurrent spontaneous and light-induced seizures in neurons and astroglia, which coincide with an abrupt increase in extracellular glutamate levels. In stark contrast to this hyperexcitability, basal brain activity was surprisingly reduced in eaat2a-/- mutant animals, which manifested in decreased locomotion, neuronal and astroglial calcium signals. Our results reveal an unexpected key role of the astroglial EAAT2a in balancing brain excitability, affecting both neuronal and astroglial network activity.

Abstract 129: A Biopolymer-Stabilized VEGF Chimera Reverses Angiogenic Imbalance in vitro in the Reduced Uterine Perfusion Pressure Model of Preeclampsia

Hypertension ◽  
2015 ◽  
Vol 66 (suppl_1) ◽  
Author(s):  
Omar C Logue ◽  
Fakhri Mahdi ◽  
Eric M George ◽  
Gene L Bidwell
Keyword(s):  
Perfusion Pressure ◽  
Placental Transfer ◽  
Umbilical Vein ◽  
Angiogenic Factors ◽  
Angiogenic Factor ◽  
Unknown Etiology ◽  
Vegf Receptor ◽  
Hypertensive Disorder ◽  
Vascular Endothelial ◽  
Uterine Perfusion

Preeclampsia (PE) is a hypertensive disorder that complicates approximately 5-8% of all pregnancies in the U.S. The unknown etiology of PE develops from molecular dysfunction at the maternal-placental interface, where inflammatory, oxidative stress, and anti-angiogenic pathways are initiated. The resulting hypoxic in utero environment contributes to placental ischemia from which the anti-angiogenic factor soluble fms-like tyrosine kinase-1 (sFlt-1) is released. A truncated isoform, sFlt-1 consists solely of the extracellular domain of the vascular endothelial growth factor (VEGF) receptor 1, and hence lacks both catalytic and regulatory activities. However, sFlt-1 retains a high affinity for VEGF and sequesters this ligand from binding with fully functional VEGF receptors, thus prevents the activation of angiogenic remodeling pathways. The rodent model of PE, reduced uterine perfusion pressure (RUPP), exhibits the sFlt-1 pathophysiology observed in human PE. In an effort to counteract excessive sFlt-1 production and restore angiogenic balance, we have constructed a VEGF chimera fused to an Elastin-like Polypeptide (ELP) carrier with increased in vivo half-life and stability which retains full VEGF signaling activity. When human umbilical vein vascular endothelial cells (HUVECs) are exposed to serum from normal pregnant or RUPP-treated rats, tube formation on extracellular matrix is inhibited 31% (± 2%) by the RUPP serum. This inhibition is reversed when ELP-VEGF, but not ELP control, is added to the culture medium ( p = 0.0007, one-way ANOVA with Bonferroni multiple comparison), suggesting that ELP-VEGF counteracts the anti-angiogenic factors present in RUPP serum. We also characterized the pharmacokinetics, biodistribution, and placental transfer of ELP-VEGF in the pregnant Sprague Dawley rat. These studies indicate that ELP-delivered VEGF has potential for counteracting the circulating anti-angiogenic factors in maternal plasma.

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