Article
Effect of blood metabolites and degradation products (BMDP) on neuronal tissue – The isolated murine retina as a new ex-vivo SAH model?
Search Medline for
Authors
-
Walid Albanna
- Universitätsklinikum der RWTH Aachen, Neurochirurgische Klinik, Aachen, Deutschland
-
Felix Neumeier
- Institute for Neurophysiology, University of Cologne, Cologne, Deutschland
-
Catharina Conzen
- Department of Neurosurgery, RWTH Aachen University, Aachen, Deutschland
-
Hans Clusmann
- Department of Neurosurgery, RWTH Aachen University, Aachen, Deutschland
-
Anke Höllig
- Department of Neurosurgery, RWTH Aachen University, Aachen, Deutschland
-
Toni Schneider
- Institute for Neurophysiology, University of Cologne, Cologne, Deutschland
-
Gerrit Schubert
- Department of Neurosurgery, RWTH Aachen University, Aachen, Deutschland
| Published: | June 9, 2017 |
|---|
Outline
Text
Objective: Metabolites and degradation products of hemoglobin - such as bilirubin and its oxidation end products (BOXes) - may be involved in the development of cerebral vasospasm after aSAH. Vascular smooth muscle cells in the brain are activated, possibly via stimulation of different voltage-gated calcium channels (VGCCs). VGCCs are also present in the retina playing a major role for signal transduction. Their interaction during transretinal excitation can be recorded as an electroretinogram (ERG). The retina as an embryological part of the brain and currently subject of clinical pilot studies may allow for direct visualization of the interactions from blood degradation products on acute signaling and thus also on pathways for vascular tone regulation. The present investigation analyses the effect of bilirubin on an isolated and superfused murine retina to determine the suitability of this new experimental ex-vivo model for SAH.
Methods: Murine retinas were isolated from wildtype (n=16) and knock-out mice (Cav2.3, R-Type; n=7), transferred to a recording chamber and superfused with nutrient solution for 45min. From the dark-adapted retina, ERGs in response to a single white flash were recorded in 3min intervals. Reactivity was tested for different pH settings. After reaching an equilibrium for the characteristic b-wave amplitude, retinas were superfused with 10µM albumin, followed by 5µM bilirubin+10µM albumin and again with 10µM albumin (bilirubin wash-out), each for 45min.
Results: In 17 separate retinae, the b-wave amplitude, as a response of the inner retina, was increased by the pH-shift (pH 7.4 to pH 7.7) from 22.9±8µV to 37.5±10.3µV (p<0.001). After optimization, in 16 wild type retinas, the b-wave amplitude decreased significantly during bilirubin superfusion by 24,9±3.9% (p<0.001). After washout of bilirubin, the amplitude returned to the baseline. Knock-out animals showed a comparable response to bilirubin superfusion. However, b-wave amplitude increased significantly during washout (12.3±4.5%; p<0.05). No significant changes of the implicit time (latency until maximum of amplitude) were found.
Conclusion: The isolated and superfused murine retina as a new ex-vivo model shows a characteristic and reproducible response to selected degradation products such as bilirubin, in this case reduction of b-wave amplitude after electrical stimulus. The described experimental setup may be used as a new neuronal model to examine BMDP effects, mimicing the alterations after SAH and utilizing BOXes and selected knock-out animals to shed more light into the underlying pathophysiology of cerebral vasospasm.
