Publikationsdatenbank

Establishing Xenopus laevis oocytes as a novel model system for blood brain barrier analyses (2019)

Art

Poster

Autoren

Brunner, Nora (WE 2)

Amasheh, Salah (WE 2)

Kongress

19th EUSAAT Congress

Linz, Österreich, 10. – 13.10.2019

Quelle

ALTEX proceedings

Bandzählung: 8

Heftzählung: 1

Seiten: 25

ISSN: 2194-0479

Sprache

Englisch

Verweise

URL (Volltext): http://eusaat-congress.eu/images/2019/pdf/altex_Linz2019_full.pdf

Kontakt

Institut für Veterinär-Physiologie

Oertzenweg 19 b
14163 Berlin
+49 30 838 62600
physiologie@vetmed.fu-berlin.de

Abstract / Zusammenfassung

Outline:
Alternative brain-barrier models to test potential drug uptake mechanisms are currently discussed. As the tight junction be-tween endothelial cells play a central role in the formation of the blood-brain barrier, Xenopus laevis oocytes were established for heterologous expression and analysis of tight junction proteins [1]. Claudin-5 is considered the predominant sealing protein of the tight junction in the brain [2]. Therefore, the current study aimed to develop human claudin-5 expressing Xenopus laevis oo-cytes as a model for testing medical substances, as exemplarily demonstrated for sodium caprate. This medium chain fatty acid is an established absorption enhancer for drug uptake in the intestine [3] as is leads to an opening of the paracellular barrier [4].

Methods:
Oocytes were collected from adult female African claw frogs in a surgical laparascopy and injected with 1 ng cRNA encoding for human claudin-5, or RNase-free water as controls, respectively. After 3 days, oocytes were devitellinized and clustered in pairs of claudin-5-expressing and control oocytes as follows: cldn5-cldn5 (n = 5-8) and ctrl-ctrl (n = 6-7), respectively. After 24 h, sodium caprate in final concentrations of 50, 100 and 500 μmol or culture medium was added to the oocyte pairs and width of contact area was measured 30, 60 and 120 min after addition via bright field microscopy. The contact area was calculated by using the circle equation (A = π × (measured width/2)2).

Results:
Oocyte contact areas showed an initial decrease of contact width after addition of sodium caprate or culture medium in both clau-din-5 and control oocytes, respectively. After 60 and 120 min the observed decrease was reversed in all tested combinations with or without the addition of different sodium caprate concentrations. After 30 min claudin-5 expressing oocytes showed a significantly larger contact area compared to water- injected oocytes in caprate concentrations of 50 μmol and 500 μmol (p < 0.05, student’s t test).

Conclusion:
In our study, we employed the heterologous Xenopus laevis oo-cyte expression system to analyze the effect of sodium caprate on claudin-5. An effect of sodium caprate on claudin-5 expressing oocytes was not observed in our current study, which might in-dicate that additional factors are required. However, with our ex-perimental setup we were able to verify a strengthening effect of claudin-5 expression on the contact area of oocyte pairs.