Der Einfluss mitochondrialer KATP-Kanäle auf das Überleben retinaler Ganglienzellen in vivo

Background: Recently, gabapentin-lactam (GBP-L) was shown to be neuroprotective in vivo. It has been suggested that it may act by opening mitochondrial ATP-sensitive potassium (KATP) channels. We tested this hypothesis by quantifying the effect of GBP-L on the survival of purified retinal ganglion cells (RGCs). Methods: RGCs were purified from early postnatal rat retinae by immunopanning with antibodies against Thy1.1 and cultured in serum-free medium for two days. Cell survival was quantified by counting vital cells under phase-contrast optics. Results were normalized to controls. RGCs were treated with various concentrations (3.2 - 320 µM) of GBP-L with and without 1 µM glibenclamide, blocking both plasmalemmal and mitochondrial KATP channels, or 100 µM 5-hydroxydecanoate (5-HD), antagonizing selectively mitochondrial KATP channels. For comparison, additional cultures were treated with 32 µM gabapentin, the parent drug of GBP-L. A combination of neurotrophic factors BDNF plus CNTF (50 ng/ml each) served as a positive control. Results: GBP-L increased RGC survival to a maximum of 145 ± 5% (mean ± SEM) in a concentration-dependent manner. The pEC50 was 5.0, CI95 [4.7, 5.3]. Preincubation with glibenclamide changed the dose-response of GBP-L, indicating that it acted as a competitive antagonist with a pA2 value of 6.8, CI95 [5.9, 7.5]. 5-HD completely blocked the survival-promoting effect of GBP-L. Gabapentin had no effect whereas the combination of CNTF plus BDNF enhanced survival to 177 ± 9%. Conclusions: GBP-L, but not gabapentin, can promote the survival of cultured central nervous system neurons, eventually by opening mitochondrial KATP channels. These results suggest further testing of GBP-L as a potentially neuroprotective drug.

Ansprechpartner: Dr. W. Lagrèze
Email: mail@lagreze.de

Projektbeginn: 2000
Projektende: 2004

Dr. W. Lagrèze

Albert-Ludwigs-Universität Freiburg
Augenklinik
Abteilung Allgemeine Augenheilkunde mit Poliklinik
Killianstrasse 5
79106 Freiburg

Telefon: +49 (761) 270-40060
Fax: +49 (761) 270-40630
Email: augenklinik.direktion@uniklinik-freiburg.de
http://www.uniklinik-freiburg.de/augenklinik.html

T. J. Feuerstein, Sektion klin. Neuropharmakologie, Universität Freiburg H. Hofmann, Institut I, Universität Freiburg