Abstract
Abstract: :
Purpose: We have previously found that bradykinin protects cultured retinal neurons against glutamate neurotoxicity by opening the ATP dependent potassium channel of mitochondria (Mit. K(ATP) channel). The purpose of this study is to elucidate the role of PKC on Mit. K(ATP) channel- mediated neuro-protection by bradykinin. Methods: Primary cultures were obtained from the retina of fetal rats (gestation day 17-19). Cytosine arabinoside(10 µM) was added to the culture on the 6th day to eliminate non-neuronal cells. We used only those cultures maintained for 7-8 days in vitro. Glutamate neurotoxicity was assessed by 10-min exposure to 1mM glutamate followed by 1-hour incubation in glutamate free media, using trypan blue exclusion method. Results: Simultaneous application of bradykinin and diazoxide (the opener of Mit. K(ATP) channel) with glutamate suppressed the glutamate-induced neurotoxicity, and this protective effect was inhibited by the simultaneous application of 5-HD (the selective blocker of Mit. K(ATP) channel). Protective effect of bradykinin was inhibited by the simultaneous application of chelerythrine (PKC inhibitor). Protective effect of diazoxide was inhibited by 10 minutes’ pre-application of, but not by simultaneous application of, chelerythrine. Simultaneous application of rottlerin (PKC-delta inhibitor) inhibited the protective effect of bradykinin, but simultaneous or pre application of rottlerin had no effect on the protective effect of diazoxide. Conclusions: These results suggest that PKC acts on both upstream and downstream to Mit. K(ATP) channel, and that PKC-delta acts on upstream to Mit. K(ATP) channel in the bradykinin-induced protection against glutamate neurotoxicity.
Keywords: mitochondria • neuroprotection • retinal culture