Inhibition of mitochondrial respiratory chain complex I is protective against ischemia induced rat cortex and cerebellum mitochondrial damage

Abstract

Aim: To investigate the effect of mitochondrial respiratory chain complex I inhibitor rotenone (Rot) on respiration, calcium induced- mitochondrial permeability transition pore (mPTP) opening of isolated rat brain cortex and cerebellum mitochondria and necrosis after 120 min. ischemia. Methods: Brains of adult Wistar male rats were exposed to 120 min. ischemia with/without Rot. Respiration of isolated cortical and cerebellar mitochondria was measured oxygraphically using a Oroboros instrument. Ca2+-induced mPTP opening determined as calcium retention capacity (CRC) was measured using fluorescent dye Calcium Green 5N. Necrosis was detected as the release of lactate dehydrogenase (LDH) into perfusate which activity was measured spectrophotometrically following oxidation of NADH in the presence of pyruvate. Results: Brain ischemia significantly decreased resistance of isolated cortex and cerebellum mitochondria to calcium-induced mPTP opening and inhibited respiration rate in state 3 with substrates pyruvate plus malate and succinate. However, Rot infusion to vena cava before ischemia re-established CRC of both, cortex and cerebellum mitochondria to control level. Rot infusion also protected against ischemia-induced inhibition of state 3 respiration with succinate of cerebellum mitochondria, while state 3 respiration of cortex mitochondria with succinate as well as respiration of cortex and cerebellum mitochondria with pyruvate and malate was not changed with Rot after ischemia. LDH activity as necrosis marker was increased in perfusate of both cortex and cerebellum after ischemia comparing to control, however, Rot infusion did not prevent necrosis in both brain regions. Conclusions: These results demonstrate that Rot protects against 120 min ischemi.