Fig. (7). Activation of mGluRIs prevents mitochondrial membrane depolarization and cytochrome c release.

(A) Exposure to NO produced a significant decrease in the red/green fluorescence intensity ratio using a cationic membrane potential indicator JC-1 within 3 hours when compared with untreated control cultures (A, B), suggesting that NO results in mitochondrial membrane depolarization. Application of DHPG (750 μM) 1 hour prior to NO exposure significantly increased the red/green fluorescence intensity of neurons, indicating that ΔΨ_m was restored to baseline (A, B). Application of Atr (5 mmol/L) produced a significant decrease in the red/green fluorescence intensity ratio within 3 hours when compared with untreated control cultures. Application of CsA (5 μmol/L) with Atr administration significantly increased the red/green fluorescence intensity of neurons, indicating that ΔΨ_m was restored to baseline. (B) The relative ratio of red/green fluorescent intensity of mitochondrial staining in both untreated (control) neurons and neurons exposed to NO or DHPG (750 μM) plus NO 3 hours following the initial insult was measured in 4 independent experiments with analysis performed using the public domain NIH Image program (developed at the U.S. National Institutes of Health and available on the Internet at http://rsb.info.nih.gov/nih-image/) (Control vs. NO, *p<0.01; NO vs. DHPG/NO, †p<0.01). (C) A representative Western blot with equal amounts of mitochondrial protein and cytosol extracts (50 μg/lane) illustrates that cells treated with DHPG (750 μM) prior to NO significantly prevents cytochrome c release from mitochondria to the cytosol when compared to untreated control neurons.