Gentamicin Affects the Bioenergetics of Isolated Mitochondria and Collapses the Mitochondrial Membrane Potential in Cochlear Sensory Hair Cells

Abstract

Aminoglycoside antibiotics are widely prescribed to treat a variety of serious bacterial infections. They are extremely useful clinical tools, but have adverse side effects such as oto- and nephrotoxicity. Once inside a cell they are thought to cause mitochondrial dysfunction, subsequently leading to apoptotic cell death due to an increase in reactive oxygen species (ROS) production. Here we present evidence of a direct effect of gentamicin (the most commonly prescribed aminoglycoside) on the respiratory activities of isolated rat liver and kidney mitochondria. We show that gentamicin stimulates state 4 and inhibits state 3u respiratory rates, thereby reducing the respiratory control ratio (RCR) whilst simultaneously causing a collapse of the mitochondrial membrane potential (MtMP). We propose that gentamicin behaves as an uncoupler of the electron transport chain (ETC) – a hypothesis supported by our evidence that it reduces the production of mitochondrial ROS (MtROS). We also show that gentamicin collapses the MtMP in the sensory hair cells (HCs) of organotypic mouse cochlear cultures.

The Role of Mitochondria in Drug-Induced Kidney Injury

“…In cochlear sensory hair cells, gentamicin stimulates state 4 and inhibits state 3u respiratory rates by inhibiting complex II of the electron transport chain, thereby reducing the respiratory control ratio and collapsing the mitochondrial membrane potential as an uncoupler of the electron transport chain. As already known for other uncouplers, gentamicin reduced ROS production in isolated mitochondria ( O’reilly et al, 2019 ). By contrast, intact cells and animals treated with aminoglycosides overproduce ROS ( Cuzzocrea et al, 2002 ; Kalghatgi et al, 2013 ), perhaps in a mitochondrion-independent manner.…”

“…Mitochondrial DNA is double stranded like the nuclear DNA, but circular instead of linear. The mitochondrial genome encodes exclusively for two ribosomal RNAs (rRNAs), 22 transfer RNAs (tRNAs), and the messenger RNA (mRNA) of 13 protein subunits that are assembled with nuclear-encoded proteins to form the four enzymatic complexes constituting the mitochondrial (Teuber and Bader, 1976;Suzuki et al, 2013;Deris et al, 2014;Lu et al, 2016;Visentin et al, 2017) Doxycycline OATs Mitochondrial ribosome (Clark-Walker and Linnane, 1966;Babu et al, 2002;Houtkooper et al 2013;Moullan et al, 2015) Gentamicin Megalin and OCT2 Mitochondrial ribosome Complex II (Prezant et al, 1993;Moestrup et al, 1995;Qian and Guan, 2009;Gai et al, 2016;O'reilly et al, 2019) Vancomycin OCTs Complex I (Sokol, 1991;Arimura et al, 2012;Fujiwara et al, 2012;Sakamoto et al, 2017) Anticancer Cisplatin OCTs Mitochondrial DNA VDAC (Yang et al, 2006;Garrido et al, 2008;Filipski et al, 2009;Ciarimboli et al, 2010)…”

From Design to in Vivo Active Organometallic-Containing Antimycotic Agents

“…12 Rat liver mitochondria were harvested and isolated in accordance Home office guidelines, using the method described previously. 13 . Inhibitors were tested in a 96-well plate format using a Thermoscientific TM Multiskan Sky and packaged SkanIt 5.0 software, with dose response curves generated using the least squared method in GraphPad PRISM version 7.0.…”

“…Thin-layer chromatography (TLC) was performed using silica gel 60 F-254 (Merck) plates with detection of spots being achieved by exposure to UV light. 1 H and 13 C NMR spectra were recorded in deuterated solvents on Bruker AV-400 ( 1 H, 500 MHz; 19 F, 376 MHz) and AV-500, AV-501 ( 1 H, 500 MHz; 13 C, 126 MHz) spectrometers at room temperature. The chemical shifts, δ, are reported in ppm (parts per million).…”

From Design to in Vivo Active Organometallic-Containing Antimycotic Agents

“…A 1:1 mixture of conformers is observed leading to all signals in 1 H, 13 C and 19 F analyses to be doubled. 1 H NMR (400 MHz, MeOD): δ 8.43 (s, 1H), 8.34 (s, 1H'), 7.95 (s, 1H),S107.89 (s, 1H'), 7.74 (td, J = 9.0, 6.1 Hz, 1H), 7.66 -7.51 (m, 1H'), 7.32 -7.16 (m, 2H), 7.14 -6.95 (m, 2H'), 4.92 -4.41 (m, 2H+2H'), 4.41 -3.88 (m, 9H+9H'+2H+2H'), 3.78 -3.37 (m, 1H+1H'+2H+2H'), 1.41 -1.01 (m, 6H+6H') 13. C NMR (101 MHz, MeOD): δ 165.2 (dd, J = 250.2, 12.2 Hz), 160.8 (dd, J = 224.1, 12.0 Hz), 152.3, 146.9, 131.57 (dd, J = 9.7, 5.1 Hz), 131.42 -130.88 (m), 124.9 -124.7 (m), 124.6 -124.2 (m), 123.0 -122.7 (m), 113.4 (d, J = 22.1 Hz), 112.9 (d, J = 21.7 Hz), 106.2 (q, J = 26.5 Hz), 105.7 (q, J = 26.5 Hz), 75.4, 74.5, 73.8 (d, J = 35.9 Hz), 73.2, 72.7 (d, J = 27.1 Hz), 72.2, 71.9, 71.4, 71.2 (d, J = 5.4 Hz), 70.2 (d, J = 17.0 Hz), 58.2, 56.5, 55.6, 54.7 (d, J = 33.1 Hz), 53.9, 53.0, 50.8, 18.6 (d, J = 11.9 Hz), 18.3, 16.7, 14.8.…”