Protective effects of tetramethylpyrazine on rat retinal cell cultures

Abstract

The retinal degeneration characterized with death of retinal ganglion cells is a pathological hallmark and the final common pathway of various optic neuropathies. Thus, there is an urgent need for identifying potential therapeutic compounds for retinal protection. Tetramethylpyrazine has been suggested to be neuroprotective for central neurons by acting as an antioxidant and a calcium antagonist. In this study, we tested the effects of tetramethylpyrazine on the viability of both neuronal and non-neuronal cells in mixed rat retinal cell cultures during a long-term cultivation or following hydrogen peroxide treatments. Cellular and biochemical analyses demonstrated that 50 μM tetramethylpyrazine significantly preserved neuronal morphology and survival in retinal cell cultures following 4-week in vitro cultivation as well as lethal exposures to hydrogen peroxide (10μM or 50 μM for 24 hr). Hydrogen peroxide treatments induced remarkable increases in lipid peroxidation and mitochondrial ROS generation paralleled by the loss of mitochondrial membrane potential, microtubule-associated protein-2 (MAP-2) in neuronal soma and rattin peptide in cultured cells. Addition of tetramethylpyrazine in the cultures efficiently attenuated the signs of oxidative stress and retained abundance of MAP-2 and rattin in association with cell survival. In addition, siRNAmediated downregulation of MAP-2 or rattin significantly increased the vulnerability of retinal neurons or the number of degenerating cells in the cultures, respectively, whereas exogenous humanin peptide, an analog of rattin, promoted cell survival in cultures under hydrogen peroxide attacks. These results suggest that tetramethylpyrazine protect retinal cells through multiple pathways and might be a potential therapeutic candidate for retinal protection in certain optic neuropathies.

Humanin Peptides Regulate Calcium Flux in the Mammalian Neuronal, Glial and Endothelial Cells under Stress Conditions

“…Bcl-2 protein family and caspases are intimately associated with the mitochondrial function and progression of the apoptotic events. HN were shown to block pro-apoptotic activities of Bax and Bak proteins [21,39]. It is interesting to note that Bax is not only mitochondrial, but also ERassociated protein [40].…”

Tetramethylpyrazine attenuates PPAR-γ antagonist-deteriorated oxazolone-induced colitis in mice

“…TMP can protect against MNU-induced retinal damage (17), iron-induced oxidative damage and apoptosis in cerebellar granule cells (18), gastric mucosal injury in a rat model of acute necrotizing pancreatitis, spinal cord ischemia, gentamicin-induced apoptosis in murine renal tubular cells (19), rat asthma, acute liver and lung injury after burn trauma (20), acute myocardium injury after thermal trauma (21) and accelerated anti-glomerular basement membrane antibody nephritis (22). Several studies have also reported that one of the underlying mechanisms of TMP is its reactive oxygen species (ROS)-scavenging activity (21)(22)(23)(24). ROS are also important mediators in the pathogenesis of inflammatory bowel disease (IBD).…”

The Nervous System Cytoskeleton under Oxidative Stress

“…It is unclear which of Parkin's functions is neuroprotective [55]. Hydrogen peroxide treatment of neuronal and non-neuronal mixed rat retinal cell cultures causes the loss of MAP2 in the neuronal soma, and downregulation of MAP2 increases the vulnerability of retinal neurons to oxidative stress [56].…”