Astrocyte Activation: A Key Step in Rotenone Induced Cytotoxicity and DNA Damage

Abstract

Astrocytes are the most abundant glial cells, which provide metabolic support for neurons. Rotenone is a botanical pesticide of natural origin, known to exhibit neurotoxic potential via inhibition of mitochondrial complex-I. This study was carried out to explore the effect of rotenone on C6 cells. The cell line C6 derived from rat glioma cells represents astrocyte-like cell. C6 cells were treated with rotenone (0.1, 1 and 10 μM) for 4 h. The effect of rotenone was studied on cell survival (MTT reduction and PI uptake); free radicals (ROS and RNS) and DNA damage (comet assay and Hoechst staining). The glial cell activation and apoptotic cell death was evaluated by expression of Glial fibrillary acidic protein (GFAP) and caspase-3 respectively. The treatment with rotenone resulted in decreased cell survival and increased free radical generation. Altered nuclear morphology and DNA damage were evident following rotenone treatment in Hoechst staining and Comet assay. Rotenone elevated expression of GFAP and caspase-3 that indicates glial cell activation and apoptosis, respectively. We further studied the effect of melatonin, an antioxidant, on the observed toxic effects. Co-incubation of antioxidant, melatonin (300 μM), significantly suppressed rotenone induced above-mentioned effects in C6 cells. Inhibitory effects of melatonin suggest that free radicals play a major role in rotenone induced astrocyte activation and cellular toxicity leading to apoptosis of astroglial cells.

PDGF-BB Protects Mitochondria from Rotenone in T98G Cells

“…Rotenone has a direct effect on mitochondrial functions, including an interference with the electron transport chain, loss of mitochondrial membrane's potential, and ATP generation (Greenamyre et al 2003;Sarafian et al 2010;Simpkins et al 2010). These cellular processes in turn cause the release of cytochrome C from the inner mitochondrial membrane, thus activating apoptotic effectors such as Bid, Bax, caspase 3, and 9 in neurons (Gyulkhandanyan et al 2003;Swarnkar et al 2012;Tiwari et al 2011;Wang et al 2011). Similarly, our experiments showed that 50 lM rotenone drastically affected cell Our results suggest that PDGF-BB diminished the damaging effects of rotenone by preserving several functions in the cell, including viability, ROS production, and maintenance of mitochondrial functions.…”

“…Previous studies have suggested that rotenone induced the nuclear condensation and fragmentation in different cell models, this event being described as the first indication of apoptotic process in the nervous system cells (Swarnkar et al 2012;Watabe and Nakaki 2004). Figure 4 shows that 24 h of rotenone treatment increased the nuclear condensation and fragmentation in T98G cells compared with control (p \ 0.0001).…”

“…However, there is little information about rotenone effects on astrocytes and astrocytic-like models, such as T98G cells (glioblastoma). Previous studies have shown that different rotenone doses increase glial reactivity and ROS (reactive oxygen species) generation (Swarnkar et al 2012), suggesting the importance of astrocytic protection during ROS processes such as that in PD development.…”

Endoplasmic Reticulum Stress Instigates the Rotenone Induced Oxidative Apoptotic Neuronal Death: a Study in Rat Brain

“…Histopathological changes induced by rotenone administration were also correlated with the biochemical alterations in striata and midbrain regions of rat brain [8]. Our previous studies in neuronal and astrocytes cells have also shown that rotenone treatment caused oxidative stress and apoptosis in both neuronal as well as astroglial cells [10,11]. Involvement of astroglial activation and apoptosis are also reported as the major features in rotenone-induced dopaminergic neuronal death in rat brain [12].…”

Promising Role of Melatonin as Neuroprotectant in Neurodegenerative Pathology

“…Melatonin treatment in degenerating neurons attenuates the increased level of proapoptotic factor Bax and caspase-3 activity [77,78]. It significantly decreased the number of TUNEL-positive neurons along with improving spatial memory performance in cognitively impaired, ovariectomized adult rats [79] and Alzheimerlike tau hyperphosphorylation in wortmannin-induced neuro2A cells [80]. Melatonin treatment also inhibits the rotenone-induced impaired neuromuscular coordination, neuronal death, and DNA damage [81,82].…”