Protective effects of quercetin on cadmium-induced cytotoxicity in primary cultures of rat proximal tubular cells.

To investigate the protective effects of quercetin on cadmium-induced cytotoxicity in primary cultures of rat proximal tubular (rPT) cells. Primary cultures of rPT cells undergoing exponential growth were incubated with 1.0 μg/mL quercetin and/or cadmium (2.5, 5.0 μmol/L), in a serum-free medium at 37 °C at different time intervals. Commercial kits were used and flow cytometric analyses were performed on rPT cell cultures to assay apoptosis and oxidative stress. Exposure of rPT cells to cadmium acetate (2.5, 5.0 µmol/L) induced a decrease in cell viability, caused an increase in apoptotic rate and apoptotic morphological changes. Simultaneously, elevation of intracellular reactive oxygen species, malondialdehyde and calcium levels, depletion of mitochondrial membrane potential and intracellular glutathione, and inhibition of Na+, K+-ATPase, Ca2+-ATPase, glutathione peroxidase (GSH-Px), catalase (CAT), and superoxide dismutase (SOD) activities were revealed during the cadmium exposure of rPT cells. However, simultaneous supplementation with 1 µg/mL quercetin protected rPT cells against cadmium-induced cytotoxicity through inhibiting apoptosis, attenuating lipid peroxidation, renewing mitochondrial function and elevating the intracellular antioxidants (non-enzymatic and enzymic) levels. The present study has suggested that quercetin, as a widely distributed dietary antioxidant, contributes potentially to prevent cadmium-induced cytotoxicity in rPT cells.

Wang L ，Lin SQ ，He YL ，Liu G ，Wang ZY ... -  《BIOMEDICAL AND ENVIRONMENTAL SCIENCES》

Puerarin protects against lead-induced cytotoxicity in cultured primary rat proximal tubular cells.

Puerarin, a potent free radicals scavenger, has been demonstrated to have protective efficacy in oxidative damage induced by nephrotoxins. In the present study, the attenuating effect of puerarin (PU) on lead (Pb)-induced apoptosis and oxidative stress was investigated in cultured primary rat proximal tubular (rPT) cells. Results showed that exposure to 0.5 µM Pb induced a decrease in cell viability accompanied with obvious cellular morphological alterations and caused an increase in apoptotic rate and apoptotic morphological changes. Simultaneously, depletion of mitochondrial membrane potential (ΔΨ) and intracellular glutathione (GSH); elevation of caspase-3 activity, intracellular reactive oxygen species, and malondialdehyde levels; and inhibition of GSH peroxidase (GSH-Px) activity were revealed in the cells exposed to Pb alone. However, simultaneous supplementation with PU (50 and 100 µM) protected rPT cells from Pb-induced cytotoxicity through inhibiting apoptosis, attenuating lipid peroxidation, renewing mitochondrial function, and elevating the intracellular antioxidants (nonenzymatic and enzymic) levels. In conclusion, these findings suggested that PU, as a widely distributed dietary antioxidant, contributes potentially to inhibition of Pb-induced cytotoxicity in rPT cells.

Liu G ，Li Z ，Wang J ，Wang H ，Wang Z ，Wang L ... -  《-》

Role of oxidative stress, apoptosis, and intracellular homeostasis in primary cultures of rat proximal tubular cells exposed to cadmium.

Wang L ，Cao J ，Chen D ，Liu X ，Lu H ，Liu Z ... -  《-》

Simultaneous effects of lead and cadmium on primary cultures of rat proximal tubular cells: interaction of apoptosis and oxidative stress.

The combined effects of lead (Pb) and cadmium (Cd) on primary cultures of rat proximal tubular (rPT) cells were studied. These cells were either treated with Pb acetate (0.5 and 1 μM) alone, Cd acetate (2.5 and 5 μM) alone, or a combination of Pb and Cd acetate, and then joint cytotoxicity was evaluated. The results showed that the combination of these two metals decreased cell viability and increased the number of apoptotic and necrotic cells and lactate dehydrogenase release synergistically. Simultaneously, increased intracellular reactive oxygen species, malondialdehyde, and calcium levels and decreased mitochondrial membrane potential, intracellular acidification, and inhibition of Na(+), K(+)-, and Ca(2+)-ATPase activities were shown during the exposure. In addition, apoptotic morphological changes induced by these treatments in rPT cells were demonstrated by Hoechst 33258 staining. The apoptosis was markedly prevented by N-acetyl-L-cysteine, whereas necrosis was not affected. In summary, there was a synergistic cytototic effect of Pb combined with Cd on rPT cells. Cell death induced by Pb-Cd mixture was mediated by an apoptotic and a necrotic mechanism. Apoptotic death was the chief mechanism. Changes of intracellular events were intimately correlated with both oxidative stress and mitochondrial dysfunction, which promoted the development of apoptosis.

Wang L ，Wang H ，Li J ，Chen D ，Liu Z ... -  《-》

Puerarin protects against cadmium-induced proximal tubular cell apoptosis by restoring mitochondrial function.

Puerarin (PU) is a potent free radical scavenger with a protective effect in nephrotoxin-mediated oxidative damage. Here, we show a novel molecular mechanism by which PU exerts its anti-apoptotic effects in cadmium (Cd)-exposed primary rat proximal tubular (rPT) cells. Morphological assessment and flow cytometric analysis revealed that PU significantly decreased Cd-induced apoptotic cell death of rPT cells. Administration of PU protected cells against Cd-induced depletion of mitochondrial membrane potential (ΔΨm) and lipid peroxidation. Cd-mediated mitochondrial permeability transition pore (MPTP) opening, disruption of mitochondrial ultrastructure, mitochondrial cytochrome c (cyt-c) release, caspase-3 activation and subsequently poly ADP-ribose polymerase (PARP) cleavage could be effectively blocked by the addition of PU. Moreover, up-regulation of Bcl-2 and down-regulation of Bax and hence increased Bcl-2/Bax ratio were observed with the PU administration. In addition, PU reversed Cd-induced ATP depletion by restoring ΔΨm to affect ATP production and by regulating expression levels of ANT-1 and ANT-2 to improve ATP transport. In summary, PU inhibited Cd-induced apoptosis in rPT cells by ameliorating the mitochondrial dysfunction.

Song XB ，Liu G ，Wang ZY ，Wang L ... -  《-》