Berberine alleviates chlorpyrifos-induced nephrotoxicity in rats via modulation of Nrf2/HO-1 axis

Abstract

Chlorpyrifos (CPS), an organophosphorus insecticide, is widely used for agricultural and non-agricultural purposes with hazardous health effects. Berberine (BBR) is a traditional Chinese medicine and a phytochemical with anti-inflammatory and anti-oxidative properties. The present study evaluated the effects of BBR against kidney damage induced by CPS and the underlying mechanisms. An initial study indicated that BBR 50 mg/kg was optimal under our experimental conditions. Then, 24 rats (6/group) were randomized into: control, BBR (50 mg/kg/day), CPS (10 mg/kg/day), and CPS + BBR. BBR was administration 1 h prior to CPS. Each treatment was delivered daily for a period of 28 consecutive days using a gastric gavage tube. Compared to CPS-alone treated rats, BBR effectively improved renal function by preventing the rise in serum urea, creatinine, and uric levels. The reno-protective effects of BBR were confirmed through a histological examination of kidney tissues. BBR restored oxidant-antioxidant balance in renal tissues mediated by Keap1/Nrf2/HO-1 axis modulation. In addition, BBR decreased nitric oxide (NO) and myeloperoxidase (MPO) activity. This was paralleled with the potent down-regulation of NF-κB. Furthermore, BBR exhibited anti-apoptotic activities supported by the upregulation of Bcl-2 and down-regulation of Bax and caspase-3 expression. In conclusion, our data suggest that BBR attenuates CPS-induced nephrotoxicity in rats by restoring oxidant-antioxidant balance and inhibiting inflammatory response and apoptosis in renal tissue. This is mediated, at least partly, by modulation of the Nrf2/HO-1 axis.

Keywords: Berberine; Chlorpyrifos; Keap1/Nrf2/HO-1; NF-κB; Nephrotoxicity.

Fig. 1

Effect of different dose levels of BBR on markers of kidney function in CPS-treated rats. A: Urea, B: Creatinine, C: Uric acid. Data are mean ± SD (n = 6). a, b, c significantly different from Control, BBR, or CPS, respectively, at p < 0.05 using one-way ANOVA followed by Tukey post-analysis.

Fig. 2

Effect of BBR (50 mg/kg) on serum markers of kidney function in CPS-treated rats. A: Urea, B: Creatinine, C: Uric acid, D: Cystatin C, E: NGAL. Data are mean ± SD (n = 6). a, b, c significantly different from Control, BBR, or CPS, respectively, at p < 0.05 using one-way ANOVA followed by Tukey post-analysis.

Fig. 3

Impact of BBR on kidney histopathological changes in CPS-treated rats. A represents a photomicrograph obtained from a kidney of a control rat showing glomeruli (G) made of tufts of capillaries lined with endothelium on the basement membrane, pericytes, and intramesengial cells as well as proximal (P) and distal convolutes tubules (D). Also, similar findings were observed in B, which represents a photomicrograph of a kidney of a rat in the BBR (50 mg/kg) group with normal glomeruli (G), proximal (P), and distal convolutes tubules (D). On the other hand, rat kidneys that received 10 mg/kg CPS only showed marked thickening of the basement membranes of the capillary tufts (black arrow), as represented in C. Also, a substantial decrease of cellularity (blue star) of the glomeruli and obliteration of the capsule (O) were observed in 10 mg/kg CPS-treated rats, as shown in D. Further, a marked thickening of the blood vessel (V) and perivascular inflammatory cellular reaction (yellow star) were also detected as shown in E. In contrast, co-treatment with 50 mg/kg BBR potently attenuated these histopathological changes, as evidenced by apparently healthy glomeruli (G), as shown in F. H&E. Scale bar = 50 μm. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)

Fig. 4

Effect of BBR on renal oxidative injury in CPS-treated rats. A: MDA, B: SOD, C: GST, D: GSH, E: GSSG, F: Ratio GSH/GSSG. Data are mean ± SD (n = 6). a, b, c significantly different from Control, BBR, or CPS, respectively, at p < 0.05 using one-way ANOVA followed by Tukey post-analysis.

Fig. 5

Impact of BBR on kidney expression of Keap-1, nuclear Nrf2, total Nrf2, and HO-1 in kidneys of CPS-treated rats. A: Western blot of control, BBR, CPS and BBR + CPS. B, C, D, and E: Graphical presentation of Keap-1, nuclear Nrf2, total Nrf2, and HO-1 relative optical densities, respectively. Data are mean ± SD (n = 6). a, b, c significantly different from Control, BBR, or CPS, respectively, at p < 0.05 using one-way ANOVA followed by Tukey post-analysis. Full, non-adjusted images of Fig. 5A are provided as Supplementary Material.

Fig. 6

Effect of BBR on MPO activity and total nitrite content in kidney tissues of CPS-intoxicated rats. A: MPO, B: Total nitrite (NO₂−). Data are mean ± SD (n = 6). a, b, c significantly different from Control, BBR, or CPS, respectively, at p < 0.05 using one-way ANOVA followed by Tukey post-analysis.

Fig. 7

Effect of BBR on NF-κB2 expression in kidney tissues of CPS-treated rats. A Control, B BBR, C CPS, D BBR + CPS, and E graphic presentation of % positive areas in each section. Data are mean ± SD (n = 6). a, b, c significantly different from Control, BBR, or CPS, respectively, at p < 0.05 using one-way ANOVA followed by Tukey post-analysis.

Fig. 8

Effect of BBR on the expression of Bcl-2 (upper panel), Bax (middle panel), and caspase-3 (lower panel) in kidney tissues of CPS-treated rats. Bar charts represent semi-quantification of expression of corresponding proteins. Data are mean ± SD (n = 6). a, b, c significantly different from Control, BBR, or CPS, respectively, at p < 0.05 using one-way ANOVA followed by Tukey post-analysis.

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