The mechanism of oxidative damage in the nephrotoxicity of mice caused by nano-anatase TiO₂

Figures & data

Figure 1. The (101) X-ray diffraction pattern of anatase TiO_2.

Figure 2. Sizes of TiO₂ particles observed by TEM: (a) nano-anatase TiO₂ particles and (b) bulk TiO₂ particles.

Table 1. Increase of net weight and coefficients of the kidney of ICR mice after abdominal cavity was injected with nano-anatase TiO₂ suspensions.

Index	Nano-anatase (mg/kg BW)						Bulk TiO2 (mg/kg BW)
	0	5	10	50	100	150	150
Net increase of BW (g)	7.86 ± 0.39	8.22 ± 0.41	7.94 ± 0.4	7.79 ± 0.39	7.46 ± 0.37	7.23 ± 0.36	7.55 ± 0.37
Kidney/BW (mg/g)	6.92 ± 0.35	6.94 ± 0.35	7.05 ± 0.35	8.38 ± 0.42*	8.59 ± 0.43*	11.18 ± 0.56**	8.61 ± 0.43*
Notes: Values represent means ± SE, n = 10.
Ranks marked with an asterisk or double asterisks means it is significantly different from the control (no nano-anatase or bulk TiO2) at the 5% or 1% confidence level, respectively.

Table 2. Contents of titanium in the kidneys of mice after abdominal cavity was injected with nano-anatase TiO₂ suspensions.

Index	Nano-anatase-TiO2 (mg/kg BW)						Bulk TiO2 (mg/kg BW)
	0	5	10	50	100	150	150
Kidney (ng/g)	80.6 ± 4.0	144.2 ± 7.2*	193.7 ± 9.7*	423.5 ± 21.1	672.7 ± 33.6*	1249.6 ± 62.5*	778.6 ± 38.9*
Notes: Values represent means ± SE, n = 10.
Ranks marked with an asterisk means it is significantly different from the control (no nano-anatase or bulk TiO2) at the 5% confidence level.

Figure 3. Histopathology of the nephric tissue in female mice after intraperitoneal injection with various doses of nano-anatase TiO₂ suspensions for consecutive 14 days. (a) control group (400×): renal glomerulus is complete and renal tubule is normal; (b) 5 mg/kg BW nano-anatase TiO₂ group (100×): without abnormal pathology changes; (c) 50 mg/kg nano-anatase TiO₂ group (200×): arrows indicate focal basophilia; (d) 100 mg/kg BW nano-anatase TiO₂ group (200×): arrows indicate focal congestion; (e) 150 mg/kg BW nano-anatase TiO₂ group (200×): diffuse basophilic degeneration and (f) 150 mg/kg BW bulk TiO₂ group (100×): obvious congestion, basophilic degeneration.

Table 3. Changes of biochemical parameters in the blood serum of mice kidneys after abdominal cavity was injected with nano-anataseTiO₂ suspensions.

	Nano-anatase (mg/kg BW)						Bulk TiO2 (mg/kg BW)
Index	0	5	10	50	100	150	150
UA (µmol/l)	219.5 ± 10.98	223.7 ± 11.84	219.6 ± 10.98	120.7 ± 6.04**	110.3 ± 5.52**	105.2 ± 5.26**	179.5 ± 8.98*
Cr (µmol/l)	8.81 ± 0.44	8.62 ± 0.43	8.77 ± 0.44	9.13 ± 0.45	9.26 ± 0.46	9.39 ± 0.47	8.97 ± 0.45
BUN (mmol/l)	9.28 ± 0.46	9.31 ± 0.47	9.12 ± 0.45	7.71 ± 0.40*	7.45 ± 0.39*	7.31 ± 0.37*	8.16 ± 0.41*
Ca (mmol/l)	2.39 ± 0.12	2.41 ± 0.12	2.60 ± 0.13	2.68 ± 0.13	2.75 ± 0.14	2.99 ± 0.15	2.69 ± 0.13
P (mmol/l)	3.38 ± 0.17	3.40 ± 0.17	3.44 ± 0.17	3.72 ± 0.19	3.86 ± 0.19	3.92 ± 0.20	3.67 ± 0.18
Notes: Values represent means ± SE, n = 10.
Ranks marked with an asterisk or double asterisks means it is significantly different from the control (no nano-anatase or bulk TiO2) at the 5% or 1% confidence level, respectively.

Table 4. Generating rate of ROS and lipid peroxidation of the kidneys of ICR mice after abdominal cavity was injected with nano-anataseTiO₂ suspensions.

Nano-anatase (mg/kg BW)	generating rate (µmol/mg protein min)	H2O2 generating rate (nmol/mg protein min)	MDA content (µmol/g tissue)
0	51.60 ± 2.58	24.27 ± 1.21	7.27 ± 0.36
5	55.15 ± 2.76	24.82 ± 1.24	8.59 ± 0.43
10	58.54 ± 2.93*	29.47 ± 1.47*	13.89 ± 0.69**
50	60.05 ± 3.00*	35.49 ± 1.77**	16.15 ± 0.81**
100	85.49 ± 4.27**	55.73 ± 2.79**	22.72 ± 1.14**
150	111.60 ± 5.58**	76.08 ± 3.80**	27.06 ± 1.35**
150 Bulk TiO2	79.15 ± 3.96*	45.96 ± 2.30*	14.07 ± 0.70**
Notes: Values represent means ± SE, n = 10.
Ranks marked with an asterisk or double asterisks means it is significantly different from the control (no nano-anatase or bulk TiO2) at the 5% or 1% confidence level, respectively.

Table 5. Activities of antioxidative enzymes of the kidneys of ICR mice after abdominal cavity was injected with nano-anataseTiO₂ suspensions.

Nano-anatase (mg/kg BW)	SOD (U/mg protein min)	CAT (U/mg protein min)	APX (U/mg protein min)	Total antioxidant capacity (unit/mg protein)
0	33.06 ± 1.65	101.25 ± 5.06	428.57 ± 21.43	29.80 ± 1.49
5	30.25 ± 1.51	93.50 ± 4.68	414.29 ± 20.71	25.00 ± 1.25
10	28.19 ± 1.41*	55.13 ± 2.76**	360.00 ± 18.00*	23.50 ± 1.18
50	22.79 ± 1.14**	30.38 ± 1.52**	242.86 ± 12.14**	22.1 ± 1.11*
100	11.43 ± 0.57**	19.13 ± 0.96**	142.86 ± 7.14**	11.20 ± 0.56**
150	4.59 ± 0.23**	10.00 ± 0.50**	107.14 ± 5.36**	7.62 ± 0.38**
150 bulk TiO2	15.44 ± 0.77**	27.50 ± 1.38**	271.43 ± 13.57*	15.50 ± 0.78**
Notes: Values represent means ± SE, n = 10.
Ranks marked with an asterisk or double asterisks means it is significantly different from the control (no nano-anatase or bulk TiO2) at the 5% or 1% confidence level, respectively.

Figure 4. Ratios of AsA to DAsA and GSH to GSSGG of kidneys of mice after nano-anatase TiO₂ suspensions were injected into abdominal cavity. Note: bars marked with an asterisk or double asterisks means it is significantly different from the control (no nano-anatase or bulk TiO₂) at the 5% or 1% confidence level, respectively. Values represent means ± SE, n = 5.