Protective effect of maternal N-acetyl-cysteine supplementation during pregnancy against cadmium-induced renal damage in male mouse offspring

Background  Previous studies have found that maternal N-acetyl-cysteine (NAC) supplementation during pregnancy can alleviate cadmium-induced fetal growth restriction in mice. However, the effect on cadmium-induced renal development impairment in offspring is unclear.

Objective The present study is to explore the effect of maternal NAC supplementation during pregnancy on Cd-impaired renal development in male mouse offspring and its mechanisms.

Methods A total of 65 CD-1 pregnant mice were raised to gestational day7 (GD7) and randomly divided into control group (n=12), NAC group (n=13), low-concentration cadmium (LCd) group (n=12), high-concentration cadmium (HCd) group (n=13), and NAC plus highconcentration cadmium (NCd) group (n=15). In the LCd group, HCd group, and NCd group, pregnant mice were exposed to different concentrations of cadmium (50, 150, and 150 mg·L^-1) by drinking water from GD8 to GD17. In the NAC group and NCd group, pregnant mice were treated with NAC (500 mg·kg^-1) daily by intragastrical administration from GD7 to GD17. Four to five pregnant mice in each group were sacrificed by cervical dislocation to collect maternal serum and fetal kidneys on GD18. The remaining pregnant mice delivered naturally; and the male offspring mice were raised to postnatal day 35 (PND 35) and PND 98, and sacrificed by cervical dislocation to collect their serum and kidneys. The levels of renal function indicators in male offspring mice serum were detected. Kidney pathological changes were observed. Bowman space area was measured by Image J 1.51. The expression levels of nicotinamide adenine dinucleotide phosphate oxidase 4 (NOX4), super oxygen dehydrogenises 2 (SOD2) in fetal kidney and proliferating cell nuclear antigen (PCNA) in kidney of offspring mice at different developmental stages were detected by Western blotting.

Results The maternal low-concentration cadmium exposure during pregnancy reduced the weight and coefficient of fetal kidneys and the weight of adolescent kidneys (P < 0.05). The maternal high-concentration cadmium exposure during pregnancy reduced the weight and coefficient of fetal and adolescent kidneys and the weight of adulthood kidneys (P < 0.05). The maternal low-concentration and high-concentration cadmium exposure during pregnancy down-regulated the expression of PCNA, a proliferation-associated protein, in offspring kidneys (P < 0.05). The LCd group showed decreased Bowman space area in adolescent and adulthood kidneys compared with the control group(4 346.45±205.27) μm² vs (17 823.50±150.55) μm², (4 774.00±843.29) μm² vs (17 869.81±665.93) μm²; P < 0.01. So did the HCd group(4 516.20±113.44) μm² vs (17 823.50±150.55) μm², (4 483.97±146.47) μm² vs (17 869.81±665.93) μm²; P < 0.01. The maternal cadmium exposure during pregnancy increased the levels of NOX4 and SOD2 in fetal kidneys (P < 0.05). However, the maternal NAC supplementation during pregnancy markedly alleviated the oxidative stress in fetal kidneys (P < 0.05), reversed the down-regulated PCNA levels in offspring kidneys (P < 0.05), and antagonized the decreases of kidney weight(0.56±0.02) g vs (0.43±0.01) g, (0.66±0.02) g vs (0.58±0.03)g; P < 0.05 and Bowman space area(21158.41±971.19)μm² vs (4516.20±113.44)μm², (19538.48±178.13)μm² vs (4483.97±146.47)μm²; P < 0.01 in adolescent and adult offspring kidneys induced by the high-concentration cadmium exposure.

Conclusion Maternal NAC supplementation during pregnancy could markedly alleviate Cd-impaired renal development in male mouse offspring, which is related to the antagonism of oxidative stress in fetal kidneys.