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. 2011 Jan 18;32(4):554–560. doi: 10.1093/carcin/bgr004

Fig. 1.

Fig. 1.

Treatment protocol and histopathology of tongue at 8 weeks of NQO exposure. (A) Treatment protocol. Experiment A (high NQO doses): 55 male rats (6-week-old) were fed a Zn-sufficient diet (65 p.p.m. Zn as Zn carbonate) and received drinking water exposure to high doses of NQO for 8 weeks (20 p.p.m. for 4 weeks followed by 30 p.p.m. for 4 weeks). At 8 weeks, five rats were killed for the determination of the status of lingual lesions. The remaining rats were taken off NQO and given deionized water with 0, 5 or 20 p.p.m. Zn (as Zn gluconate) to form the control (16 rats), low Zn (17 rats) and high Zn (17 rats) groups. Experiment B (low NQO doses): 56 Zn-sufficient rats (6-week-old) received drinking water exposure to low doses of NQO (10 p.p.m.) for 8 weeks. At 8 weeks, five rats were killed; the remaining rats were taken off NQO and given deionized water with 0 and 20 p.p.m. Zn (as Zn gluconate) to form the control (25 rats) and high Zn (26 rats) groups. All animals were fed the Zn-sufficient diet throughout the study period. The animals were killed at 13 (Experiment A) and 10 weeks (Experiment B) of Zn intervention. (B) Histopathology of tongues at 8 weeks of NQO exposure (scale bar, 100 μm).