Abstract: Objective： To study the effect of titanium dioxide (TiO2) nanoparticles on intestinal glucose absorption in young rats and its size effect. Methods: In the study, 63 small intestine segments were isolated from 63 Sprague-Dawley rats (SD rats, 4-week-old) to prepare the everted gut sac model. In the first part of our work, the everted sacs were exposed to 0, 50 mg/L TiO2 nanoparticles (24 nm) for 2 h with the presence of a series of glucose concentrations (10, 25, 50, 100, 200, 400, and 800 mmol/L), and the glucose absorbing function of the everted sacs were assessed in the process. On the basis of the work, utilizing the same method, further study was carried out to compare the effects of TiO2 nanoparticles (24 nm) and fine-particles (120 nm) on intestinal glucose absorbing function with the presence of 400 mmol/L glucose and 0, 10, 50, 200 mg/L TiO2. 3 intestine segments were used in each group. Results: The cumulative glucose absorption increased with time extension and increased glucose concentration. In the first part of our work, with the presence of 400 mmol/L glucose, the group treated with 50 mg/L TiO2 nanoparticles showed significantly lower cumulative glucose absorption and glucose absorbing rate than the control group at the exposure time of  30 min (tcumulative absorption=3.254, P<0.05; tglucose absorbing rate=3.958, P<0.05), 90 min (tcumulative absorption=3.323, P<0.05; tglucose absorbing rate=3.063, P<0.05) and 120 min (tcumulative absorption=2.834, P<0.05; tglucose absorbing rate=3.002, P<0.05). At other glucose concentrations, statistically significant differences in cumulative glucose absorption or glucose absorbing rates were not found between the TiO2 nanoparticle exposed group and the control group. In the second part of our work, when compared with the control group, no significant downregulations in cumulative glucose absorption or glucose absorbing rates were observed in both TiO2 nano-particle treated group and TiO2 fine particle treated group. Differences between the TiO2 nanoparticle treated group and the TiO2 fine particle treated group were not statistically significant. Conclusion: Short-term exposure to TiO2 nanoparticles may downregulate the intestinal glucose absorbing function in young rats, and the difference with TiO2 fine particlesis is not obvious.

Key words: Titanium dioxide, Glucose absorption, Everted gut sac