Pathologic changes in hippocampus of rats exposed to fluoride and aluminum.

Abstract

Objective To establish a combined intoxication model of fluoride and aluminum to observe the impact of these chemicals on pathologic changes in hippocampus of rats. Methods Forty male 5 - week old Wistar rats were assigned into control (distilled water), fluoride (50 mg/L F-), aluminum (100 mg/L Al3+) and fluoride + aluminum exposure (50 mg/L F- and 100 mg/L Al3+) groups by random number table method according to body weight (120 - 150 g), ten rats in each group, and the experiment lasted for 3 months. Urine samples of 24 hours, brain and hippocampus of rats were collected. The concentrations of fluoride and aluminum in urine and brain were measured by ion selective electrode method and inductively coupled plasma atomic emission spectrometry, respectively. The pathologic and microstructural changes in the hippocampus were observed via light microscope (HE staining) and transmission electron microscopy. Results The differences of the concentrations of fluoride in urine and brain among groups were statistically significant (F = 36.790, 4.185, all P < 0.05). The concentration of urinary fluoride in fluoride group [(22.494 ± 6.130)mg/L] was higher than that of the combined group [(13.739 ± 1.878)mg/L, P < 0.01]; the concentration of brain fluoride in fluoride group [(0.191 ± 0.176)mg/kg] was higher than that of the control group [(0.064 ± 0.037)mg/kg, P < 0.01]. The differences of the concentrations of aluminum in urine and brain were statistically significant between groups (F = 19.117, 2.304, all P < 0.05). The concentrations of urine aluminum in aluminum and fluoride + aluminum groups [(3.722 ± 0.635), (4.750 ± 1.878)mg/L] were higher than that of the control group [(1.418 ± 0.733)mg/L, all P < 0.01]. HE staining showed irregular arrangement of neuron cells in aluminum group. Electron microscope showed that the mitochondria decreased significantly in aluminum group, and the number of mitochondria of fluoride + aluminum group was in between of the aluminum and the fluoride groups. Conclusion Combined intake of fluoride and aluminum may alleviate the deficits to pathologic and microstructural changes caused by aluminum intoxication. Key words: Pathology; Fluoride; Aluminum