Objective To study the effect of coal-burning fluorosis on protein and mRNA expression of neuronal nicotinic acetylcholine receptor (nAChR) in brain tissue of offspring rats.
Methods Forty eight Sprague-Dawley (SD) rats (32 females and 16 males) were used in the study. The female rats were randomly divided into a control group and three (low, moderate, and high) fluoride treatment groups supplied with the feed containing fluoride at concentrations of 5.2, 24.4, 47.8, and 106.0 mg/kg continuously from puberty to lactation period. After 3-months′ fluoride treatment, the female rats of each groups were cohabited with 4 male rats. The females' offspring were fed with normal diet after weaning. Morris water maze test was performed for 30-day old offspring rats for evaluations of their learning and memory ability and the offspring rats′ brain tissues were collected for the determinations of nAChR protein with Western blot and nAChR mRNA with real-time fluorescent quantitative PCR.
Results The brain tissue fluoride content of the offspring rats in moderate and high fluoride groups increased significantly compared to the offspring rats of the control group (both P < 0.05). On the 3rd and 4th day of Morris water maze test, the average escape latency of offspring rats of high fluoride group was significantly longer than that of the control offspring rats (P < 0.05). Significantly decreased expressions of nAChR a7, a4 and β2 mRNA in the offspring rats with moderate and high maternal fluoride exposure and nAChR a7, a4 and β2 protein in all the offspring rats with maternal fluoride exposure were detected in comparison with the offspring rats of control group (all P < 0.05).
Conclusion Maternal fluoride exposure could reduce the expression of neural nicotine receptor protein and mRNA in brain tissue of offspring rats and the decreases may contribute to impacted learning and memory ability of the offspring rats.
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