| Objective: To study the influence of coal-burning fluorosis on learning and memory and the expression of glial fibrillary acidic protein(GFAP)and brain derived neurotrophic factor(BDNF)in hippocampus of newborn rats.To investigate the possible mechanism of off springs nervous system's injury by maternal chronic fluorosis.Methods: 112 SD rats were weaned for two weeks(96 females and 16 males).According to body weight,female rats were randomly divided into control,low-fluorine,medium-fluorine and high-fluorine group with 24 rats in each group.Fluoride exposed groups' female rats were fed with the local corn dried by burning coal from the endemic fluorosis area for 150 days,the fluoride content in feed of high,medium and low dose group was 106.0,47.8 and 24.4 mg/kg,but the control and male rats were fed with normal diet.The female rats and male rat were mated in cages at 2:1 in 90 days,120 days and 150 days respectively.Before mating,the female rats' growth and dental fluorosis were observed and urine samples were collected for 24 hours.Continue poisoning after pregnancy until offspring wean,young mice were given normal diet after weaning.Observing the body weight,head-body length and tail length,auricle separation,hair growth,growth of upper and lower incisors and eye opening of each group's pup rats at different time points after birth and the neurobehavior such as planar righting reflex and cliff avoidance reflex.Calculating the offsprings' brain weight coefficient.Fluorine in urinary?bone and brain of neonatal rats,and female rats' urinary fluorine detected by fluorine ion selective electrode method.30-day-old rats' learning and memory ability were tested by Morris water maze.ELISA for detection of the expression level of BDNF in hippocampus of offspring.Western blot was used to detect the expression of GFAP in hippocampus of filial generation.Results:1.Establishment coal-burning fluorosismodel of during puberty and pregnancy and suckling period: No obvious dental fluorosis occurred in the control group.Different degrees of dental fluorosis occurred in the other groups and the degree of dental fluorosis in the other groups was increased with the increase of the dose(P<0.05).The results showed that the concentration of urinary fluoride in other groups was higher than the control group before mating in cage with the increase of the dose and exposure time(P<0.05).Combined with the dental fluorosis and urinary fluorine index of rats,it can be concluded that the animal model of puberty fluorosis has been successfully reproduced in this study,subsequent experiments can be carried out.2.Fluoride levels in urine,bone and brain tissue of offspring rats: At the same exposure time,the offsprings' fluorous level of urine,bone and brain in exposure groups were higher than control,and with the prolongation of fluorine exposure time,the offsprings' fluorous level of nurine,bone and brain in each group were increased,and the difference was statistically significant(P<0.05).3.The growth and neurobehavior reflection of offspring rats: Female rats exposed to fluoride for 90 and 120 days,the PND1,PND6,PND11 offsprings' weight has no significant difference(P>0.05),compared with the control group,the offsprings' weight of high fluorine group in PND16?PND21 was significantly lower(P < 0.05),female rats exposed to fluoride for 150 days,the offsprings' weight of high fluorine group in PND11,PND16,PND21 and the offsprings' weight of medium fluorine group's in PND21 was significantly lower than control(P<0.05);Female rats exposed to fluoride for 90 and 120 days,the PND6,PND11,PND16 offsprings' head-body length and tail length has no significant difference(P>0.05),compared with the control and low fluorine group,the offsprings' head-body length and tail length of high fluorine group in PND16,PND21 was significantly shorter(P<0.05),female rats exposed to fluoride for 150 days,the offsprings' head-body length and tail length of high fluorine group in PND16,PND21,PND26 was significantly lower than control(P<0.05);At every period of fluorous exposure,the brain weight coefficient,auricle separation,hair growth,growth of upper and lower incisors and eye opening of exposure group's offsprings has no significantly different than control(P>0.05);At every period of fluorous exposure,compared with the control and low fluorine group,the time of planar righting reflex in the high fluorine group's offspring was longer(P<0.05),the female rats exposed to fluoride for 150 days,the time of cliff avoidance reflex in high fluoride group's offspring was longer than control(P<0.05).4.Spatial learning and memory ability of offspring rats: Female rats exposed to fluoride for 90 and 120 days,compared with the control and low-fluorine group,the escape latency in the 3rd day and the 4th day of offsprings in the high-fluoride group was significantly prolonged(P<0.05);Female rats exposed to fluoride for 150 days,compared with the control,the escape latency in the 2nd day,3rd day and 4th day of offsprings in the high-fluoride group was significantly prolonged(P<0.05),and the escape latency in the 3rd day and 4th day of offsprings in the middle-fluorine group was significantly prolonged(P<0.05).Different stages of exposure to female rats,compared with the control and lowfluorine group,the time of first reaching platform of the high-fluorine group's offsprings was significantly prolonged(P<0.05);Female rats exposed to fluoride for 150 days,the time of first reaching platform of middle-fluorine group's offspring was longer than the control(P<0.05);Female rats exposed to fluoride for 90 and 120 days,the times of across platform of the high-fluorine group's offsprings were less than the control;Female rats exposed to fluoride for 150 days,the times of across platform of high-fluorine group's offsprings were decreased compared with control and low-fluoride group(P<0.05).5.Expression of GFAP,BDNF protein in hippocampus of offsprings: At the same exposure time,the content of BDNF in hippocampus of offsprings decreased gradually,Compared with the control and the low-fluoride group,in each stage of fluoride exposure in female rat,the offsprings' BDNF content in the hippocampu of the high-fluoride group was decreaed(P<0.05);The expression level of GFAP in hippocampu of each group increased gradually,compared with other groups of offspring,the expression level of GFAP in hippocampu of high-fluoride group was higher(P<0.05).Conclusion: 1.Coal burning fluorosis of female rats can inhibition the growth and development of offspring rats;2,Coal burning fluorosis of female rats harmed the spatial learning and memory abilities of the offspring rats;3.The decrease of learning and memory ability of offspring ratsexposed to coal-burning fluorosis may be related to the increased expression of GFAP protein and the decrease of BDNF protein content in hippocampal area of offspring rats. |
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