Effect Of Lanthanum Exposure During Pregnancy And Lactation On Calcium And Apoptosis Level In Hippocampus Cell And Glutamate Concentration Of Central Nervous System Of Baby-rats

PrefaceWith the rapid development of rare earth industry and extensive application of rare earth inagriculture, a great many of rare earth elements(REEs)were released into environment, especiallywater environment, and the consequent serious environment pollution has attracted people'sattention. However, to date, studies still concentrate mostly on REEs effects in increasing yield andenhancing resistance but little work has been done on their environmental safety, moreover, onlyanimals.The toxic effects of rare earth elements such as lanthanum, cerium and heavy metal elementssuch as chromium, were studied, the lanthanum can break the balance of protective enzymesystems, reduce the content of chlorophyll and protein, aggravate membrane lipids damage. REEand heavy metal element have similar pollution mechanism. In shorter time and at lowerconcentration, all of them show stimulating action. However, when their concentration ortreatment time exceeds a certain range, all of them have toxic effects on animal.Hippocampus is the key brain region of study and memory. It is received study model ofstudy and memory's function of brain at the synapse level. It's induction and maintenance isdepended on the multiple fore-synaptic and post-synaptic. Consequently, studying the Effect ofLanthanum during pregnancy and lactation and approaching it's possible mechanisms can elucidatethe mechanisms of Lanthanum on study and memory.It is indicated that Lanthanum's toxic effect on rats' growth period may be most important. Therefore, to establish the according animal models to observe the effect of lanthanum exposureduring pregnancy and lactation on calcium and apoptosis level in hippocampus cell and glutamateconcentration of central nervous system of baby-rats is significant to understand Lanthanum'sneurotoxicity. Our study is to offer some data to clear the neurotoxic mechanism of Lanthanum.Material and Methods1,Animal and treatment40Wistar female Rats, weighting between 260 to 280 gram, 40male Rats,weighting between 280 to 300 gram, the female rats were administrated with lanthanumfrom pregnancy to 21th day after delivery, measuring the apoptosis level inhippocampus cell of baby-rats.the offsprings are divided randomly into fourgroups. Lanthanum chloride was administered by water at the doses of 0.25%, 0.5%and1.0%(m/v) for 49days. Weighting the body weight every 5 days.2,Methods(1) Body weight and brain coefficientsBrain coefficients=[brain weight(g)/body weight×100%].(2) Ethology detectionEthology detection was detected by jumping stand experiment,recording the timecourse of the first step (latency)and the frequency of shock in 5 min(fault frequency)(3)The Ca²⁺ concentration determineFura-2/AM calcium ions fluorescence indicator was used to measure Ca²⁺concentration in hippocampal neurons(4) The level of Glu determineImmunohistochemical method was used to determine the level of Glu in hippocampalneurons(5) The apoptosis levelMicronucleated polychromatic erythrocytes to determine the apoptosis level in hippocampus cell of baby-rats(6) Morphous of hippocampal neuronsThe histological structure was observated under the optical microscope.(7) Ultrastructure of hippocampal neuronsElectron microscope was used to observe the ultrastructure of hippocampal neurons3,StatisticsThe data sign to mean with the mean±SE. Changes in every array were analyzedby analysis of variance (ANOVA) followed by Fisher's least significant difference(LSD) after those have been showed as the normal distribution by the SPSS13.0. If theanalysis of normal distribution was not appropriate, the Kruskal-Wallis test was usedidentify the statistical significance of the individual groups.Results1,Body weight and brain coefficientsThe body weights did not show any significant changes in the Lanthanum exposedrats compared with those of the corresponding group of control animals. The braincoefficients in the rats of high Lanthanum exposed group ware decreased significantlywith respected to the group of control animals.2,Ethology detectionThe learning and memory were significant decreased in in the rats of Lanthanumexposed groups. The latency period was significant longer than the control group, andthe error times was significant increased than the control group.3,The Ca²⁺ concentrationThe Ca²⁺ concentration was increased in the rats of Lanthanum exposed groups.And the higher dose the Lanthanum exposed the mucher increased4,The level of GluDose elevated, the value of optical density increased gradually. The OD value of three brain region in control is control is significant different with expose group.5,The apoptosis levelThe apoptosis level was significant increased in the rats of Lanthanum exposedgroups. The level of apoptosis in the rats of high Lanthanum exposed group wereincreased significantly with respected to the group of control animals.6,Morphous of hippocampal neuronsThe morphous of neuron showed that Lanthanum exposed resulted in greatsignificant difference in pathologic injury.7,Ultrastructure of hippocampal neuronsThe ultrastructure of neuron showed that Lanthanum exposed resulted inkytoplasm obviously reduced, mitochondria cristae fractured, neuron nuclear damaged,nuclear tightened, nuclear matrix partly lost, euchromatin obviously reduced,heterochromatin obviously accrescence, showed "urmular hollow", neurofilaments andneurotubules interlaced together. There were nothing but only naked nuclear in theneuron high Lanthanum exposed groups.Conclusions1,Lanthanum could cause learning and memory problems.2,The Ca²⁺ concentration was increased, and the level of Glu andapoptosis was increased after exposed Lanthanum.3.,Ultrastructure and morphous of hippocampal neurons showed thatLanthanum exposed were damaged.