Toxicological study of injuries of rat’s hippocampus after lead poisoning by synchrotron microradiography and elemental mapping

The hippocampus, a major component of the brain, is one of the target nervous organs in lead poisoning. In this work, a rat’s hippocampal injury caused by lead was studied. The lead concentrations in blood, bone and hippocampus collected from rats subject to lead poisoning were quantified by Inductively Coupled Plasma Mass Spectrometry while morphological information and elemental distributions in the hippocampus were obtained with synchrotron radiation X-ray phase contrast imaging and synchrotron radiation micro-beam X-ray fluorescence, respectively. For comparison, identical characterization of the specimens from the rats in the control group was done in parallel. Results show that the ratios between the lead content in the treated group and that in the control group of the hippocampus, bone, and blood are about 2.66, 236, and 39.6, respectively. Analysis also revealed that some health elements such as S, K, Cl and P increase in the regions with high lead content in the treated hippocampus. Morphological differences between the normal and lead-exposed hippocampus specimens in some local areas were observed. Explicitly, the structure of the lead-exposed hippocampus was tortuous and irregular, and the density of the neurons in the Dentate Gyrus was significantly lower than that from the control group. The study shows that the synchrotron radiation methods are very powerful for investigating structural injury caused by heavy metals in the nervous system.