Different Trends Of GAP-43 Gene And Protein Expression In The Hippocampus Of Mouse After Chronic Lead Exposure During Development

ObjectiveThe lead is a well - known heavy metal environmental toxicant, which is very prevalent. Due to nervous system being in the stage of rapid development and in completely developed blood brain barrier, lead can cause apparently irreversible damage to the nervous system. Result in impairment of learning and memory and cognitive functions, this impairment can persist to adult. Consistent with these observation, studies on animal models have indicated an impairment of learning and memory following low level lead exposure, which results in relevant blood concentration.The study of clinic and experiment clew that the hippocampus and its structure were very important to learning and memory. Hippocampus was one of the key limbic regions involved in learning and memory, and LTP in hippocampus was one of mechanism of forming of memory. Norden( 1991) discovered that the expression of growth - associated protein had a close connection with the form of LTP, during observe of the inducement course in the hippocampus' LTP.GAP -43 is a special phosphor protein on the nerve cell membrane of am-niote, it is widely distribute but not equal in brain, it has a close correlation with the plasticity of synaptic. In a subsequent paper, the author showed that we firstly set up a protocol for chronic exposure to lead, and then using the RT -PCR and Western blots to investigated the expression of GAP - 43 messenger RNAs (mRNAs) and proteins, to discuss the nerval mechanism of the impairment of learning and memory caused by lead.Materials and MethodsKunming mouses were purchased from animal department of china medical university and were individually housed in plastic cages and one male mouse was mated with two female mouses of same strain. Mouses were randomly and equally divided into four groups. On postnatal day 1, the dam began to be exposed to lead at 0, 4. 8, 9. 6, 14. 4mmol. L-1 in drinking water. Food and water were free provided to all animals. At postnatal 28d, anatomise the animals for determining the blood lead and brain lead, individually the hippocampus were got from pups in different groups to observed the change of microstructure, the expression of GAP - 43 was determined by Western blots and the expression of GAP -43 gene was determined by RT - PCR.Results1. Effect of chronic lead exposure on the concentration of blood lead,brain lead in mouse in the region of the hippocampusUse the atomy absorb to determine the concentration of blood lead, brain lead in mouse in the region of the hippocampus, the results shows that the concentration of blood lead,brain lead which were exposed to lead were distinctly higher than the control group, and it was correlated with concentration of drinking lead.2. Effect of chronic lead exposure on the microstructural changes in the region of the hippocampus of the mouseThrough the electron microscopy we find that vacuole were detected in the nerve cell in the region of the hippocampus of the mouse after chronic lead exposure, cytoplasm disslived, the nerve cell was destroyed.3. Different trends of GAP - 43 gene expression in the hippocampus of mouse after chronic lead exposure during developmentExpression of GAP - 43 gene in hippocampus of pup mouses chronic expo-sured to lead were determined by using RT - PCR. The results indicate that de-...