Effect Of Aluminium On Long-Term Potentiation In Hippocampal CA1 And Ca～(2+) Concentration And Activity Of PKC In Hippocampal Neurons In Weaning Rats

PrefaceAluminium is one of the most redundant elements in the crust of the earth. Athough it is not highly noxious, too much of it in our body can cause toxicity. There are many investigations and researches show that Aluminium is most likely cause neurons impairment and decrease mentality and recognization. It is confirmed by animal experiments that exposure of Aluminium can cause rats dementia, which is not only appearances behavioral disturbance but also it's morph changes are remarkably like AD.Hippocampus is the key brain region for study and memory, Long — Term Potentiation(LTP) is Synaptic transmissions continuity enhancing of the NMDA receptors depended. It is received model of study and memory's function of brain at the synapse level. Its induction and maintenance is depended on the multiple fore - synaptic and post - synaptic. Consequently, studying the Effect of Aluminium on Long -Term Potentiation and approaching it's possible mechanisms can elucidate the mechanisms of Aluminium on study and memory.It is indicated that Aluminium's toxic effect on rats'growth period may be most important. Therefore, to establish the according animal models to observe the effect of Aluminium on long - term potentiation in hippocampal CA1 and Ca²⁺ concentration and activity of PKC in hippocampal neurons in Weaning Rats is significant to understand Aluminium's neurotoxicity. Our study is to offer some data to clear the neurotoxic mechanism of Aluminium.Material and Methods1. Animals and treatmentsWeaning Wistar Rats, weighting between 50 to 60 grams, are divided randomly into three groups based on their body weight. Each group has 9 males and 9 females. Aluminium chloride was administered by water at the doses of 0. 2% and 0. 6% (m/v) for 90 days. Weighting the body weight every 7 days.2. Methods2. 1 Body weight and brain coefficientsBrain coefficients = [brain weight(g)/body weight(lOOg) ]2. 2 Aluminium concentration analysisAtomic absorption spectrophotomery (AAS) was used to detect the content of Aluminium in blood and brain.2. 3 Ethology detectionEthology detection was detected by jumping stand experiment2.4 LTP recordThe technique of extracellular electrophysiological was used to record the effect of Aluminium on LTP in hippocampal CA1 area.2. 5 The Ca + concentration determineFura - 2/AM calcium ions fluorescence indicator was used to measure Ca concentration in hippocampal neurons.2. 6 The activity of PKC determineIsotope labelling method was used to determine the activity of PKC in hippocampal neurons2. 7 Ultrastructure of hippocampal neuronsElectron microscope was used to observe the ultrastructure of hippocampal neuronsResults1. Body weight and brain coefficientsThe body weights did not show any significant changes in the Aluminium exposed ratscompared with those of the corresponding group of control animals. The brain coefficients in the rats of high Aluminium exposed group ware decreased significantly with respected to the group of control animals.2. Aluminium concentration in blood and brainThe blood Aluminium concentration in the rats of Aluminium exposed groups were much higher than those of control groups. And there were significant changes in low and high Aluminium exposed groups. The same changes were there in brain Aluminium concentration except the significant changes in low and high Aluminium exposed groups.3. Ethology detectionThe learning and memory were significant decreased in in the rats of Aluminium exposed groups. The latency period was significant longer than the control group,and the error times was significant increased than the control group.4. LTP recordThe population spike (PS) in hippocampal CA1 was depressed in the rats of Aluminium exposed groups. And the higher dose the Aluminium exposed the mucher depressed.5. The Ca + concentrationThe Ca + concentration was reduced in the rats of Aluminium exposed groups. And the higher dose the Aluminium exposed the mucher reduced.6. The activity of PKCThe activity of PKC of membrane was inhibited in Aluminium exposed groups but there were no significant changes in the activity of PKC of endochyle-ma.7. Ultrastructure of hippocampal neuronsThe ultrastructure of neuron showed that Aluminium exposed resulted in ky-toplasm obviously reduced, mitochondria mitochondria cristae fractured,neuron nuclear damaged, nuclear tightened, nuclear matrix partly lost, euchromatin obviously reduced, heterochromatin obviously accrescence, showed " unnular hollow" , neurofilaments and neurotubules interlaced together. There were nothingbut only naked nuclear in the neurons of high Aluminium exposed groups.Conclusions1. The blood and brain Aluminium concentration were increased distinctively after exposed to Aluminium, and the ultrastructure of hippocampal neurons were damaged.2. Aluminium could cause learning and memory problems.3. The PS in hippocampal CA1 was depressed, and the Ca + concentration was reduced ,and the activity of PKC of membrane was inhibited after exposed Aluminium.