A Study On The Expression Of The Excitatory Amino Acid Receptor, Inhibitory Amino Acid And Its Receptor In The Marginal Division

PurposeAmong the excitatory amino acid (EAA), the glutamate is most abounded in the brain. It is also one of the majority of excitatory neurotransmitter between the synapse in the central nervous system and mediates the normal synaptic activation of excitatory synaptic transmission. Glutamate play both role in the physiology and pathology through its receptors, among them the N-methyl-D-aspartate (NMDA) has an important role within the process of learning and memory. At present, mostneuroscientists have approved the cell model of learning and memory-------Long-term potentiation (LTP) was based on the NMDA receptor. Some dates of experiment have proved the NMDA subunits also can influence the process of learning and memory. LTP depends on the permanent functional alterations in neuron that require the reprogramming on the expression of gene. In this process the transcription factor-encoding immediate-early genes (lEGs) act as a message in coupling short-term neuronal activity at the level of gene transcription and promote the reprogramming of gene. Therefore lEGs consist of a part of signal transduction in the process of learning and memory, y -Amino butyric acid (GAB A) is the main inhibitory neurotransmitter in the central nervous system. Its affect on learning and memory one side is related with the synaptic plasticity of Long-term depression (LTD), the other side modulated the classic neurotransmitter such as acetylcholine (Ach) and serotonin (5-HT) to release.In order to investigation the membrane receptor of the signal transduction in the marginal division (MrD) of striatum within the process of learning and memory from molecular genetic aspect, the expression of NMDA receptor subunits such as NR1, NR2A and NR2B gene were investigated in the marginal division of striatum. To confirm the function ofthe MrD involved in learning and memory from behavior and functional aspect, the expression of IGEs c-fos and c-jun were investigated in the MrD of striatum after an avoidance learning task training in Y-maze. Whether the inhibitory amino acid GABA and the GABAei receptor mRNA expressed in the MrD, so that to understand the MrD within the process of learning and memory from the modulation aspect of inhibitory. The study will provide some significant materials for further to investigate the mechanism of signal transduction in MrD within the process of learning and memory.Methods and ResultsPart one: Using digoxigenin labeled oligonucleotide probes detected theexpression of the mRNA of NR1, NR2A and NR2B in the MrD by in situ hybridization. The results were found as follows: NR1 appears throughout the brain and evenly in striatum, some of positive medial fusiform neurons were fond in the MrD between the caudate putamen and globus pallidus. The distribution of expression of the NR2A mRNA was in a gradiently increase respectively from dorsolateral to ventromedial in striatum, especially a strong most strongly expressed in the MrD. The expression of NR2B mRNA showed an intensity band in MrD and in hippocampus and cerebral cortex, however there has only a little positive signal in globus pallidus. Part two: Sprague-Dawleg(SD) rats were given a stimulation of footshock to acquisition of a Y-maze avoidance learning task. After 1 hour over trainning, to combine the Western blot and immunocytochemical methods to detected the expression of c-fos, c-jun. The Western blot revealed there have separately two immunoractive band at 54 and 47KD, 54 and 39KD. The immunocytochemistry showed there have significant expression of c-fos and c-jun in the MrD, especially c-jun was exclusively in the MrD of striatum. The positive results also appeared in the hippocampus, cingulum cortex.From quantitative analyses there have significant different of expression in the MrD (p<0.01) between the training and pseudotraining groups. Part three: At first immunocytochemistry methods was used to investigate the expression of GABA, using GABA antibody and glutamic acid decarboxylase (GAD), a GABA synthetase, antibody includi...