Question

Please answer the question fully while keeping your essay to 100 words. This may take careful editing on your part. ESSAY QUESTION ON AP5: In research using the drug, AP5, the implications are clear about what receptors are important for new learning and what receptors are important for old learning. Briefly, in the experiment, rats were being trained to learn a maze. Rats who had not learned the maze had AP5 administered to the areas of their dendritic spines. This blocked the formation of longterm potentiation, thus, blocking new learning. What receptors were blocked in this case? Other rats who had already learned the maze had AP5 administered to their dendritic spines. AP5 did not remove the longterm potentiation which had already formed, and did not remove the learning which had already occurred. What receptors were involved in this case? To repeat the essay question, the experiments with AP5 show clearly that there is a difference between new learning and old learning. These differences have to do with the receptors involved. What does AP5 show us in terms of the receptors involved with new learning and with old learning? Name the receptors and the logical process by which you deduce them. (You may have to go beyond the AP5 experiments to discuss the receptors of old learning, but do not go into extended detail.)

Answer 1

The AP5 or APav ((2R)-amino-5-phosphonovaleric acid; (2R)-amino-5-phosphonopentanoate) is a selective NMDA receptor antagonist that competitively inhibits the ligand (glutamate) binding site of NMDA receptors. AP5 blocks NMDA receptors in micromolar concentrations. An increasing level of N-methyl-D-aspartate NMDA receptor hypofunction within the brain is associated with memory and learning impairments. NMDA receptor antagonist drugs administered to the hippocampus interfere with long-term potentiation, learning, and memory. NMDA when systematically administered in rats, has shown to potentiate cognitive functions. It has been shown that blockade of NMDA sites with the AP5 drug does not detectably affect synaptic transmission in the hippocampus, but prevents the induction of long term potentiation. In the above experiment NMDA receptors were blocked. The NMDA receptor channels play an important role in synaptic plasticity and synapse formation underlying memory, learning and formation of neural networks during development in the central nervous system. Blocking if these receptors may be useful in treating neurodegenerative disorders such as Alzheimer's disease, Parkinson's disease and Huntington's disease.