MCAT Behavioral Sciences Question 232: Answer and Explanation

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Question: 232

2. One treatment for Alzheimer's disease involves a drug that blocks NMDA receptors. This treatment could lead to all of the following EXCEPT:

  • A. a suppression of LTP.
  • B. a suppression of gene expression.
  • C. a significant decrease in intracellular sodium.
  • D. a significant decrease in intracellular calcium.

Correct Answer: C

Explanation:

If NMDA receptor activation is necessary for LTP, then blocking this receptor would likely suppress LTP (choice A could occur and can be eliminated). Based on Figure 1, activation of the NMDA receptor triggers an influx of intracellular calcium and a cascade of events resulting in activation of gene expression; thus, blocking this receptor could lead to both a significant decrease in intracellular calcium and a suppression of gene expression (choices B and D could occur and can be eliminated). Since the NMDA receptor allows an influx of sodium, some reduction in intracellular sodium could be expected; however, this is unlikely to be significant since the AMPA receptor would still be functional and is the main source of Na+ influx (choice C would not occur and is the correct answer choice).

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