Rats are made dependent on morphine and then given an injection of naloxone while housed in a novel cage. You would expect these rats to express
A) an aversion to the cage in which naloxone caused withdrawal.
B) fewer kappa receptors in the forebrain.
C) more mu receptors in the forebrain.
D) an attraction to the cage in which naloxone caused withdrawal.
E) more consumption of water in the home cage.

Question

Quizplus · Accepted Answer

The injection of naloxone causes withdrawal in the rats, and this aversive experience is associated with the novel cage. Therefore, the rats are expected to express a conditioned aversion to the cage in which naloxone caused withdrawal.

Answer: C 
 Morphine use leads to an increase in mu opioid receptors in the brain. Therefore, rats that are made dependent on morphine are expected to have more mu receptors in the forebrain.

Answer: D 
 This is an incorrect answer. Rats are expected to express a conditioned aversion to the cage in which naloxone caused withdrawal, due to the negative experience associated with the withdrawal. They would not be attracted to this cage.

Answer: B 
 This is an incorrect answer. Kappa opioid receptors are involved in the dysphoric effects of opioids and are upregulated after chronic opioid use. However, the question is asking for changes in the forebrain, and kappa receptors are more commonly found in other regions of the brain, such as the amygdala and periaqueductal gray.

Answer: E 
 This is an incorrect answer. There is no reason to expect that the rats would consume more water in their home cage after the injection of naloxone.

Rats Are Made Dependent on Morphine and Then Given an Injection