Study of Morphine Tolerance in Rats

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Charles Scharfen
PSY 111 G
SONA Deadline 1
Questions 1,3,4,8,10

The study titled Evidence from Rats That Morphine Tolerance is a Learned response, is an experiment providing evidence that drug tolerance can be affected by environmental cues when theses cues are paired with the administered drug. In simpler words, drug tolerance may not just be the result in a change in ones psychological chemistry, but the result of environmental cues that trigger the subject to assume an increase in tolerance. Shepard Siegal, the scientist who developed this theory, injected rats with morphine or a placebo and their reaction to pain was recorded. A key to running the placebo trials correctly was making sure that the rats being tested were in the exact same kind of environment as when they were being injected with the morphine. The results of the test gave evidence that tolerance can be a conditioned response. A conditioned response is a learned response from an originally neutral stimulus (in this case the neutral stimulus is the environment the rats were in). Rats that were injected with the placebo, yet were in the same environment where they received morphine injections, did show reactions of increased tolerance of the drug (i.e. a greater reaction to pain). This article explores the natural phenomenon of drug tolerance. In the past, scientists have agreed that drug tolerance is the result of the brain adapting to the chemicals of the drug. It is believed that drugs such as opiates actually alter the way our receptors handle these chemicals. More recently, and as a result of experiments like these, there is speculation that drug tolerance is the result of a conditioned response. I believe that over time, the results of this experiment will be developed further by other researchers. At this time, the results of this experiment are by no means conclusive. Further testing and experimentation are required to increase the validity of this claim. This article has given be...
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