The results in the two papers seemed to compliment one another nicely. Holly et al. confirmed that females are more vulnerable than males to cocaine addiction. The results discussed in Vassoler et al. seem to confirm the idea that females are more vulnerable to addiction as evidenced by their lack of resistance to reinforcement. Holly et al. compared female responses to cocaine at different points in the estrus cycle, which I wish Vassoler et al. had done. It would have been interesting to see if estradiol levels affected females’ resistance to reinforcement since estradiol seems to modulate both behavioral sensitization and neural sensitization to cocaine based on the Holly et al research.
I wish the Holly et al. paper discussed why episodic social defeat stress induces increased cocaine response/cocaine-seeking behavior or why it augments extracellular dopamine. The researchers touched on the idea that episodic stress may alter dopamine reuptake mechanisms but did not expand on it. I think a useful follow up paper could take a deeper dive at parceling out the neuroadaptations episodic stress has on the dopamine system and then relating them to the results seen in this paper.
I found it interesting that the Vassoler et al. researchers stated their results are at odds with human epidemiological data. It made me question if their model is valid to translate to humans. In a way it seems a bit like the nature vs. nurture debate. Biologically having a cocaine-administering father may cause male progeny to be resistant to cocaine usage; sociologically it may not be as simple. Children of cocaine users may turn to cocaine because of the environment they were raised in may have normalized it or cocaine is a more easily accessible than other substances. While I think it is great that the researchers were able to offer some insight into the neurobiology behind cocaine usage, I do not believe you can discount environmental influences when translating the results to humans.