Holly et. al

The paper this week focused on how cocaine changed behavior in stressed and non-stressed rats of both sexes. I found the premise of this study really interesting, because it emphasized the sex differences particularly in terms of stress. In Figure 2, Holly et. al (2012) show that stressed females in general have a longer walk duration and thus greater behavioral sensitization to cocaine. Non-stressed females in estrus showed an increase in walk duration after cocaine administration, while only males who were stressed showed a short-term increase in sensitization. These results are important because they demonstrate that females have increased walking behavior and that cocaine causes longer lasting effects in females than in males. I think this is extremely relevant for human application, because it implies that females might be more vulnerable to addictive drug sensitization, especially during menstruation.

Additionally, Holly et. al (2012) found a large difference between males and females in terms of dopaminergic sensitization in the nucleus accumbens. What particularly interested me was that stressed females seemed to have a prolonged change in dopamine, while males spiked to approximately the same level but returned to baseline levels after ninety minutes. Holly et. al (2012) seemed think that the reason for this was estradiol, but they weren’t very specific about which group of females (estrus or diestrus) was used in Figure 4, though their explanation indicates that it was likely estrus females. This is interesting, because the authors noted no difference when they castrated males, indicating that either the duration of dopamine change due to estradiol occurs only in females (as they believe) or that there is an alternative that has yet to be determined.

In terms of both binge infusion and duration stressed males and females binged more than control, but females more so than males. I thought it was interesting that stressed females had more infusions and a significantly longer duration than stressed males, but there were no differences in non-stressed females, especially since it again wasn’t clear as to whether the females were in estrus or diestrus. I think it would be helpful in the future to run diestrus versus estrus tests and show those results clearly, since I found the results in diestrus stressed females Figure 2 (who had a higher walk duration after cocaine) intriguing. Overall, I think that there is a lot of further research that could be done, and that the figures should have been clearer since the authors originally split their rats into three groups (male, female diestrus, and female estrus).