Sex differences in cocaine addiction


 This week’s paper investigated sex differences in addiction behavior. Sex differences always reveal hard to probe as there are usually many confounding factors. Holly et. al (2012) looked at differences in stress induced increased addictive behavior in response to cocaine. One of the most important factors accounted for in this paper was the phase of the estrous cycle in females. This allowed for the observation that females in the estrous phase of the cycle respond differently to cocaine when compared to both males and females in the diestrus cycle. Specifically, cocaine addiction is facilitated in this phase. Cycle specific DA levels in the NAcc were, unfortunately, not probed. This limits the conclusions that can be taken from the correlational observations made. Those effects should be investigated, along with direct manipulation of estradiol levels to determine if there is cause-effect relationship by which estradiol facilitates cocaine addiction by inducing DA signaling changes in the corticolimbic circuit of reward.
                The second paper, by Vassoler and colleagues (2012), also looked at sex differences in cocaine addiction behavior, although in a more roundabout way. This investigation was primarily concerned with the inheritance of cocaine resistance from cocaine addicted male progenitors. Female progenitors were not investigated due to alterations in maternal behavior which could confound the results. The effects of progenitor cocaine administration were, interestingly, specific to males when the progenitor was a male as well. Females showed no differences regardless of whether their male progenitor was administered cocaine or not. This is unlike other effects which are specific to females with paternal cocaine exposure, which have impaired working memory, while male offspring do not. The cocaine resistance effect seems to be mediated by increased BDNF expression, associated with AcH3. While no clear explanation from the results can be made for the sex specific effect observed here, the data indirectly suggests that the cocaine resistance is somehow mediated via the y-chromosome. Future lines of research should look at genes associated with BDNF activity which are coded in the y-chromosome, in order to further clarify how this progenitor effect is passed onto male offspring.

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