Vassoler et al. (2012)

In this week’s article, Vassoler et al. (2012) investigated the impact of paternal self-administered cocaine on the offspring using an experimental design model that examined cocaine reinforcement, gene expression, and chromatin remodeling. Most notably, only the male offspring yielded significant results in contrast to the females, which seemed to remain unaffected by the cocaine administration of the father in comparison with the control saline sired females. The male cocaine sired rats demonstrated a reduced breakpoint during the progressive ratio cocaine self administration test, indicating decreased acquisition and increased BDNF levels in the mPFC. The research team had a few control experiments, for example, testing sucrose preference to rule out a possible learning deficit for cocaine self administration and monitoring maternal behavior toward the pups. They also continued to explore the mPFC BDNF expression in relation to the decreased cocaine reinforcement by using a TrkB receptor antagonist (ANA-12) to block the TrkB receptors utilized by BDNF, which increased the reinforcement of self-administration to that of the control.

I thought this study was very interesting, more so because I was unaware of the epigenetic factors that contribute to inheritance. It’s fascinating (and rather terrifying) that ancestral behaviors can have such a profound and specific effect on certain offspring. In particular, the stark difference in how male and female progeny are affected by the same paternal influence is very drastic. Regarding the behavioral results, I would have assumed that paternal cocaine administration would have increased the cocaine administration acquisition in the offspring given the logic that maybe they would be more sensitive to the effects. This seems like a rather protective inherited trait. Also, I found it interesting that the cocaine concentration was so high in the testes, implying that it likely epigenetically alter the progeny. I would like to know what other chemicals or substances have this affect, or if it examined in common drugs. Additionally, this study also supports that of Holly et al. (2012) in that the females showed higher cocaine self-administration levels in comparison to the males in all of the figures shown. Although they differ in that Vassoler et al. sites cycling gonadal hormones as a possible contributing factor in male and female differences, whereas Holly et al. saw effects even in the absence of gonadal hormones, though they were examining dopamine.