Week 9

The Holly paper showed significant differences between male and female rats in cocaine addiction and the correlation to stress. The researchers investigated the susceptibility to cocaine addiction between males and females with  a variation in estrus cycle and amount of stress. They did this via two different tests, the first being a walk duration recording after injection of cocaine, which was taken after a stress paradigm vs. non stressed controls. Non stressed males and females showed significantly less walking duration (less reaction to cocaine) to their stressed counterparts, but the control differences between male and females also showed significant differences. In the estrus cycle, not only did stressed females showed large increases in walking duration, but their non stressed counterparts were similar to that of the diestrus cycle stressed subjects.

Dopamine levels were measured during cocaine administration, and it is here where stress played an important role. Dopamine levels in non stressed females and both control and stressed males increased and then decreased at similar rates. Stressed females however, showed a sustained level of dopamine, which may indicate their increased walking time after injection.

In the self administration portion of the experiment, stress played an important role in the amount of self administered cocaine. While the differences in binge duration and total injections was higher in stressed animals vs  control, there was not a major significant difference between males and females, and ovulation cycle did not play a major role due to the longevity of this given experiment. however, previous data does show that there is a significant difference between the sexes and cocaine addiction susceptibility. females were overall shown to have a higher response to the drug.