Researchers Investigate Positive and Negative Effects of Cocaine
Scientists examined an animal’s desire to seek pleasure, rather than the pleasure itself, which they believe is the key to understanding drug abuse.
Researchers at the Behavioral Pharmacology Laboratory at the University of California, Santa Barbara have examined the motivational systems that induce animals to seek cocaine from both a positive and a negative perspective.
In the March 2014 issue of The Journal of Neuroscience, scientists reported that the neural mechanism responsible for some of the negative effects of cocaine actually contributes to an animal’s motivation to chase after the drug.
Aaron Ettenberg, a professor in UCSB’s Department of Psychological and Brain Sciences, described the approach of the research. “We weren’t looking at pleasure; we were looking at the animal’s desire to seek that pleasure, which we believe is the key to understanding drug abuse,” Ettenberg said. “Just looking at the positive is looking at only half the picture; you have to understand the negative side as well. It’s not just the positive, rewarding effects of cocaine that drive this desire to seek the drug. It’s the net reward, which takes into account the negative consequences in addition to the positive. Together the two determine the net positive output that will lead to the motivated behavior.”
Rather than conduct another dopamine study, Ettenberg’s team focused on norepinephrine (noradrenaline), a neurotransmitter that plays a part in regulating anxiety when cocaine acts upon it. The researchers selectively blocked the neurotransmitter, revealing negative effects in the animals despite a continued desire for cocaine.
The animals were given a single cocaine injection each day. The natural extension of the research is how the positive and negative systems associated with cocaine usage are affected when animals are exposed to multiple doses and ultimately addiction. The belief is that as the animals become addicted, positive consequences get reduced and the negative effects are intensified.
Ettenberg described his long-term goals for the study. “We need to more fully understand the underlying neuronal mechanisms altered by cocaine before we can treat people," he said. "Once we understand how the brain systems producing the positive/euphoric and negative/anxiety effects of the drug interact, we might be able to produce treatments that address the balance between these two opposing actions.”