On November 6th 2014, I had the pleasure of listening to a lecture by Andrew Haack from the University of Utah on dopaminergic pathways in ethanol-seeking behaviour in rats. While his lecture was quite intriguing, it left me looking for more information in regards to these pathways being modulated, and what other factors have influences in these reward pathways. Additionally, I wanted to learn how the described alcohol-seeking behavioural pathway differers under the influence on other drugs.

I stumbled upon this interesting article which discussed the influence cocaine has on alcohol-seeking behaviour in rats. The researchers were interested in seeing how exposure of a drug during recovery of addiction to another drug could actually increase the addiction to both drugs.

To initiate this specific experiment, the researchers began by initiating ethanol into the rats everyday lives. In a similar manner to that described by Haack in Thursday’s lecture. This method involved slowly inducing ethanol to the rats via lever-pressing behaviours. After ‘addiction’ has occurred, the rats willingly lever-press to receive ethanol. “alcohol-seeking was assessed through the use of the Pavlovian Spontaneous Recovery (PSR) model, while alcohol-relapse drinking was assessed through the use of the alcohol-deprivation effect”. The PSR condition involved depriving the rats of their ethanol levers for the 60-minute session. For the relapse condition, rats were deprived of their ethanol levers for 7 days, before being returned to a cage with ethanol levers for their testing.

Cocaine HCl (0, 1, or 10mg/kg) was injected either immediately, 30 minutes or 4 hours before their testing sessions. In the PSR condition, researchers found that the dose of Cocaine HCl increased the rats responding to the ethanol lever compared to those with saline controls.

With the relapse condition, Cocaine HCl (1 or 10mg/kg) was injected. In the conditions where rats were given cocaine HCl immediately before being returned to their cage with an ethanol lever, there was no effect on their responding. However, in the condition where they were given Cocaine HCl injections 4 hours prior to their relapse testing, their ethanol responding was severely enhanced in comparison to the saline controls.

What we can determine from this study is that Cocaine HCl can have an effect on the ethanol-seeking and relapse behaviours. The effect of Cocaine HCl on the ethanol-relapse drinking could be indicative of a more complex interaction occuring between abuse of multiple drugs, but ultimately leading to priming of relapse with a four-hour delay.

If we are able to generalize some of these animal research studies to humans, it seems that humans with severe drug abuse issues may be prone to relapse, and these neuronal connections can be targeted in therapies to help aid relapse.

Works Cited:

Hauser, Sheketha R., et al. “Cocaine Influences Alcohol-Seeking Behavior and Relapse Drinking in Alcohol-Preferring (p) Rats.” Alcoholism, Clinical and Experimental Research 38.10 (2014): 2678-86.