Thanks to a protein integral to HIV’s life cycle, cocaine may have a greater effect on people with HIV and make those who have gotten sober more susceptible to relapse, The Scientist reports.

Publishing their findings in Neuropharmacology, researchers gave cocaine to mice whose immune systems had been primed to express Tat, which is a protein that helps in the transcription process of HIV genes, and which is apparently toxic to the brain. The investigators also administered cocaine to mice who lacked the gene to express Tat, as well as to mice who had the Tat gene but who were not primed to express Tat.

While all of the mice became hyperactive as a result of the cocaine, those with Tat expression ran around far longer than the two control groups, implying that the cocaine was having a more dramatic effect. Also, while all of the mice spent more time in the area where the cocaine was administered, those with the Tat protein spent three to five times longer there than the others.

The mice eventually lost their taste for this area. However, re-exposing the mice to cocaine re-established their preference for the site. Re-inducing the Tat protein expression after it had dissipated also re-established a preference for the cocaine administration area, even though the mice had not actually been given cocaine. The researchers believe this finding implies that the Tat found in the brains of people with HIV may make them more likely to relapse.

To read the Scientist article, click here.

To read the study abstract, click here.