MOLECULE CAN CURB ADDICTS' CRAVINGS Blocking Agent Not Yet Tested In Humans SASKATOON - A University of Saskatchewan-led team has developed an agent that could universally block a gamut of addictions, from nicotine to alcohol to cocaine. But researchers don't know yet if the synthetic peptide that stemmed addiction to nicotine and marijuana in rats is safe or effective in humans. In research published yesterday in the March edition of Nature Medicine, investigators show a molecule called PTEN interacts with receptors that in turn excite dopamine neurons --the cells responsible for signalling pleasure. A synthetic peptide called Tat-3L4F interrupted that interaction and stopped rats from being addicted to both nicotine and marijuana. Although only tested with nicotine and marijuana, Dr. Xia Zhang, associate professor of psychiatery at the University of Saskatchewan, said the treatment could work for a range of illicit drugs because they all act by exciting dopamine neurons in the ventral tegmental area of the brain. In the study, rats were placed in a white box after receiving injections of addictive drugs, and placed in a black box on alternate days, when they received a placebo, or drugless, injection. Later, researchers placed the rats between the black and white boxes and recorded how much time they spent in each. Rats who were addicted to nicotine or marijuana, but received the special interfering peptide, spent equal time in the black and white boxes, signalling they had kicked their addictions. Rats who didn't get the peptide spent most of their time in the white boxes.