Currently, the main concern in treating opiate addiction is the possibility of relapse, even after long periods of abstinence. This concern is particularly relevant in the case of addiction to certain drugs, such as cocaine, for which there is no specific medical treatment. 

A study published in the advanced online edition of the journal Neuropsychopharmacology, co-authored by Rafael Maldonado, director of the Neuropharmacology Laboratory at the UPF's Department of Experimental and Health Sciences (CEXS), along with Samantha Mancino, Sami Kummer and Elena Martín-García, all members of his research team, and involving researchers from University College Cork (Ireland), has identified the role of specific components of the endogenous opioid system in cocaine relapse.

The endogenous opioid system is involved in the control of brain reward circuits that play a role in addictive processes. The continued use of cocaine produces alterations in the expression of some of the system's components. The study's authors examined the involvement of endogenous opioid peptides and receptors in the process of cocaine relapse. 

According to Maldonado, 'Our study has demonstrated that endogenous peptides that act on mu and delta opioid receptors play a role in cocaine relapse.' 'However', he added, 'our research also suggests that the opioid peptides derived from the precursor protein prodynorphin seem to play the opposite role of that of the identified peptides.'

A mouse model has been shown to have a high predictive value

The authors used a mouse model of cocaine relapse implemented at the Neuropharmacology Laboratory that has proven to have a high predictive value. Cocaine relapse behaviour was evaluated in different lines of genetically modified mice that lacked components of the endogenous opioid system.

The identification of these new neurobiological mechanisms opens the door to the future development of innovative specific therapeutic strategies to prevent relapse in patients addicted to cocaine. 

This research is part of the doctoral theses of Sami Kummer and Samantha Mancino at the UPF CEXS Neuropharmacology Laboratory, which are being carried under the direction of Professor Maldonado.

Paper reference:

Javier Gutierrez-Cuesta, Aurelijus Burokas, Samantha Mancino, Sami Kummer, Elena Martín-García and Rafael Maldonado. (2014). 'Effects of genetic deletion of endogenous opioid system components on the reinstatement of cocaine-seeking behavior in mice'. Neuropsychopharmacology, 19 June.