Drug addiction is a chronic, relapsing conditioning. Approximately 75% of individuals seeking treatment for drug use, regardless of the drug they use (e.g., alcohol, nicotine, heroin, cocaine, methamphetamine), will relapse to drug use within 12 months of treatment.

Contexts and places play an important role in influencing this relapse. There are “Achilles’ heel” situations where relapse is more likely than at other times. Such places could be bars or pubs, stressful situations, or even people previously associated with drug taking. We are using an animal model of drug-seeking to study how the brain controls this relapse.

One part of the brain which we have shown to be important for contextual control over relapse is the hypothalamus. The top image shows a section through the hypothalamus taken during relapse to drug-seeking.

The bottom image shows a high magnification image of the hypothalamus during relapse. The green marker stains for the neuropeptide orexin. Orexin is an important neuropeptide controlling motivated behaviour. The red marker stains for the c-Fos protein. This protein is a transcription factor and its expression indicates that the cell was active during relapse. The cells expressing only this marker are indicated via arrowheads. The yellow marker, which is a product of the co-expression of the red and green marker in the same cell, is only observed in cells which express orexin and c-Fos, showing that these cells were active during relapse. These cells are indicated by the arrows.

This approach to modelling and studying relapse is able to tell us not only about which regions of the brain contribute to relapse but also which specific cells in specific brain regions contribute to this relapse. This knowledge is a prerequisite to developing a more sophisticated understanding of relapse to drug-taking and for the rational design of novel approaches to preventing such relapse.

Research Contact

Asso Prof Gavan McNally

Behavioural Neuroscience Webpage

http://www.psy.unsw.edu.au/research/groups/behavioural.html

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