Scientists have identified the brain structures responsible for compulsive drug-seeking behaviours due to repeated use of cocaine. The findings, published in Biomedicines, identifies the structures involved and neural pathways activated with repeated exposure to the drug. Researchers hope the study could help inform treatment for drug addiction.
Researchers from the Federal University of São Paulo, Brazil, and the University of Bristol Veterinary School, UK, aimed to identify the brain structures involved in behavioural responses to cocaine. Scientists believe the phenomenon underpins abusers compulsive desire for the drug by causing changes in several areas of the brain's neural pathways which mediate reward and adaptive behaviours.
Using animal models and an innovative state-of-the-art 3D quantitative image analysis, known as stereology, the team were able to identify the specific areas of the brain activated when these were repeatedly exposed to cocaine.
Their results show the brain's dorsomedial prefrontal cortex (dmPFC), the nucleus accumbens core (NAc core) and the basolateral amygdala (BLA) participate in both the developing phase (induction) and the expression phase of behavioural responses to cocaine, while the ventral area of the mesencephalic tegument (VTA) has greater participation in the induction phase only.
The findings indicate repeated use of cocaine leads to associate learning, so an individual associates the euphoric effect promoted by the drug with the environment where it is consumed. As a result, a reinforcing system is established, meaning that two stimuli will be associated with choice or compulsive desire for the drug. The environment, therefore, plays a key role in the activation and expression of behavioural responses to cocaine.
Professor Beatriz Longo from the Federal University of São Paulo, the lead author of this study, Dr Renan Baldaia, the first author of the article, and Dr Augusto Coppi, a world-leader in 3D quantitative image analysis and Lecturer in Veterinary Clinical Anatomy at the University of Bristol, said: "Understanding behavioural changes involved in drug addiction, as well as identifying the brain structures involved in such behaviours in animal models, opens up possibilities for new therapeutic tools and interventions in the management of drug addiction."
The team hope to continue their work in identifying other brain structures involved in behavioural responses to other drugs, such as alcohol, marijuana and nicotine.
The study was funded by CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior), FAPESP (Fundação de Amparo à Pesquisa do Estado de São Paulo) and CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico) in Brazil.
Paper
'Distinctive neuroanatomic regions involved in cocaine-induced behavioral sensitization in mice' by B M Longo et al. in Biomedicines
