Socially Engaged Mice Used in Drug ResearchGeneral

Mr Chris Ajonijebu presenting at the Research Symposium.Mr Chris Ajonijebu presenting at the Research Symposium.

A PhD student in the Discipline of Human Physiology in the School of Laboratory Medicine and Medical Sciences, Mr Chris Duyilemi Ajonijebu, presented his research findings at the College of Health Sciences’ Annual College Research Symposium.

His thesis was titled: “Characterising Drug Intake in Socially Engaged Mice”.

The Symposium Committee received 124 submissions for presentation at the two-day event but of this number only 100 were accepted - 70 were oral while the remainder were poster presentations.

Ajonijebu of Nigeria graduated in 2008 with a BTech degree in Physiology at the Ladoke Akintola University of Technology, and later proceeded to the University of Ibadan where he obtained his MSc in the same field.

He worked as an academic at Afe Babalola University between 2013 and 2015 before coming to South Africa to further his academic career.

His PhD project focuses on drug addiction and epigenetics. Characterising Drug Intake in Socially Engaged Mice focused on developing a mouse model of drug addiction within a social environment in a manner which mirrors the actual condition in humans as opposed to previous models that studied rodents or primates in isolation. ‘We used the Intellicage system which is an automated learning apparatus - also known as “social box” - that allowed spontaneous learning and social interaction among group-housed mice,’ said Ajonijebu

As part of the protocol, each mouse was tagged with a transponder (a device with unique identification code) that enabled individual monitoring of the rodents’ behavioural response to drugs of abuse (alcohol and cocaine) within the testing apparatus. The addictive potential of the preferred drug was later tested by imposing resistance scheduled tasks on the animals. In these tasks, each mouse was expected to learn to make correct pokes at doors in the drug corners to get rewarded. Incorrect nose-pokes or visiting wrong corners were not rewarded.

‘This approach demonstrates drug seeking behaviour observed in human addicts where the drive to obtain drugs often requires developing sophisticated goal directed behaviours to overcome various challenges faced in obtaining drugs. Overall, our model examined drug motivation and preference, loss of control over intake behaviours, withdrawal and relapse propensity,’ said Ajonijebu.

‘Interestingly, this is the first animal model of drug addiction that allowed an extended access to cocaine for more than two months in a drug self-administration paradigm while addiction-like behaviours were assessed according to Diagnostic and Statistical Manual of Mental Disorders (DSM-V) criteria for substance use disorders,’ he said.

‘Drug addiction is still a global challenge as we speak, therefore the need to provide solutions to this rising human health problem in Africa constitutes my passion for this research.

Sinenhlanhla Ngubane