Centre for Youth Mental Health - Research Publications
Permanent URI for this collection
Search Results
1 - 2 of 2
-
ItemMGLU5 receptors are necessary for extinction of drug associated cues and contexts(Wiley, 2017-08-01)Drug-associated cues and contexts are strong predictors of relapse. We used complex behavioural preparations to examine whether extinction of such cues reduces their capacity to trigger drug-seeking. We also examined whether the mGlu5 receptor is necessary for extinction learning. In Experiment 1, rats were trained to lever press for cocaine. Once stable responding was established, the context was extinguished by replacing the rats in the chambers, but with no opportunity to respond (levers were retracted). Control group remained in their home cage. An mGlu5 receptor negative allosteric modulator (MTEP) or vehicle was administered immediately after context extinction sessions. During subsequent drug-induced reinstatement, rats responded less if they had received context extinction; however, this effect was attenuated where MTEP had been applied. In Experiment 2, rats were trained to lever press for cocaine, now paired with a cue light. To extinguish the cue, half of the rats were placed in the chambers and given non-reinforced presentations of the cue, but with the levers retracted. Control rats remained in home cage. All rats received either MTEP or vehicle 20 minutes prior. Cue-induced reinstatement was tested the following day by re-pairing the lever with the light. Rats gave fewer drug-seeking responses following cue extinction. This effect was attenuated by MTEP. Experiment 3 followed the same protocol as Experiment 2, except that a positive allosteric modulator CDPPB or vehicle was administered 20 minutes before CS extinction. At reinstatement, cue-elicited cocaine seeking was lower for the animals that had previously been administered CDPPB, regardless of extinction condition. This study highlights the important role cues and contexts play in driving drug-seeking behaviour during reinstatement. It also shows that mGlu 5 signalling is necessary for extinction of drug-cue associations, and that mGlu5 positive allosteric modulators are promising targets for treating cocaine addiction.
-
ItemNo Preview AvailableBrain Aging in Major Depressive Disorder: Results From the ENIGMA MDD Consortium(ELSEVIER SCIENCE INC, 2018-05-01)Background: Major Depressive Disorder has been associated with accelerated biological aging. From a brain perspective, normal aging is associated with significant loss of grey matter and depression may have an accelerating effect on age-related brain atrophy. Here, data on brain aging in MDD from the ENIGMA MDD Working Group will be presented. Methods: A normative model of brain-based age was devel- oped in 4708 healthy controls by applying a Gaussian Process Regression analysis with 10-fold cross-validation to estimate chronological age from structural MRI scans, separately for males and females. This model was then applied to 2924 MDD individuals to predict their brain-based age. Accelerated brain aging was measured as the difference between predicted brain-based age and actual chronological age (brain age gap). Results: The brain age model explained 92% and 93% of the age variance in female and male healthy controls, respectively. The mean absolute error (MAE) was 6.79 years in females and 6.60 in males. Application of the model to MDD patients showed a mean brain age gap of 0.75 years in females (MAE¼6.82) and 0.64 in males (MAE¼6.68), which were significantly lower than brain age gap estimates in healthy controls in both females (F(1,4379)¼6.10,P¼0.01) and males (F(1,3166)¼4.07,P¼0.04). Our preliminary analysis also showed greater brain age gap associations with various clinical characteristics. Conclusions: We found preliminary evidence for accelerated brain aging in MDD, however, the brains of patients were estimated to be only <1 years older than healthy controls. The impact of different methods, feature selection and potential confounding effects will also be discussed.