Dopamine Transmission through D1 versus D2 Receptors Controls the Encoding of Opiate Reward Memory as a Function of Opiate Exposure State
Date of Award
Master of Science
Anatomy and Cell Biology
Dr. Steven R. Laviolette
Considerable evidence has demonstrated the importance of basolateral amygdala (BLA) in associative learning and memory processing. Furthermore, recent evidence at the behavioural and molecular levels, implicates an important role for the BLA in the processing of drug-related learning and memory events. Through anatomical connections with the mesolimbic dopamine (DA) system, neuronal activity and plasticity within the BLA are altered through DA receptor transmission originating in the ventral tegmental area (VTA). However, the specific function of DA receptors within the BLA during associative opiate reward learning is not clear. We used a place preference conditioning paradigm and pharmacological manipulations of DA D1 and D2 receptors to examine the role of DA Dl-like versus D2-like receptors within the BLA, as well as the downstream secondary messenger cAMP during associative opiate reward memory encoding in both opiate-naive and opiate-dependent rats. We report that blockade of DA D1 receptors within the BLA disrupts the acquisition of associative reward memory in opiate-naive state, whereas DA D2 receptor blockade does so in the opiate-dependent state. Furthermore, DA D1 receptor activation potentiates the rewarding effects of morphine in the opiate-naive state, while DA D2 receptors activation exerts the same action in the opiate-dependent state. Finally, pharmacological manipulation of cAMP levels in the BLA is not only able to mimic the behavioural effects of DA receptor blockade or activation, but also reverses the effect of both DA receptor agonists and antagonists, regardless of opiate exposure state. These results indicate that depending on the opiate exposure state, DA D1 versus D2 receptors within the BLA play differential roles in modulating the encoding of associative opiate reward memory through a cAMP dependent mechanism.
Chi, Ning, "Dopamine Transmission through D1 versus D2 Receptors Controls the Encoding of Opiate Reward Memory as a Function of Opiate Exposure State" (2011). Digitized Theses. 3377.