Cortical dopamine D5 receptors regulate neuronal circuit oscillatory activity and memory in rats

Introduction: The dopamine D5 receptor (D5R) shows high expression in cortical regions, yet the role of the receptor in learning and memory remains poorly understood. This study evaluated the impact of prefrontal cortical (PFC) D5R knockdown in rats on learning and memory and assessed the role of the D5R in the regulation of neuronal oscillatory activity and glycogen synthase kinase-3 (GSK-3 beta), processes integral to cognitive function. Materials and Methods: Using an adeno-associated viral (AAV) vector, male rats were infused with shRNA to the D5R bilaterally into the PFC. Local field potential recordings were taken from freely moving animals and spectral power and coherence were evaluated in, and between, the PFC, orbitofrontal cortex (OFC), hippocampus (HIP), and thalamus. Animals were then assessed in object recognition, object location, and object in place tasks. The activity of PFC GSK-3 beta, a downstream effector of the D5R, was evaluated. Results: AAV-mediated knockdown of the D5R in the PFC induced learning and memory deficits. These changes were accompanied by elevations in PFC, OFC, and HIP theta spectral power and PFC-OFC coherence, reduced PFC-thalamus gamma coherence, and increased PFC GSK-3 beta activity. Conclusion: This work demonstrates a role for PFC D5Rs in the regulation of neuronal oscillatory activity and learning and memory. As elevated GSK-3 beta activity has been implicated in numerous disorders of cognitive dysfunction, this work also highlights the potential of the D5R as a novel therapeutic target via suppression of GSK-3 beta.

Automated summary

This study evaluated the impact of prefrontal cortical dopamine D5 receptor (D5R) knockdown on learning and memory in rats, and also assessed the role of D5R in the regulation of neuronal oscillatory activity and glycogen synthase kinase-3 beta (GSK-3 beta). The results showed that knockdown of D5R led to deficits in learning and memory, accompanied by increased theta oscillations in the prefrontal cortex, orbitofrontal cortex, and hippocampus, increased coherence between prefrontal cortex and orbitofrontal cortex, and decreased coherence between prefrontal cortex and thalamus.