Generation and Characterization of a NovelPrkcd-Cre Rat Model

Abstract

Activity of central amygdala (CeA) PKCδ expressing neurons has been linked to appetite regulation, anxiety-like behaviors, pain sensitivity, and addiction-related behaviors. Studies of the role that CeA PKCδ+ neurons play in these behaviors have largely been carried out in mice, and genetic tools that would allow selective manipulation of PKCδ+ cells in rats have been lacking. Here, we used a CRISPR/Cas9 strategy to generate a transgenicPrkcd-cre knock-in rat, and characterized this model using anatomical, electrophysiological and behavioral approaches in both sexes. In the CeA, Cre was selectively expressed in PKCδ+ cells. Anterograde projections of PKCδ+ neurons to cortical regions, subcortical regions, several hypothalamic nuclei, the amygdala complex, and midbrain dopaminergic regions were largely consistent with published mouse data. In a behavioral screen, we found no differences between Cre+rats and Cre-wildtype littermates. Optogenetic stimulation of CeA PKCδ+ neurons in a palatable food intake assay resulted in an increased latency to first feeding and decreased total food intake, once again replicating published mouse findings. Lastly, using a real-time place preference task, we found that stimulation of PKCδ+ neurons promoted aversion, without affecting locomotor activity. Collectively, these findings establish the novelPrkcd-Cre rat line as a valuable tool, that complements available mouse lines for investigating the functional role of PKCδ+ neurons.Significance StatementThe central nucleus of the amygdala (CeA), involved in processing threat and aversion signals, comprises multiple neuronal subtypes. Expression of protein kinase C isoform δ, PKCδ, marks CeA neurons that respond to aversive stimuli, and have also been shown to play a role in alcohol-related behaviors. Genetic tools to investigate the functional role of PKCδ+ neurons in rat models have been lacking. We describe the development and characterization of a novelPrkcdknock-in transgenic rat generated using CRISPR strategy. In this model, we confirm known projection targets of CeA PKCδ+ neurons and replicate functional consequences of their activation previously found in mice. This establishes the line as a novel model to study the role of PKCδ+ neurons in rat models.