Ventral pallidum CaMKIIa neurons modulate affective behavior in wistar rats

The ventral pallidum (VP) is a basal forebrain nucleus composed of GABAergic, cholinergic, and glutamatergic neurons, playing a crucial role in processing both rewarding and aversive stimuli. Here, the pontetial affective role of CaMKIIa-expressing neurons in the VP was investigated by selectively inhibiting them using chemogenetics in Wistar rats. Inhibition of these neurons led to reduced locomotor activity and exploratory behavior in the open field test, elevated plus maze, and social approachavoidance test. The experimental group spent less time in the social interaction zone and exhibited increased anxiety-like behavior, as indicated by reduced open-arm exploration in the elevated plus maze. Depression-like behaviors, assessed by sucrose preference and forced swimming remained unchanged. In the novelty-suppressed feeding test, approach latency to food was similar between groups, while experimental animals took longer to begin eating in their home cage. During auditory fear conditioning, chemogenetic inhibition increased freezing, suggesting a heightened fear response. To characterize the neurochemical profile of CaMKIIa-expressing neurons in the VP, their co-expression with various molecular markers was examined. A small subset of CaMKIIa+ cells coexpressed parvalbumin, with fewer of them expressing calbindin, secretagogin, and choline acetyltransferase, highlighting the limited heterogeneity of this population. These results reveal the specific contributions of CaMKIIa-expressing putative glutamatergic neurons to the specialized role of VP in translating motivation into action.