Distribution of D1 and D2-dopamine receptors in calcium-binding-protein expressing interneurons in rat anterior...

Dopamine plays an important role in cognitive functions including decision making, attention, learning and memory in the anterior cingulate cortex (ACC). However, little is known about dopamine receptors (DAR) expression patterns in ACC neurons, especially GABAergic interneurons. The aim of the present study was to investigate the expression of the most abundant DAR subtypes, D1 receptors (D1Rs) and D2 receptors (D2Rs), in major types of GABAergic interneurons in rat ACC, including parvalbumin (PV)-, calretinin (CR)-, and calbindin D-28k (CB)-containing interneurons. Double immunofluorescence staining and confocal scanning were used to detect protein expression in rat brain sections. The results showed a high proportion of PV-containing interneurons express D1Rs and D2Rs, while a low proportion of CR-positive interneurons express D1Rs and D2Rs. D1R- and D2R-expressing PV interneurons are more prevalently distributed in deep layers than superficial layers of ACC. Moreover, we found the proportion of D2Rs expressed in CR cells is much greater than that of D1Rs. These regional and interneuron type-specific differences of D1Rs and D2Rs indicate functionally distinct roles for dopamine in modulating ACC activities via stimulating D1Rs and D2Rs.