Short communicationCalcium-binding protein, secretagogin, characterizes novel groups of interneurons in the rat striatum

•SCGN+ interneurons show vast species differences between rats and mice.•Rat striatum contains numerous SCGN+ neurons of various structural features.•Rat striatal SCGN+ neurons overlap with PV or CR or ChAT+ interneurons.•A population of SCGN+ neurons contain none of these interneuron markers.•There are some novel groups of interneurons in the rat striatum.

In the rat striatum numerous secretagogin (SCGN) positive neurons were scattered. They were heterogeneous in their morphological and chemical properties. We examined the colocalization of SCGN with known four interneuron markers, parvalbumin (PV), calretinin (CR), nitric oxide synthase (NOS) and choline acetyl transferase (ChAT). 60-70% of SCGN positive striatal neurons contained either PV or CR or ChAT, but none contained NOS. On the other hand the remaining 30-40% expressed none of these markers, most of which were GAD positive. The present study indicates that there are hitherto unknown groups of striatal interneurons in the rat striatum.