Subpopulations of Calbindin-, Calretinin-, and Parvalbumin-Immunoreactive Interneurons in the Dorsal Horn of the Spinal Cord in Female C57BL/6 Mice

Abstract

Objective. To conduct a comparative analysis of subpopulations of interneurons containing calbindin (CAB), calretinin (CAR), and parvalbumin (PAV) in the dorsal horn of segments T3–T5 of the spinal cord (SC). Materials and methods. Immunoreactive (IR) interneurons were studied in female C57BL/6 mice aged 16 weeks using immunohistochemical methods. Results. All IR-interneuron subpopulations were topographically detected in all laminae of the dorsal horn of the SC, though PAV-IR interneurons were not detected in lamina I. The content of CAB interneurons dominated in laminae I (27%) and II (29%), CAR interneurons in lamina II (21.5%), and PAV interneurons in laminae IV (5.7%) and V (6.2%). In addition, the PAV interneuron subpopulation consisted of a smaller group of cells than those of the other calcium-binding proteins in laminae II and III and the medial border (MB) of the dorsal horn, while CAR interneurons were a smaller group in laminae III, IV, and V and the MB. Quantitatively, calbindin-containing interneuron subpopulations dominated in all laminae of the dorsal horn of the SC. Cell sizes in these subpopulations of IR interneurons were statistically significantly different – CAB- and CAR-containing interneurons being larger and PAV-containing cells being smaller. Conclusions. Different subpopulations of interneurons immunoreactive to calbindin, calretinin, and parvalbumin were found in the dorsal horn of the SC and were specific to each lamina.