Calcium/calmodulin-dependent protein kinase II in dorsal horn neurons in long-term diabetes

Abstract

The aim of this study was to investigate the expression of total calcium/calmodulin-dependent protein kinase II (CaMKII) and its phosphorylated α isoform in the dorsal horn of the spinal cord in an animal model of long-term diabetes. Diabetes was induced in Sprague–Dawley rats using 55 mg/kg streptozotocin, and expression of total CaMKII, the phosphorylated α-CaMKII isoform, and isolectin B4 was analyzed by immunohistochemical analysis in the dorsal horn of the spinal cord 6 and 12 months after diabetes induction. Results were compared with those for control rats of the same age. Increased expression of total CaMKII and its activated α isoform was seen in the dorsal horn of diabetic rats 6 months after diabetes induction. The increase in CaMKII fluorescence was restored to control values after 12 months. The expression of activated α-CaMKII 12 months after diabetes induction was most pronounced in laminae I–VI of the dorsal horn, not corresponding with the highest expression of isolectin B4 in laminae I–III. Increased expression of CaMKII in the dorsal horn during long-term diabetes could be involved in the development of neuropathic symptoms in diabetes. The expression pattern of CaMKII during long-term diabetes indicates that it affects the entire sensory input.